There’s a lot of hype around hydrogen (see blog: Keeping Warm – how to solve the problem of heating our homes). But how easy is it to move across from a fossil fuelled system to one based on hydrogen? How is the hydrogen created? And how is it stored?
Hydrogen Transport
Hydrogen powered vehicles have been around for a long time using a fuel cell to create electricity to power a vehicle’s electric motor as effectively as a battery. The difference is that the vehicle has a hydrogen tank rather than a bank of batteries as its energy source. Filling the tank is just like filling a petrol car – you simply drive up to the filling station, attach a hose to the car (screw it in place to avoid leakage) and a few minutes later you have enough hydrogen to travel 300 miles. Hydrogen filling points are being added to filling stations across the UK at the moment. See www.itmpower.com .
(see also presentation by CEO of itmpower. https://youtu.be/Sa789z7BBts He’s on from 5.18 to 22.18)
What’s a Fuel Cell
The fuel cell is like a sandwich with hydrogen on one side, oxygen (the atmosphere) on the other and a polymer membrane in the middle. Simply put, the membrane allows the protons from the hydrogen to pass through. This sets up a potential difference between the two sides of the fuel cell. Connecting a wire (plus machine/motor/heater etc) between the two sides allows a current to flow to drive the machine etc. The electrons passing through the wire to rejoin the protons that have passed through the membrane and recombine to make hydrogen. The hydrogen combines with oxygen to create water. The only output from the fuel cell is water! All the Apollo and Space Shuttle missions used hydrogen fuel cells as their source of electricity on board. Johnson Matthey has recently signed a major contract to create fuel cells in America, moving away from producing batteries.
Hydrogen Storage – not such a problem
Hydrogen storage isn’t what most people think. Rather than having to reduce the temperature and put it under huge pressure in giant tanks, modern hydrogen storage relies on ‘metal hydrides’ within the tank that allow safe and compact storage of relatively large amounts of hydrogen at low pressures. The hydrogen molecules bond with the hydrides: you can visualise this as the hydrogen atoms sitting neatly side by side on the metal hydride fibrils, close enough to be considered a pseudo-liquid. Releasing the pressure allows the hydrogen to be released and fed to the fuel cell.
Where does the Hydrogen Come From?
The main question people ask is ‘where will the hydrogen come from and can it be produced affordably? To produce so called ‘green hydrogen’ relies on electrolysis of water. An electric current is passed through the water and this causes the hydrogen to separate from the oxygen in the H2O molecule of water. Around 12l water is required to produce 1 kg Hydrogen (or around 20l sea water). By comparison it requires 168l to produce 1 pint of beer!
Immediately this begs the question, where will the electricity come from? The answer is that, during the night, when demand falls (most of us are asleep and businesses aren’t operating) the excess electricity generated by windfarms can be redirected to electrolyse water and then the hydrogen can be stored, either in the gas mains or in redundant salt mines or other caverns.(www.hydrogen-uk.org/the-hydrogen-story/storage/).
Is it safe?
Everyone has seen the Hindenburg footage – but watching it carefully will show that the initial fire was the skin of the airship and it took a while for the huge mass of hydrogen to ignite. Many tests have been done to ensure that households and cars using hydrogen are at least as safe as what we are used to today and a recent government report confirms this.
In the UK there are tests to establish that hydrogen is feasible by building ‘Hydrogen Villages’. Fyfe and areas within Whitby, Ellesmere Port and within Redcar, Teesside have been identified as potential areas for a hydrogen heating village trial. It is already possible to buy ‘hydrogen ready’ gas boilers and Bosch has 17 patents in place for hydrogen appliances.
A Global Market for Hydrogen
However the UK doesn’t have to produce all its own hydrogen (just as we don’t produce all our own gas, oil or electricity at the moment). Many countries are building huge electrolysis facilities powered by wind or solar and intend to export hydrogen across the globe, including Australia, Canada, Saudia Arabia and several across Africa. It will be shipped in the form of ammonia liquid (NH3) and ports such as Milford Haven that now receive LNG (liquid natural gas) imports, will be repurposed to receive ammonia for conversion to Hydrogen.
Conclusion
The whole world is making huge strides towards a hydrogen powered system (even if it’s still rather under the radar in the UK). This is a major opportunity and perhaps the UK should be paying more attention.
If you would like to know more about the opportunities that hydrogen offers see blog: Keeping Warm – how to solve the problem of heating our homes or look at the Thought Provoking Questions on Outreach link on this website, Thought provoking questions – Livery Climate Action Group (liverycag.org.uk)