Protein generates electricity from the air – New Scientist

Simply ‘sucking’ energy from the air could be possible in the future, Australian scientists say. They discovered an enzyme that generates electricity using hydrogen from the atmosphere.

Removing electricity from the air seems like a dream. However, it is not impossible. This is already happening in nature. Some bacteria appear to be able to use air as a ‘food source’ and convert hydrogen, which occurs in very small quantities as a molecule in the atmosphere, into energy. They mainly apply this trick in places where few other nutrients are available, such as at great depths in the sea, at the South Pole or in volcanic craters. It was not known for a long time how exactly these bacteria manage to do this.

Australian scientists now have a particular type of bacteria, the soil-dwelling ones Mycobacterium smegmatissubjected to further investigation. They discovered that the organism produces various proteins that can generate electricity from hydrogen.

The team was able to isolate one of these proteins, an enzyme called Huc, from the bacteria. Using advanced microscopes, they revealed its structure and function. The results were published last week in the scientific journal Nature.

Efficient energy maker

The enzyme appears to have some surprising properties. This makes it very efficient: even at extremely small concentrations of hydrogen in the air – so small that the researchers could no longer measure them even with their most sensitive detectors – Huc was still able to ‘capture’ hydrogen particles and produce a stream with them.

In addition, the enzyme also works properly outside the bacteria. It is also very stable there: Huc continues to generate electricity at temperatures between 80 and -80 degrees Celsius and can be stored for a long time.

“Overall, Huc is much more stable and works much more efficiently than we had hoped,” said study leader Rhys Grinter of Melbourne’s Monash University. “That’s one of the things that makes this story so exciting.”

Rosy future

Thanks to its favorable properties, the scientists foresee a bright future for the enzyme as an important component of a ‘natural battery’. A layer of Huc could power devices with electricity literally falling from the sky.

This means that it can make a chemical battery, a solar panel or a way of generating electricity with fossil fuels superfluous. ‘Then you may be able to power devices that require a small but continuous amount of electrical current, such as a watch or a simple computer circuit,’ says Griinter.

At least, if only ‘normal’ air from the atmosphere is available. ‘When the protein is supplied with concentrated hydrogen, it produces more electricity. In that case, we see opportunities to include it in fuel cells for larger devices, such as a smartphone or even an electric car.’

Wishful thinking

The necessary steps still need to be taken for this, Griinter notes. ‘At the moment we can only produce a few milligrams of Huc – which is sufficient for experiments. For applications in electronics, we want to scale up production to grams and eventually kilos. We are trying to do that, for example, by adapting the bacteria in such a way that they produce more Huc.’

Will the enzyme therefore play a major role in the devices of the future? Microbiologist Nico Claassens of Wageningen University and Research, not involved in the study, is sceptical. ‘The researchers’ ideas sound a bit like wishful thinking. With the total amount of hydrogen in the air in a normal room, Huc can run an LED lamp for roughly half a minute. I think it is especially useful for small devices in places where fuel is scarce, such as on mountain tops or in polar regions. Just as bacteria only use it in extreme places.’

He also does not see applications in fuel cells, with the supply of concentrated hydrogen, getting off the ground immediately. ‘Huc will not soon take the place of the metals that currently convert hydrogen into electricity. Although these metals are expensive and rare, they probably work much faster than the enzymes.’

Fascinating

Nevertheless, Claassens is enthusiastic about the research result. ‘It is unique that the researchers reveal the functioning of this enzyme with such precision. It is fascinating that we now understand how these bacteria can survive using air as an energy source.’

He also believes that Huc can be useful in another way. ‘In the future, hydrogen will become an important fuel. Because Huc is so incredibly sensitive to this, it can work very well as a sensor for leaking hydrogen. This prevents the amount of hydrogen in the atmosphere from increasing – the gas makes a very small contribution to the greenhouse effect – and above all you prevent unnecessary fuel loss,’ says Claassens.