What are blue, green and grey hydrogen? | Jargon buster
Utopian visions of a fossil fuel-free future often feature hydrogen. But is it as sustainable as it sounds? And what’s holding it back from mass adoption? Much of this comes down to production.
Why is hydrogen touted as the next big thing?
As a fuel source, hydrogen is great: it’s in everything – or, more accurately, about 74% of all matter in the universe. You can produce it by combining electricity with water, and when it burns, it doesn’t release carbon dioxide.
Sounds ideal. What’s the catch?
There are a few problems: its low density makes it difficult to store, and it’s prone to leaking. At high concentrations, it takes relatively little energy to make it explode. These are not insurmountable issues – think of the dangers of natural gas, for example – rather, the problem is that hydrogen can be sneakily dirty depending on how you produce it.
Is that where the colours come in?
Correct. The colours refer to hydrogen production. At the risk of oversimplifying, these are:
- Green: as the name suggests, green hydrogen is the ideal. Using renewable energy, the process splits water into hydrogen and oxygen through electrolysis.
- Blue: this is where hydrogen starts to get messy. This process combines natural gas and steam to create hydrogen and carbon monoxide. That carbon is then captured and stored. Proponents might call it carbon neutral, but in reality, not all carbon will be captured.
- Grey: like blue hydrogen without carbon capture
What’s stopping us pumping out loads of green hydrogen?
Several reasons, but a key one – unsurprisingly – is cost. Grey and blue production are based on established, mature technology. Bloomberg estimates that the cost of producing blue hydrogen is less than half of producing green.
As a result, blue features heavily in hydrogen strategies around the world. For example, while the EU Hydrogen Strategy does identify green as a priority, it concedes that blue plays a role in the transition in the medium-term.
Another hurdle for green is sourcing enough renewable energy for electrolysis.
Are those impossible problems to fix?
No. In fact, that same Bloomberg estimate forecasts that green hydrogen costs will “plummet” and be cheaper than blue hydrogen by 2030.
Why should real estate care about hydrogen?
Hydrogen is potentially another alternative to heating buildings with natural gas. Understanding where and when hydrogen works as either the primary or secondary fuel source is crucial, especially as prices fall.
Another question to consider is how to approach EV charging infrastructure if hydrogen-powered engines pan out as proponents believe. Will we need EV chargers in a few decades? Are we going to be back at the pump to top up on hydrogen fuel?
Buildings could also play a role in producing hydrogen. One startup, Modern Electron, raised $30m earlier this year to fund a converter that takes natural gas in buildings and turns it into hydrogen and solid carbon.