Hydrogen Demystified - Part 1
Full disclosure, in my day job I work as an engineer for a fuel cell manufacturer, where I work on the design of electrolysers that produce hydrogen and power plants that consume it. Any views expressed here are my own and do not represent any views or positions held by my employer. - Edward Wilson
“Hydrogen is today enjoying unprecedented momentum. The world should not miss this unique chance to make hydrogen an important part of our clean and secure energy future.”
“(Hydrogen is) the most dumb thing I could possibly imagine for energy storage”
No topic splits opinions in the energy world quite like hydrogen.
For some its seen as the decarbonising solution to a whole host of sectors, from personal vehicles to home heating to long term energy storage, for others it is considered an expensive distraction, inefficient compared to other solutions or potentially even a way for oil & gas majors to stay relevant in a world heading for Net Zero.
What’s more, those who have followed the energy industry for a long time will know that hydrogen has a hype-cycle. It has been touted as the wonderous fix to the world’s energy problems before, particularly when George W Bush was in office in the US. And it is certainly riding another wave of enthusiasm.
Unsurprisingly, the reality is more nuanced than many of these views. Hydrogen has the potential to decarbonise large chunks of the energy industry, but there are sectors where it will lose out to other forms of generation and use. A lot of investment is needed to bring the cost of hydrogen solutions down and government regulations need to allow for it to be incorporated into the energy mix. At the same time, while oil and gas majors are talking about investing in hydrogen they are not the only ones, and serious capital is flowing into R&D and government strategies.
All the while the climate crisis continues to be more and more dramatically apparent and finding solutions to these various decarbonisation problems is becoming more and more urgent.
In this blog we’ll give an introduction to what hydrogen is, what it is used for now, and how we could produce it in a greener way. Then in follow-up blogs as part of this series we’ll look at what problems hydrogen could help solve and which technologies are most likely to succeed.
What is Hydrogen?
Hydrogen is the lightest, and most abundant, element in our Universe.
In normal conditions two hydrogen atoms join to make H2, a gas that is colourless, odourless, tasteless, energy dense and extremely combustible.
If you think back to your chemistry class you might remember that a hydrogen atom has one proton and one electron, and therefore very easily bonds to other atoms molecules such as oxygen, nitrogen and carbon to form many common substances such as water (H20), methane (CH4), ammonia (NH3) and more complex hydrocarbons such as propane (C3H8) and butane (C4H10) .
This means it is not actually found naturally occurring on its own. There aren’t clouds of hydrogen floating about, if you want it, you have to make it (more on that later).
Hydrogen is often described as a “fuel” but most of the time it is really much more like an “energy carrier”. The difference is subtle but essentially, because it is not found on its own in nature, in the way that you can find a seam of coal, you have to make it, then use it, so it “carries” energy from one form to another to be used, much like electricity can carry energy from hot steam in a power plant to a lightbulb in your room. One time it can be described as a fuel is when it is put into a device called a fuel cell, which generates electricity from a chemical reaction that turns hydrogen and oxygen into water.
Another thing to note about hydrogen is that it can be very dangerous. It is very combustible and when it burns the flame is nearly invisible to the naked eye. Luckily it is much lighter than air so it dissipates rapidly when it is released and disperses far faster than other flammable gases like the natural gas we use in our ovens, for example, meaning less hydrogen is left lingering around in the air to ignite.
How do we currently make it?
Around 90 million tonnes (Mt) of hydrogen were produced and consumed in 2020. Which is a huge amount for something often touted as an energy form of the future rather than something we think of being used a lot today. But the fact is hydrogen is already essential to several industries, notably oil refining (which uses 40 Mt), producing ammonia for fertilizer (34 Mt), producing methanol (11 Mt) and in steelmaking (5 Mt).
The vast majority of the hydrogen produced today is made through a process called Steam Methane Reforming (SMR), in which steam reacts with methane to produce hydrogen and carbon monoxide, a second reaction then reacts those products with more steam to give carbon dioxide and hydrogen as end products.
Methane vs Natural Gas – whats the difference?
Methane, a greenhouse gas = CH4
Natural Gas (sometimes called Fossil Gas), a fuel = CH4 + ethane, propane, CO2, and water vapor
Producing the 90 Mt of hydrogen we do today, using the SMR process, causes the emissions of 830 Mt of CO2 per year, over 2% of the World’s total CO2 emissions, and that doesn’t include the methane released during the production of the natural gas that flows into the SMR process.
If the current Hydrogen production industry were a country it would be the 6th largest emitter, sitting somewhere between Japan and Germany.
If we want to reach Net Zero, one huge aspect of the energy industry’s future will be decarbonising the hydrogen we already make. When it comes to guessing the future of hydrogen – at least that much is certain.
How do we make clean Hydrogen?
The good news is that SMR is not the only process we have to produce hydrogen, it just happens to be the cheapest, for now.
The other major way we can produce hydrogen is through a process called Electrolysis. With electrolysis, water and an electrical current are supplied to a device called an electrolyser, which splits the water into hydrogen and oxygen – basically a fuel cell working in reverse. No carbon molecules are lingering in the inputs to this chemical reaction, so no CO2 is produced. This means that hydrogen is as clean as the method of generating the electricity used for the reaction.
And so, we come to the Colours of Hydrogen.
You may have heard the terms Grey/Blue/Green Hydrogen before, which are the terms most commonly associated with a means of generating hydrogen. Beyond those three it gets a little confused and the terms intermingle, which each niche demanding its own colour. But if you remember any of them it should be the big three: Grey, Blue & Green.
Grey Hydrogen is just the SMR process we have already covered. Methane in, hydrogen and CO2 out.
Blue Hydrogen is Grey Hydrogen, but with most (up to 90%) of the CO2 captured at the end using any Carbon Capture, Utilisation & Storage (CCUS) technology.
Green Hydrogen is made by renewable energy powering an electrolyser, which means it has zero CO2 produced in the production of the electricity and the electrolysis reaction, so it can truly be called Green!
The figure below shows how we end up with all the colours of hydrogen, combining the input with the various production processes to get the end product.
Now that you have produced hydrogen (hopefully in a clean way) you can use it in a huge variety of applications. You can produce power via a fuel cell to power transport, you can use it as a chemical feedstock or put it into the steel making process, you can burn it to generate heat or store it to produce electricity in a few months time. All these applications are what get people excited about hydrogen as a possible solution to some of the tricky problems of decarbonising our industry.
In Part 2 of this series, we will look at all these technological possibilities once you have produced the hydrogen, determine which technologies it could be used for, and dive into the controversial area of which technologies it should be used for.
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