A new method for producing electricity from carbon dioxide could be the start of a classic trash-to-treasure story for the troublesome greenhouse gas, scientists are reporting.

Described in an article in American Chemical Society (ACS)’s newly launched journal Environmental Science & Technology Letters, the method uses CO2 from electric power plants and other smokestacks as the raw material for making electricity.

Netherlands-based researchers led by Bert Hamelers, PhD, explain that electric power-generating stations worldwide release about 12 billion tonnes of CO2 annually from the combustion of coal, oil and natural gas. Home and commercial heating produces another 11 billion tonnes. Smokestack gas from a typical coal-fired plant contains about 10 per cent CO2, which not only goes to waste, but is a key contributor to global warming. Hamelers’ team sought a way to change that trash into treasure.

They describe technology that would react the CO2 with water or other liquids and, with further processing, produce a flow of electrons that make up electric current. It could produce about 1,570 billion kilowatts of additional electricity annually if used to harvest CO2 from power plants, industry and residences. That’s about 400 times the annual electrical output of the Hoover Dam. Like that dam and other hydroelectric power facilities, that massive additional amount of electricity would be produced without adding more CO2 to the atmosphere, Hamelers pointed out.

It was explained that when  two  fluids  of  different  composition  are  mixed,  mixing  energy  is  released.   This holds true for both liquids and gases, though in case of gas, no technology is yet available to harvest this energy source. Mixing the CO2 in combustion gases with air represents a source of energy with a total annual worldwide capacity of 1,570 TWh. To harvest the mixing energy from CO2 containing gas emissions, the team used pairs of porous electrodes, one selective for anions and the other selective to cations. It was  demonstrated that, when an aqueous electrolyte, flushed with either  CO2 or  air,  alternately  flows  between  these  selective  porous  electrodes,  electrical  energy  is  gained.  The  efficiency  of  this  process  reached  24 per cent for  deionised  water  as  aqueous  electrolyte  and  32 per cent  for  0.25 M  monoethanolamine  (MEA)  solution as  electrolyte.  The highest average power density obtained with a MEA-solution as electrolyte was 4.5 mW/m, significantly higher than for water as electrolyte where the power density is 0.28 mW/m.

The authors acknowledge funding from the Dutch Ministry of Economic Affairs, the European Regional Development Fund, the Province of Fryslân, the City of Leeuwarden, the EZ/Kompas programme of the “Samenwerkingsverband Noord-Nederland” and the European Union Seventh Framework Programme.

The American Chemical Society is a nonprofit organisation chartered by the US Congress. With more than 163,000 members, ACS is the world’s largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, DC, and Columbus, Ohio.