Hydrogen: What colour?
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| 19,4 KWh in Li-ion, H2 and NH3 |
In June, I had the chance to bike with my son Léopold from San Francisco (California) to Denver (Colorado). I planned several meetings with companies dedicated to developing solutions to overcome climate change. That's how I came to meet with Joe Beach, the president of Starfire Energy. From there, I started to learn about hydrogen and ammonia.
First, I realize that hydrogen is so colourful. You have many different types of hydrogen: the "black," the "green," the "blue," even the "turquoise."
The black: Today, 95% of hydrogen is produced from fossil fuels and is responsible for 800 million tons of CO2 (1.9% of the 43.1 billion tons of CO2 produced in 2019). In 2019, 75 million tons of hydrogen were produced worldwide (one ton of H2 creates 10 tons of CO2). The technique used is called methane reforming. We take water (2*H2O) and methane (CH4) that we heat, and we obtain after cooking: 4*H2 + CO2 (this is where it gets stuck). We use this hydrogen (60 million tons/year) practically in the industry for three activities: to produce synthetic fertilizers (to feed 7.8 billion people), to remove sulphur from fuels in refineries, and to reduce iron ore in metallurgy.
The blue: blue Hydrogen comes from natural gas, CO2 capture and underground storage. In Europe, this process does not attract much attention, and rightly so. What an idea to go and store CO2 underground; it would only postpone the problem elsewhere.
The Turquoise: Hydrogen comes from the pyrolysis of methane (CH4). The pyrolysis transforms CH4 into 2H2 + C. So, there is no CO2, but only stable carbon (C) that can be used in the industry.
The Green. The Graal. It is obtained by electrolysis of water (H2O) with green electricity (nuclear, wind, hydraulic). But to break the O-H bond, it requires energy. It requires precisely the same amount of energy to break this relationship as the amount that can then be supplied by the hydrogen when it burns. The role of hydrogen would be a storage role when electricity can be produced in overabundance.
Where should this green hydrogen be used?
Two industrial applications are immediately apparent: fertilizer production and the reduction of iron ore to produce steel. All you have to do is change the colour of the hydrogen and replace black with green.
But when is it for transport or heat?
For transport, it depends on the weight!
For a car, hydrogen loses its interest compared to batteries. The hydrogen cars are only half as efficient. An electric car converts 86-90% of the energy initially harnessed by a wind turbine into moving the vehicle forward; the hydrogen car has access to only about 45%. A car with fuel cell also has more moving parts and is more expensive to maintain than one with a battery. And, unlike the battery car, it can't be recharged at home.
For trucks, we can debate.
For the train, we can also debate. It would eliminate the need to electrify the track but would be more complex and less efficient. Jean-Pierre Farandou, CEO of SNCF, declared in June that he wanted SNCF to be a pioneer in hydrogen-powered trains.
For long-haul aviation and ocean shipping, it makes sense as hydrogen has a higher energy density. Samsung has, through its subsidiary SHI, concluded in June 2020 a partnership with Bloom Energy to develop and design ships equipped with fuel cells. In terms of energy density, we could even think about ammonia (NH4). Companies such as MAN Energy Solutions and Wartsila are working to adapt NH4 solutions for recent ship engines. Ammonia offers the advantage of being liquid at -33°C (instead of -253°C for H2) and is stored at a pressure of less than 10 bars (instead of 350 to 700 bars for H2). And in case of leakage, you can smell it immediately...
For heat? Hydrogen doesn't work well in heating residential buildings. It's usually easier to use green electricity to power heat pumps. Hydrogen requires about six times as much electricity as using heat pumps.
A major application of H2 will be to play a role in storing electricity produced by renewable energies. When the sun is shining and the wind is blowing but the demand for electricity is low, the electrolyzers will be turned on to produce H2, which will then be stored. H2 will later be able to provide electricity when there are peaks in demand and the wind and sun fail.
To conclude, what are the countries' ambitions in this area?
- For Germany: it's an investment plan of 9 billion euros with the stated ambition of becoming world leader.
- For France: a €7 billion investment plan, including €3.5 billion allocated over the period 2020-2023.
- For Portugal: an investment of 3 billion euros to host a site for the production of green H2 by electrolysis using solar energy.
- 40 GW of electrolyzers for hydrogen production
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