(Invited) Benchmarking a Metal Oxide-Based Thermochemical Cycle for Solar Hydrogen Production

It is estimated that growth in global population and continued industrialization of developing countries will double world energy consumption by 2035¹. This rising demand for energy will be largely met by burning fossil fuels, thereby increasing anthropogenic carbon in the atmosphere and fuelling the socioeconomic strife associated with climate change. Developing transformational energy technologies that efficiently and cost-effectively convert solar energy into simple chemical fuels is therefore necessary in order to realize a carbon-neutral, sustainable energy future.

In this talk we will critically assess a two-step, high temperature thermochemical water splitting (WS) cycle powered by concentrated solar energy. This conceptually simple technology, outlined in Figure 1, can theoretically achieve greater solar-to-hydrogen (STH) conversion efficiency than alternative WS routes such as photosynthesis (natural or artificial) or photovoltaic-driven electrolysis². However, many engineering and material science challenges must be overcome to demonstrate economic viability at large scales.

Cost and scalability issues for solar thermal hydrogen production will be addressed within the context of a particle-based solar receiver reactor concept^3–5developed at Sandia through a multi-year research initiative sponsored by the US Department of Energy. Key design principles will be reviewed and create a framework for discussing the synergistic interplay of materials chemistry, reactor design, and system operation necessary for this technology to achieve optimal STH conversion efficiency. The successful implementation of this solar energy conversion technology is predicated on meeting stringent requirements for cost and scalability that are deeply rooted in STH efficiency.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.

(1)   International Energy Outlook 2011; DOE/EIA-0484(2011); U.S. Energy Information Administration, DOE/EIA-0484(2011) | September, 2011.

(2)   Siegel, N. P.; Miller, J. E.; Ermanoski, I.; Diver, R. B.; Stechel, E. B. Ind. Eng. Chem. Res. 2013, 52, 3276–3286.

(3)   Ermanoski, I.; Siegel, N. P.; Stechel, E. B. J. Sol. Energy Eng. 2013, 135, 031002.

(4)   Ermanoski, I.; Miller, J. E.; Allendorf, M. D. Phys. Chem. Chem. Phys. 2014, 16, 8418.

(5)   Ermanoski, I. Int. J. Hydrog. Energy 2014, 39, 13114–13117.