Hydrogen cannot be Japan’s silver bullet in its decarbonization efforts
Japan is betting on Hydrogen to be a major contributor to its 2050 environmental goals. METI has a target of 10% of its power mix to be covered by power plants firing hydrogen/ammonia in 2050 and is also expecting hydrogen to be used for mobility applications. Understanding the physical limitations behind the hydrogen supply chain casts doubts on Japan’s strategy.
The efficiency of the hydrogen supply chain
The total efficiency of creating hydrogen by electrolyze and using it to generate power is close to 34%
A typical electrolyzer requires ~56kWh to create 1Kg of Hydrogen. Compressing it to 350bars requires ~2.7kWh. A CCGT firing 1Kg of hydrogen would generate ~20kWh
The total efficiency would therefore be ~34%. If the electrolyzer draws power from the grid, grid losses of ~3% would also have to be accounted for.
How green is “green” hydrogen?
Touted as a solution to decarbonizing the energy mix, “green” hydrogen fired power generation might not be as low carbon as expected. If we assume that the electrolyzer is powered by solar PV, then the carbon content of a kWh out of our hydrogen powered CCGT would be close to 250g/kWh (assuming 85g/kWh for solar PV) Powered by wind, it would be closer to 75g/kWh (assuming 26g/kWh for Wind). This does not account for the carbon content of manufacturing and maintaining the electrolyzer nor for the supply chain necessary to import the hydrogen in Japan.
For comparison, Japan’s current carbon content of electricity is ~450g/kWh. France’s is ~50g/kWh thanks to its high use of nuclear power.
Limited opportunities in mobility
In mobility applications the efficiency of the supply chain is even worse. A typical fuel cell generates 16kWh from 1Kg of hydrogen, bringing the total efficiency down to ~26%. An EV battery has an efficiency of ~82% (88% charge and 93% discharge). Hydrogen only makes sense for vehicles that needs a long range between charges or that cannot be immobilized for the time of the recharge.
In December 2022 Japan signed cooperation agreements with Oman and Saudi Arabia on long-term procurement of blue hydrogen. This might be a good replacement solution to green hydrogen. It however comes with 2 major caveats.
- Can CCUS be deployed at scale and fast enough to meet the world environmental goals?
- And will natural gas supply be sufficient to generate enough hydrogen to power the ever growing economy promised by “green growth” proponents? A recent publication by The Shift Project, conducted under the supervision of the French Armed Forces, alerts on the risks of hitting “peak LNG” by ~2025
Hydrogen will not save Japan
In an infinite world with no physical constraints on resources, in which renewable power assets could be deployed with no limitations, hydrogen could play a major role in power generation and mobility applications. But in today’s world, with increasing limitations on available resources, hydrogen use would be better limited to essential applications in which no serious low-carbon alternatives are available. Steel and fertilizers production would be at the top of the list. Japan plans to import hydrogen is only displacing its energy supply and decarbonization problems to other countries.