Debate rages as to which applications hydrogen is best suited for. Making ammonia and decarbonising steel-making look obvious choices. Most people say that hydrogen isn’t right for home heating or powering vehicles, with the possible exception of long distance heavy trucks.

There’s not enough discussion about another vital role of hydrogen: storing excess renewable electricity to avoid the problems of intermittent renewables. But this might be the single most important use by 2050. Trial projects are beginning around the world and one in Guiana, the overseas department of France on the northern coast of South America, is the largest.(1) Construction of this €170m scheme started late last year and opening is planned for 2024.(2)

An impression of what the CEOG project will look like.

The CEOG project will take electricity from a new 55 MW solar farm and distribute at least 10 MW into the local grid during daylight hours (8am to 8pm). Excess power will be stored in 38 MWh of batteries or converted to hydrogen via 16 MW of alkalne electrolysers provided by the French manufacturer McPhy. The hydrogen storage capacity appears to be almost 100 MWh. The electricity in the batteries plus conversion of hydrogen back to electricity via an adapted Ballard fuel cell will feed at least 3 MW into the distribution system for the hours of darkness (8pm to 8am), meaning the hydrogen storage is enough for at least four nights.

The structure of the CEOG scheme (batteries omitted).

Electricité de France (EdF) is the local electricity supplier and has signed a 20 year power purchase agreement guaranteeing the offtake of 10 MW in the day and 3 MW at night for the next 25 years. I think this makes the project by far the largest ‘dispatchable’ renewable electricity scheme in the world. It will provide guaranteed power for about 10,000 homes, allowing 300 watts a household at night, enough for a TV, fridge and some lighting. The scheme will be disconnectable from the wider grid, allowing it to continue to operate even during an electricity failure in the rest of this small and highly forested country.

This is an expensive project and required substantial help from the French state and support from the European Investment Bank. The price to be paid by EdF for the guaranteed output has not been specified although it is said to be less than the cost of generating electricity by diesel, which would be the only realistic alternative.

A quick estimate of the underlying economics shows how far from financially viable this scheme might be in mainland Europe. A 55 MW solar farm will produce very approximately an average 20% of its rated output in Guiana. The scheme will therefore generate about 100,000 MWh a year. If the capital cost is €170m or $200m and the project lasts 25 years, then the depreciation is at least $8m a year. The cost of the project per MWh produced is $80, considerable more than the typical (not today) wholesale price of electricity. This is without thinking about the running costs or the re-equipping needed for the electrolysers and fuel cells.

But this a ‘first of a kind’ project and costs will fall, possibly dramatically, as solar farms, batteries, electrolysers and fuel cells all get cheaper to make.

In my view, this development will be the first of many similar schemes. The main developer behind this innovative project – Hydrogène de France (HDF) - claims a list of prospects in at least 20 different countries with a total potential value of €3bn. I imagine most will be planned for remote areas currently using oil for power production.

When completed, the Guiana scheme will be a vital demonstration that renewable electricity supply need not be ‘intermittent’. Adding hydrogen storage allows the operator to offer fully reliable and dispatchable power. We urgently need many copies of this scheme around the world to demonstrate whether or not ‘renewables plus hydrogen’ can be economic.

(1) https://en.ceog.fr (2) https://www.bloomberg.com/press-releases/2021-09-29/hdf-energy-breaks-ground-on-world-s-largest-green-hydrogen-power-project