(319b) Efficient Solar Thermal Hydrogen, Electricity and Fresh Water Coproduction Process Synthesis

Authors: 
Gençer, E., Purdue University
Agrawal, R., Purdue University
Global population growth, increase in per capita GDP and change in consumption habits create increasing pressure on food, energy and water (FEW) supply. For the past century, with lower FEW needs and abundant fossil resources, energy, chemical, fertilizer and even fresh water supply via desalination have been predominantly dependent on limited fossil resources. However, concerns regarding limited fossil fuel reserves and increasing greenhouse gas (GHG) emissions from fossil fuels accelerate advancements and implementation of renewable energy conversion processes. Among these alternatives, solar energy conversion processes are particularly prominent because of sunâ??s tremendous potential [1]. Yet intermittencies and land availability constraints for solar energy collection are the grand challenges for solar energy conversion technologies and demand high conversion efficiency and synergistically integrated energy storage solutions [2-3]. Recently, it has been shown that hydricity concept, synergistic solar thermal hydrogen and electricity coproduction, presents a potential solution for continuous and efficient power supply and also an exciting opportunity to envision and create a sustainable economy to meet all the human needsâ??namely, food, chemicals, transportation, heating, and electricity [1].

Here, we introduce an integration strategy for the coproduction of fresh water, hydrogen and electricity from concentrated solar thermal energy and present potential impacts of the proposed system on FEW nexus. The integration of solar thermal power production and solar thermal hydrogen production techniques reduces the exergy losses associated with each one of the systems and thus provide an efficient solution. Solar conversion processes are evaluated based on the process exergy efficiency that refers to the fraction of incident solar exergy that is directly recovered as the net exergy output, which is defined as the sum of electricity and the hydrogen exergy output.

The proposed efficient solar trigeneration process presents: i) a continuous power and fresh water supply solution that can achieve high solar conversion efficiencies when combined with the proper hydrogen power cycle and ii) numerous opportunities in chemical industry, transportation sector and in particular in food production via continuous supply of fresh water for irrigation and fertilizer production from coproduced hydrogen. Coproduced products can supply all FEW needs especially in the case of production of fertilizers from the coproduced hydrogen. [1] Gençer E, Mallapragada DS, Marechal F, Tawarmalani M, Agrawal R. Round-the-clock power supply and a sustainable economy via synergistic integration of solar thermal power and hydrogen processes, Proceedings of the National Academy of Sciences (PNAS), 112(52), 15821-15826, 2015.

[2] Gençer E, Al-musleh E, Mallapragada D, Agrawal R. Uninterrupted Renewable Power through Chemical Storage Cycles. Current Opinion in Chemical Engineering, 5, 29-36, 2014.

[3] Gençer E, Agrawal R. A commentary on the US policies for efficient large scale renewable energy storage systems: Focus on carbon storage cycles, Energy Policy, 88, 477-484, 2016.