Resource Efficiency

Hydrolytic softening is a lower-cost process to remove CO2 from the oceans. It has similarities to processes at conventional water treatment facilities, which mix hydrated lime to “soften” water by precipitating dissolved inorganic carbon as calcium carbonate. In hydrolytic softening, however, instead of a consumptive use of lime, the calcium carbonate is decomposed. This releases CO2 gas for sequestration or industrial use and regenerates the lime for continued cycles of carbon removal.

The Massachusetts Institute of Technology proposes to use electrochemical modulation of a proton gradient within electrochemical cells to initially release the CO2 in seawater, and then to alkalize the water before it is returned to the ocean. This battery-like electro-swing approach does not require expensive membranes or addition of chemicals, is easy to deploy, and does not lead to formation of byproducts. Innovative electrode configurations will be employed to reduce overall transport and electrical resistances while still enabling large quantities of water to be treated efficiently.

The University of Michigan, in collaboration with the University of Massachusetts Amherst, will develop a technology that captures CO2 from the atmosphere using an electrochemical approach, rather than the temperature swing cycle which is typically powered by fossil fuel combustion. The team’s concept is a pH swing cycle that changes conditions between basic and acidic to capture and release CO2, respectively. Direct air capture (DAC) of CO2 by inexpensive renewable electricity could reduce the cost and improve the efficiency of DAC.

The University of Pittsburgh’s team will develop a hybrid plant model consisting of a natural gas combined cycle (NGCC) power plant coupled with membrane and sorbent carbon capture systems. During peak hours, the NGCC plant produces power, and the two sequential carbon capture systems capture roughly 99% of the CO2 produced by the combustion of natural gas. During off-peak hours, the NGCC plant powers the two carbon capture systems to capture the CO2 from the air, as well as capturing all the CO2 produced by the plant.

The Georgia Institute of Technology (Georgia Tech) will develop a modular direct air capture (DAC) process to be integrated with flexible natural gas-fired combined cycle (NGCC) power plants. This approach couples CO2 emissions capture from the NGCC plant using conventional technology with a novel design based on materials capable of removing CO2 from the air. The NGCC plant will run continuously, and the conventional technology will perform at its most efficient level. Steam and power from the natural gas plant are directed to remove CO2 from the atmosphere in times of low demand.

The National Renewable Energy Laboratory (NREL) will adapt an existing, rigorous multiscale electricity modeling platform to evaluate carbon capture and sequestration and negative emissions technologies from the ARPA-E FLECCS program. NREL’s platform includes the Regional Energy Deployment System (ReEDS) electric sector capacity expansion model, which projects future electricity generation mixes at sub-state geographic resolution.

Los Alamos National Laboratory (LANL) seeks to increase the efficiency with which oil and gas are extracted from unconventional reservoirs while reducing the environmental impact of such processes. Current hydrofracturing-enabled extraction efficiencies are only 5 to 10%. LANL seeks to improve upon these levels by developing physics-informed machine learning (ML) based models from field data to discover effective well design characteristics.

Susteon will evaluate a CO2 capture technology using solid sorbents based on thermal swing adsorption that enables power generators to operate the power plant in a "load following" mode in response to grid conditions in a high VRE penetration environment. The proposed capture technology, based on novel structured adsorbents incorporating advanced nanomaterials, is currently being demonstrated with flue gas derived from natural gas combustion.