Hydrogen is widely regarded as the energy carrier of the future. Its widespread use is expected to support economies’ efforts to decarbonize. Green hydrogen as a storage medium is attracting particular attention. How exactly does it work? Who might be interested in it? What are the benefits of using this technology?
A few words about hydrogen
Hydrogen is the first chemical element on the periodic table. It is designated by the symbol H. It is the lightest and most common gas in the universe. Under standard conditions, it is colorless, odorless and non-metallic. It is the main building block of life on Earth. The indicated properties determine that hydrogen is the fuel with the highest calorific value and combustion heat in relation to its mass. Attempts to use it for energy purposes date back to the 18th century. It is now considered to be the energy carrier of the future.
What types of hydrogen are there?
One of the main barriers associated with the widespread and environmentally friendly use of hydrogen for energy purposes is how it is produced. Currently, it is most often obtained by steam reforming of methane or coal gasification. In both of these production models, a side effect is high carbon dioxide emissions. Experts estimate that we are talking about as much as 19 tons of CO2 per 1 ton of hydrogen in the case of gasification and about 9-10 tons of CO2 per 1 ton of hydrogen in steam reforming of methane. It is clear that such emission-intensive processes should be extinguished rather than supported by international institutions. Hydrogen obtained by the described technologies is called gray. According to the Institute of Energy – Research Institute, as much as 96% of the hydrogen currently produced is produced in this ‘dirty’ way. Other types of hydrogen include:
- Blue hydrogen – this type of element is obtained by the same process as gray hydrogen. The difference lies in the ability to capture and store the byproduct, carbon dioxide. Unfortunately, improved carbon performance here comes with a number of challenges, namely high costs, necessary space and storage time, among others.
- Turquoise hydrogen – is produced through the pyrolysis of natural gas, and its byproduct is pure carbon. It can later be used to produce printer inks and toners, as well as lubricants, tires and much more. The technology for producing this product is at an early stage of development, so it is difficult to estimate its economic viability and potential for widespread use.
- Green hydrogen – this term appears most often in the context of the energy carrier of the 21st century. And this is no coincidence. Pure hydrogen is obtained through a zero-emission process, so it is completely neutral for the environment. How does this happen?
How is the green hydrogen produced?
The process of water electrolysis is used to produce green hydrogen. What does it consist of? In simple terms, water is subjected to an electric current. This breaks it down into oxygen and hydrogen molecules. The ionic hydrogen leaves the system in the form of observable bubbles in the liquid. It can later be stored and used as an energy source. The entire process is based on a specific technology. The most popular solutions are:
- Polymer electrolyte membrane (PEM)
- Solid Oxide Electrolyzer Cell (SOEC).
- Alkaline Electrolysis (ALK).
The key environmental issue here is the power source for the process. For hydrogen to be called clean, it should be electricity obtained in an environmentally friendly way, without emitting toxic byproducts. This is where renewable energy sources come into play, most notably photovoltaic panels.
Photovoltaic energy storage is still a big challenge
Renewable energy sources have many advantages. They are relatively inexpensive, environmentally friendly, self-service. Unfortunately, they also have one big disadvantage – they are unstable. PV panels do not work at night, on the other hand, when there is a lot of sunshine, they generate a surplus. A similar mode of operation applies to wind turbines or hydropower plants. The resulting demand-supply imbalance translates into too high a voltage on the grid and creates a risk of overloading.
The solution to this challenge is energy storage. Today, the use of individual storage in home or business installations is growing strongly. This is a great solution, but it is not applicable on a national scale and seasonal storage.
An alternative is to use surplus energy from RES installations to electrolyze water. The resulting green hydrogen can be stored in special tanks or using hydrogen fuel cells.
Green hydrogen vs. photovoltaics – what are the benefits of using photovoltaics to produce green hydrogen?
Photovoltaics clearly have an impact on the end result of green hydrogen, since the very energy needed to produce it will come from a green source, and the use of green hydrogen as an energy carrier itself has many benefits. These include:
- The possibility of storage, so that its resources are independent of weather conditions.
- Ability to be transported via pipelines or tank cars, railroads and others.
- Ability to be used in a variety of processes, such as powering machinery, equipment, driving vehicles or providing thermal energy.
- Possibility of use in the private sector, chemical, automotive, metallurgical, power generation, refining or gas industry.
Why is green hydrogen still being used on such a small scale?
Europe is to achieve climate neutrality by 2050. Greater use of green hydrogen is expected to help achieve this. However, to achieve this state, barriers to development must be removed, such as :
- High production costs.
- High energy losses in the chain.
- Infrastructure constraints.
- Lack of regulation.
According to M. Sobolewski, it takes about 9 liters of water and about 50 kWh of electricity to produce 1 kg of hydrogen. Production of the element is therefore expensive. A sample of estimates was presented in the report “Value Chain of the Hydrogen Economy in Poland”. Its results (taking into account the conditions of the Polish economy) are as follows:
- Electrolysis powered by wind farms – 4-6 euros per 1 kilogram of hydrogen.
- Electrolysis powered by photovoltaics – 5-7 euros per 1 kilogram of hydrogen.
- Electrolysis powered by nuclear energy – 5-7 euros per 1 kilogram of hydrogen.
- Coal gasification – 3-5 euros per 1 kilogram of hydrogen.
- Steam reforming of methane – 2-4 euros per 1 kilogram of hydrogen.
- Electrolysis fed from the national grid – 5-7 euros per 1 kilogram of hydrogen.
- Waste conversion – 7-9 euros per 1 kilogram of hydrogen.
- Thermochemical processes – 3-7 euros per 1 kilogram of hydrogen.
- Natural gas pyrolysis – 5-7 euros per 1 kilogram of hydrogen.
This is far too much to invest heavily in this energy storage source already.
The development of hydrogen production is strongly dependent on clear and transparent regulations. At the moment, the main market regulations are pan-European acts (EU ETS, RED III, EED, ETD, IEO, FUEL EU). Not all of them have been transposed to the Polish legal order, so there is still a lack of guidelines for connecting generation facilities to the grid or certifying green hydrogen. Also of concern among potential investors is the efficiency of alkaline and PEM electrolyzers (SOEC technology is in the commercialization phase). It is around 65-82%, so energy losses are significant. Finally, the last issue is logistics infrastructure. Using existing gas networks and transporting hydrogen with gas is economically unviable (the need for purification). Also, transmission of already processed electricity is out of the question. Polish electricity grids are not suitable for this type of operation. It would be necessary to build and maintain new networks or transport rolling stock. And that’s not all, as suitable power plants or storage containers must also be set up. In fact, the problem is much more complex, and satisfactory solutions are so far lacking.
Hydrogen energy vs. PV energy storage – will it work?
A prerequisite for ensuring electricity security in systems based on renewable sources is the development of an energy storage system. A necessary element for implementing this strategy is the use of hydrogen. The report “Green Hydrogen from Renewable Energy Sources in Poland” confirms that the initiatives planned to be launched in the next few years have many benefits, but are not able to ensure the stability of the NPS. Will technological developments in the future make it possible to effectively use hydrogen for photovoltaic energy storage. There are many indications that it will. Experts believe that scientists are able to overcome the obstacles. The difficult path is already being traversed by the German side. According to the “Nationale Wasserstoffstrategie,” a total of 10 GW of RES capacity is to be built by 2030 for the production of green hydrogen. Facilities that can efficiently store green hydrogen are already being built. An example is the underground storage facility of the multienergy company EWE in Rüdersdorf near Berlin, located at a depth of 1,000 meters.
It’s worth watching what our western neighbors are doing, because this is a scenario that the Polish economy will also be going through in some time.
 Zielony wodór z OZE w Polsce, PSEW 2021, str. 67.
 M. Sobolewski, Gospodarka wodorowa, Infos nr 6(298), s.2.
 Łańcuch wartości gospodarki wodorowej w Polsce, Instytut Energetyki-Instytut Badawczy, Warszawa 2023.
 Przykładem mogą być technologie cyklu siarkowo-jodowego czy miedziowo-chlorowego.