Ethanol as a Liquid Organic Hydrogen Carrier for Seasonal Microgrid Application: Catalysis, Theory, and Engineering Feasibility

In
this work, we describe the benefits and challenges of a green
approach to seasonal energy storage using ethanol as a liquid organic
hydrogen carrier (LOHC). We evaluate the cycling efficiency of hydrogen
release from ethanol (EtOH) to form ethyl acetate (EtOAc) as the spent
LOHC and the subsequent regeneration of EtOH from EtOAc catalyzed
by a single molecular catalyst, Ru-MACHO, at a moderate pressure of
H2, mild reaction temperature, and high selectivity. From
experimental and computational studies, we were able to minimize catalyst
deactivation, regenerate the active catalyst post reactions, and establish
the energy profile of the deactivation pathway relative to the on-cycle
pathway catalyzed by Ru-MACHO. Based upon these findings, we performed
a reactor design analysis to determine the footprint of an EtOH-based
storage system to provide 85 MWh of energy by storing 5 metric tons
(MT) of H2. We conclude that the heating and cooling required
to maintain H2 partial pressure present a significant engineering
challenge for widespread deployment of this system.