What about storing energy in hydrogen instead of batteries?

As more and more electricity is generated from clean sources such as solar and wind, it is becoming increasingly important to temporarily store energy. The most common way to do this is to store it in batteries: They are simple to use and install, lose relatively little energy and are rapidly becoming cheaper. But an alternative to batteries is storage in hydrogen: What are the advantages and disadvantages of this technique?

Electrolysis

Principle of electrolysis in the production of hydrogen

Storing a surplus of green energy and using it later with the help of hydrogen involves a number of steps. First, the generated energy is used for the electrolysis of water: H₂O is converted into O₂ (oxygen) and H₂ (hydrogen). The hydrogen is stored locally in tanks, or possibly transported in pipelines to a central storage facility. At a later time, when the energy is needed again, the hydrogen is converted back into electricity in an efficient fuel cell. This conversion only produces clean H₂O, i.e. water, as a waste product.

It's a nice, clean way to temporarily store green energy and use it again when needed. However, it is rarely used, because it has a number of disadvantages. What are these?

Losses

Hydrogen is stored under high pressure in special storage tanks

First of all, there are the losses: With every conversion, you lose a portion of the energy. With electrolysis, this is often more than 20%. The hydrogen gas then has to be stored or transported: This is done under pressure. To create that pressure, you need some more energy. When it is eventually converted back into electricity, in a fuel cell (which is a lot more efficient than a regular gas engine), you lose a lot of energy again, up to 50%. All in all, there's not much left!

Furthermore, there are some practical problems: Hydrogen gas is a very small molecule, which can easily escape and evaporate through small holes. Additional measures must therefore be taken to ensure that this hydrogen gas cannot escape. In addition, there are not many installations where the hydrogen gas can be converted back into electricity; in order to be able to contribute to the electricity supply, a lot of investments would have to be made.

Since hydrogen is currently economically inferior to increasingly efficient and cheaper batteries due to the losses and the required investments, we rarely see hydrogen being used at the moment. But not everything is to the disadvantage of hydrogen.

Preserving the summer sun until winter

Batteries are not suitable for storing energy over long periods: For example, you cannot put your surplus solar energy in a battery in the summer and expect that there will still be a lot of it left by December. Batteries tend to slowly discharge over time, regardless of whether they are used or not. They are very suitable for storage for a few hours or days, but as the storage period becomes longer, they become less and less efficient. Moreover, it's a waste to charge and discharge a rechargeable battery only twice a year. The strength of a battery is precisely that it can be reused almost every day.

This is different with hydrogen gas in a storage tank: It can easily remain there for months until it is used. And building extra storage for more hydrogen is a lot cheaper than installing extra battery banks.

A natural-gas-free future

Solar panels in the desert

Transporting energy is also a lot easier with hydrogen gas than with a battery. Suppose we were to install a lot of solar panels in the Sahara and want to use the energy they produce in the Netherlands, then transporting hydrogen in large tankers over the sea is a possible solution, whereas building thousands of kilometers of electricity cables would be expensive and loss-making.

And finally, hydrogen gas does not necessarily have to be used to generate electricity again; it can also be burned toi create heat for industrial processes. That may offer a solution for our natural gas-free future.

All in all it could well be that we will hear more about hydrogen gas as a storage medium for renewable energy in the future. In the short term, however, batteries will probably remain the best option. Are you also interested in batteries? Read our article about battery storage or check out our product page.