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Abstract This research investigates the environmental sustainability of three integrated power cycles: combined geothermal-wind, combined solar-geothermal, and combined solar-wind. Here, a promising solar technology, the perovskite solar cell, is considered and analysed in conjunction with another renewable-based cycle, evaluating 17 scenarios focusing on improving the efficiency and lifespan. Among the base cases, combined solar-wind had the lowest ozone depletion impact, while combined geothermal-wind had the lowest freshwater ecotoxicity and marine ecotoxicity impacts. The study shows that extending the perovskite solar cell lifespan from 3 to 15 years reduces CO2 emissions by 28% for the combined solar-geothermal and 56% for the combined solar-wind scenario. The most sustainable cases in ozone depletion, marine ecotoxicity, freshwater ecotoxicity, and climate change impacts are combined solar-wind, combined solar-geothermal, and combined geothermal-wind, respectively, among all evaluated scenarios. This research suggests investing in the best mix of integrated power cycles using established and emerging renewable technologies for maximum environmental sustainability.

Abstract In this paper, a multigeneration cycle of electricity, cooling, and Bitcoin whose energy source is geothermal, has been subjected to energy, exergy, and economic analyses. The cycle under consideration includes the steam cycle (upstream cycle), the carbon dioxide cycle (downstream cycle), and the liquid–gas line to absorb the heat dissipated by the carbon dioxide cycle. In this cycle, the steam cycle condenser acts as the carbon dioxide cycle evaporator. Part of the electricity generated by this cycle is used to generate Bitcoins. Energy and exergy efficiencies at baseline (excluding Bitcoin production) are 45.8% and 38.1%, respectively. In this cycle, if more power is spent on producing Bitcoin as a product, the energy and exergy efficiencies of the cycle are reduced. Because Bitcoin itself is not valuable in terms of energy and exergy. Considering the average price of Bitcoin during the years 2015–2022 and if 100% of the electricity generated by the system is spent on Bitcoin production, the payback period in 2018, 2021, and 2022 when the price of Bitcoin is equal to $13,412.4, $21,398.8, and $47,743.0, respectively, are less than the baseline. Therefore, the production of Bitcoin with a variety of renewable energies can be considered as a solution. Of course, it should be noted that large changes in the price of Bitcoin can affect the issue of economic benefit.

Abstract Various heat pump technologies are examined from an environmental perspective using a life cycle assessment approach. The investigated heat pump systems utilize air, ground, and water as their energy sources. Additionally, an innovative heat pump powered by green hydrogen is investigated in this study, to evaluate its environmental impacts and potential to commercialise on a large scale. A range of supply chain scenarios is explored, considering the main suppliers of the UK market. The reshoring heat pump industry and supply chain are evaluated to enhance energy resilience and security within the UK. The findings indicate that the hydrogen-based heat pump presents a promising option for the UK market, offering the advantages of reducing stress on the national grid network and minimizing the environmental impacts associated with the supply chain. Furthermore, a forecasting analysis is conducted based on the UK's net-zero emission plan to provide insight into future developments.

Poland has significant geothermal water resources and the study presents a list of 29 undeveloped but existing intakes of ready-thermal waters with temperatures ranging from 21 to 86 °C. In this study, important issues related to the hitherto unused intakes of geothermal waters will be discussed in a comprehensive manner: a review has been made with regard to the location of geothermal water resources in Poland, where there are already wells, but not yet exploited – list of all undeveloped geothermal water intakes. Estimated calculations were made for 29 wells, of Thermal Power [MW] and Thermal Energy [GWh/year] and estimated Exergy [kJ/kg] analysis for selected intakes. In the context of air protection, calculations were made related to the estimated reduction of harmful air pollutants, if the geothermal intakes presented in the article were to be used. Presents the results for coagulation for water from a selected geothermal water intake, from which it was possible to remove the total iron content from the water with high efficiency. This is the proposed method of treating geothermal water, supported by the results of the researcher's own research. The thermal energy that these sources can generate amounts to a total of approximately 247.5 [GWh/year]. Moreover, this energy would allow to heat about 8250 single-family houses, covering a total area of 350,000 square meters. The problem of geothermal water quality was discussed and the results were presented after it had been subjected to the coagulation process. Coagulation has been proposed as an effective method to remove undesirable compounds from geothermal water before it enters the installation. A satisfactory total iron removal effect at the level of 99% was obtained thanks to the use of highly polymerized aluminum coagulants in combination with filtration.

Energy, exergy, and exergoeconomic evaluations of various geothermal configurations are reported. The main operational and economic parameters of the cycles are evaluated and compared. Multi-objective optimization of the cycles is conducted using the artificial bee colony algorithm. A sensitivity assessment is carried out on the effect of production well temperature variation on system performance from energy and economic perspectives. The results show that the flash-binary cycle has the highest thermal and exergy efficiencies, at 15.6% and 64.3%, respectively. The highest generated power cost and pay-back period are attributable to the simple organic Rankine cycle (ORC). Raising the well-temperature can increase the exergy destruction rate in all configurations. However, the electricity cost and pay-back period decrease. Based on the results, in all cases, the exergoenvironmental impact improvement factor decreases, and the temperature rises. The exergy destruction ratio and efficiency of all components for each configuration are calculated and compared. It is found that, at the optimum state, the exergy efficiencies of the simple organic Rankine cycle, single flash, double flash, and flash-binary cycles respectively are 14.7%, 14.4%, 12.6%, and 14.1% higher than their relevant base cases, while the pay-back periods are 10.6%, 1.5% 1.4%, and 0.6% lower than the base cases.

This research presents the energy, exergy, economic, and environmental assessment, and multi-objective optimization of a flash-binary geothermal CCHP cycle. A sensitivity analysis of production well inlet temperature and cooling to power flow ratio on exergetic, economic, and environmental parameters was conducted. Furthermore, the effects of the inflation rate and plant working hours on economic parameters were investigated. Results showed that increasing the production well inlet temperature harms exergy efficiency and exergetic performance criteria and results in a gain in exergo-environmental impact index and heating capacity. In addition, the total plant cost increased by raising the production well temperature. Furthermore, increasing the cooling to power flow ratio caused a reduction in exergy efficiency, exergetic performance criteria, and produced net power and an enhancement in exergy destruction, cooling capacity, and total plant cost. The exergy efficiency and total cost rate in the base case were 58% and 0.1764, respectively. Optimization results showed that at the selected optimum point, exergy efficiency was 4.5% higher, and the total cost rate was 10.3% lower than the base case. Levelized cost of energy and the pay-back period at the optimum point was obtained as 6.22 c$/kWh, 3.43 years, which were 5.14% and 6.7% lower than the base case.

A comprehensive cost correlation analysis was conducted based on available cost correlations, and new equipment cost correlation models were proposed based on QUE$TOR modeling. Cost correlations for various types of equipment such as pumps, compressors, heat exchangers, air coolers, and pressure vessels were generated on the basis of extracted cost data. The models were derived on the basis of robust multivariable regression with the aim of minimizing the residuals by using the genetic algorithm. The proposed compressor models for both centrifugal and reciprocating types showed that the Turton cost estimation for carbon steel compressor and Matche’s and Mhhe’s data were compatible with the generated model. According to the results, the cost trend in the Turton correlation for carbon steel had a somewhat lower estimation than these correlations. Further, the cost trend of the Turton correlation for carbon steel pressure vessels was close to the presented model trend for both bullet and sphere types. The Turton cost trend for U-tube shell-and-tube heat exchangers with carbon steel shell and stainless steel tube was close to the proposed heat exchanger model. Furthermore, the Turton cost trend for the flat-plate heat exchanger using carbon steel was similar to the proposed model with a slight difference.