(176a) High Efficiency Solar Thermal Power and Integrated Chemical Storage Cycles for Continuous Grid Power Supply

Gençer, E., Purdue University
Marechal, F., École Polytechnique Fédérale de Lausanne
Mallapragada, D., Purdue University
Tawarmalani, M., Purdue University
Agrawal, R., Purdue University

Limited fossil fuel reserves and increasing greenhouse gas (GHG) emissions from fossil fuels make it necessary to develop alternative renewable energy sources to meet energy needs. Advancements in renewable power production are especially important since electric power is the largest consumer of primary energy resources with the highest growth rate among alternate energy use sectors, and is currently responsible for >40% of the global CO2emissions. Among the renewable energy sources, solar energy is prominent due to its abundance. Yet intermittencies and land availability constraints for solar energy collection are the grand challenges for solar thermal power generation and demand a high efficiency solar power generation cycle that synergistically integrates energy storage.

Here, we introduce new alternative processes that produce and store solar thermal power efficiently to enable for round-the-clock power supply.  Solar power production processes are evaluated based on the process sun-to-electricity (STE) efficiency that refers to the fraction of incident solar energy that is directly recovered as the net electricity output. The second metric of interest is the overall sun-to-electricity (OSTE) efficiency. It is the net STE efficiency averaged over 24 hours, i.e. accounting for energy storage and delivery of the stored energy while solar energy is not available.  

The novel solar thermal power cycle has a potential to generate electricity with STE efficiencies greater than 30% at low solar heat collection temperature. The cycle also promises STE efficiencies greater than 40% for the high solar heat collection temperatures.

For the cases with higher solar heat collection temperatures, the solar water with reheat power cycle is modified by coproducing chemicals for storing energy from solar irradiation. When solar energy is not available, we propose the use of the same power cycle. This is achieved by addition of combustors that burn the stored chemicals to provide the high temperature heat. The overall sun-to-electricity efficiency of a twenty-four hour cycle is estimated to be greater than 30%. In summary, we propose a thermodynamic cycle that has the potential to generate uninterrupted electricity for grid distribution around the clock at GWh levels.