Climate protection: experts advise against hydrogen in cars – knowledge


The EU Commission considers it “essential” for Europe to become CO₂-neutral by 2050: Hydrogen is probably indispensable for a climate-friendly world. In a comprehensive report, the German Advisory Council on the Environment (SRU), which advises the Federal Government, now draws a differentiated picture of the energy source. This could be an important building block for the goal of greenhouse gas neutrality – but only “where there are no more efficient options for climate protection”. In contrast, it makes no sense to use it in cars or building heating systems.

Why is hydrogen so important?

Hydrogen (H₂) is the lightest element in the universe and a fairly universal energy carrier: in a fuel cell it reacts with oxygen and generates electricity, for example to drive an electric motor. No greenhouse gases are produced as waste products, only water and waste heat. It can also be burned directly, for example in industrial blast furnaces, without releasing CO₂. This makes it a potentially climate-friendly alternative to fossil fuels such as crude oil or natural gas. However, it is also an important raw material in the chemical industry, for example to produce ammonia. When hydrogen is generated with the help of renewable energies, there are little or no greenhouse gases.

How can the energy carrier be generated?

Black, blue, turquoise, gray, green, pink: a whole range of colors is now needed to differentiate between the individual hydrogen production processes. Germany is already the country of hydrogen, the Federal Republic of Germany consumes around 1.65 million tons per year, mostly in the chemical industry or as a coolant. However, around 99 percent of this is obtained from natural gas, which is called gray hydrogen. Only green hydrogen that is generated with the help of electricity from renewable energies such as wind power or photovoltaics is climate-neutral, emphasizes the SRU. With the help of this current, water is electrolytically split into hydrogen and oxygen. On the other hand, the experts want to reject the blue variant, hydrogen from fossil sources, whereby the CO₂ emissions are separated and stored underground (“Carbon Capture and Storage”, CCS). However, this also causes “significant greenhouse gas emissions”, for example when extracting natural gas or during transport. In addition, separate infrastructures would have to be built for blue hydrogen, which could compete with green hydrogen and make it less attractive, the authors fear. Here “path dependencies and bad investments” threatened. Generating hydrogen from fossil sources also runs the risk of unnecessarily delaying the abandonment of natural gas and oil.

Other types of generation, on the other hand, are likely to play a niche role or are still at a very early stage: the by-product of the production of turquoise hydrogen is solid carbon instead of CO₂, pink hydrogen is generated from atomic electricity, and black hydrogen is the starting material.

How environmentally friendly is green hydrogen?

The SRU experts now want to add another color palette: dark green hydrogen should not only come from renewable energies, but also be environmentally and socially acceptable. Because in order to meet the increasing demand for green hydrogen, it is essential, according to the authors, that the expansion of renewable energies in Germany is “massively accelerated”. However, this would “have an impact on the environment in particular through the need for land and raw materials,” warns the SRU. In order to limit the loss of habitat, for example, the experts therefore recommend that sustainability criteria be anchored at an early stage. For example, electrolysers for producing hydrogen should not be installed in protected areas or endanger the drinking water supply.

Can the demand be met from domestic sources?

Only a small part of the green hydrogen required can probably be produced in Germany. The federal government calculates that domestic wind turbines and solar systems can cover a maximum of 16 percent of the demand by 2030. The rest has to be imported from regions that receive more sun and wind than Germany or have larger areas available, such as Australia and Chile or North African countries such as Morocco. In these countries, however, it must be ensured that hydrogen production does not create new environmental problems or, for example, unduly pollute water resources, according to the SRU – the solution could be certified “dark green” hydrogen.

How can hydrogen be transported?

Pipelines are ideal for short and medium-sized distances, but they often have to be newly constructed. A reallocation of the existing natural gas network is also conceivable, albeit technically demanding. In addition, hydrogen can be compressed or cooled and liquefied so that it can be shipped to Europe.

For which areas of application is hydrogen useful?

Far from everywhere. According to the SRU, hydrogen is required above all in the chemical industry and in steel production, which accounts for around six percent of total German emissions. Also in international shipping and air traffic, as it is practically impossible to drive them electrically. “The use of hydrogen is inefficient and significantly more expensive than electrification by means of heat pumps,” says the SRU report, “particularly in the case of decentralized building heating and in car traffic.” The reason is that around a third of the energy is lost when converting electricity to hydrogen – e-cars do not have this disadvantage, and the cost of batteries has recently fallen sharply. “Political efforts should therefore focus on battery-electric cars and create long-term planning security for them.” An assessment that not all hydrogen researchers share. All technological solutions would be needed to achieve the CO₂ targets in mobility, says Christopher Hebling, Head of Hydrogen Technologies at the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg. However, the SRU experts do not rule out the use of fuel cells, at least for heavy haulage and rail traffic.

Where does Germany stand?

With the National Hydrogen Strategy, the federal government defined the political framework around a year ago, and around nine billion euros in funding are to flow into the technology in the coming years, two billion of which will go to international partnerships. The “market ramp-up” is to take place by 2030: the domestic production of green hydrogen is to multiply, the industry is working on the series production of electrolysers, which up to now have mostly been screwed together by hand. Last but not least, the government hopes that the export of hydrogen generation plants will also generate industrial policy impetus and create new jobs.

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