kth.sePublications
Change search
Refine search result
123 1 - 50 of 134
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-mechanical solar receiver design and validation for a micro gas-turbine based solar dish system2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 196, article id 116929Article in journal (Refereed)
    Abstract [en]

    This work presents the comprehensive development of a solar receiver for the integration into a micro gas-turbine solar dish system. Special focus is placed on the thermo-mechanical design to ensure the structural integrity of all receiver components for a wide range of operating conditions. For the development, a 3-dimensional coupled multi-physics model is established and is validated using experimental data. Contrary to previous studies, the temperature of the irradiated front surface of the absorber is included in the comprehensive validation process which results in a high level of confidence in the receiver design.

    Finally, a full-scale solar receiver for the integration into the OMSoP solar dish system is designed and its performance determined for a wide operating range to define its safe operating envelope using the validated model. It is shown that the receiver is capable of operating at 803_C with an efficiency of 82.1% and a pressure drop of 0.3% at the nominal operating point, while at the same time functioning effectively   for a wide range of off-design conditions without compromising its structural integrity. At the nominal operating point, the maximum comparison stress of the porous absorber is 5.6 MPa compared to a permissible limit of 7.4 MPa.

    Download full text (pdf)
    fulltext
  • 2.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    Abstract [en]

    This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

  • 3.
    Alirahmi, Seyed Mojtaba
    et al.
    Aalborg Univ, Dept Chem & Biosci, Niels Bohrs Vej, DK-6700 Esbjerg, Denmark..
    Behzadi, Amirmohammad
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Ahmadi, Pouria
    Univ Tehran, Coll Engn, Sch Mech Engn, Tehran, Iran..
    Sadrizadeh, Sasan
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings. Mälardalen Univ, Sch Business Soc & Engn, Västerås, Sweden..
    An innovative four-objective dragonfly-inspired optimization algorithm for an efficient, green, and cost-effective waste heat recovery from SOFC2023In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 263, article id 125607Article in journal (Refereed)
    Abstract [en]

    This work proposes a novel yet practical dragonfly optimization algorithm that addresses four competing ob-jectives simultaneously. The proposed algorithm is applied to a hybrid system driven by the solid oxide fuel cell (SOFC) integrated with waste heat recovery units. A function-fitting neural network is developed to combine the thermodynamic model of the system with the dragonfly algorithm to mitigate the calculation time. According to the optimization outcomes, the optimum parameters create significantly more power and have a greater exergy efficiency and reduced product costs and CO2 emissions compared to the design condition. The sensitivity analysis reveals that while the turbine inlet temperatures of power cycles are ineffective, the fuel utilization factor and the current density significantly impact performance indicators. The scatter distribution indicates that the fuel cell temperature and steam-to-carbon ratio should be kept at their lowest bound. The Sankey graph shows that the fuel cell and afterburner are the main sources of irreversibility. According to the chord diagram, the SOFC unit with a cost rate of 13.2 $/h accounts for more than 29% of the overall cost. Finally, under ideal conditions, the flue gas condensation process produces an additional 94.22 kW of power and 760,056 L/day of drinkable water.

  • 4.
    Anglart, Henryk
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.
    Li, Haipeng
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.
    Niewinski, Grzegorz
    Warsaw Univ Technol, Inst Heat Engn, Nowowiejska 21-25, PL-00665 Warsaw, Poland..
    Mechanistic modelling of dryout and post-dryout heat transfer2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 161, p. 352-360Article in journal (Refereed)
    Abstract [en]

    In this paper a new mechanistic model for the diabatic annular two-phase flow is presented and applied to prediction of dryout and post-dryout heat transfer in various channels. The model employs a computational fluid dynamics code - OpenFOAM (R) - to solve the governing equations of two-phase mixture flowing in a heated channel. Additional closure laws have been implemented to calculate the location of the dryout and to predict wall temperature in the post-dryout region. Calculated results have been compared with experimental data obtained in pipes and good agreement between predictions and measurements has been achieved. The presented model is applicable to complex geometries and thus can be used for prediction of post-dryout heat transfer in a wide variety of energy conversion systems.

  • 5. Anjo, J.
    et al.
    Neves, D.
    Silva, C.
    Shivakumar, Abhishek
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Howells, Mark I.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Modeling the long-term impact of demand response in energy planning: The Portuguese electric system case study2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 165, p. 456-468Article in journal (Refereed)
    Abstract [en]

    With the urge to decrease carbon emissions, electricity systems need to evolve to promote the integration of renewable resources and end-use energy efficiency. Demand Response (DR) can be used as a strategy, one among many, to improve the balance between demand and supply of electricity, especially in systems that rely heavily on variable energy renewable resources. Thus, it is important to understand up to what extent a countrywide system would cope with DR implementation. In this work, the impact of demand response in the long-term is assessed, using a model of the Portuguese electricity system in the modeling tool OSeMOSYS. The theoretical potential of DR is computed to understand better the impact on the overall system planning, by analyzing three scenarios – a business as usual scenario, a carbon-free system scenario in 2050, and a scenario without heavy carbon emission restrictions. DR impact in all three scenarios results in a decrease in the overall costs, on the capacity installed and in an increase in the percentage of renewable capacity. Further, an economic analysis showed that DR would take 15 years, on average, to influence the average electricity cost and that the reduction in total costs is mainly due to the avoided capacity investments. 

  • 6.
    Arnaudo, Monica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Dalgren, Johan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Waste heat recovery in low temperature networks versus domesticheat pumps - A techno-economic and environmental analysis2021In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 219, article id 119675Article in journal (Refereed)
    Abstract [en]

    The planning of energy infrastructures in new districts often follows the practice adopted for the rest of the city. In Stockholm, district heating is a common solution for multi-apartment neighborhoods. Recently, because of an average clean electricity mix, heat pumps have gained interest. However, European studies suggest to limit the reliance on electrification to avoid an extreme demand increase. Thus, an effort is required to improve the environmental impact of alternative options. This study proposes waste heat recovery in low temperature networks as a promising solution. By means of a techno-economic and environmental analysis, this option is compared to domestic heat pumps. A new approach is proposed to combine a district level perspective with simulation tools able to capture sector-coupling interactions. Scenarios, for a real neighborhood, assess waste heat recovery potential and electricity grid loading status. Results show that a waste heat recovery capacity equal to 10% of the peak load can reduce fossil fuel use of 40%. Local grid limitations are shown to be a bottleneck for the feasibility of domestic heat pumps. Their heat generation cost is 28% higher than for district heating. The carbon footprint is strongly dependent on the emission factor of the electricity mix (+11%/-24%).

  • 7.
    Arnaudo, Monica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic analysis of demand side flexibility to enable the integration of distributed heat pumps within a Swedish neighborhood2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 195, article id 117012Article in journal (Refereed)
    Abstract [en]

    The energy infrastructure in Stockholm faces an imminent problem caused by the saturation of the electricity distribution grid capacity. Given promising economic savings, a few city neighborhoods have decided to switch from district heating to domestic heat pumps. Thus, technical concerns arise. This study aims at proposing demand side management solutions to unlock the integration of distributed heat pumps. A techno-economic analysis is presented to assess the potential of using the buildings’ thermal mass as energy storage. By means of co-simulation, the electricity grid and the buildings are coupled through a feedback control. The grid capacity is monitored to avoid overloadings. The indoor temperature is controlled in order to serve as thermal energy storage. It is found that, given the grid's capacity limits, the infrastructure should still be partly connected to the district heating (around 7% of the heat demand). This dependency decreases of around 1% when the buildings’ thermal mass is used as thermal storage, with a range of ±0.5 °C. On a heat pump level, the disconnections decrease up to 50%, depending on the buildings’ thermal mass capacity. Thus better techno-economic (about −2% on the levelized cost) and environmental (about −1% on the CO2 emissions) performances are unlocked.

  • 8.
    Arnaudo, Monica
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Puerto, P.
    CREM Centre de Recherches Énergétiques et Municipales, Martigny, Switzerland. HES-SO Haute École Spécialisée de Suisse Occidentale, Sion, Switzerland.
    Widl, E.
    AIT Austrian Institute of Technology, Center for Energy, Vienna, Austria.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Heat demand peak shaving in urban integrated energy systems by demand side management - A techno-economic and environmental approach2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 186, article id 115887Article in journal (Refereed)
    Abstract [en]

    The integration of variable renewable resources and decentralized energy technologies generates the need for a larger flexibility of the energy demand. In order to fully deploy a demand side management approach, synergies between interconnected energy systems have to be systematically implemented. By taking this standpoint, this study proposes a new approach to explore the potential of multi-energy integrated energy systems. This approach is constituted by two main steps, which are (1) the performance simulation of selected energy infrastructures and (2) the estimation of related techno-economic performance indicators. Step (1) expands the work presented in previous literature, by including a novel co-simulation feature. In step (2), the levelized cost of energy and location-dependent emission factors are used as key performance indicators. In this paper, the presented approach is demonstrated by implementing two demand side management options for heat peak demand shaving. A Swedish residential neighborhood is considered as a case study. The first option explores the potential of storing heat in the thermal mass of residential buildings. The proposed strategies lead to a decrease of up to 70% of primary energy consumption, depending on the indoor comfort requirements. The second option estimates the techno-economic feasibility of a new set of scenarios based on the integration of geothermal distributed heat pumps within a district heating network. The district heating scenario is found to be the most techno-economical convenient. Nevertheless, a moderate penetration of distributed heat pumps (around 20%) is shown to have a good trade-off with the reduction of CO2 emissions.

  • 9.
    Ayele, Getnet Tadesse
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Mabrouk, Mohamed Tahar
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Haurant, Pierrick
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. KTH Royal Inst Technol, Dept Energy Technol, S-10044 Stockholm, Sweden..
    Lacarrière, Bruno
    CNRS, UMR 6144, GEPEA, IMT Atlantique, F-44307 Nantes, France..
    Optimal placement and sizing of heat pumps and heat only boilers in a coupled electricity and heating networks2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 182, p. 122-134Article in journal (Refereed)
    Abstract [en]

    Multi-energy systems are reported to have a better environmental and economic performance relative to the conventional, single-carrier, energy systems. Electrification of district heating networks using heat pumps and combined heat and power technologies is one such example. Due to lack of suitable modelling tools, however, the sizing and optimal placement of heat pumps is always done only from the heating network point of view which sometimes compromises the electricity network. This paper proposes an integrated optimization algorithm to overcome such limitation. A load flow model based on an extended energy hub approach is combined with a nested particle swarm optimization algorithm. A waste to energy combined heat and power plant, heat pumps (HPs), heat only boiler (HOB), solar photovoltaic, wind turbines and imports from the neighborhood grids are considered in the case studies. The results show that optimal placement and sizing of HPs and a HOB using the proposed methodology avoids an unacceptable voltage profiles and overloading of the electricity distribution network, which could arise while optimizing only from the heating network point of view. It also shows that up to 41.2% of the electric loss and 5% of the overall operating cost could be saved.

  • 10.
    Balderrama, Sergio
    et al.
    Univ Liege, Integrated & Sustainable Energy Syst, Liege, Belgium.;San Simon Univ, Ctr Univ Invest Energia, Cochabamba, Bolivia..
    Lombardi, Francesco
    Politecn Milan, Dept Energy, Milan, Italy.;Delft Univ Technol, Dept Engn Syst & Serv, Delft, Netherlands..
    Stevanato, Nicolo
    Politecn Milan, Dept Energy, Milan, Italy.;FEEM Fdn Eni Enrico Mattei, Milan, Italy..
    Pena Balderrama, J. Gabriela
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Colombo, Emanuela
    Politecn Milan, Dept Energy, Milan, Italy..
    Quoilin, Sylvain
    Univ Liege, Integrated & Sustainable Energy Syst, Liege, Belgium..
    Surrogate models for rural energy planning: Application to Bolivian lowlands isolated communities2021In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 232, article id 121108Article in journal (Refereed)
    Abstract [en]

    Thanks to their modularity and their capacity to adapt to different contexts, hybrid microgrids are a promising solution to decrease greenhouse gas emissions worldwide. To properly assess their impact in different settings at country or cross-country level, microgrids must be designed for each particular situation, which leads to computationally intractable problems. To tackle this issue, a methodology is proposed to create surrogate models using machine learning techniques and a database of microgrids. The selected regression model is based on Gaussian Processes and allows to drastically decrease the computation time relative to the optimal deployment of the technology. The results indicate that the proposed methodology can accurately predict key optimization variables for the design of the microgrid system. The regression models are especially well suited to estimate the net present cost and the levelized cost of electricity (R-2 = 0.99 and 0.98). Their accuracy is lower when predicting internal system variables such as installed capacities of PV and batteries (R-2 = 0.92 and 0.86). A least-cost path towards 100% electrification coverage for the Bolivian lowlands mid-size communities is finally computed, demonstrating the usability and computational efficiency of the proposed framework.

  • 11. Bauer, N.
    et al.
    Hilaire, J.
    Brecha, R. J.
    Edmonds, J.
    Jiang, K.
    Kriegler, E.
    Rogner, Hans-Holger
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis. Int Inst Appl Syst Anal IIASA, Austria.
    Sferra, F.
    Assessing global fossil fuel availability in a scenario framework2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 111, p. 580-592Article in journal (Refereed)
    Abstract [en]

    This study assesses global, long-term economic availability of coal, oil and gas within the Shared Socio-economic Pathway (SSP) scenario framework considering alternative assumptions as to highly uncertain future developments of technology, policy and the economy. Diverse sets of trajectories are formulated varying the challenges to mitigation and adaptation of climate change. The potential CO2 emissions from fossil fuels make it a crucial element subject to deep uncertainties. The analysis is based on a well-established dataset of cost-quantity combinations that assumes favorable techno-economic developments, but ignores additional constraints on the extraction sector. This study significantly extends the analysis by specifying alternative assumptions for the fossil fuel sector consistent with the SSP scenario families and applying these filters (mark-ups and scaling factors) to the original dataset, thus resulting in alternative cumulative fossil fuel availability curves. In a Middle-of-the-Road scenario, low cost fossil fuels embody carbon consistent with a RCP6.0 emission profile, if all the CO2 were emitted freely during the 21st century. In scenarios with high challenges to mitigation, the assumed embodied carbon in low-cost fossil fuels can trigger a RCP8.5 scenario; low mitigation challenges scenarios are still consistent with a RCP4.5 scenario.

  • 12.
    Behi, Mohammadreza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Univ Sydney, Sch Chem & Biomol Engn, Sydney, NSW 2006, Australia..
    Mirmohammadi, Seyed Aliakbar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Univ Sydney, Sch Civil Engn, Sydney, NSW 2006, Australia..
    Ghanbarpour, Morteza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Behi, Hamidreza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Evaluation of a novel solar driven sorption cooling/heating system integrated with PCM storage compartment2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 164, p. 449-464Article in journal (Refereed)
    Abstract [en]

    Recently the interest in solar thermal cooling has been growing for Air Conditioning (AC) applications. This paper presents an applied experimental and numerical evaluation of a novel triple-state sorption solar cooling module. The performance of a LiCl-H2O based sorption module (SM) for cooling/heating system with integration of an external energy storage has been evaluated. The dynamic behavior of the SM, which can be driven by solar energy, is presented. Two PCM assisted configurations of the SM have been studied herein; (i) PCM assisted sorption module for cooling applications (ii) PCM assisted sorption module for heating applications. Initially, an experimental investigation was carried out to evaluate the charging/discharging process of the SM without external energy storage. Secondly, the initial experimental configuration was modeled with a PCM integrated storage compartment. The PCM storage compartment was connected to the Condenser/Evaporator (C/E) of the SM. The temporal history of the sorption module's C/E and PCM storage, the cyclic and average performance in terms of cooling/heating capacity, cooling/heating COP, and the total efficiency were experimentally and numerically investigated. Furthermore, PCM charging/discharging power rate and solidification/melting process of the PCM in the integrated storage compartment to the SM were predicted by the model.

  • 13.
    Behi, Mohammadreza
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Shakorian-poor, M.
    Mirmohammadi, Seyed Aliakbar
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Behi, H.
    Rubio, J. I.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Nikkam, N.
    Farzaneh-Gord, M.
    Gan, Y.
    Behnia, M.
    Experimental and numerical investigation on hydrothermal performance of nanofluids in micro-tubes2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 193, article id 116658Article in journal (Refereed)
    Abstract [en]

    Nanoscale solid particles suspended in a base liquid are a new class of nano-engineered colloidal suspension, defined with a coined name of nanofluids (NFs). The effect of dispersing nanoparticles (NPs) on the hydraulic and thermal (hydrothermal) performance of the conventional coolants is a matter of importance in many applications. This work experimentally and numerically presents the effect of different parameters, including the concentration and size of the NPs, on two primary parameters, namely heat transfer coefficient and friction factor in a microtube. The numerical modeling of colloidal suspensions was conducted based on single-phase as well as Eulerian-Mixture two-phase approaches and showed a good agreement with experimental results. The numerical results displayed that the suspended NPs remarkably increased the convective heat transfer coefficient as well as friction factor by as much as 42% and 22% (in NP concentration range of 1%–9%, and NP size range of 13–130 nm and Reynolds number of 400) respectively. Besides, two new correlations were developed based on the results obtained from experimentally validated models to predict the hydrothermal response of NFs in the laminar regime. Moreover, correlations were successfully created to predict the Nusselt number and friction factor of nanofluids, with ±8% and ±5% agreement between numerical data and predictions, respectively.

  • 14.
    Bian, Xiaolei
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Liu, Longcheng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Yan, Jinying
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    A model for state-of-health estimation of lithium ion batteries based on charging profiles2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 177, p. 57-65Article in journal (Refereed)
    Abstract [en]

    Using an equivalent circuit model to characterize the constant-current part of a charging/discharging profile, a model is developed to estimate the state-of-health of lithium ion batteries. The model is an incremental capacity analysis-based model, which applies a capacity model to define the dependence of the state of charge on the open circuit voltage as the battery ages. It can be learning-free, with the parameters subject to certain constraints, and is able to give efficient and reliable estimates of the state-of-health for various lithium ion batteries at any aging status. When applied to a fresh LiFePO 4 cell, the state-of-health estimated by this model (learning-unrequired or learning-required)shows a close correspondence to the available measured data, with an absolute difference of 0.31% or 0.12% at most, even for significant temperature fluctuation. In addition, NASA battery datasets are employed to demonstrate the versatility and applicability of the model to different chemistries and cell designs.

  • 15.
    Bundschuh, Jochen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. University of Southern Queensland, Australia.
    Yusaf, Talal
    Maity, Jyoti Prakash
    Nelson, Emily
    Mamat, Rizalman
    Mahlia, T. M. Indra
    Algae-biomass for fuel, electricity and agriculture2014In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 78, p. 1-3Article in journal (Refereed)
  • 16.
    Chiu, Justin N. W.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Castro Flores, José Fiacro
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Lacarrière, B.
    Industrial surplus heat transportation for use in district heating2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 110, p. 139-147Article in journal (Refereed)
    Abstract [en]

    M-TES (Mobile Thermal Energy Storage) technology is explored in this paper for transportation of industrial surplus heat for use in LTDH (low temperature district heating network). LTDH has promising potential in utilizing low grade heat, on the other hand, 20%–50% of industry generated surplus heat is often released to the ambient environment. M-TES is used to match thermal energy supply and demand that occur at different locations and that are shifted in time. In this paper, design of M-TES is conducted, optimization in operating strategies is performed, sensitivity analysis on levelized cost is studied, and environmental impact of CO2 emissions due to transportation is evaluated. The results of the study show an array of transportation means and storage operating strategies under which M-TES is technically, economically and environmentally sound for transportation of industrial surplus heat for use in LTDH network.

  • 17.
    Choque Campero, Luis Antonio
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Facultad de Ciencias y Tecnologia (FCyT), Universidad Mayor de San Simon (UMSS), Cochabamba, Bolivia.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Cardozo, Evelyn
    Facultad de Ciencias y Tecnologia (FCyT), Universidad Mayor de San Simon (UMSS), Cochabamba, Bolivia.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Biomass-based Brayton-Stirling-AGMD polygeneration for small-scale applications in rural areas2024In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 304, article id 132033Article in journal (Refereed)
    Abstract [en]

    The lack of access to electricity and clean water still affects a substantial proportion of rural areas worldwide, in particular the global south. This paper presents a sustainable polygeneration system that can provide electricity, heat, and drinking water by using agricultural residues in remote rural areas. This polygeneration system consists of a solid biomass-fueled Brayton-Stirling combined cycle system, a boiler, and an air-gap membrane distillation unit. Four different system operation modes were designed to examine the most ideal configurations for maximizing power output, overall efficiency, and/or clean water production, considering a polygeneration system designed for a rural village with daily demands of 13450 kWh electricity and 7.5 m3 drinking water. A thermodynamic analysis are employed to analyze and compare these modes, each operating under steady state conditions. The highest electricity output, up to 160 kW, while the highest clean water is up to 0.7 m3/h. The fuel consumption can reach 0.9 kWh/kg of solid fuel and provide up to 0.0045 m3 of freshwater. In addition, nonlinear multi-objective optimization is used to meet the power demands of typical day in rural areas by varying the polygeneration operation modes and turbine inlet temperature.

  • 18.
    Curiel, Jose Adrian Rama
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thakur, Jagruti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems. KTH, Dept Energy Technol, Stockholm, Sweden..
    A novel approach for Direct Load Control of residential air conditioners for Demand Side Management in developing regions2022In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 258, p. 124763-, article id 124763Article in journal (Refereed)
    Abstract [en]

    The rapid growth of air conditioners (ACs) in developing regions exacerbates some of the issues present in their electricity systems. Direct Load Control strategies can manage peak loads for optimizing energy usage for users and utilities. When applied to air conditioning, these strategies can be used for Demand Side Management which has not been fully explored for developing regions. In this paper a novel Direct Load Control mechanism is proposed, wherein control is based on technical constraints (generation capacity). To determine the effects of the proposed mechanism, a case study of the Indian State of Karnataka is carried out. The results indicate 0.88% energy savings and a reduction of almost 2% in regional peak loads in a state where only around 5% of all households have AC units. The case study shows that an AC Direct Load Control can have significant economic and environmental impacts, and can help improve current energy, water and climate issues. Continuous improvements in both energy access and economic conditions of developing regions are leading to a larger number of AC???s installed, meaning that a mechanism that enables sustainable AC consumption could be of great use for all the stakeholders in the developing countries??? electricity sectors.

  • 19.
    Dabar, Omar Assowe
    et al.
    CERD, Inst Sci Terre, Route Aeroport,BP 486, Ville, Djibouti..
    Awaleh, Mohamed Osman
    CERD, Inst Sci Terre, Route Aeroport,BP 486, Ville, Djibouti..
    Kirk-Davidoff, Daniel
    Univ Maryland, Dept Atmospher & Ocean Sci, College Pk, MD 20742 USA..
    Olauson, Jon
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Awaleh, Said Ismael
    CERD, Inst Sci Terre, Route Aeroport,BP 486, Ville, Djibouti..
    Wind resource assessment and economic analysis for electricity generation in three locations of the Republic of Djibouti2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 185, p. 884-894Article in journal (Refereed)
    Abstract [en]

    In the Republic of Djibouti, due to increasing electricity demands, the government has planned to increase power supply by using renewable resources such as geothermal, solar and wind energy. This work presents the first wind resource assessment in the Republic of Djibouti using measured wind speed data for the period of three years by meteorological stations at eight locations. The results confirmed that three of the eight locations (i.e. GaliMa-aba, Ghoubbet and Bada Wein) have the best resource, with mean annual wind speeds of more than 6.0 m/s. Wind simulations using NCEP-CFSR and ERA5 models reanalysis shows that the seasonal variations are stable between different years and are broadly consistent with the observed wind speed. The feasibility of three wind farms with total capacity of 275 MW at GaliMa-aba, Ghoubbet and Bada Wein is examined. Using the WindPRO program and two commercial wind turbines in according to IEC 61400-1 design criteria, the electricity generation were technically assessed. These wind farms can produce 1073 GWh of electricity per year, approximately equal to Djibouti's expected average annual electrical demand in 2030. The economic evaluation using the present value cost (PVC) method estimate that the generation cost per kWh at these locations varies from 7.03 US.$ cent/kWh to 9.67 US.$ cent/kWh. Elsevier Ltd. All rights reserved.

  • 20. Dhakouani, A.
    et al.
    Gardumi, Francesco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Znouda, E.
    Bouden, C.
    Howells, Mark I.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Long-term optimisation model of the Tunisian power system2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 141, p. 550-562Article in journal (Refereed)
    Abstract [en]

    The electricity mix in Tunisia mainly relied on conventional energy sources for over 50 years. Recently, due to fossil fuel prices oscillations and national reserves shortage, the need arose for restructuring the energy supply system. Targeting the integration of renewable energies could be a plan for satisfying the increasing demand and the supply independence. However, several macroeconomic conditions and policies present barriers for the integration of Renewable Energy Sources (RES), despite their abundance, availability and environmental benefits. This paper presents a long-term model of Tunisia electricity system, based on OSeMOSYS (Open Source energy MOdelling SYStem), aimed at unveiling potential benefits of increasing RES in electricity production. The paper first investigates peculiarities of Tunisia electricity system, arguing the necessity to include them in the electricity system model. Then, it explains the choice of OSeMOSYS and brought modifications, including peculiar system characteristics. Finally, the model is applied to two scenarios, a Business As Usual case and a 30% RES target in electricity production case, for time horizon 2010–2030. Results demonstrate the importance of system features detailed modelling. Specifically, they show that targeting RES state-invested integration in the electricity mix may allow higher energy independence to be reached, without increasing significantly system costs.

  • 21. Eid, Cherrelle
    Market integration of local energy systems: Is local energy management compatible with European regulation for retail competition?2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 114, p. 913-922Article in journal (Refereed)
    Abstract [en]

    The growing penetration of distributed energy resources is opening up opportunities for local energy management (LEM) – the coordination of decentralized energy supply, storage, transport, conversion and consumption within a given geographical area. Because European electricity market liberalization concentrates competition at the wholesale level, local energy management at the distribution level is likely to impose new roles and responsibilities on existing and/or new actors. This paper provides insights into the appropriateness of organizational models for flexibility management to guarantee retail competition and feasibility for upscaling. By means of a new analytical framework three projects in the Netherlands and one in Germany have been analysed. Both the local aggregator and dynamic pricing projects present potentials for retail competition and feasibility of upscaling in Europe.

  • 22.
    Endalew, Abebe K.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Kiros, Yohannes
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Zanzi, Rolando
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Heterogeneous catalysis for biodiesel production from Jatropha curcas oil (JCO)2011In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 36, no 5, p. 2693-2700Article in journal (Refereed)
    Abstract [en]

    This work focuses on the development of heterogeneous catalysts for biodiesel production from high free fatty acid (FFA) containing Jatropha curcas oil (KO). Solid base and acid catalysts were prepared and tested for transesterification in a batch reactor under mild reaction conditions. Mixtures of solid base and acid catalysts were also tested for single-step simultaneous esterification and transesterification. More soap formation was found to be the main problem for calcium oxide (CaO) and lithium doped calcium oxide (Li-CaO) catalysts during the reaction of jatropha oil and methanol than for the rapeseed oil (RSO). CaO with Li doping showed increased conversion to biodiesel than bare CaO as a catalyst. La(2)O(3)/ZnO, La(2)O(3)/Al(2)O(3) and La(0.1)Ca(0.9)MnO(3) catalysts were also tested and among them La(2)O(3)-ZnO showed higher activity. Mixture of solid base catalysts (CaO and Li-CaO)and solid acid catalyst (Fe(2)(SO(4))(3)) were found to give complete conversion to biodiesel in a single-step simultaneous esterification and transesterification process. (C) 2011 Elsevier Ltd. All rights reserved.

  • 23.
    Fan, Wenyuan
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering.
    Cherdantsev, Andrey, V
    Kutateladze Inst Thermophys, 1 Lavrentiev Ave, Novosibirsk 630090, Russia.;Novosibirsk State Univ, 2 Pirogov Str, Novosibirsk 630090, Russia..
    Anglart, Henryk
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering. Warsaw Univ Technol, 21-25 Nowowiejska St, PL-00665 Warsaw, Poland..
    Experimental and numerical study of formation and development of disturbance waves in annular gas-liquid flow2020In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 207, article id 118309Article in journal (Refereed)
    Abstract [en]

    Disturbance waves in a downwards annular gas-liquid flow were investigated experimentally and numerically in this study. In the experiment, the brightness-based laser-induced fluorescence (BBLIF) technique was utilized to obtain high-resolution spatiotemporal measurements for the film thickness. In the simulations, the two-phase system was simulated by the volume of fluid (VOF) method together with newly developed turbulence damping models, without which the turbulence level around the film surface is considerably under-predicted. Qualitative and quantitative comparisons were carried out for the experimental and numerical data, during which a novel method was developed to extract complex wave structures in a direct manner. Comparisons showed that the model is able to reproduce the main stages of flow evolution, including development of high-frequency initial waves, their coalesce into stable large-scale disturbance waves, generation of slow and fast ripples, and disruption of fast ripples into droplets. The main properties of modeled waves are in decent agreement with the measured ones, apart from noticeably rarer generation of ripples. The presented methods offer a new and promising option to model various energy technology systems, where annular two-phase flow occurs.

  • 24.
    Fischer, David
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Wolf, T.
    Wapler, J.
    Hollinger, R.
    Madani Larijani, Hatef
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Model-based flexibility assessment of a residential heat pump pool2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 118, p. 853-864Article in journal (Refereed)
    Abstract [en]

    This paper presents and demonstrates a methodology to explore the flexibility of a heat pump pool. Three points are in the focus of this work: First the procedure to model a pool of residential heat pump systems. Second the study of the response of a large number of heat pumps when the Smart-Grid-Ready interface is used for direct load control. Third a general assessment of flexibility of a pool of heat pump systems. The presented pool model accounts for the diversity in space heating and domestic hot water demands, the types of heat source and heat distribution systems used and system sizing procedures. The model is validated using field test data. Flexibility is identified by sending trigger signals to a pool of 284 SG-Ready heat pumps and evaluating the response. Flexibility is characterized by maximum power, shiftable energy and regeneration time. Results show that flexibility is highly dependent on the ambient temperature and the use of an electric back-up heater. It is found that using SG-Ready-like signals offers significantly higher flexibility than just switching off heat pumps, as it is mostly done today.

  • 25.
    Fuso-Nerini, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Dargaville, Roger
    Howells, Mark
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis. Columbia Univ, NY USA.
    Bazilian, Morgan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems Analysis.
    Estimating the cost of energy access: The case of the village of Suro Craic in Timor Leste2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 79, p. 385-397Article in journal (Refereed)
    Abstract [en]

    Energy access targets at national, sub-national, and local levels, are often not specified in great detail - and tend to focus on supply. Another approach to better inform policy and investment might benefit from an indicator that focuses on the services derived from electricity access. To provide support for decision-making, this research investigates the costs of reaching different levels of energy access in rural areas, with a case study of a village in the Ainaro district of Timor Leste. Utilizing the multi-tier definition of energy access proposed in the World Bank's "Global Tracking Framework" for Sustainable Energy for All, we present results both on the cost difference of achieving different tiers of energy access, and on the comparison among selected electrification and cooking options. Results show that in the period 2010-2030 achieving the highest tier of electricity access could be as much as seventy-five times more costly than achieving the lowest one. In addition moving across tiers, least cost solutions shift from stand-alone to mini-grid and finally grid connected options as electricity access increases. Regarding cooking, moving from open fires to some of the more modern solutions has the potential to reduce overall costs over the same period.

  • 26.
    Gardumi, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Keppo, I.
    Howells, M.
    Pye, S.
    Avgerinopoulos, Georgios
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electric Power and Energy Systems.
    Lekavičius, V.
    Galinis, A.
    Martišauskas, L.
    Fahl, U.
    Korkmaz, P.
    Schmid, D.
    Montenegro, R. Cunha
    Syri, S.
    Hast, A.
    Mörtberg, Ulla
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability Assessment and Management.
    Balyk, O.
    Karlsson, K.
    Pang, Xi
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability Assessment and Management.
    Mozgeris, G.
    Trubins, R.
    Jakšić, D.
    Turalija, I.M.
    Mikulić, M.
    Carrying out a multi-model integrated assessment of European energy transition pathways: Challenges and benefits2022In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 258, p. 124329-124329, article id 124329Article in journal (Refereed)
    Abstract [en]

    With the publication of the European Green Deal, the European Union has committed to reaching carbon neutrality by 2050. The envisaged reductions of direct greenhouse gases emissions are seen as technically feasible, but if a wrong path is pursued, significant unintended impacts across borders, sectors, societies and ecosystems may follow. Without the insights gained from an impact assessment framework reaching beyond the techno-economic perspective, the pursuit of direct emission reductions may lead to counterproductive outcomes in the long run. We discuss the opportunities and challenges related to the creation and use of an integrated assessment framework built to inform the European Commission on the path to decarbonisation. The framework is peculiar in that it goes beyond existing ones in its scope, depth and cross-scale coverage, by use of numerous specialised models and case studies. We find challenges of consistency that can be overcome by linking modelling tools iteratively in some cases, harmonising modelling assumptions in others, comparing model outputs in others. We find the highest added value of the framework in additional insights it provides on the technical feasibility of decarbonisation pathways, on vulnerability aspects and on unintended environmental and health impacts on national and sub-national scale.

  • 27.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Abou-Taouk, Abdallah
    Azelio, Regnbagsgatan 6, S-41755 Gothenburg, Sweden..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental and numerical performance analyses of Dish-Stirling cavity receivers: Radiative property study and design2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 169, p. 478-488Article in journal (Refereed)
    Abstract [en]

    The solar receiver performance has a direct impact on the CSP power plant performance and, thereby, its levelized cost of electricity. Improved receiver designs supported by new advanced numerical tools and experimental validation campaigns directly help to make CSP technology more competitive. This paper presents an experimental and numerical investigation of the influence of the cavity receiver radiative properties and the thermal power input on the Dish-Stirling performance. Three cavity coatings are experimentally investigated: the original cavity material (Fiberfrax 140), Pyromark 2500 and Pyro-paint 634-ZO. Moreover, simulations validated with the experimental measurements are utilized to define a higher performance cavity receiver for the Eurodish system. The results indicate that the absorptivity of the cavity should be as low as possible to increase the receiver efficiency whereas the optimum emissivity depends on the operating temperatures. If the cavity temperature is lower than the absorber temperature, low emissivities are recommended and vice-versa. All material/coatings analyzed for the cavity provide similar receiver efficiencies, being Fiberfrax 140 slightly more efficient. Finally, a total receiver efficiency of 91.5% is reached by the proposed Eurodish cavity receiver when operating under the most favorable external conditions. 

  • 28.
    Garrido, Jorge
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Characterization of the KTH high-flux solar simulator combining three measurement methods2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 141, p. 2091-2099Article in journal (Refereed)
    Abstract [en]

    This paper presents the characterization of the first Fresnel lens-based High-Flux Solar Simulator (HFSS) showing the evaluation of the total thermal radiative power dependent on the aperture radius at the focal plane. This result can be directly applied to calculate the thermal power input into any solar receiver tested in the KTH HFSS. Three measurement setups were implemented and their results combined to assess and verify the characterization of the solar simulator: a thermopile sensor measuring radiative flux, a CMOS camera coupled with a Lambertian target to obtain flux maps, and a calorimeter to measure the total thermal power within an area of 300×300 mm. Finally, a Monte Carlo analysis was performed to calculate the total uncertainties associated to each setup and to combine them to obtain the simulator characterization. The final result shows a peak flux of 6.8 ± 0.35 MW/m2 with a thermal power of 14.7 ± 0.75 kW within an aperture of 180 mm in diameter at the focal plane, and a thermal-electrical conversion efficiency of 25.8 ± 0.3%. It was found very good repeatability and a stable energy output from the lamps during the experiments.

  • 29.
    Ghaem Sigarchian, Sara
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Paleta, Rita
    Malmquist, Anders
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pina, André
    Feasibility study of using a biogas engine as backup in a decentralized hybrid (PV/wind/battery) power generation system: Case study Kenya2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 90, no 2, p. 1830-1841Article in journal (Refereed)
    Abstract [en]

    In this study, a hybrid power system consisting of PV (Photovoltaics) panels, a wind turbine and a biogas engine is proposed to supply the electricity demand of a village in Kenya. The average and the peak load of the village are around 8kW and 16.5kW respectively.The feasibility of using locally produced biogas to drive a backup engine in comparison to using a diesel engine as backup has been explored through a techno-economic analysis using HOMER (Hybrid Optimization Model for Electric Renewables). This hybrid system has also been compared with a single diesel based power system.The results show that the hybrid system integrated with the biogas engine as backup can be a better solution than using a diesel engine as backup. The share of power generation by PV, wind and biogas are 49%, 19% and 32%, respectively. The LCOE (Levelized Cost of Electricity) of generated electricity by this hybrid system ($0.25/kWh) is about 20% cheaper than that with a diesel engine as backup ($0.31/kWh), while the capital cost and the total NPC (Net Present Cost) are about 30% and 18% lower, respectively.Regarding CO2 emissions, using a biogas engine as backup saves 17 tons of CO2 per year compared to using the diesel engine as backup.

  • 30. Ghezelbash, Reza
    et al.
    Farzaneh-Gord, Mahmood
    Behi, Hamidreza
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sadi, Meisam
    Khorramabady, Heshmatollah Shams
    Performance assessment of a natural gas expansion plant integrated with a vertical ground-coupled heat pump2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 93, p. 2503-2517Article in journal (Refereed)
    Abstract [en]

    In the present paper, a vertical ground-coupled heat pump system is proposed for energy saving in a natural gas expansion plant. Such plant is a modern type of conventional natural gas pressure drop station. Unlike the conventional type, which waste the natural gas pressure exergy in throttling process, the modern one uses the pressure exergy of the natural gas for producing electrical power. A remarkable feature of the proposed system is the type of energy resource used for preheating aim. In previous studies, natural gas was used for the preheating process, however: the proposed system employs geothermal energy as a renewable energy resource for providing part of heating demand. Initially, the vertical ground-coupled heat pump system preheats the natural gas stream up to medium temperatures, then, gas stream passes through station heater and reaches the desired temperature. For studying the economic and thermal performance of the proposed system, first of all, a system with a high net present value is selected, and then the performance of the selected system is studied in detail. The analysis revealed that the fuel saving potential of the system is 45.80% annually. Economically, the discounted payback period was also calculated about 6 years.

  • 31.
    Grönkvist, Stefan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Bryngelsson, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Westermark, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Oxygen efficiency with regard to carbon capture2006In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 31, no 15, p. 3220-3226Article in journal (Refereed)
    Abstract [en]

    Carbon capture is often discussed in the literature with the sole focus on power processes, despite the fact that carbon dioxide emissions from other sources are just as relevant for the impact on the atmosphere. Furthermore, some carbon capture methods are relatively inefficient when applied to power production processes. Carbon capture should preferably be performed where the cost is as low as possible, i.e. not necessarily from power production processes. As an example, carbon capture using combustion with pure oxygen is far more energy efficient if it is used together with lime kilns or cement kilns than together with power production processes. A new concept termed "oxygen efficiency" is introduced in this paper. It describes the amount of carbon dioxide that can potentially be captured per unit of oxygen. As such, the oxygen efficiency quantifies the value of a certain unit of oxygen for carbon capture reasons. The base concept is that the energy penalty for the production of one part of oxygen is the same no matter where it is produced; hence, if this unit of oxygen can be used to capture more carbon dioxide, it is more efficient. Typically, the oxygen efficiency would be five times greater for carbon capture when utilising pure oxygen together with cement kilns rather than together with methane-fired power plants. Furthermore, the concept of oxygen efficiency illustrates the importance of considering how carbon capture methods can be utilised in the most efficient way, in addition to evaluating which carbon capture method is the most suitable for a particular technology.

  • 32.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic optimization of molten salt based CSP plants through integration of supercritical CO2 cycles and hybridization with PV and electric heaters2023In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 283, article id 128528Article in journal (Refereed)
    Abstract [en]

    The present study explores the integration of supercritical CO2 (sCO2) power cycles into Concentrating Solar Power (CSP) plants using molten salt, and the hybridization of these plants with solar photovoltaic (PV) systems through electric heaters. Techno-economic evaluations determined the optimal power cycle configuration and subsystem designs for two different scales and locations and then compared them with state-of-the-art solar power plants. The results show that hybridizing PV with state-of-the-art CSP can lead up to a 22% reduction in the Levelized Cost of Electricity (LCOE) compared to standalone CSP systems. This hybridization and the use of electric heaters are particularly beneficial for small-scale installations and locations with low DNI/GHI ratios. By replacing the steam Rankine cycle with a sCO2 power block, a further 42% reduction in LCOE can be achieved at small scales, even with a simple recuperated cycle. In conclusion, the hybridization with PV and the integration of sCO2 power blocks provide cost benefits despite the temperature limitations imposed by the molten salt. Hybrid PV-CSP plants with sCO2 power blocks prove to be a cost-effective solution for capacity factors exceeding 60%. For lower capacity factors, configurations combining PV with battery energy storage or PV with electric heaters, thermal energy storage, and sCO2 power blocks are preferable options.

  • 33.
    Gunarathne, Duleeka Sandamali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Mueller, Andreas
    Fleck, Sabine
    Kolb, Thomas
    Chmielewski, Jan Karol
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Blasiak, Wlodzimierz
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Gasification characteristics of steam exploded biomass in an updraft pilot scale gasifier2014In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 71, p. 496-506Article in journal (Refereed)
    Abstract [en]

    Pretreatment of biomass becomes more and more important due to the large scale application of biomass having low energy density. In this paper, steam exploded biomass pellets (Black pellets) and unpretreated biomass pellets (Gray pellets) were gasified with air and steam at an updraft HTAG (High Temperature Agent Gasification) unit. Decomposition characteristics of pellets were first analyzed with TGA (thermo gravimetric analysis). Early decomposition of hemicellulose and cellulose were seen with Black pellets around 241 degrees C and 367 degrees C respectively. Introducing CO2 led comparatively high mass loss rate with Black pellets. Gasification of Black pellets resulted in syngas with high CO and hydrocarbon contents while Gasification of Gray pellets resulted in high H-2 content of syngas. LHV (lower heating value) of syngas was high around 7.3 MJ/Nm(3) and 10.6 MJ/Nm(3) with air gasification and steam gasification respectively. Even with significantly low syngas temperature with gasification of Black pellets, only slightly high total tar content was seen compared to that of Gray pellets gasification. Phenolic compounds dominated the tar composition. In general, steam gasification of Black pellets seems to be more feasible if syngas with high energy value is desired. If higher H-2 yield is preferred, gasification of unpretreated pellets likely to be more attractive.

  • 34.
    He, Bo
    et al.
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Martin, Viktoria
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Setterwall, Fredrik
    Phase transition temperature ranges and storage density of paraffin wax phase change materials2004In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 29, no 11, p. 1785-1804Article in journal (Refereed)
    Abstract [en]

    Paraffin waxes have been used in many latent thermal energy storage applications because of their advantageous thermal performances. In this paper, the liquid-solid phase diagram of the binary system of tetradecane and hexadecane has been used to obtain information of the phase transition processes for cool storage applications. The analysis of the phase diagram indicates that, except for the minimum-melting point mixture, all mixtures melt and freeze in a temperature range and not at a constant temperature. The latent heat of fusion evolves throughout this temperature range. Differential scanning calorimetry (DSC) was used to determine the thermophysical properties of the binary system. Depending on the DSC settings throughout the measurements, varying results were obtained. For example, when the DSC runs at a high heating/cooling rate, it will lead to erroneous information. Also, the correct phase transition temperature range cannot be obtained simply from DSC measurement. By combining phase equilibrium considerations with DSC measurements, a reliable design method to incorporate both the heat of phase change and the temperature range is presented.

  • 35.
    Henke, Hauke
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy Systems.
    Gardumi, Francesco
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Howells, Mark I.
    Loughborough University, Epinal Way, Loughborough, LE11 3TU, Leicestershire, United Kingdom.
    The Open Source electricity Model Base for Europe - An engagement framework for open and transparent European energy modelling2021In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 239, article id 121973Article in journal (Refereed)
    Abstract [en]

    The transition to a low carbon energy system as laid out in the Paris Agreement and the European GreenDeal presents challenges that involve society at all levels from planners to consumers. A key challenge isthe communication across these levels. Tools to foster engagement and discussion between the differentactors are open-source models with a low threshold for uptake. This paper presents the Open-Sourceelectricity Model Base for Europe an electricity sector engagement model covering all member statesof the EU, Norway, Switzerland and the United Kingdom. Built in OSeMOSYS and available on GitHub, themodel provides a starting point into energy systems modelling and can be further developed in acollaborative manner. It enables non-experts to develop an understanding of energy systems models andenergy planning. Thereby, it can serve as an engagement tool to carry the debate on the future of theEuropean power system beyond the academy, which might contribute to finding societal consensus onhow to decarbonise our energy system. The model allows dynamic power sector expansion analysis ofthe European power system till 2050. It can be used for scenario analysis and is expandable to othersectors to analyse the benefits of sector coupling.

    Download full text (pdf)
    fulltext
  • 36.
    Huang, Yalin
    et al.
    KTH, School of Electrical Engineering (EES).
    Söder, Lennart
    KTH, School of Electrical Engineering (EES).
    Evaluation of economic regulation in distribution systems with distributed generation2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 126, p. 192-201Article in journal (Refereed)
    Abstract [en]

    The economic regulation impact on distribution system investment is evaluated by a network expansion planning model in this paper. Distributed generation (DG) integration has been taken into consideration in network investment worldwide. In most studies DG units are planned by distribution system operators (DSOs). However, in some countries DSOs are not allowed to own generation due to unbundling regulation. In the proposed model formulation, DG units are not owned by the DSOs. Moreover, fluctuation from load and DG in the planning periods, DG curtailment possibility and regulation on losses and DG connection fees are altogether considered. Different regulation arrangements are studied in the same testing network and the resulting network expansion costs are compared. The main value of this paper lies in the application of network planning model to the economic regulation analysis, in the quantification of the impact of different economic regulation frameworks, and in the implications of different regulation choices concerning distributed generation integration.

  • 37.
    Islam, M. S.
    et al.
    KTH, School of Electrical Engineering (EES).
    Akhter, R.
    Rahman, M. A.
    A thorough investigation on hybrid application of biomass gasifier and PV resources to meet energy needs for a northern rural off-grid region of Bangladesh: A potential solution to replicate in rural off-grid areas or not?2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 145, p. 338-355Article in journal (Refereed)
    Abstract [en]

    Rural electrification is a critical global challenge specifically in developing countries and Bangladesh is no exception. Most of the people live in the rural areas of the country and having no access to grid electricity hindering the development of these areas and the overall progress of the country's economy severely. In this regard, renewable energy based hybrid mini-grid can be a viable solution to ensure access to electricity for all. This paper presents a case study of supplying electricity through hybrid mini-grid to the rural unelectrified areas of the northern region of Bangladesh, and provides an analysis of its business creation, operation and related challenges. The study involves modelling of three alternative configurations for electricity generation with the different combination of solar energy, biomass generator, diesel generator and battery storage resources. Hybrid Optimization Model for Electric Renewable (HOMER) software is used to carry out the techno-economic analysis and identify the optimal off-grid system configuration. The analysis exposed that the per unit cost of electricity from the optimum off-grid supply configuration is much higher than the regulated tariff for grid connected residential consumers and cannot reach grid parity even with the full capital subsidy. However, the cost of off-grid supply is economical than the diesel-only supply option or the cost of owning a solar home system. The analysis further considered different electricity selling tariff to obtain a practical and reasonable payback period to make the proposed hybrid mini-grid system economically worthwhile. From the emission analysis, it is found that the proposed hybrid system would produce 75% lower CO2 than the existing methods of fulfilling energy needs in the study area. 

  • 38.
    Jagodzińska, Katarzyna
    et al.
    Silesian University of Technology, Institute of Power Engineering and Turbomachinery.
    Mroczek, Kazimierz
    Silesian University of Technology, Institute of Power Engineering and Turbomachinery.
    Nowińska, Katarzyna
    Silesian University of Technology, Department of Applied Geology.
    Gołombek, Klaudiusz
    Silesian University of Technology, Institute of Engineering Materials and Biomaterials.
    Kalisz, Sylwester
    Silesian University of Technology, Institute of Power Engineering and Turbomachinery.
    The impact of additives on the retention of heavy metals in the bottom ash during RDF incineration2019In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 183, p. 854-868Article in journal (Refereed)
    Abstract [en]

    Up to now, a few studies on the efficiency of heavy metal(-oid)s capture by a sorbent directly mixed with fuel, have been performed. For this reason, the main objective of the study is to determine whether or not such a solution is effective when RDF is incinerated. The paper presents a two-step analysis of the impact of three sorbents (ammonium sulphate, kaolinite and halloysite) in three dosages (2, 4 and 8 wt%) on heavy metal(-oid)s retention in the bottom ash. 12 heavy metal(-oid)s were taken into consideration - As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, V and Zn. Samples were incinerated in a lab-scale tubular reactor at two temperatures - 900 °C and 1100 °C. The first step of investigation constitutes ICP analysis of heavy metal(-oid)s content in the bottom ash, coupled with SEM/EDS analysis. Afterwards, the second step was to determine the stability of formed additive-heavy metal(-oid)s complexes via leachability tests in neutral and acid environments. The performed research has shown that ammonium sulphate is effective in Cr, Cu and Hg capture, halloysite – in Cd, Co, V and Mn capture, whereas kaolinite – in Pb capture.

  • 39.
    Jin, Yanghao
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Liu, Sirui
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Shi, Ziyi
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Wang, Shule
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. Jiangsu Province Key Laboratory of Biomass Energy and Materials, Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry (CAF), No. 16, Suojin Five Village, Nanjing, 210042, China, No. 16, Suojin Five Village; International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Longpan Road 159, Nanjing, 210037, China, Longpan Road 159.
    Wen, Yuming
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process. Department of Chemical and Biomolecular Engineering, National University of Singapore, 117585 Singapore.
    Zaini, Ilman Nuran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Tang, Chuchu
    School of Design and Art, Hunan Institute of Technology, 421001 Hengyang, China; Program of Visual Arts, Faculty of Creative Arts, University of Malaya, 50603 Kuala Lumpur, Malaysia.
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Lu, Xincheng
    Jiangsu Province Key Laboratory of Biomass Energy and Materials, Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry (CAF), No. 16, Suojin Five Village, Nanjing, 210042, China, No. 16, Suojin Five Village; International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Longpan Road 159, Nanjing, 210037, China, Longpan Road 159.
    Kawi, Sibudjing
    Department of Chemical and Biomolecular Engineering, National University of Singapore, 117585 Singapore.
    Wang, Chi Hwa
    Department of Chemical and Biomolecular Engineering, National University of Singapore, 117585 Singapore.
    Jiang, Jianchun
    Jiangsu Province Key Laboratory of Biomass Energy and Materials, Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry (CAF), No. 16, Suojin Five Village, Nanjing, 210042, China, No. 16, Suojin Five Village; International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Longpan Road 159, Nanjing, 210037, China, Longpan Road 159.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Process.
    A novel three-stage ex-situ catalytic pyrolysis process for improved bio-oil yield and quality from lignocellulosic biomass2024In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 295, article id 131029Article in journal (Refereed)
    Abstract [en]

    This study aims to improve the quality and yield of bio-oil produced from ex-situ catalytic pyrolysis of lignocellulosic biomass (sawdust) using a combination of stage catalysts with Al-MCM-41, HZSM-5, and ZrO2. The research employed various methods, including thermogravimetric analysis (TGA), differential scanning calorimetry, bench-scale experiments, and process simulations to analyze the kinetics, thermodynamics, products, and energy flows of the catalytic upgrading process. The introduction of ZrO2 enhances the yield of monoaromatic hydrocarbons (MAHs) in heavy organics. Compared with the dual-catalyst case, the MAHs yield escalates by approximately 344% at a catalyst ratio of 1:3:0.25. Additionally, GC-MS data indicate that the incorporation of ZrO2 promotes the deoxygenation reaction of the guaiacol compound and the oligomerization reactions of PAHs. The integration of ZrO2 as the third catalyst enhances the yield of heavy organics significantly, achieving 16.85% at a catalyst ratio of 1:3:1, which increases by nearly 35.6% compared to the dual-catalyst case. Also, the addition of ZrO2 as the third catalyst enhanced the energy distribution in heavy organics. These findings suggest that the combination of these catalysts improves the fuel properties and yields of the bio-oil.

  • 40. Jonsson, M.
    et al.
    Yan, Jinyue
    KTH, Superseded Departments (pre-2005), Chemical Engineering and Technology.
    Ammonia-water bottoming cycles: a comparison between gas engines and gas diesel engines as prime movers2001In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 26, no 1, p. 31-44Article in journal (Refereed)
    Abstract [en]

    Ammonia-water cycles can produce more power than steam Rankine cycles in several applications. One of these applications is as a bottoming cycle to internal combustion engines. In the present study, ammonia-water bottoming cycle configurations for spark-ignition gas engines and compression-ignition gas diesel engines have been compared, Single-pressure Rankine cycles have been used as a basis for the comparison. Low heat source temperatures should increase the difference in power output between the ammonia-water cycle and the Rankine cycle. However, in this study, the results of the simulations show different trends. In most cases, the ammonia-water bottoming cycles with gas engines as prime movers generate more power compared to a Rankine cycle than when gas diesel engines are the prime movers. The temperature of the most important waste heat source, the exhaust gas, is approximately 100 degreesC higher for the gas engines than for the gas diesel engines. Therefore, for the gas engines, most of the waste heat available to a bottoming cycle is in the form of relatively high-temperature exhaust gas, while for the gas diesel engines more of the waste heat is in the form of relatively low-temperature heat sources.

  • 41. Jonsson, M.
    et al.
    Yan, Jinyue
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Humidified gas turbines - a review of proposed and implemented cycles2005In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 30, no 7, p. 1013-1078Article, review/survey (Refereed)
    Abstract [en]

    Gas turbines with air-water mixtures as the working fluid promise high electrical efficiencies and high specific power outputs to specific investment costs below that of combined cycles. Different humidified gas turbine cycles have been proposed, for example direct water-injected cycles, steam-injected cycles and evaporative cycles with humidification towers. However, only a few of these cycles have been implemented and even fewer are available commercially. This paper comprehensively reviews the literature on research and development on humidified gas turbines and identifies the cycles with the largest potential for the future. In addition, the remaining development work required for implementing the various humidified gas turbine cycles is discussed. This paper can also be used as a reference source that summarizes the research and development activities on humidified gas turbines in the last three decades.

  • 42.
    Kabalina, Natalia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Universidade de Lisboa, Portugal.
    Costa, Mario
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Energy and economic assessment of a polygeneration district heating and cooling system based on gasification of refuse derived fuels2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 137, p. 696-705Article in journal (Refereed)
    Abstract [en]

    Conventional district heating and cooling (DHC) systems are compelled to reduce their fossil fuel dependency while ensuring profitability as cooling and heating demands decline. One solution is to retrofit the system with a gasifier and product gas upgrading equipment so that the system will be able to diversify its fuel input, including biomass and waste resources, while simultaneously producing synthetic natural gas (SNG), synthetic gas (syngas) and char complementarily to heat, cold and electricity. The main objective of this study is to assess energetically and economically a polygeneration DHC system based on gasification of refuse derived fuels considering the following sub-product scenarios: char; char and syngas; char and SNG; and char, syngas and SNG. The results show that when char is the only sub product of the modified DHC system, the investment payback is 3 years, the discounted net cash flow (DNCF) is 142 mln USD, and the system trigeneration efficiency is 83.6%. When other sub-products are supplied by the system, its performance reduces but the system DNCF increases, while the investment payback remains constant.

  • 43.
    Khan, MD. Ershad Ullah
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimization of hybrid renewable energy polygeneration system with membrane distillation for rural households in Bangladesh2015In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 93, p. 1116-1126Article in journal (Refereed)
    Abstract [en]

    Despite the country's rural electrification program, kerosene is the predominant source for lighting, and woody biomass is virtually the only option available for cooking. The rural population also struggles with unsafe drinking water in terms of widespread arsenic contamination of well water. Biogas plants and pV are individually impractical to serve both cooking, lighting and water purification systems, and their combined applications are extremely limited. This study considers a holistic approach towards tackling both of these issues via integrated renewable energy-based polygeneration employed at the village level. The polygeneration unit under consideration provides electricity via a pV array and animal and agriculture waste-fed digester, which in turn is coupled to a gas engine. Excess digester gas is employed for cooking and lighting, while waste heat from the process drives a membrane distillation unit for water purification. Technical assessments and optimization have been conducted with HOMER (Hybrid Optimization of Multiple Energy Resources). Results show that daily electricity demand can be met with such a system while simultaneously providing 0.4 m3 cooking fuel and 2e3 L pure drinking water. Cost estimates indicate that this approach is highly favorable to other renewable options. The pay back period of such system is between 3 and 4 years.

  • 44.
    Khatiwada, Dilip
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Seabra, Joaquim
    Faculdade de Engenharia Mecânica, UNICAMP, and Brazilian Bioethanol Science and Technology Laboratory (CTBE), Campinas, SP, Brazil.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Walter, Arnaldo
    Faculdade de Engenharia Mecânica, UNICAMP, and Brazilian Bioethanol Science and Technology Laboratory (CTBE), Campinas, SP, Brazil.
    Power generation from sugarcane biomass - A complementary option to hydroelectricity in Nepal and Brazil2012In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 48, no 1, p. 241-254Article in journal (Refereed)
    Abstract [en]

    This paper discusses the complementarity between hydroelectricity and surplus electricity from sugarcane biomass based cogeneration plants in sugarcane mills. The paper investigates opportunities and barriers in the context of governments' initiatives, institutions and prevailing regulatory frameworks in Brazil and Nepal. The paper finds that bioelectricity from cogeneration can be a good complementary option for hydroelectric power, helping foster diversification on the generation side and enhance security of electricity supply based on local resources. Bioelectricity potential from sugarcane biomass is estimated to be in the range of 209 - 313 GWh for Nepal and 62 -93 TWh for Brazil. In Nepal, the grid connected bioelectricity can provide power for operating industries, and support local development through rural electrification. In Brazil, the biomass potential can be further enhanced through a better utilization of the biomass in the sugar-ethanol industry to balance hydropower availability. This comparative study offers a reflection on the need for better planning and policies to address the barriers which are hindering the development of bioelectricity even in places where the potential is large.

  • 45.
    Khatiwada, Dilip
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Scenarios for bioethanol production in Indonesia: How can we meet mandatory blending targets?2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, ISSN ISSN: 0360-5442, Vol. 119, p. 351-361Article in journal (Refereed)
    Abstract [en]

    This study investigates the potential of bioethanol production and fossil fuel substitution using sugarcane feedstock in Indonesia. Current production practices, government biofuel policies (esp. mandatory blending targets), and sugar self-sufficiency are simulated to project the total potential of fuel ethanol and land requirements in the timeframe between 2015 and 2025. At present conditions, 450 million liters bioethanol can be annually produced in Indonesia using sugarcane molasses, a low-value co-product. This gives only a marginal contribution equivalent to 1% of the total gasoline consumption in 2015. The study examines the ethanol production potential after domestic sugar self-sufficiency is achieved by 2020. In 2015, 0.71 Mha land were required for sugarcane cultivation in order to meet a 2% blend mandate i.e. 0.68 billion liters (BL) ethanol using only cane-molasses. Juice ethanol is needed to meet the blending targets set for 2020 (i.e., 4.45 BL ethanol) and 2025 (i.e., 11.48 BL ethanol). This translates into sugarcane feedstock obtained from 1.60 Mha and 2.76 Mha land, respectively. The study also evaluates how improved resource efficiency can be achieved, exploring the bioelectricity production potential from sugarcane biomass, improvements in yields, and modernization of sugarcane mills. The results highlight how the use of established technologies and production methods can help develop agro-industries in the sugar ethanol segment of Indonesia.

  • 46.
    Koide, Hiroaki
    et al.
    Hokkaido University.
    Kurniawan, Ade
    Hokkaido University.
    Takahashi, Tatsuya
    Hokkaido University.
    Kawaguchi, Takahiro
    Hokkaido University.
    Sakai, Hiroki
    Hokkaido University.
    Sato, Yusuke
    Hokkaido University.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nomura, Takahiro
    Hokkaido University.
    Performance analysis of packed bed latent heat storage system for high-temperature thermal energy storage using pellets composed of micro-encapsulated phase change material2022In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 238, article id 121746Article in journal (Refereed)
    Abstract [en]

    High temperature latent heat storage has gained increasing attention owing to its potential in the integration of renewable energy sources. This study is a novel experimental investigation on the heat storage performance of a horizontal packed bed containing composites comprising Al-Si-based microencapsulated phase change material in a high-temperature air heating system. The pellet type composites with 3 mm is tested here in a 1L scale packed bed heat exchanger at airflow rates between 75 and 150 L min−1. The composite exhibited a narrow phase change temperature range and high heat storage/release characteristics. As the airflow increased, the phase change time of the composite decreased, and the heat exchanging rate increased. The heat exchange efficiency during charging and discharging ranged from 71.0 % to 98.3 % and 69.0 %–90.2 %, respectively. In the discharging mode, although supercooling which comes from the microencapsulated phase change material, was observed, this did not noticeable effect on the heat transfer.

  • 47.
    Lei, Lei
    et al.
    Zhejiang Sci Tech Univ, Sch Civil Engn & Architecture, Hangzhou 310018, Peoples R China..
    Wu, Bing
    Guangxi Vocat & Tech Coll Commun, Coll Civil Engn & Architecture, 1258 Kunlun Ave, Nanning 530216, Peoples R China..
    Fang, Xin
    Alibaba Grp, Alibaba Cloud, 969 West Wen Yi Rd, Hangzhou 311121, Peoples R China..
    Chen, Li
    Alibaba Grp, Alibaba Cloud, 969 West Wen Yi Rd, Hangzhou 311121, Peoples R China..
    Wu, Hao
    Alibaba Grp, Alibaba Cloud, 969 West Wen Yi Rd, Hangzhou 311121, Peoples R China..
    Liu, Wei
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Sustainable Buildings.
    A dynamic anomaly detection method of building energy consumption based on data mining technology2023In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 263, p. 125575-, article id 125575Article in journal (Refereed)
    Abstract [en]

    Due to the equipment failure and inappropriate operation strategy, it is often difficult to achieve energy-efficient building. Anomaly detection of building energy consumption is one of the important approaches to improve building energy-saving. The great amounts of energy consumption data collected by building energy monitoring platforms (BEMS) provides potentials in using data mining technology for anomaly detection. This study pro-poses a dynamic anomaly detection algorithm for building energy consumption data, which realizes the dynamic detection of point anomalies and collective anomalies. The algorithm integrates unsupervised clustering algo-rithm with supervised algorithm to establish a semi-supervised matching mechanism, which avoids the influence of error label and improves the efficiency of anomaly detection. A particle swarm optimization (PSO) is used to optimize the unsupervised clustering algorithm. This investigation tests the effectiveness of the proposed algo-rithm and evaluates the performance of the energy consumption clustering algorithm by using the annual electricity consumption data of an experimental building in a university. The results show that the clustering accuracy of the algorithm can reach more than 80%, and it can effectively detect the building energy con-sumption data of two different forms of outliers. It can provide reliable data support for adjusting building management strategies.

  • 48.
    Levihn, Fabian
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    CHP and heat pumps to balance renewable power production: Lessons from the district heating network in Stockholm2017In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 137, p. 670-678Article in journal (Refereed)
    Abstract [en]

    There is a potential for utilizing a combination of combined heat and power (CHP) plants together with large scale heat pumps in district heating systems to balance intermittent renewable power production. The thought is to use a combination of both power production and consumption to balance both surplus and deficit in the electric power market. Much research has presented different modelling and simulations of such systems. This particular study present lessons and empirics from operating such a system. The DH system in Stockholm is large with over 12 TWh of heat demand annually. Since the 1970s the system has been operated with both CHPs and heat pumps. About 660 MW of heat pumps and 300 MW of electric boilers are currently operational in this system. Both the district heating and district cooling systems are equipped with storage. Besides constituting an empirical example, the paper contributes with input to future modelling of this kind of system.

  • 49.
    Levihn, Fabian
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    CO2 emissions accounting: Whether, how, and when different allocation methods should be used2014In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 68, p. 811-818Article in journal (Refereed)
    Abstract [en]

    CO2 abatement and the transition to sustainable energy systems are of great concern, calling for investments in both old and new technologies. There are many perspectives on how to account for these emissions, not least when it comes to how the roles of different alternative energy production options should be emphasized. Confusion and conflicting interests regarding the appropriate accounting methods for allocating CO2 emissions interfere with effective energy policy and the efficient use of corporate and national resources. Possible investments in the Stockholm district heating network and how they interact with the electric power grid illustrate the influence of different accounting methods on alternative energy production options. The results indicate that, for several abatement options, performance in terms of reduced CO2 emissions might be either improved or degraded depending on whether or how alternative electricity production is accounted for. The results provide guidelines for whether, how, and when different allocation methods are appropriate, guidelines relevant to academia, industrial leaders, and policymakers in multiple areas related to power production and consumption.

  • 50.
    Levihn, Fabian
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Sustainability and Industrial Dynamics.
    On the problem of optimizing through least cost per unit, when costs are negative: Implications for cost curves and the definition of economic efficiency2016In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 114, p. 1155-1163Article in journal (Refereed)
    Abstract [en]

    For society and industry alike, efficient allocation of resources is crucial. Numerous tools are available that in different ways rank available options and actions under the aim to minimize costs or maximize profit. One common definition of economic efficiency is least cost per unit supplied. A definition that becomes problematic if cost take negative values. One model, where negative costs are not uncommon, is expert based/bottom up [marginal abatement] cost curves. This model is used in many contexts for understanding the impact of economic policy as well as optimizing amongst potential actions. Within this context attention has been turned towards the ranking problem when costs are negative.

    This article contributes by widening the discussion on the ranking problem from the MACC context to the general definition of least cost per unit supplied. Further it discuss why a proposed solution to the ranking problem, Pareto optimization, is not a good solution when available options are interdependent. This has particular consequences for the context of energy systems, where strong interdependencies between available options and actions are common. The third contribution is a proposed solution to solve the ranking problem and thus how to define economic efficient when costs are negative.

123 1 - 50 of 134
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf