Search Results (3)

Coal constitutes China’s most significant resource endowment at present. Utilizing coal resources for hydrogen production represents an early-stage pathway for China’s hydrogen production industry. The analysis of energy quality and carbon emissions in coal gasification-based hydrogen production holds practical significance. This paper integrates the exergy analysis methodology into the traditional LCA framework to evaluate the exergy and carbon emission scales of coal gasification-based hydrogen production in China, considering the technical conditions of CCUS. This paper found that the life cycle exergic efficiency of the whole chain of gasification-based hydrogen production in China is accounted to be 38.8%. By analyzing the causes of exergic loss and energy varieties, it was found that the temperature difference between the reaction of coal gasification and CO conversion unit and the pressure difference due to the compressor driven by the electricity consumption of the compression process in the variable pressure adsorption unit are the main causes of exergic loss. Corresponding countermeasures were suggested. Regarding decarbonization strategies, the CCUS process can reduce CO₂ emissions across the life cycle of coal gasification-based hydrogen production by 48%. This study provides an academic basis for medium-to-long-term forecasting and roadmap design of China’s hydrogen production structure. Full article

This paper aims to evaluate the feasibility and performances of a novel hybrid solar–gas system, which provides electric power and cooling. By using Ebsilon (V15.0) software, the operation, advanced exergic and economic analyses of this hybrid system are conducted. The analysis results show that the total electric power and energy efficiency of the hybrid system are 96.0 MW and 45.8%. The solar energy system contributes an electric power of 9.0 MW. The maximum cooling load is 69.66 MW. The exergic loss and exergic efficiency of the whole hybrid system are 119.1 MW and 44.6%. The combustion chamber (CC) has the maximum exergic loss (56.5 MW). The exergic loss and exergic efficiency of the solar direct steam generator (SDSG) are 28.5 MW and 36.2%. For the air compressor (AC), CC, heat recovery steam generator (HRSG) and refrigeration system (CSS), a considerable part of the exergic loss is exogenous. The avoidable exergic loss of the CC is 11.69 MW. For the SDSG, there is almost no avoidable exergic loss. Economic analysis shows that for the hybrid system, the levelized cost of energy is 0.08125 USD/kWh, and the dynamic recycling cycle is 5.8 years, revealing certain economic feasibility. The results of this paper will contribute to the future research and development of solar–gas hybrid utilization technology to a certain extent. Full article

Hydrogen is a clean secondary energy source that plays an important role in promoting the region’s low-carbon energy mix transition. Currently, most of the evaluations of hydrogen production technologies in terms of energy consumption focus on energy efficiency, and fewer studies have been conducted at the level of exergy. In this paper, we use the life-cycle approach and the energy quality coefficient method to assess and discuss the exergic efficiency of three technology routes, namely hydrogen production from natural gas, propane dehydrogenation, and hydrogen production from green electricity, which were carried out in China. Hydrogen production from natural gas was found to have the lowest exergic efficiency, with exergic losses mainly from the compression process, high-temperature chemical reactions, and reduced catalyst activity. Propane dehydrogenation was found to be about 16% more exergic efficiency than natural gas to hydrogen, with exergic losses mainly from compression. Hydrogen production from wind power has the highest exergic efficiency, with exergic losses mainly due to the electricity required to run the electrolyzer. By analyzing the changes in energy consumption and exergy consumption of China’s future hydrogen supply, this paper found that the energy consumption per unit of hydrogen production will decrease to 9.2 kg of SC/kg of H₂ and the exergy consumption per unit of hydrogen production will decrease to 9.6 kg of SC/kg of H₂ in 2030. The exergic efficiency of the hydrogen production process in China will be further improved as the proportion of hydrogen production from electrolytic water in the hydrogen production structure increases. Full article