In the context of the carbon peaking and carbon neutrality goals

coal-fired power generation is a crucial “ballast” to ensure energy security. However

it also faces the challenges of high emissions and low energy efficiency. Therefore

the development of high-efficiency

low-carbon coal-fired power generation technologies has become an urgent priority. This paper innovatively proposes a semi-closed thermodynamic cycle with coal and CO2 synergistic conversion. On the heat source side

coal is gasified into CO-rich syngas in a CO2 atmosphere. The syngas is then burned with pure oxygen and directly heats the circulating working CO2，so as to reduce the irreversible energy losses of the chemical energy release process. On the cycle side

the semi-closed supercritical CO2 cycle is adopted to generate electricity efficiently. The combustion products are then directly separated and stored at the cold end of the cycle to achieve zero carbon emissions. Results show that the net power generation efficiency of the basic cycle is 48.72% with the fuel utilization efficiency and thermal power conversion efficiency are 97.86% and 60.87%

respectively. Furthermore

based on the exergy destruction and loss distribution

the recompression is carried out and optimized

reducing the recuperator exergy destruction by 49.18%

and the net efficiency soars to 51.31%. Compared with a typical 330 MW coal-fired power generation system

in the semi-closed cycle

the exergy destruction and loss of fuel conversion is reduced by 46.80%

which is more than the exergy destruction increase resulted from the air separation for oxygen production

compression power consumption

and other processes. As a result

the total exergy loss of the system is reduced by 12.31%. The semi-closed CO2 power generation cycle constructed in this paper provides important theoretical and technical support for the low-carbon transformation of coal-fired power generation.