EAGER: CET: Can Carbon-Negative Hydrogen Production be Self-Sustained in the Earth's Subsurface?

Texas Tech University, Lubbock TX

Investigators

Abstract

This EArly-concept Grants for Exploratory Research (EAGER) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Hydrogen (H2) is one of the cleanest potential energy sources as only water is generated when it is consumed. As of 2022, the global hydrogen demand is 95 Mt, while it will increase to be more than 500 Mt by 2050 to reach net zero according to the International Energy Agency. However, the current hydrogen production technologies, such as water electrolysis and steam methane reforming (SMR), are either too costly or emits too much greenhouse gases (i.e., methane and carbon dioxide, CO2). For example, the SMR process generates about 9-10 kg CO2e/kg H2. Therefore, carbon-negative hydrogen production technology is needed to simultaneously provide low-cost hydrogen energy and sequestrate CO2. Through this interdisciplinary project scientists from Texas Tech University advance clean energy technologies by developing a new, high-risk carbon-negative hydrogen production approach from the reactions of iron-rich rocks and water in the Earth's subsurface. The ‘cost-free’ geothermal energy and heat generated by exothermic reactions will be leveraged to sustain the hydrogen production for extraction; in particular, this innovative technology may enable a new clean hydrogen source with a cost lower than blue/green H2. Simultaneous CO2 injection will also tackle climate change by permanently locking CO2 as carbonate minerals. This interdisciplinary research will improve the fundamental understanding of the involved geochemistry, geophysics, heat transfer, and fluid flows from pore to reservoir scales. Additionally, a planned one-day ‘Clean Energy and Hydrogen’ workshop aims to enhance middle school girls’ interests in clean energy, while the integration of the research outcomes into an undergraduate course will transform students’ skills from petroleum engineering to clean geo-energy. The principal investigators investigate a potentially transformative approach to initiate and stimulate the in-situ, carbon-negative H2 production via serpentinization reactions of olivine-rich rocks and water. CO2 is co-injected with water to achieve carbon-negative H2 production. Assessing and deciphering the self-sustainability of this carbon-negative hydrogen production process over the human time scale is at the center of the project. A synergistic combination of rigorous core-scale reactive percolation experiments, advanced characterization, and numerical modeling are performed. More specifically, the principal investigators characterize the physicochemical and geomechanical coupling between reactions, fluid transport, and evolution of rock properties. The new data, knowledge, and insights obtained at the core scale are integrated into the reservoir-scale assessment of the self-sustained H2 production process by both analytical approaches and thermal-hydro-mechanical-chemical modeling. This work is expected to yield unprecedented understanding of the fundamental mechanisms and build a necessary framework for the game-changing innovation in large-scale, low-cost, and in-situ carbon-negative H2 production. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.