New York, Oct 31 (IANS): In a new twist to waste-to-fuel technology, scientists at the US Department of Energys Oak Ridge National Laboratory have accidentally discovered a process to turn carbon dioxide (CO2), a greenhouse gas, into ethanol, a renewable fuel.

The researchers used tiny spikes of carbon and copper to turn CO2 into ethanol.

"We discovered somewhat by accident that this material worked," said lead author of the study Adam Rondinone.

"We were trying to study the first step of a proposed reaction when we realised that the catalyst was doing the entire reaction on its own," Rondinone noted.

The team used a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process.

With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 per cent, showed the study published in the journal ChemistrySelect.

Typically, this type of electrochemical reaction results in a mix of several different products in small amounts.

"We're taking carbon dioxide, a waste product of combustion, and we're pushing that combustion reaction backwards with very high selectivity to a useful fuel," Rondinone said.

"Ethanol was a surprise -- it's extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst," Rondinone noted.

The catalyst's novelty lies in its nanoscale structure, consisting of copper nanoparticles embedded in carbon spikes. This nano-texturing approach avoids the use of expensive or rare metals such as platinum that limit the economic viability of many catalysts.

Given the technique's reliance on low-cost materials and an ability to operate at room temperature in water, the researchers believe the approach could be scaled up for industrially relevant applications.

"A process like this would allow you to consume extra electricity when it's available to make and store as ethanol," Rondinone said.

"This could help to balance a grid supplied by intermittent renewable sources," Rondinone pointed out.