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Exciting Discovery

Paul Kando

Last year, from a pre-industrial 280 parts per million (ppm), the atmospheric CO2 level rose to 400 ppm – a level last seen 800,000 years ago – and Earth’s average temperature is 1.6°F higher than it was century ago. Therefore, it is welcome news that scientists at Oak Ridge National Laboratory (ORNL) have developed an electrochemical process that turns carbon dioxide into ethanol fuel.

Electron-microscopic image of a catalyst made of
copper nanoparticles (the spheres) embedded in
carbon nanospikes that can convert carbon dioxide
into ethanol.
photo credit: Oak Ridge National Laboratory

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

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

In common parlance “catalyst” refers to something that causes activity between two or more persons or forces without itself being affected; or to a person that precipitates an event or change. In chemistry, a catalyst is a substance that causes or accelerates a chemical reaction without itself being affected. Nanoscale refers to technology executed on the scale of less than 100 nanometers, the goal of which is to control individual atoms and molecules. A nanometer is one-billionth of a meter (3.93701 x 10-8 inches).

Initial analysis suggests that the spiky textured surface of the catalyst provides ample reactive sites to facilitate the carbon dioxide-to-ethanol conversion. The spikes are like 50-nanometer lightning rods that concentrate electrochemical reactivity at their tips.

Given the technique’s reliance on low-cost materials and an ability to operate at room temperature in water, ORNL researchers believe it could be scaled up for industrial applications, where it has the potential of turning a dangerous waste product into a useful, green fuel. In transportation, for example, ethanol can substitute for petroleum, with virtually no engine modifications required.

Last year, for the first time, renewable energy accounted for more than half of new power generation worldwide. In the next five years, China and India alone will account for almost half of global renewable capacity additions. Yet renewable energy is likely to provide only about a fourth of the world’s electricity by 2021, in part because the intermittent nature of solar and wind energy challenges power grid integration.

The new nanoprocess could also be used to store excess electricity generated from variable power sources such as wind and solar, without relying on batteries and exotic materials. It could allow extra electricity, when it’s available, to be stored indefinitely as ethanol, which could be burned as a fuel later. This could help balance an electric power grid supplied by intermittent renewable sources.

Exciting, hopeful news indeed.