Solar-powered gas converter could shine a light on energy research

31 Jul 2017

Image: Polamaii/Shutterstock

Most of the fuel produced or used on Earth is damaging the planet, which is why a new solar-powered carbon monoxide converter could be big.

Renewable forms of energy are becoming more and more important as fossil fuels run out, the planet feels the effect of overusing its finite resources, and power requirements soar.

It’s why wind and solar farms are becoming such big business, or why wave after wave of investment is put into tidal research.

Future Human

And it’s also why a new discovery in the US and Singapore could lead to an energy revolution.

Scientists at the US-based Lawrence Berkeley National Laboratory (Berkeley Lab) and Nanyang Technological University (NTU) in Singapore have teamed up to find a new use of solar power.

They have developed a light-activated material that can chemically convert carbon dioxide (CO2) into carbon monoxide (CO) without generating unwanted byproducts.

When exposed to visible light, the material, a “spongy” nickel-organic crystalline structure, converted the CO2 in a reaction chamber exclusively into CO gas, which can be further turned into liquid fuels, solvents and other useful products.

A big deal

“We show a near 100pc selectivity of CO production, with no detection of competing gas products like hydrogen or methane,” said Haimei Zheng, co-corresponding author of the study published in Science Advances.

“That’s a big deal. In carbon dioxide reduction, you want to come away with one product, not a mix of different things.”

Researchers have for a long time been looking into eliminating competing chemical reactions in the reduction of CO2.

Zheng and her team dissolved nickel precursors in a solution of triethylene glycol and exposed the solution to an unfocused infrared laser, which set off a chain reaction in the solution as the metal absorbed the light.

The resulting reaction formed metal-organic composites that were then separated from the solution.

The latest study is one in a long line of attempts to convert CO2 into an energy source, potentially harvesting the planet’s atmospheric CO2 and using chemistry to create a cycle of power generation.

Batteries and graphene

In February, for example, researchers from Pennsylvania State University developed a rechargeable battery called a flow cell, which can be recharged with a water-based solution containing dissolved CO2.

Sourced from fossil fuel power plants, the device works by taking advantage of the CO2 concentration difference between CO2 emissions and ambient air, which can ultimately be used to generate electricity.

In the team’s paper published in Environmental Science & Technology Letters, the CO2 and ambient air are dissolved in separate containers of an aqueous solution, in a process called sparging.

Meanwhile, last December, researchers found a way to harness graphene to make it convert CO2 into liquid fuels.

Using a single one-atom-thick sheet of graphene, the Rice researchers split it into small dots just a few nanometres in width. On their own, they do nothing to alter the surrounding air but when nitrogen is introduced, the resulting chemical reaction turns it into an electrocatalyst.

However, why exactly the chemical reaction of the nitrogen and carbon is able to turn CO2 into liquid fuels remains something of a mystery.

“The world right now is in need of innovative ways to create alternatives to fossil fuels, and to stem the levels of excessive CO2 in the atmosphere,” said Zheng of the newest study.

“Converting CO2 to fuels using solar energy is a global research endeavour. The spongy nickel-organic photocatalyst we demonstrated here is a critical step toward practical production of high-value multi-carbon fuels using solar energy.”

Gordon Hunt was a journalist with Silicon Republic