Resource Efficiency

Envergex aims to integrate a flexible, low-temperature CO2 capture system (E-CACHYSTM) into a natural gas combined cycle (NGCC) power plant, capable of operating in a high VRE environment, to attain a net-zero carbon electricity system. The technical approach is based on an innovative multi-phase sorbent technology for post-combustion capture of CO2 from flue gas. The hybrid sorbent technology, which consists of a regenerative sorbent and a novel heat exchange system for optimal energy recovery, seamlessly integrates into the NGCC architecture.

The Massachusetts Institute of Technology (MIT) will investigate the cost-effective design and operation of a negative carbon emissions power plant concept, invented by 8 Rivers Capital, that combines flue gas CO2 capture with a lime-based direct air capture (DAC) process while not affecting power plant flexibility. First, the power plant flue gas is fed into a calciner, a reactor that breaks down calcium carbonate (CaCO3) into lime and CO2. Next, the CO2-rich gas (>30% CO2) from the calciner is separated to recover high- purity CO2, which can be stored.

Colorado State University and its partners—ION Clean Energy, Worcester Polytechnic Institute, and Bright Generation Holdings—will develop a thermal energy storage system with flexible advanced solvent carbon capture technology. The system aims to decrease the levelized cost of electricity for natural gas-fired combined cycle (NGCC) power plants to <75 $/MWh while simultaneously capturing >95% of CO2 emissions when operating in highly VRE penetration markets. The team's approach uses a novel and low-cost heat-pump thermal storage system.

Luna Innovations is developing FlueCO2, a process that enables traditional power generators to respond to increased VRE while reducing greenhouse gas emissions. FlueCO2 is a combined membrane and gas processing technology that integrates into existing natural gas combined cycle power plants and actively removes CO2 from the exhaust gas. The membrane separates CO2 at unrivaled rates using steam generated within the plant. The CO2-rich steam leaving the membranes is processed further to remove the water so it can be regenerated into steam at the most energy efficient conditions.

Georgia Institute of Technology aims to develop a simple, scalable, and modular device that can remove CO2 from the atmosphere. The device will be designed such that ambient wind is sufficient to contact the CO2-laden air with the materials that filter CO2 out. The filtered CO2 will then be concentrated using localized electric heating, which allows the device to be easily deployed and integrated with renewables or the existing electrical grid.

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.