CO2 May One Day Power Our Cars

One way to reduce carbon dioxide – a greenhouse gas – is to capture and sequester it, that is, store the CO2 in geologic formations like abandoned oil fields or salt mines. There is a better solution. Since CO2 contains carbon, the main ingredient of fossil fuels, why not ‘mine’ the CO2 for carbon that could be turned into fuels? This would not only reduce CO2 but also recycle it into needed carbon fuels.

Scientists have known for a long time that it is possible to get carbon from CO2, at least theoretically. The challenge is finding practical and economic ways to do it. Now researchers are developing promising technology to turn CO2 into fuels.

The Department of Energy’s Sandia National Laboratories uses concentrated solar energy to chemically ‘reenergize’ CO2 into carbon monoxide in its ‘Sunshine to Petrol’ project. The CO is then used to synthesize a liquid combustible fuel like gasoline, diesel, and jet fuel. Researchers have already shown proof of concept for their technique. They are now completing a prototype device, called the Counter Rotating Ring Receiver Reactor Recuperator, which uses solar energy to break down CO2. While this isn’t going to produce fuel commercially tomorrow – Sandia researchers say it could be 15 or 20 years before that happens – it is an exciting and important move forward.

In another approach, Los Alamos National Laboratory’s ‘Green Freedom’ technology would extract carbon dioxide from the atmosphere and turn it into fuels. Air would be blown over a liquid potassium carbonate liquid to absorb the CO2, and then the CO2 would be extracted from the liquid and electrochemically separated to turn it into fuel. The Green Freedom system could use existing cooling towers, like those at nuclear power plants, which would eliminate the need to build additional structures for processing large volumes of air.

CO2-to-fuel technology at Carbon Sciences technology is based on natural organic chemistry processes that occur in all living organisms. Here, carbon atoms extracted from CO2 and hydrogen atoms extracted from H2O are combined, creating hydrocarbon molecules using biocatalysts and small amounts of energy. Using advanced nano-engineered biocatalysts, the technology lends itself to very large industrial scale production. The company plans to demonstrate the technology within the next several months with a prototype that can convert a stream of CO2 into an immediately flammable liquid fuel.

In the ELCAT (Electrocatalytic gas-phase conversion of CO2 in confined Catalysts) project, researchers at several European universities have shown the feasibility of gas-phase CO2 conversion in a catalytic process that recycles carbon dioxide into liquid hydrocarbons and alcohols. The technology, which has the potential to cut global CO2 emissions by 5 percent, could be ready for application in a decade.

The University of Nottingham's Centre for Innovation in Carbon Capture and Storage in the UK has successfully completed transforming CO2 into natural gas. The CICCS group has replicated the process in plants, capturing CO2, water, and solar light and transforming it into carbohydrates to create methane.

Unlike technologies being developed for large-scale sources such as powerplants, Georgia Institute of Technology’s research is aimed at CO2 emitted from automobiles, trucks, buses, and industrial diesel power generators, which produce nearly two-thirds of global carbon emissions.

Initially, GTRI is developing the technology only to eliminate CO2 emissions. Rather than combusting the fuel, an onboard fuel processor separates the hydrocarbon fuel into hydrogen and carbon. The hydrogen is used in an internal combustion engine or fuel cell, while the carbon is stored onboard in a liquid form until it is disposed of at a refueling station. It is then transported to a centralized site to be sequestered.

A hydrogen-fueled vehicle is used because pure hydrogen produces no carbon emissions while powering the vehicle. Not combusting the hydrocarbon fuel means highly diluted carbon dioxide emissions, which are very difficult to capture in vehicles or other small systems, are never produced. The system’s fuel processor, the CO2/H2 Active Membrane Piston (CHAMP) reactor, has been developed.

The eventual goal is to use a processing plant to transform the recovered CO2 into liquid fuel that could be used in vehicles, thus completing the cycle. Using an onboard reformer to produce hydrogen from either carbon-containing liquid fuels, either fossil or synthetic, overcomes the lack of a hydrogen infrastructure since the liquid carbon-based fuels would use existing pipelines, tanks, and filling stations.