The above-ground strategies to approach the goal of geothermal power generation in China: State of art and future researches

Geothermal power generation (GPG) is a technology that need to be promptly developed due to the high capacity factor and the low environmental impacts. In the year of 2020, as the pivotal juncture of China's 13th Five-Year Plan, it is necessary to summarize the GPG history of China in the past 60 years and comprehend its technological status to secure a promising future of the GPG in China. In this regard, this paper aims to reveal the challenges, opportunities and outlooks of GPG technologies in China from the perspective of the above-ground strategies. The possibility of realizing the planned GPG goal in 2020 in China was firstly discussed. In addition, a technical analysis was done to obtain the main technical obstacles, including the poor energy endowment of the geothermal resources and the immature technology of GPG systems. It is evident that the poor matching between the geothermal fluid and the adopted thermal power cycle hinders the development of GPG, especially for the technologies using the organic Rankine cycle(ORC). Nevertheless, there are many opportunities for improving the level of GPG in China, which may be based on transforming abandoned oil wells into geothermal wells, exploiting dry hot rocks, or developing multi-energy complementary systems. Except for the above, by interpreting the experimental research and the energic, economic and environmental optimization of ORC-GPG systems worldwide, crucial recommendations are provided for the promotion of the GPG technologies in China. These include the performance decoupling based on thermodynamic process, multi-objective optimization based on Pareto's non-inferior solution, comprehensive utilization based on cascading principle, environmental impact assessment based on life cycle assessment, as well as experimental studies on Flash-ORC.