The transition from fossil-energy systems to renewable energy is a necessary step in addressing the issue of climate change. However, the solution to climate change cannot be achieved in isolation from the surrounding natural environment and societies. Chap. 2 provides a more detailed examination of three planetary boundaries that are strongly interlinked and that also relate closely to renewable energy production: climate change, biosphere integrity (biodiversity loss), and land system change. The chapter provides a general overview of the concept of the carbon budget and the Earth’s annual biocapacity, emphasizing the importance of biodiversity to humanity and the impacts of land use resulting from energy production. The chapter also presents a case example of how to measure the biodiversity footprint of a large-scale energy project. Furthermore, the principles of social sustainability and the measures of a good life are introduced, with particular emphasis on the importance of considering the social aspects of large-scale energy projects. The chapter also highlights the importance and means of social participation and how power relations influence energy policy decision making. Finally, basic economic tools to evaluate the economic feasibility of renewable energy projects are presented. Energy engineers should have a solid foundational understanding of these different aspects of energy projects in their everyday work in designing and building sustainable energy systems for a de-carbonized, sustainable, and just future.

Even with favorable policy frameworks, green hydrogen has not been cost-competitive in Europe. Optimizing hydrogen production can reduce the Levelized Costs of Hydrogen (LCOH). In this research, an electrolysis system model is developed to optimize hydrogen production in two industrial settings. The model incorporates technical aspects such as part-load behavior, stack degradation, and energy inputs (i.e., electricity price and volume projections). Mid-scale hydrogen production for heavy-duty transport refuelling in Germany has the lowest LCOH at 8 <euro>/kg (with a 16 MWel electrolysis system), whereas large-scale hydrogen production for the refinery industry in Portugal achieves 4 <euro>/kg (with a 128 MWel system). The study reveals that the optimal system configuration depends on energy prices, technology costs, efficiency, load flexibility, and storage options. This study could be helpful in operationalizing hydrogen production systems (e.g., stack operation and replacement strategies) depending on energy supply and hydrogen demand over the lifetime.

Energy availability and reliability are essential for economic growth and sustainable development. The problems with growing energy demand could be addressed by supply-side energy management. However, this task has become increasingly challenging due to high fluctuations in electricity demand and the increasing penetration of intermittent renewable energy into the electricity supply mix. This study aims to investigate the energy demand flexibility potential in the energy-intensive cement production sector. A mixed integer linear programming model (MILP) has been developed to flatten the grid's hourly demand curve by minimizing the industrial customer's hourly peak loads and maximizing the shifting of demand to off-peak periods. The result reveals that the demand flexibility potential of the case study cement plants is about 495 MWh per day, constituting approximately 28 % of the daily total electrical energy used by these cement plants, proving that the cement industry is a potential candidate for demand response strategies. By adapting the proposed model, the loads of the case study plants during the peak period of the day are reduced by an average of 75 %. In addition, case study plants have achieved an overall reduction of 188 t of CO2 emissions per day. Furthermore, the cost of consumed electrical energy for a day decreased on average by 14 % in these plants. Thus, the proposed model can help minimize the impact on grid instability and the cost of energy consumption of an industrial customer. Scenarios such as the variation of the capacity factor and onsite electrical power generation, i.e., waste heat recovery power plants, can promote the demand response strategies in the cement sub-sector. The study could be useful to energy-intensive industries and relevant policymakers to understand the demand response in maintaining power system reliability and explore ways to implement demand-side energy management strategies with appropriate electricity tariffs.

Achieving sustainable biowaste management is a key challenge for cities worldwide. In this context, biowaste valorization is an indispensable option for managing unavoidable biowaste and reducing the associated methane emissions. Several innovations that enable biowaste valorization are technologically mature. However, their implementation is still limited in most cities around the world. Therefore, it is essential to better understand the different pathways towards implementing biowaste valorization. This paper presents a case-study of two countries at different phases in their transition to biowaste valorization: Sweden as a case at a mature phase and Greece as a case at a formative phase. We apply the Technological Innovation Systems framework to investigate how innovation systems for biowaste valorization develop and associated path-dependencies. Our findings show that various path-dependence lock-ins can occur at different transition phases. Our empirical insights suggest that a focus on the diffusion of certain mature innovations can support the growth of biowaste valorization systems. However, it can also lead to path-dependence lock-ins that influence the systems’ resilience to shocks. We thus recommend decision-makers to pursue balance between the rapid diffusion of mature innovations for biowaste valorization and parallel support for experimenting with more radical innovations to harness the systems’ resilience to shocks.

Even if aviation only accounts for 2 % of global energy-related CO2 emissions, but it is the most challenging sector to decarbonize. As aviation demand grows and the need for sustainable jet fuels becomes urgent, green hydrogen could substitute conventional fossil fuels, thereby enabling carbon-free flights. This study investigates a techno-economic analysis of on-site versus off-site green hydrogen supply chains. A case study at the ToulouseBlagnac airport (Europe's first station for the production and distribution of renewable hydrogen) in France is developed to meet commercial aviation's hydrogen fuel demand between 2025 and 2050. Demand of hydrogen is projected based on the trend of jet fuel consumption. First, the cost of solar-based renewable electricity is estimated at the two green hydrogen production sites using levelized cost of electricity production. Second, levelized cost of hydrogen (LCOH) is evaluated for three value chain scenarios: one on-site (Toulouse airport) and two off-site (Marseille) for gaseous and cryogenic transportation of liquid hydrogen (LH2). A relative cost advantage is shown for the off-site case with cryogenic truck transportation at LCOH of <euro>9.43/kg.LH2. This study also reveals the importance of electricity price, investment costs, operation costs, economies of scale, and transportation distance in different scenarios.

The barriers and drivers of industrial decarbonization through energy efficiency (EE) improvements have been extensively explored in energy-intensive industries in developed countries; however, research in developing country contexts remains limited. This paper addresses the gap by investigating a broad range of barriers and drivers of decarbonization efforts in the Ethiopian Cement Industry (ECI). A PESTLE (political, economic, social, technological, legal, and environmental) framework-based measurement theory is developed to analyze the barriers and drivers. The measurement theory suitability is confirmed statistically through exploratory and confirmatory factor analyses, using response data collected from relevant stakeholders via a five-point Likert-scale survey. In this paper, the top-ranked barriers (rating > 3.76/5) identified by respondents are insufficient stakeholder collaboration, weak top-management support, inadequate infrastructure, and absence of economic subsidies. The highly ranked drivers (> 3.77/5) are cost reductions resulting from lowered energy use, threats of rising energy prices, and effective environmental management systems. On the other hand, respondents ranked competing priorities for capital investment (3.41/5) and strengthening the image of a company (3.22/5) at the bottom of barriers and drivers, respectively. The survey also highlighted gaps in EE implementations, proactive energy management (EnM) systems, and industrial EE policies. The key findings and insights drawn from the survey results and analysis are used to formulate several decarbonization strategies for short- and long-term planning, along with policy instruments (e.g., tax rebate/credits, energy/carbon taxes, removing energy subsidies, polluters pay principle, landfill taxes, minimum equipment standards, energy audit regulation) and stakeholder engagement. The main strategies include adopting cost-effective EE technologies and demand response programs, deploying emerging/innovative low carbon technologies, utilizing alternative fuels (waste/biomass), and reducing clinker-to-cement ratio. Strengthening government engagement, stakeholder collaborations, and waste collection and pre-processing infrastructure, reforming EE policies, regulations, and financial schemes, mandating EnM systems, and creating green certifications are essential for advancing decarbonization efforts in ECI. Finally, this paper contributes to the global decarbonization effort by providing a robust methodological framework that leads to formulation of actionable, sector-specific strategies.

Cement manufacturing is a highly energy-intensive process, with a significant amount of the thermal energy in the production chain being lost. Consequently, exploring ways to capture and utilize this wasted heat to generate electricity and meet industrial energy requirements is crucial. This study investigates the potential for Waste Heat Recovery (WHR) power generation with a case study in the Ethiopian cement industry. The levelized cost of energy (LCOE) and the Net Present Values (NPV) of the WHR power plant based on 3 options (i.e., steam Rankine cycle, Organic Rankine cycle, and Kalina Rankine cycle) are evaluated. The findings reveal that the steam Rankine cycle-based waste heat recovery power plant is the only feasible option in the Ethiopian cement plant, with a NPV of 0.35 million USD and a LCOE of about 0.04 USD per kWh. The power capacity of the feasible plant is about 8.9 MW for the studied cement plant with an annual production capacity of 2.3 Mt of cement, covering about 18% of its electricity demand. The plant's associated reduced CO₂ emissions potential is insignificant, as the hydropower sources dominate the national power grid. However, assuming the proposed WHR power plant reduces the activation of diesel power plants during peak hours in the Ethiopian power grid, the Steam Rankine Cycle (SRC)-based waste heat recovery power plant (WHRPP) in the case study cement plant has the potential to reduce CO₂ emissions by approximately 7.9 million tonnes per year. Sensitivity analysis has been conducted to ensure that the results derived from the base case assumptions remain reliable despite potential fluctuations in the key parameters. This study could be a useful reference for policymakers and industries to harness alternative and sustainable electricity generation potential from onsite power generation plants in the cement industry.

Cement production is a major consumer of energy and the largest source of industrial CO2 emissions. This study aims to perform an environmental life cycle assessment of clinker and cement production in Ethiopia, using ReCiPe impact assessment method. Inventory data (material, energy, and transportation) is collected from seven major Ethiopian cement industries. The midpoint analysis identified nine hotspot environmental concerns: global warming, ozone formation (human health and terrestrial ecosystem), particulate matter formation, terrestrial (acidification and ecotoxicity), freshwater eutrophication, human carcinogenic toxicity, and fossil resource scarcity. Human health emerged as the most significantly affected endpoint damage category by the midpoint impacts. Among the process stages included in clinker system boundary, clinker production phase (kiln emissions) is a significant contributor to the total score of the hotspot impacts, ranging from 60.7% to 91.8%. The clinker system is responsible for over 81.03% of the overall environmental burden of cement. The sensitivity analysis reveals that a 5% change in kiln energy consumption and transportation burden could lead to a reduction in hotspot impacts ranging from 1.8% to 5%. To foster reliability of this study, uncertainty analysis is also conducted. Overall, the findings indicate the need to enhance environmental sustainability in Ethiopian cement production.

In life-cycle costing of thermal energy systems, the basis of costing could be mass or exergy and the approach followed could be deterministic or stochastics. In thermal energy systems with end products/services such as hot air, hot water, steam etc. the value addition is due to higher exergy content; therefore, exergy is a logical basis of costing and stochastics is a practical approach capturing uncertainties of input variables. This paper proposes a novel framework named as stochastic Monte Carlo-based exergy costing (SMXC) for assessment of solar hot water systems. The annual hours of operation, maintenance cost, service life, and capital cost have been identified as highly sensitive input variables. The costs based on mass and exergy content of hot water in deterministic life-cycle costing method are estimated at 0.296 and 0.304 US cent/kg, respectively. The mean values of mass and exergy costs of hot water using Monte Carlo-based stochastics life-cycle costing method are 0.302 and 0.310 US cent/kg. A very low value (i.e. 2.4%) of the exergo-economic factor (f) for the solar water heater indicates the poor exergetic efficiency; therefore, capital investment to improve its efficiency is justified. The methodological approach can be extended to examine the probabilistic exergo-economic cost of array of thermal energy products when the parametric uncertainties play a key role.

The upscaling of novel carbon dioxide removal, such as bioenergy carbon capture and storage (BECCS), to gigatonne scales is an urgent priority if global warming is to be limited to well below 2 °C. But political, economic, social, technological, environmental and regulatory uncertainty permeates BECCS projects and deters investors. To address this, we explore options to improve the robustness of BECCS deployment strategies in the face of multi-dimensional uncertainties. We apply Dynamic Adaptive Planning (DAP) through expert interviews and Robust Decision Making (RDM) through exploratory modelling, two decision making under deep uncertainty methods, to the case of Stockholm Exergi, an early mover aiming to deploy BECCS at a combined heat and power plant in the capital of Sweden. The main contributions of the research are to 1) illustrate how a quantification of robustness against uncertainty can support an investment decision to deploy BECCS 2) comprehensively cover uncertain vulnerabilities and opportunities of deploying BECCS, and 3) identify critical scenarios and adaptations to manage these uncertainties. The main conclusions are: investing in BECCS is relatively robust if assessing performance across many scenarios and if comparing the worst-cases of either investing, or not doing so. Not investing could miss out on up to € 3.8 billion in terms of net present value. The critical uncertainties of BECCS can be managed by strengthening biomass sustainability strategies and by gaining support for negative emission trading regulation on carbon markets, e.g., voluntary or Paris Agreement Article 6. Even in vulnerable scenarios of average electricity prices above 82 €/MWh, if trading regulation is implemented before 2030 and if negative emission prices exceed 151 €/CO2, investing in BECCS performs better than not doing so in 96% of cases. We suggest that facility-level parameters and cost-reductions are of little importance for BECCS investments and upscaling. It is regulatory certainty of operating revenues, e.g., through negative emission markets, that needs to be provided by policymakers.