Energy and Climate
Energy and ClimateECAbout ECFacilitiesCenter for Infrastructure Research and Innovation (CIRI)High-Efficiency Solar Thermochemical Reactor for Hydrogen Production

High-Efficiency Solar Thermochemical Reactor for Hydrogen Production

On June 16th, the Department of Energy Fuel Cell Technology Office (FCTO) announced $20 million for 10 R&D projects to advance technologies that can economically produce and deliver hydrogen to power fuel cells from diverse, domestic, and renewable resources thereby enabling substantial reductions in energy use and carbon emissions. Advancing these technologies is critical to the widespread commercialization of fuel-cell electric ve­hicles and other fuel-cell technologies.

The CPR2 technology improves Sandia’s patented reactor design by significantly lowering the thermal reduction step’s pressure, which is key to achieving high extents of oxide reduction and solar-to-hydrogen efficiency. The downward-moving packed bed of particles provides the necessary pressure separation (i.e., gas seal) between thermal reduction chambers. Pressure separation also allows for the vacuum pumping of oxygen from each thermal reduction chamber, thus avoiding the energy-intensive use of sweep gas.

The CPR2 technology improves Sandia’s patented reactor design by significantly lowering the thermal reduction step’s pressure, which is key to achieving high extents of oxide reduction and solar-to-hydrogen efficiency. The downward-moving packed bed of particles provides the necessary pressure separation (i.e., gas seal) between thermal reduction chambers. Pressure separation also allows for the vacuum pumping of oxygen from each thermal reduction chamber, thus avoiding the energy-intensive use of sweep gas.

The Sandia-led project has three main objec­tives:

  1. Develop a 3 kW-scale cascading pressure reactor/receiver (CPR2) designed to pro­duce hydrogen by splitting water in a two-step solar-driven thermochemical cycle.
  2. Develop advanced, redox-active perovskite oxides with physical/chemical properties specifically tailored for use in the CPR2.
  3. Apply knowledge gained from developing the CPR2 and associated materials as a basis for analytically up-scaling a solar thermochemical process to produce 100,000 kg H2/day in a centralized plant.

This project seeks to address the scientific and engineering challenges that must be surmounted to develop large-scale, solar-driven hydrogen produc­tion systems. The project team will leverage (a) years of experience developing and demonstrating concen­trating solar technologies using cutting-edge experimental tools, computational tools, and solar reactor testing facilities specialized for evaluating thermochemical processes operating in very high temperature environments and (b) a Sandia-patented solar thermochemical reactor design that uniquely embodies key, efficiency-enhancing operating principles in a simple and scalable package. Sandia’s transformative design is enabled by using a moving packed bed of particles as the active media.

The team will closely couple material development with reactor design to achieve high solar-to-hydrogen (STH) efficiency in the CPR2. This coupling departs from conventional approaches that focus exclusively on either reactor or redox material. By formulating oxides with chemical and physical properties matched to the thermal and mass-transport characteristics of the CPR2 (and vice versa), they can achieve higher STH efficiency than if either were developed separately. Their search for new materials will focus exclusively on the perovskite oxide family, which were recently demonstrated to outperform ceria, considered the current state of the art.

The final component of this R&D effort will be to use knowledge gained from developing the CPR2 as a basis for generating a detailed design of a 1–5 MW tower receiver. This will provide a realistic size for up-scaling to a multiple-tower, 100,000 kg H2/day centralized plant.

The Sandia-led project team and key participants include

  • Sandia National Laboratories: Drs. Anthony McDaniel, Ivan Ermanoski, and James Miller
  • German Aerospace Center (DLR): Drs. Martin Roeb, Martina Neises-von Puttkamer, and Stefan Brendelberger
  • Arizona State University: Prof. Ellen Stechel
  • Bucknell University: Prof. Nathan Siegel
  • Colorado School of Mines: Profs. Ryan O’Hayre and Jianhua Tong
  • Stanford University: Prof. William Chueh

Ultimately, the project team will demonstrate that a novel and scalable particle-based reactor is capable of meeting long-term DOE/FCTO targets for hydrogen production cost and process efficiency. As this solar thermochemical technology accelerates into the marketplace, it will create jobs, support US clean-energy technology competitiveness, and contribute to a secure and sustainable low-carbon energy future that is encouraged by national, state, and regional policies.

Comments are closed.