Fuel cell technology could cover 40 percent of the energy requirements in future traffic. But are hydrogen-powered cars also a future scenario, even an alternative to the e-cars with accumulators that are currently much touted?
Hydrogen could become the energy source of the future. According to some experts, it also plays an important role in traffic; depending on the scenario, it could cover up to 40 percent of the energy requirements there in 2050. Whether or not gas can make a breakthrough in the car depends not least on the infrastructure. And there is still a lot to do there.
Hydrogen is only really green when it is generated with green electricity.
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The big advantage of hydrogen is its clean “combustion”. Regardless of whether it is fired in power plants or internal combustion engines or used in the fuel cell to generate electricity – pure water is created as a waste product. The electricity or heat generated is correspondingly clean in this regard. The problem: The energy drawn must first be used in the production.
Only green, even if the production is green
As with electric cars, it is the same with hydrogen: it is only really green if the electricity used to manufacture it is green. And there is another problem: Hydrogen can also be obtained from clear water, but in most cases fossil fuels are used as the raw material. Today, it is mostly natural gas, and coal is expected to assume this role in the next few years. In both variants, CO2 is released during the synthesis, which, however, can ideally be separated and stored.
The advantages of the fuel cell drive are especially on the long haul.
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In addition to production, there is another problem: Transporting the very volatile and extremely light gas is not that easy. Classic natural gas pipelines are not sufficiently dense, so that large amounts of the gas were lost over long distances. If the hydrogen is mixed with the natural gas, which reduces losses, it can hardly be separated later if necessary.
Pressurized hydrogen pipelines are only expected to become available in the coming decade. The hydrogen gas at the German hydrogen filling stations is currently mostly delivered by truck. This is not very efficient and only works for relatively small quantities. A noteworthy fleet of fuel cell cars can therefore not be refueled.
Decentralized hydrogen factories
A hydrogen filling station for local public transport.
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Decentralized H2 factories are a possible solution to the transport problem. According to the Fraunhofer Institute for Factory Operation and Automation (IFF), green hydrogen could be produced and distributed in a decentralized and modular manner for industry, trade and transport along the value chain. With the help of solar or wind power, water is to be split into oxygen and hydrogen at precisely this point. The latter is stored directly on site and made available, for example, for refueling fuel cell cars.
The Fraunhofer researchers do not only think of private cars, but above all of vehicle fleets with vans and forklifts that are used in industrial and commercial parks. “In addition, we want to supply industry with electricity, gas and heat. The hydrogen generated during electrolysis can be fed into the gas network, used as fuel, converted into methane or methanol and made available to industry as a raw material,” said the IFF scientist Torsten Birth. The by-products of hydrogen production should also be recycled on site if possible: oxygen from industry, ozone for wastewater treatment in sewage treatment plants.
Several car manufacturers are keeping a close eye on the fuel cell and believe in the future of technology.
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The concept developed by the researchers has a modular structure. Where solar or wind energy is not sufficiently available, it can also be linked to a biogas plant. A special fermentation process, similar to that of biogas production, and using certain microorganisms could produce hydrogen directly from organic residues.
Transportable small filling stations
“The fermentative production of biohydrogen will play an important role in the decentralized production of the energy source,” predicts Birth. The principle of decentralization can even be taken to extremes with the Fraunhofer modules. In this way, a kind of portable small filling station could be built that goes wherever there is a need. On a small trailer there are expandable pressure storage systems with compressors that can be filled up and are also able to release hydrogen. The stock could be enough for users to travel around 200 kilometers.
It remains to be seen whether hydrogen and car manufacturing will prevail when it comes to solving the transport and manufacturing problems. Because the overall efficiency of a fuel cell car does not reach that of a battery electric car – from an efficiency point of view, it is cheaper to fill up with green electricity directly than to convert it to hydrogen at a loss. Nevertheless, from today’s perspective there are sensible applications, for example for the energy supply of long-distance trucks, ships and perhaps also planes. Large ranges are important there, which are currently only possible with batteries for an unfavorable cost-benefit calculation.
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