Challenges and opportunities for using formate to store, transport, and use hydrogen
In this perspective article, the synthesis and thermodynamic properties of aqueous solutions of formate salts (FS, HCO2−) are described in relationship to the concept of H2 carriers. The physiochemical properties of solid FS, aqueous formate solutions, and aqueous bicarbonate solutions set the limitations for storage capacity, deliverable capacity, and usable H2 capacity of these H2 carriers, respectively. These parameters will help in the design of systems that use H2 carriers for storage and transport of H2 for fuel cell power applications. FS, as well as admixtures with formic acid (FA, H2CO2), have potential to address the goals outlined in the U.S. Department of Energy's H2@scale initiative to store in chemical bonds a significant quantity of energy (hundreds of megawatts) obtained from large scale renewable resources.