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Secret to 100% renewable energy system?

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Buildings are blanketed in heavy smog in China’s capital, Beijing, earlier this month. A new study says part of China’s pollution can be attributed to the manufacture of goods for export. XINHUA

By turning renewable electricity into fuel, power-to-X could free transport, heating and industrial process from fossil fuels, once costs fall.

Around the world, more and more electricity is being generated from the sun and wind. The technology has advanced massively over recent decades and the price of renewable power is plummeting.

But if we look beyond the power sector at our overall energy consumption, renewables are still only a bit player. Heating, transport and industrial processes are still dominated by fossil fuels and many of these systems can’t run on electricity; they need fuel.

That’s where power-to-X (also referred to as P2X or PtX) comes in. An umbrella term, it covers various processes that turn electricity into heat, hydrogen or synthetic fuels, meaning that ever-more of our energy system might say goodbye to coal, oil and natural gas.


Turning power into hydrogen


Power-to-X could also solve another of the energy transition’s biggest hurdles: storage. At the moment, wind turbines in northern Germany, for example, sometimes produce so much power they have to be disconnected from the grid to prevent it from overloading.

Instead, that excess power could be used to split water into oxygen and hydrogen, through electrolysis. Not only can hydrogen be stored and saved for less blustery days, it can be used to heat buildings, manufacture steel, or go into fuel cells for trucks and ships.

Once you’ve got your hydrogen, in fact, the possibilities go on. Through a process that adds carbon dioxide, you can then produce synthetic kerosene, petrol or diesel. “Power-to-liquid”, as this is known, can also be used to manufacture various chemicals.

The technology itself is actually nothing new – during the Second World War, Germany produced large quantities of synthetic kerosene for its air force. Now, as we look for ways to do without fossil fuels, it’s having a renaissance and several demonstration plants have been built, mainly in Europe.

The CO2 needed to make these fuels can be filtered from the emissions from coal-fired power, cement, or biogas plants – or, better still, for a carbon-neutral world, direct from the air.


Bringing down costs


In 2017, Swiss company Climeworks opened a commercial plant with huge absorber fans that suck around 900 tonnes of CO2 from the air every year. The company says this currently costs around 550 euros per tonne of CO2 – although experts say with greater demand, prices could fall as low as 50 euros per tonne by 2050. There are now 14 such plants in Europe and more are on the way.

Right now, high costs are probably the biggest barrier to power-to-X covering ever-more of our energy needs. Most hydrogen is still produced from crude oil and natural gas, which is a good deal cheaper than getting it from wind power.

Still, Michael Sterner, professor of energy economics at Germany’s Regensburg University of Applied Sciences, points out that if the costs of climate damage were factored in, “hydrogen would quickly establish itself as an alternative”.

Sterner is a pioneer in the technology, and says we’ve reached a stage where costs could start falling. “We are now starting to enter industrial production,” he said.

He points out that 20 years ago, photovoltaic solar power still seemed prohibitively expensive but, with state support, demand soared, the technology improved and economies of scale helped costs plummet. DW


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