What is hydrogen?
Hydrogen is a chemical element just like oxygen, carbon and iron. It is the lightest and the most abundant element in the universe. On Earth, it is found above all in water (H2O), a compound consisting of two hydrogen atoms and one oxygen atom.
What role is hydrogen set to play in the energy transition?
While hydrogen is an ideal resource for industrial processes, it can also be used for energy storage and as fuel. In a process known as “electrolysis”, an electric current is used to split water into hydrogen and oxygen. Hydrogen can be stored and transported by pipelines or – in its liquefied form – by truck or tanker. Fuel cells make it possible to induce a reaction between hydrogen and oxygen to form water again. The energy released in the process can be used, for example, to power an electric motor. Moreover, hydrogen is a feedstock for a range of products in the chemical and transport sectors. For example, it can be converted into other (green) gases such as e-methane (“power-to-gas”), into liquid energy sources such as fuels (“power-to-liquids”), and into basic chemicals for industry (“power-to-chemicals”).
What is the meaning of the various colours used to describe hydrogen?
At present, hydrogen is still mainly sourced from fossil fuels such as natural gas. Steam reforming is a process used to convert natural gas into hydrogen and carbon dioxide (CO2). As a result, CO2 is generated and released into the atmosphere, adding to the greenhouse effect. The hydrogen produced in this way is called “grey” hydrogen.
If hydrogen is produced on the basis of renewable energy, for example using electricity from wind energy or solar installations, the process is virtually free of greenhouse gas emissions. Hydrogen sourced in this way is called “green” hydrogen.
“Pink”, “red” or “yellow” hydrogen are also generated through electrolysis – very much like green hydrogen. The electricity used here, however, is sourced from nuclear energy rather than renewables.
“Blue” hydrogen is produced in the same way as grey hydrogen. However, rather than being released into the atmosphere, the CO2 caused in the process is, for the most part, captured and stored below the ground – e.g. on the seafloor or in old saline aquifers. Therefore, blue hydrogen contributes far less to the greenhouse effect than grey hydrogen.
“Turquoise” hydrogen is also sourced from natural gas. Rather than CO2, pure carbon (in solid form) and hydrogen are produced in the process.
How can hydrogen be used for mobility?
Fuel cells enable a reaction between hydrogen and oxygen to form water, thus generating energy to power an electric motor. While battery-operated cars are far more energy-efficient than hydrogen-powered cars, battery electric energy storage systems do come with their share of disadvantages, e.g. the batteries are heavy, their manufacturing is environmentally problematic, and they are quite limited in range based on the current state of the art, particularly in the case of heavy vehicles. This is why, according to experts, long-distance and heavy-duty haulage as well as air and maritime transport will be among the first sectors where fuel cell vehicles may have a key role to play.
Also, the growing demand for climate-neutral fuels seen in the aviation and maritime industries, in particular, can be covered by hydrogen derivatives (known as e-fuels). These can be used in today’s vehicles – either directly or following a retrofit –, providing an alternative to electric mobility where it is not (yet) available.
What does hydrogen have to offer for industry?
Hydrogen already plays a key role in the chemical industry, for example, in the production of synthetic fuels, plastics or fertiliser. While grey hydrogen is still frequently used, green hydrogen will soon prove a viable alternative in these and in other areas, such as the extraction of raw materials for the chemical industry. Moreover, wherever high temperatures are needed for industrial processes, e.g. in the production of steel, glass or cement , hydrogen is a promising option to reduce production-related emissions. There are pilot projects, for example, investigating how hydrogen can be used in the steel industry for the direct reduction of iron ore. The process has so far relied on the use of coke, causing very high greenhouse gas emissions.
Can hydrogen also be used for heating?
It is basically possible to use hydrogen in fuel cells or in boilers to heat buildings. Investigations are still ongoing to determine the conditions that prove this technology efficient for private homes, companies or communities. There are, however, other climate-friendly and far more efficient methods for supplying heat to buildings, such as heat pumps, geothermal energy and solar thermal energy.
What is sector coupling and what role does hydrogen play in this regard?
In the past, the electricity, heat and transport sectors were seen as largely independent from each other. However, if the energy transition is to be a success in the long term, we cannot stop at transforming the power sector. Renewables must also play a greater role in the heat and transport sectors. Sector coupling, i.e. using renewable electricity in a way that aims to reduce fossil fuel consumption in other sectors, can help to make this possible. For example, renewable electricity can be used in electric cars – or in the production of hydrogen, which may then be used to generate industrial process heat in a climate-friendly manner.
Where will all the hydrogen come from?
German industry has already reached a high level of technological sophistication regarding the production and use of hydrogen. However, the generation of green hydrogen from renewable energy is not yet economically viable in contrast with conventional “grey” hydrogen that is sourced from natural gas. Moreover, it will be impossible to cover tomorrow’s enormous hydrogen needs through domestic production capacities alone. The National Hydrogen Strategy contains a range of measures to address these challenges. Developing and setting up industrial-scale generating installations will help to lower prices. In addition, the strategy provides for an increase in the number of renewable energy installations. Apart from this, international partnerships will be established and expanded with a view to ensuring the import of green hydrogen from European neighbours or from countries outside Europe blessed with abundant sunshine or wind.
