Renewable energy is increasingly producing more than we are able to consume at any given time. On sunny or windy days, surpluses grow, whilst in the evening or during winter, a shortfall arises. This is precisely where hydrogen energy storage comes in; it is increasingly being viewed not as a technological curiosity, but as a viable component of the future energy system.
Hydrogen does not solve every problem, but it does address one very specific issue: how to store large amounts of energy for long periods without having to use it immediately. This is a completely different role from that of conventional batteries. That is precisely why this topic comes up so often in discussions about the energy transition today.
What is hydrogen energy storage?
Hydrogen energy storage is based on a simple principle: electrical energy is converted into the chemical energy of hydrogen and then, when needed, back into electrical or thermal energy. This is most commonly achieved through the electrolysis of water, in which an electric current breaks down H₂O molecules into hydrogen and oxygen.
The key point is that hydrogen is becoming an energy carrier, not just a fuel. It can be stored, transported and used at a different time and place from where the energy was produced. As a result, the energy system is no longer dependent solely on current weather conditions and momentary demand.
Why is hydrogen making a comeback in the energy sector right now?
Hydrogen is not a new discovery. Industry has been using it for decades, mainly as a chemical feedstock. The difference is that today there is increasing talk of so-called green hydrogen, i.e. hydrogen produced using renewable energy, without carbon dioxide emissions.
The expansion of renewable energy sources has meant that the problem is no longer energy production itself, but rather balancing the supply. Wind and solar farms generate energy at irregular intervals, and the power grids are not always able to absorb it. Hydrogen energy storage allows surplus energy to be converted into a resource that can be used later, even after several weeks.
Electrolysis as a key component of the entire system
At the heart of every hydrogen energy storage system lies the electrolyser. This device determines the efficiency, costs and flexibility of the entire solution. The most common types are alkaline and PEM electrolysers, which differ in how they operate and how they respond to variable loads.
Electrolysis is not a perfectly efficient process. Some of the energy is always converted into heat, and the efficiency of the entire process depends on the quality of the materials, the temperature and the control systems. Nevertheless, electrolysers are becoming increasingly capable of operating in variable modes. This is of great importance when used in conjunction with renewable energy sources.
Hydrogen storage – gas, liquid or chemical compound
The hydrogen itself still needs to be stored somewhere. The simplest method is to store the gas under high pressure, but this involves costs and safety requirements. An alternative is to liquefy the hydrogen, which reduces its volume but requires very low temperatures.
An increasing number of studies are also focusing on the storage of hydrogen in solid materials or chemical compounds, where hydrogen is bound and released in a controlled manner. These solutions are still at the development stage, but they demonstrate that hydrogen energy storage need not be limited to a single technological approach.
Energy recovery and actual system efficiency
When energy is needed, hydrogen can be used in fuel cells or gas turbines. Fuel cells offer high efficiency and quiet operation, but they are expensive and sensitive to fuel quality. Turbines are less efficient, but they are easier to integrate into the existing energy infrastructure.
It must be made clear that the overall efficiency of the electricity–hydrogen–electricity cycle is lower than that of batteries. Hydrogen energy storage cannot compete with batteries in the short term. Its advantage becomes apparent where the ability to store energy over long periods and on a large scale is what matters.
Where does hydrogen energy storage make the most sense today?
Hydrogen’s greatest potential lies in systems that need to balance energy consumption seasonally. In summer, we generate a surplus of energy from solar panels; in winter, we need more energy. Batteries do not provide a cost-effective solution to this problem, whereas hydrogen offers a viable alternative.
The second area is large-scale industrial and grid-scale installations, where hydrogen can serve as an energy buffer. There is also increasing talk of its use in heavy industry and transport, which further reinforces the case for building hydrogen infrastructure.
Technological challenges and the limits of profitability
Hydrogen energy storage remains expensive and complex. Electrolysers, storage facilities and safety systems require significant capital investment. On top of that, there are energy losses at every stage of the process.
On the other hand, the costs of the technology are gradually falling, whilst pressure to reduce emissions is mounting. Hydrogen is not a one-size-fits-all solution, but it is becoming an important piece of a larger puzzle in which different technologies complement rather than compete with one another.
Summary
Hydrogen energy storage is not a magic bullet for all the energy sector’s problems, but it addresses challenges that other technologies struggle to tackle. It enables long-term energy storage, the integration of renewable sources and greater flexibility in the energy system.
If the energy transition is to work on a national scale, it needs tools to balance energy supply across time and space. Hydrogen is increasingly proving that it can be one such tool, provided it is used sensibly and its potential and limitations are assessed realistically.
