Could rust provide an answer to the big energy storage question?

Old bikes and barbecues lying dormant in garages could be covered in stuff that can make large-scale solar energy storage a reality, after researchers found that rust can be transformed into water-splitting solar cell batteries.

Researchers at Stanford University have used rust to create solar cell batteries that can split water into hydrogen and oxygen and store energy for use when the sun isn’t shining. The splitting process is then reversed at night to reclaim energy and dispatch it back into electrical grids.

“We’ve shown that inexpensive, abundant, and readily processed metal oxides could become better producers of electricity than was previously supposed,” said Stanford University’s assistant professor of materials science and engineering William Chueh.

“By combining heat and light, solar water-splitting cells based on metal oxides become significantly more efficient at storing the inexhaustible power of the sun for use on demand. Our results shows that heating up metal oxides with sunlight can double rate of hydrogen generation.”

While silicon solar cells lose efficiency when they heat up, these new ‘rust cells’ become more efficient when exposed to the heat from sunlight. The photons captured by the cells are converted into the electrons at an increased rate, allowing for more oxygen and hydrogen to be formed from splitting water.

Currently, silicon solar cells split water during exposure to the sun and store the energy for use at night. Re-combining the hydrogen and oxygen during the night would reclaim that energy without burning fossil fuels – and the researchers believe that the oxide cells can do this when heated.

Cost-efficiency has been a key stumbling block in the exploration of water-splitting energy storage. Until the Stanford research, it was believed that metal oxides were less efficient as they became hotter which limits their use in water-splitting.

Cheuh says this method not only offers cost-effective, round-the-clock solar storage, but also creates hydrogen gas which could potentially be used to power vehicles and machines on a zero-emissions basis. This could lead to ventures in gas storage and transportation which negates any carbon releases, he says.

Future gazing…

Rust cells join a growing list of innovations that are currently being explored to accelerate a global transition to a low-carbon future.

edie recently reported that Purdue University in Illinois has been conducting tests on ‘hydricity’ – a solar-hydrogen energy hybrid system which has the potential to power cities around the clock. Hydricity combines solar generation with hydrogen production and storage that the researchers claim could rival solar PV systems and energy storage technologies in driving a low-carbon transition.

Meanwhile, Swedish researchers have developed a new paper-like material dubbed ‘Power Paper’ that can store as much energy as market-scale supercapacitors and batteries. And an American solar firm has launched a liquid technology that turns regular windows into solar panels which could be up to 50 times more productive than regular roof-based photovoltaics.

Innovation Zone at edie Live

Like this story? You might be interested in the edie Live Innovation Zone competition, which promotes and supports innovation in the sustainability space.

Taking place within the Innovation Zone at the edie Live 2016 exhibition on May 17-18 at the NEC Birmingham, this year’s Competition is looking for emerging products, technologies and solutions in the sustainability space.

Submitting an entry for the Innovation Zone is free of charge, with the deadline set at 18 March. Read full details of the competition here.

Matt Mace

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