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A magic, abundant fuel to solve our problems?
Is this a partner to Green Electricity?
With all the ‘green electricity’ talk of late, you would be forgiven for thinking that our problems are solved as we ‘decarbonise the grid’. But is it that simple?
In the UK, electricity demand is actually the smallest of a trio of key energy needs (the others being transport and heating). To meet these demands via the electricity grid would require the grid and associated infrastructure to quadruple, plus on top of that we would need some serious battery technology to hold summer power ready for winter heating.
Part of achieving a low-carbon economy will include reducing demand and better capturing of carbon wherever we continue to burn fossil fuels (which will unfortunately continue for many years). But these two options are not our saviours - we will not be able to scale down our energy needs by enough to reach our targets, and capturing carbon from combustion is impractical when it comes to household boilers and transport, for example.
The real solution to reaching a low-carbon utopia is to use energy or processes that are less carbon intensive, i.e. low-carbon sources. You’ve already seen this happening, as we move from coal fire power stations to substitutes such as gas.
Hydrogen is one such low-carbon energy source. It is abundant in the Universe and on Earth. It is also the lightest element on the periodic table giving it the highest energy density on a mass basis of any chemical fuel.
Some see hydrogen as complementary to low-carbon electricity and a key part of our future energy picture because of its physical properties and breadth of application. But there are many challenges to overcome and some applications look more likely to succeed than others.
Just checking, you all remember from school that water is hydrogen and oxygen, right?
So it’s all around, but how do you ‘produce’ hydrogen?
Because our atmosphere contains oxygen, any hydrogen that might have been present has reacted with it to form water. So you either need to separate this out again, or produce hydrogen from other compounds. These are the three methods of bulk production.
'grey' hydrogen processes make it from natural gas (carbon and hydrogen), but without capturing carbon emissions
'blue' hydrogen uses the same as above, but with carbon captured
'green' hydrogen is generated by renewable energy sources without producing carbon dioxide, e.g. using renewable electricity to electrolyse water (splitting the hydrogen and oxygen apart)
Clearly green hydrogen is the best choice, however the UK gas supply industry advocates blue hydrogen given its reliance on natural gas as a feedstock and the industry’s clear vested interest.
How might we use hydrogen?
Electricity Production - as we decarbonise our fuel sources, gas turbines at power stations could instead burn hydrogen (of which the bi-product is water) or could utilise an industrial sized hydrogen fuel cell
Heating & Energy Transmission - using hydrogen directly for heating avoids additional pressure on the electrical grid which will occur if heating in the future is all electric. Hydrogen could be added as a mix to the existing gas network, with aim to switch fully in time. It is estimated that if the gas mix fed to our homes had 20% hydrogen this would allow continued use of existing kit (boilers etc.).
The LETI Report cited below includes excellent diagrams showing the efficiencies (or lack of) when using hydrogen for heating versus electric heat pumps. The report largely dismisses hydrogen for heating for the majority of the UK in the foreseeable future.
Transport - burning of hydrogen in a more traditional combustion engine or using a more efficient hydrogen fuel cell. It is also targeted for specific uses, such as long-distance travel, for trains and HGVs, or in low population areas (all seen as big challenges for electric vehicles)
Heavy Industry - an alternative energy source for energy intensive industrial processes, particularly those using high temperatures
There must be challenges?
There are plenty! These span technical, commercial and regulatory issues, plus customer perception.
Production - the challenge here is not technical, but any production method must not emit carbon and has to be at scale to find efficiency and assist with the wider commercial arguments for hydrogen
Distribution - the most conventional way of storing hydrogen and the current state-of-the-art is to store hydrogen as a gas following compression. This requires very high pressures and extremely carefully sealed tanks.
End users - when considering hydrogen replacing a gas supply, there are many end users to consider (domestic, industry, power generation). Hydrogen burns differently to natural gas, so boilers and other kit might have to change.
Commercials - some of the other challenges listed result in commercials that are not as attractive when compared to existing energy sources. As we have seen with electric cars, there is a ‘chicken and egg’ challenge when it comes to building infrastructure before the demand has arrived, or waiting to do this after.
Regulation - depending on the use case, there could be reason to nationalise hydrogen infrastructure - this would be a huge undertaking. Until such a position is known, the path for private investment remains unclear.
The displacement of natural gas for heating initially appears the most obvious opportunity. But having read the LETI Report I struggle to see this happening UK wide, even if this mean the electrical grid must significantly expand to deal with increased load as heating shifts from gas to electric.
I actually see the future of hydrogen being focused on transport, industry and as a means of energy storage. If new strategic pipelines are built it could also be used for long distance energy transmission.
The UK’s Climate Change Committee recommends the development of a hydrogen economy and also suggests there is a role for hydrogen to play when it comes to electricity production in peak periods. Demonstration projects testing the technical and economic worth are under way in several potential ‘hydrogen cluster regions’ as a result of Government support. Time will tell if these are not just feasible, but sufficiently cost and energy efficient to warrant widespread roll-out.
Note: this was written before the recent events in Russia / Ukraine.
IChemE - Hydrogen: The Future Fuel Today - this is a collection of articles collated by the IChemE into a single document