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Water-splitting techniques that could fuel industries and cities

The SafeFlame torch could make metal joining much safer. Image: SafeFlame – courtesy of TWI Ltd
The SafeFlame torch could make metal joining much safer. Image: SafeFlame – courtesy of TWI Ltd

New techniques to split water into hydrogen and oxygen are raising hopes of a clean, cheap energy source that could power everything from blowtorches to a city’s electricity supply. 

Researchers on the SafeFlame project are using standard mains electricity to split water into oxygen and hydrogen gases, and then recombining them at the tip of a blowtorch to make a flame. Because their torch generates its own fuel on demand, it removes the need for flammable gases such as acetylene that need to be stored in fuel cylinders and are dangerous to transport due to their explosive nature.

There are many reports of human injuries and deaths due to unsafe transport or storage of acetylene fuel cylinders – particularly when carried in the back of an engineer’s van. ‘A small leak and bang – the gas can be ignited just by opening a van door with a remote key or when turning on the engine,’ said Derek Davies, technical consultant on the EU-funded SafeFlame project, which is set to conclude at the end of October. ‘There are plenty of these stories around.’

‘It’s a new safer flame from water, which is totally different to any of the existing methods of creating a flame for commercial use.’

Derek Davies, technical consultant, SafeFlame

The SafeFlame device is around 20 times cheaper than using a combination of oxygen and acetylene gases, and has lower insurance costs since the risk of explosion is eliminated. This means the technology could be applied to a range of applications that use flames, in industries as diverse as air conditioning, automotive components, glass processing, rail networks and ship building, as well as in scientific laboratories.

Jorge Huete, chairman of the project consortium, said it had achieved ‘fantastic results and prototypes’, which would be of real benefit to people working with flames. 

While so-called water electrolysers that split water into gases that can then be burnt have been around for years, the problem was that they kept the hydrogen and oxygen gas streams together – an unsafe and potentially explosive mixture because of the problem of ‘flashback’ where a flame burns too quickly and is sucked back into the gas supply.

‘It’s a new safer flame from water, which is totally different to any of the existing methods of creating a flame for commercial use,’ said Davies.

Splitting water with light

While SafeFlame uses electrolysis to split water to create a flame, other projects are aiming to mimic the process of photosynthesis and use light to split water in order to capture hydrogen molecules for renewable energies. 

‘Artificial photosynthesis offers a strategy for replacing fossil fuels with clean energy sources,’ said Dr Stefano Fabris, a researcher on the EU-funded H2OSPLIT project, based at the Italian National Research Council’s Institute of Materials.

The ultimate goal of artificial photosynthesis is to efficiently convert the sun’s energy into chemical energy and store it as a fuel. By splitting water, hydrogen molecules can be isolated and then converted into electricity to power everything from your fridge to a city.

The H2OSPLIT researchers used a synthesised group of inorganic, metal-oxide molecules, known as photocatalysts, to promote the chemical reaction of splitting water into hydrogen and oxygen when exposed to light.

In order to work out how to optimise the process, H2OSPLIT’s researchers used complex computer modelling to simulate the behaviour of the atoms and electrons during the process. The project finished in 2013 and their preliminary results have been published in Proceedings of the National Academy of Sciences.

‘The efficiency of plant photosynthesis is very low – think of the time required to grow a tree. To be meaningful for our energy-intensive society, the efficiency of artificial photosynthetic devices should be much higher. At the moment we are still far from this goal, but research is progressing fast,’ said Dr Fabris.

Professor Matthew Rosseinsky, coordinator of the EU-funded PhotoCatMOF project, agrees that it will be some time before this technology can be applied in our everyday lives. ‘Only if the efficiency gets to be high enough and the cost is reduced to be low enough, can the technology be put into practical applications,’ he said.

The PhotoCatMOF project is researching how metal-organic framework materials can help generate hydrogen from water. These materials capture light and are also porous, which promotes the chemical reaction of splitting water into hydrogen and oxygen. Prof. Rosseinsky said the next immediate challenge is to enhance the performance of their materials to produce a higher hydrogen-generation rate.

Although hundreds of photocatalyst materials have been created they are still at the laboratory-test phase. Further research by the PhotoCatMOF project and others is required to improve these technologies, if they are to address the world’s future energy needs.

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