Fusion energy is widely regarded as a promising solution for clean and sustainable power generation. However, efficient thermal-to-electric conversion remains a challenge for its practical applications.

A research team led by Prof. GUO Bin from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences developed a novel power conversion strategy which utilizes divertor heat as a preheating source in the feedwater system, significantly improving the thermal-to-electric efficiency of fusion power plants. The study was published in Energy.

Researchers proposed an advanced steam Rankine cycle for the steady-state China Fusion Engineering Test Reactor (CFETR) fusion power plant. They introduced a new thermal integration concept which systematically incorporated the divertor heat into the regenerative feedwater heating process, enabling effective use of low-temperature heat often discard as low-grade energy.

The optimized Rankine cycle system achieved a thermal efficiency of 35.36%, about 3% higher than traditional blanket-based Rankine cycles, showing that combining divertor heat recovery with a reheat stage significantly improved the overall performance of the system. The optimal steam inlet temperature and turbine isentropic efficiency were identified as 490 °C and 92%, yielding a turbine exergy efficiency of 87.23%.

Benchmark comparisons with Demonstration Power Plant (DEMO)-scale fusion plants showed good agreement, with deviations of around 2%, confirming the reliability of the proposed system design.

By enhancing heat utilization and reducing energy losses, this strategy provides an effective way to integrate multiple heat sources in fusion systems, provide a way for more efficient and economically viable fusion power. "Our study provides a feasible solution for improving the operation of the CFETR power conversion system," said Prof. GUO.