ENVIRONMENT

Repurposing CO2 with the Carbon XPRIZE

Carbon dioxide emissions represent the most dire and immediate threat to our shared environment.
20 September, 2016
47 research teams are now hunting for ways to make something useful out of carbon dioxide (CO2) emissions.
The NRG COSIA Carbon XPRIZE, which is seeking out technologies designed to remove the most CO2 emissions from the environment and harness carbon's potential for good, has announced its Round 1 list of teams competing for the $20 million prize. The 47 teams that entered the XPrize competition come from across Europe, North America, China, and India. They are tasked with creating new CO2 conversion technologies, accelerating their lab testing, and demonstrating their results with a final prototype in real-world conditions, either at a coal-fired power plant or a natural gas power facility.

Among these new solutions is an intriguing possibility under development at Cornell University, one that relies on aluminium to create "a new way of doing chemistry" by converting CO2 into a useful product. Chemical engineer Lynden Archer envisions the process as akin to artificial photosynthesis, in that it creates a chemical reaction to convert carbon that is inspired by the natural processes in green plants.
Archer and his student, Wadji Al Sadat, built a prototype reactor that combines CO2 with aluminium and oxygen to produce oxalates that are useful in industrial applications. Archer, in his July interview with Scientific American, explains that the cell runs on aluminium and air. When the oxygen interacts with an aluminium electrode, it becomes an aluminium superoxide powerful enough to coax the carbon into an aluminium oxalate – in a chemical reaction that generates more electricity than it uses in the process.

Archer's project uses aluminium because the metal is inexpensive and abundant, which is another consideration in finding workable real world solutions. The aluminium manufacturing process also generates CO2, and the metal is consumed in the experimental fuel cell exchanges, but the Cornell scientists are optimistic that their carbon conversion process will offset those CO2 "costs" with net climate impacts, which is key to any carbon conversion solution looking to make a real difference.
Finding the answers to CO2 challenges has seemed elusive to scientists whose theories and projects end up using more energy than they create, obviously failing to deliver any net improvement in CO2 emissions. With the looming specter of climate change impact at the world's door, finding a way to remove CO2 from the environment is imperative. It adds up to 57 percent of all greenhouse gas emissions, whether manmade or naturally occurring, so finding new uses for CO2 without adding more to the atmosphere is, put simply, the entire point of the XPrize contest.
Image: Aljadix
Existing carbon sequestration techniques, like injecting CO2 waste products into depleted oil and gas fields, don't have the capacity for achieving the necessary levels of reduction in the atmosphere. That remains true even as the world shifts to renewable energy sources and away from burning fossil fuels.

Archer, an advisor to the Carbon XPrize contest, is cautious about the Cornell research results because the aluminium-based project has many refinements ahead – and questions about its long-term efficacy – but it is by no means the only game in town. Other entries among competing teams include Aljadix, a Swiss team's effort to make carbon-negative biofuels from microalgae, and Carbon Capture Machine, proposed by a British team at the University of Aberdeen, to create valuable carbonate minerals. As with all entries, the CO2 science is focused on thinking of carbon emissions as an asset, and not just pollution.

The Carbon XPrize semifinalists will be announced on October 15, with the contest itself running through 2020.
Banner image: XPrize.org