Design of biomass power plant integrated with thermochemical heat storage using Ca(OH)2/CaO and evaluation of the flexibility of power generation: Dynamic simulation and energy analysis

In this study, a biomass power plant integrated with thermochemical heat storage (TCS) using Ca(OH)2/CaO particles reacted in a fluidized bed reactor was proposed. In the strategy of power generation, organic Rankine cycle (ORC) was worked by the heat from biomass combustion in normal operation. In charging time, the electricity from the power grid was stored by dehydration reaction in the daytime although the turbine output was not changed, and the amount of biomass combustion decreased compared to normal operation time. In discharging time, the heat from hydration reaction was converted to electricity through the ORC in the evening and the turbine output increased to respond to the increase of the electricity demand. The designed process was evaluated from energy efficiencies and the flexibility of the power generation by dynamic simulation. Results show energy storage efficiency and overall energy efficiency equaled 58.5% and 9.79% (only ORC: 11.4%) for base case, respectively. The energy storage efficiency increased by increasing the heat recovery from steam after a reactor, and it led to the decrease of the biomass combustion in charging time. It was found that the inlet gas flow rate into the reactor had the largest influence on energy efficiencies by changing the parameters such as fluidized bed volume, inlet gas conditions into the reactor, and heat supply into the reactor. In addition, the increase of the turbine output and discharging time were flexibly changed in discharging time by changing operational parameters. Therefore, it is possible to add flexibility to biomass power plants by integrating TCS.

Automated summary

The study proposes a biomass power plant integrated with thermochemical heat storage, using biomass combustion for power generation with an organic Rankine cycle, and storing electricity from the grid via dehydration reaction during charging time. Results showed that energy storage efficiency could be increased by improving heat recovery, with inlet gas flow rate having the largest influence on energy efficiencies. Flexibility in turbine output and discharging time could be achieved by adjusting operational parameters.