Hydrogen can be a tough technology to parse. Some folks paint it as the linchpin of a decarbonized world. Others decry it as an expensive and inefficient rear-guard action for companies motivated to extend the useful life of fossil fuel infrastructure.
It's too early to know how this will play out. What we do know is:
- Hydrogen could be useful for essential tasks that are hard to electrify, like long-distance trucking, aviation and certain industrial processes.
- To make it clean will require a massive build-out of carbon-free power plants above and beyond the levels needed to electrify everything else.
The latter point prompted Canary Media's Jason Deign to investigate just how big a build-out will be necessary to support a renewables-powered global hydrogen economy. The upshot: It's a really big build-out, but not necessarily infeasible.
The first step is to determine the demand for hydrogen in 2050. Turns out, there's no expert consensus on hydrogen demand.
Estimates vary by a factor of almost 10, from 61 million metric tons (MT) per year in Shell’s 2018 Sky Scenario to 546 MT per year in the Hydrogen Council industry consortium’s 2019 Hydrogen Scaling Up forecast.
Jason then runs through a rough calculation of what it would take to provide the high end of those projections.
One hang-up is that electrolysis, which uses electricity to split water into hydrogen and oxygen, eats up about a quarter of the power input in the process. And if you're trying to power it with solar or wind, you have to factor in how those resources don't produce all the time, which requires overbuilding capacity compared to carbon-free sources like hydro or nuclear.
Jason found that powering the world's 2050 hydrogen needs with solar alone could take 18 times the current global solar power capacity. Doing so with wind would require eight times the current global wind capacity.
In reality, whatever green hydrogen we need will be supplied with a mix of fuels. But this exercise is useful in establishing an outer limit of the work required by the more bullish projections for a green hydrogen economy.
The world will already be hustling to build enough clean power plants for basic electricity demand, plus meeting the needs of electrified buildings and transportation. Green hydrogen demands even more construction. To justify the heavy lift, it will have to do things that can't be done by any easier means.
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