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.

The global Sustainable Development Goals highlight the necessity for affordable and clean energy, designated as SDG7. A sustainable and feasible biorefinery concept is proposed for the carbon-negative utilization of biomass waste for affordable H2 and battery anode material production. Specifically, an innovative tandem biocarbon + NiAlO + biocarbon catalyst strategy is constructed to realize a complete reforming of biomass pyro-vapors into H2+CO (as a mixture). The solid residues from pyrolysis are upgraded into high-quality hard carbon (HCs), demonstrating potential as sodium ion battery (SIBs) anodes. The product, HC-1600-6h, exhibited great electrochemical performance when employed as (SIBs) anodes (full cell: 263 Wh/kg with ICE of 89%). Ultimately, a comprehensive process is designed, simulated, and evaluated. The process yields 75 kg H2, 169 kg HCs, and 891 kg captured CO2 per ton of biomass achieving approx. 100% carbon and hydrogen utilization efficiencies. A life cycle assessment estimates a biomass valorization process with negative-emissions (−0.81 kg CO2/kg-biomass, reliant on Sweden wind electricity). A techno-economic assessment forecasts a notably profitable process capable of co-producing affordable H2 and hard carbon battery anodes. The payback period of the process is projected to fall within two years, assuming reference prices of 13.7 €/kg for HCs and 5 €/kg for H2. The process contributes to a novel business paradigm for sustainable and commercially viable biorefinery process, achieving carbon-negative valorization of biomass waste into affordable energy and materials.

Ensuring access to essential services, such as clean water and electricity, is a key challenge for achieving sustainable development goals in rural areas. This study proposes a novel Brayton-Stirling combined cycle-based cogeneration system for utilizing locally available biomass waste to generate both electricity and clean water. The system employs an externally fired gas turbine, a Stirling engine, and an air–gap membrane distiller. Four operation modes—parallel-powered, fully-fired, straightforward, and by-pass—were modeled for their efficiency and output. Four operation modes can be switched by two three-way valves. Sunflower husk, identified as the most effective biomass source, enabled the system to achieve up to 160 kW of electricity and 0.7 m3/h of freshwater. The electrical and exergy efficiencies of the system peaked in the parallel-power mode, offering a practical solution for enhancing rural sustainability. Moreover, the by-pass mode maximized water production, highlighting its effectiveness in addressing water scarcity along with energy generation. Through a case study, the cogeneration system has demonstrated its capability in satisfying both rural electricity and water demands throughout the day by controlling the combination of different operation modes and parameters. Therefore, it provides a promising solution for advancing rural electrification and water purification in rural areas.

Latent heat thermal energy storage (LHTES) implemented in residential heating systems has attracted attention for its role in peak/load shifting. A novel layout integrating LHTES with a heat pump is proposed to store low grade heat during off-peak demand period, later used as heat source for the heat pump during on-peak demand period. This novel layout is assessed according to different seasons, LHTES height-to-diameter (H/D) ratios, mass ratios of inflow water to radiator return water, and levelized cost of energy (LCOE). The results show that an overall increased amount of power input is required when utilizing LHTES, while it can shift 2.8–3.6 kW electricity from on-peak to off-peak. The case with an H/D ratio of 1.7 shows slight reductions in heating costs and LCOE as compared to a H/D ratio of 0.6. Considering heating costs, a mass ratio of 50 % performs better in December 2022 and a mass ratio of 10 % performs better in January 2023 due to different operating conditions. The heating costs of the integrated system are 1.0 %–2.1 % higher than those of the typical system due to limitations in the rated capacity of the heat pump and lower effectiveness of the shell-and-tube heat exchanger.

Waste incineration with energy recovery is a matured Waste-to-Energy (WtE) technology which has contributed immensely to the disposal and management of Municipal Solid Waste (MSW) in industrialised nations. The adoption of this technology in developing countries is currently gaining momentum due to the numerous benefits that can be derived from its use. In this study, a techno-economic assessment of MSW incineration in proposed waste incineration facilities for use in Ghana was carried out. The technical assessment was conducted by determining the plant capacity and annual electricity production based on the combustible residues of MSW collected from various population sizes in the country, while the economic assessment was carried out by determining two key economic indicators, Net Present Value (NPV) and Levelised Cost of Energy (LCOE). It was found that a total of about 400 MW of electricity can be generated from the total of about 14,000 tonnes of MSW generated in the country daily. The NPV for a 35.81 MW installed capacity of waste incineration facility was found to be USD 166,410,969.24. However, the LCOE for the 35.81 MW capacity and all others considered was greater than the tariff of electricity for their respective capacities, which means waste incineration facilities are not economically viable ventures in Ghana. The implementation of these facilities in the country would, therefore, need governmental support in the form of subsidies and tax rebates. Three locations were proposed for the piloting of waste incineration facilities in the country, and these locations are in the Accra Metropolitan, Asokore-Mampong Metropolitan, and Sekondi-Takoradi Metropolitan Assemblies.

Proper sizing of energy systems is a key aspect that allows avoiding overestimated installation costs or failures in operation and dispatch. However, most of the available sizing tools focus on systems dedicated only to electrical loads, omitting combined energy systems with simultaneous supply of various thermal demands. This study presents an adaptation of an existing open access techno-economic optimization model for broadening the design tool for small-scale energy systems supplying both, electrical and thermal needs. For this, a new typology of an energy system was proposed considering the use of biogas, solar energy and adding thermal components. This was followed by modifying the model framework, constraints equations and objective function, which is the net present cost of the system. Once the design tool was verified a model was constructed to analyse the feasibility of a polygeneration plant for an association of 30 small dairy farms. The developed model was able to optimize the sizing of the main system components for different proposed scenarios, encompassing supply of electricity, refrigeration, biogas for cooking and fertilizers. For the selected application it was found that the aggregated cost of producing electricity and heat ranges from 0.044 to 0.070 USD/kWh; the penetration of solar energy can reach up to 32%; while the annual potential savings of CO2 emissions of applying the solution ranges from 109 to 127 ton of CO2.

The per capita municipal solid waste (MSW) generation per day in Ghana is estimated to be 0.47 kg/person/day, which translates to over 14,000 tonnes of solid waste generation daily. The disposal and management of this amount of solid waste has been challenging worldwide, and in Ghana, this is evident with the creation of unsanitary dumping sites scattered across most communities in the country, especially urban communities. The indiscriminate disposal of solid waste in Ghana is known to cause flooding, the pollution of water bodies, and the spread of diseases. The purpose of this review is to highlight the prospects of waste incineration with energy recovery as a waste-to-energy (WtE) technology which has contributed immensely to the disposal and management of MSW in nations worldwide (especially developed ones). The review indicates that waste incineration with energy recovery is a matured waste-to-energy technology in developed nations, and there are currently about 492 waste incineration plants in operation in the EU, over 77 in operation in about 25 states in the USA, and about 1900 in operation in Japan. Waste incineration with energy recovery is also gradually gaining prominence in developing nations like China, Brazil, Bangladesh, Nigeria, Indonesia, and Pakistan. The adoption of waste incineration with energy technology can reduce Ghana’s overdependence on fossil fuels as primary sources of energy. It is, however, recommended that a techno-economic assessment of proposed waste incineration facilities is performed considering the MSW generated in Ghana. Additionally, it is also recommended that the possibility of incorporating the use of artificial intelligence technology into the management of MSW in Ghana be investigated.

Electricity prices have increased significantly in Europe and other regions due to the recent energy crisis. Latent heat thermal energy storage (LHTES) implemented in residential heating systems has attracted attention for its role in peak/load shifting to reduce heating costs. A new layout with LHTES integrated with a heat pump (HP) is proposed here to store low grade heat during off-peak demand periods, later used as heat source for the heat pump during peak demand periods. This novel layout is assessed for its heat capacity variation and levelized cost of energy (LCOE). The results show that increased amount of power input is required when a storage component is integrated into the heating system, while it can be compensated by shifting to off-peak electricity usage.

Access to electricity in many remote rural areas of the world is wanting and often relies on decentralized concepts that are environmentally detrimental, costly, and unreliable. The purpose of this study was to examine an approach to meet this need that is based on an external biomass-fueled cogeneration system incorporating combined cycles for maximizing efficiency while ensuring robust operation. Specifically, the first and second laws of thermodynamics were analyzed in a system composed of a Brayton-Stirling cycle and a water boiler to compare efficiency, heat and electricity generation under three different power layouts of cogeneration for applications in the range of 100-200 kW electrical power output. The results show that overall efficiency is maximized at 85% with a hybrid power layout for cases where the turbine inlet temperature is 1273 K, the pressure ratio is 0.4, the regenerator effectiveness is 0.95, and the dead volume of the Stirling engine is 0.3. These findings provide a basis for implementing cogeneration systems to improve the reliability and robustness of power systems for rural electrification.

The transition towards sustainable economies with improved resource efficiency is today’s challenge for all productive sectors. The dairy sector in Latin America is growing without considering a clear path for sustainable energy and waste management solutions. This study proposes integrated solutions through a waste-to-energy approach. The solutions consider biogas production (via cow manure) as the main energy conversion pathway; technology solutions include biodigesters, power generators, and combined heat and power systems that supply not only the energy services demanded by dairy farms (for cooking gas, electricity, refrigeration and hot water) but also provide organic fertilizers. Biogas’ potential was estimated to verify whether it can cover the energy demands of the farms, while the levelized costs of producing biogas and electricity were the indicators for the techno-economic evaluation of the solutions. Greenhouse gas emission reductions were estimated by following IPCC guidelines. Specifically, the proposed solutions lead to energy self-sufficiency in most dairy farms with relevant biogas and electricity costs in the range of 1.7–3.7 and 6–12 USD cents/kWh, respectively. In addition, implementing the proposed solutions in Latin American dairy farms would allow annual greenhouse gas emission reductions of 32.8 Mton CO2 eq. with an additional 17 Mton if widespread use of the supplied organic fertilizers is achieved.