What Is Green Hydrogen, And What Are Its Use Cases?


Edit: Thanks for all the answers and the effort to answer this trendy “sciency” question.

In: 3

Green Hydrogen is Hydrogen (a flammaboe gas) created from renewable sources. For example using the wind to make electricity and use that to electrolyze water (split H2O into hydrogen and oxygen)

It can be used as a fuel in specific kind of fuelcells that turns it back to electricity, so it can power cars and similar things. It can also be used to store energy (wind energy isn’t reliable, you need a way to store some for later when no wind blows). Also a few industries could use hydrogen in their processes directly to replace things that are bad for climate (hydrogen based steel making is currently being developed)

Free hydrogen does not exist on earth in any appreciable amount. There aren’t pockets of hydrogen you can exploit. It’s an energy storage medium like a battery, not an energy source like gas. You can make it chemically, but the easiest way is electrolyzing water- passing a current through it to dump in energy, overpowering and breaking the bonds between atoms and leaving you with oxygen and hydrogen in the proportion you expect from an element made of two hydrogen atoms and one oxygen atom. You can then later re-react the hydrogen with oxygen, getting you most of your energy back and leaving the original water as the waste product.

Whatever energy you use to split the water can be green or not, and that’s what they’re talking about.

Hydrogen is a flammable gas.

We don’t have significant natural sources of it where we can just pump it out of the ground like oil. We have to make it.

* Green hydrogen is hydrogen produced in a “green” manner, typically electrolysis of water, using renewable energy. It means the production of it isn’t polluting.
* Pink hydrogen is hydrogen produced with nuclear power. Sometimes it’s also classified as “green”.
* Grey hydrogen is hydrogen produced in a polluting manner, from fossil fuels. By some calculations, it may be even worse than using fossil fuels directly.
* Blue hydrogen is grey hydrogen with emissions capture, which should be somewhat better. But so far it’s mostly a theoretical thing rather than something currently being done, and it still has a negative ecological impact, just not as bad.

The whole issue with hydrogen powered vehicles is that most hydrogen is grey because that’s the cheapest production process. Green hydrogen isn’t efficient to produce and in most cases you’d do better with a battery powered electric car.

Normal fossil fuels are mostly carbon (**C**) and burned with Oxygen (**O**) and have things like carbon-dioxide (**CO2**) as waste.

You can alternatively burn Hydrogen (**H**) and get **H2O** as a waste product. H2O is water.

Water is a lot greener as waste goes that CO2.

Even better while carbon based fossil fuels like coal and gas an oil have to be dug or pumped out of the ground. Hydrogen can be made from water and electricity.

This means that you use hydrogen more like battery than a fuel.

Still if you use solar or wind power to make hydrogen and than later burn the hydrogen for power that is green.

One downside is that hydrogen and oxygen can react quite explosively. You have to work hard to get diesel to explode, but all it takes for hydrogen is a spark.

This is no complete argument against it but it seems hydrogen gets mostly pushed by companies who missed the switch to battery electric tech.

There are three “colors” of hydrogen. First, almost all hydrogen is made by cracking natural gas(methane) into hydrogen and CO2. You can in theory do it by splitting water into hydrogen and oxygen but that takes *a lot* more energy and you end up using more energy than you can possibly get back

Grey hydrogen just cracks the methane and releases the CO2 into the air. Blue hydrogen cracks the methane and uses carbon capture to store the CO2 it produces. Green hydrogen uses renewable energy or low carbon sources to power electrolysis of water so there’s no CO2 created

In the end though, Green Hydrogen is about 5x as expensive as Grey/Blue due to the high energy cost of electrolysis, and even if today you power it off of solar panels or wind turbines you could have instead used those producers to offset a carbon producing power plant in the main grid

Hydrogen was thought to be the next great car fuel but then battery technology improved significantly and is continuing while Hydrogen never ended up building out its infrastructure. The end use case for hydrogen right now seems to be nothing, even Toyota has shifted away from it and is now pursuing electric vehicles, they were the last major hold out and it has put them far behind