A flexible hydrogen-electricity coproduction system through the decoupling of units with different dynamic characteristics

Abstract

Regarding the carbon neutrality target, the proportion of renewable energy in global energy sources is predicted to increase to 50% by 2050, and the increment in penetration requires fossil fuel power plants to play a key role in grid peak regulation. The integrated gasification combined cycle (IGCC) is a promising peak-regulating method for power grids. However, due to the strong coupling between units, the flexibility of gas turbines cannot be fully utilized in response to power demand. This paper proposed a novel polygeneration system integrating syngas storage, hydrogen production, and gas turbines for power. Through syngas storage, the dynamic characteristic of each unit can be decoupled to take advantage of the flexibility of the gas turbine. Compared to the general IGCC system, the load change rate of the new system could be increased from 0.5%/min to 3-5%/min without altering the dynamic characteristics of the original equipment. The design capacity of the syngas storage tank could be reduced by decreasing the ramp rate of the power generation unit or increasing the load change rate of the gasification and hydrogen production units. For the new 300-MW system, the required syngas storage tank capacity reached only approximately 1872 m3 under storage conditions of 35 bar and 25 °C. Furthermore, the investment in the syngas storage tank only accounted for approximately 6.6% of the total investment cost. In general, the novel system can be more flexibly operated under variable loads with low carbon emissions, which can help to increase the penetration of renewable energy in the power grid.