May 26, 2022 • 3 min read
Power-to-X: what you need to know
Renewable energy is critical to global decarbonization efforts. But it can’t decarbonize the planet’s most energy intensive processes alone.
Rapidly replacing fossil fuels in global energy systems, this low-carbon infrastructure uses sustainable sources of energy – solar, wind and water – to power millions of homes and businesses all over the world.
However, renewable energy is only part of the decarbonization story. Some industrial processes, such as chemicals production, steelmaking, and long-haul transport, can’t operate on renewable electricity alone. They often require other solutions.
That’s where an integration of established and emerging technologies – called power-to-X – can fuel the most energy-intensive processes on earth, without the CO2 emissions.
What is power-to-X?
Power-to-X solutions are about turning electricity into something else of value. The power-to-X term covers a group of technologies and processes that convert typically renewable energy into different energy carriers or feedstocks. These include hydrogen, methanol, methane, and ammonia.
The range of power-to-X definitions include power-to-hydrogen, power-to-methane, power-to-ammonia, power-to-chemicals, power-to-fuel, power-to-gas, power-to-liquid, power-to-methanol, and power-to-power, to name a few.
Power-to-X is well-suited to situations where renewable energy supply exceeds demand. It enables electricity generators to turn their excess renewable energy into liquid fuels or gases, so it doesn’t go to waste. However, there is also an increasing number of projects that are looking at dedicated power-to-X solutions, some of them non-grid connected.
How does power-to-X work?
The next step is to divert low-carbon electricity to an electrolyzer. This device is critical to all power-to-X pathways. An electrolyzer uses electrical energy to separate water into green hydrogen and oxygen. The stored green hydrogen enables the next steps.
The most straightforward power-to-X pathway ends here and is called power-to-hydrogen. Green hydrogen can provide a feedstock or fuel to various industrial activities such as refining and petrochemicals production, steelmaking, and long-haul transport. And it doesn’t need any further processing after electrolysis.
In more complex power-to-X pathways, green hydrogen contributes to producing something else. This usually requires additional conversion steps to create high-value fuels and feedstocks.
For example, combining green hydrogen with nitrogen creates green ammonia. This is an important ingredient in chemicals and fertilizer production.
Other power-to-X pathways have more conversion steps. Energy producers can create low-carbon synthetic fuels – or e-fuels – with almost identical properties to fossil fuels in the transport sector. This requires a synthesis of green hydrogen with CO2 to produce liquids, such as e-methanol, e-gasoline, or sustainable aviation fuel (SAF).
The renewable energy can also be returned to the electricity grid during shortages. By storing electricity as green hydrogen or green ammonia – through power-to-X pathways – this energy can fuel gas turbines to generate electricity or be used in boilers to generate steam and then electricity. This pathway is called power-to-power, and it’s a form of energy storage.
The future of power-to-X
The technologies to produce renewable energy, and extract green hydrogen, are already available. And each power-to-X pathway – from creating valuable gases to synthetic fuels to food products – is also technologically proven.
The missing link in the power-to-X story is scale. But with each new project, costs are falling. And the growing scale will see low-carbon fuels and feedstocks reduce global dependence on fossil fuels.
Over the coming years, power-to-X pathways will operate alongside electrification to decarbonize the most challenging industries on earth. Every sustainable project in heavy industry brings net-zero ambitions closer to reality.