Carbon Dioxide Conversion to Ethanol
Most liquid fuels used in transportation today are derived from petroleum and burned in internal combustion engines. These fuels are attractive because of their high energy density and current economics, but they remain partially reliant on imported petroleum and are highly carbon intensive. Domestically produced carbon-neutral liquid fuels (CNLFs), such as ethanol, can address both of these challenges. Typical fuel production processes require huge capital investments and supporting infrastructure, including base-load power to run continuously. Technology enabling the small- and medium-scale synthesis of liquid fuels can move the production of the fuels closer to the consumer, and - if renewable sources are used - the fuels can be produced in a carbon neutral manner. However, significant technical challenges remain in either changing these processes for smaller scale use or developing alternative electrochemical processes for fuel development. New methods would also have to employ variable rates of production to match the intermittent generation of renewable sources. Improvements in these areas could dramatically reduce the energy and carbon intensity of liquid fuel production. By taking better advantage of intermittent renewable resources in low-population areas and transporting that energy as a liquid fuel to urban centers, we can more fully utilize domestically available resources.
Project Innovation + Advantages:
Opus 12 will develop a cost effective, modular reactor to electrochemically convert CO2 to ethanol in one step using water, air, and renewable electricity. Electrochemical reduction of CO2 has been demonstrated in laboratories to produce different fuels and chemicals, but these technologies do not provide efficient conversions and can only be executed in non-economical reactors. The Opus 12 team will integrate its novel cathode layer formulation, containing CO2 reducing catalysts and a polymer electrolyte, into an existing proton exchange membrane (PEM) electrolyzer architecture. Their unique polymer-electrolyte blend used in the cathode catalyst layer acts to minimize competing reactions by controlling the pH at the active sites. Currently, PEM electrolyzers are limited to hydrogen production, but the team's approach expands their use to include high-efficiency ethanol synthesis. PEM electrolyzers are also a well-established technology and integrating them into an existing reactor architecture reduces system capital costs and scale-up risk. PEM electrolyzers can also ramp quickly, allowing the use of intermittent, low-cost renewable electricity. They operate at high current density, leading to a small footprint, and they are operationally simple, with no need for specialized operators on site. The team's system will operate at less than 80°C and near atmospheric pressure with a coproduct of pure oxygen. The team's pilot reactor will be one of the first examples of a PEM electrolysis system used to generate a liquid fuel directly.
If successful, developments from REFUEL projects will enable energy generated from domestic, renewable resources to increase fuel diversity in the transportation sector in a cost-effective and efficient way.
The U.S. transportation sector is heavily dependent on petroleum for its energy. Increasing the diversity of energy-dense liquid fuels would bolster energy security and help reduce energy imports.
Liquid fuels created using energy from renewable resources are carbon-neutral, helping reduce transportation sector emissions.
Fuel diversity reduces exposure to price volatility. By storing energy in hydrogen-rich liquid fuels instead of pure hydrogen in liquid or gaseous form, transportation costs can be greatly reduced, helping make CNLFs cost-competitive with traditional fuels.