Hydrogen drives in electric vehicles

Hydrogen as a drive for so-called fuel cell cars has some exciting properties. Basically, hydrogen cars are electric vehicles, with the difference that a hydrogen fuel cell including hydrogen tank is installed in the car. The integrated fuel cell technology generates the electricity to power the vehicle while it is moving. Today, hydrogen drives are used in cars, buses, rail vehicles and e-bikes.4

Hydrogen drive and its function

Hydrogen is the most abundant chemical element. On earth, however, hydrogen does not usually appear in gaseous form, but in combination with oxygen – i.e. as water. To use gaseous hydrogen, it must first be split off with the aid of electricity. This process is called electrolysis, but is also known as "power to gas". Incidentally, to ensure that no climate-damaging gases are produced during the manufacture of hydrogen, the electricity used should come from renewable sources. After all, only hydrogen produced with ecologically produced electricity can call itself climate-friendly.4

In the direct methanol fuel cell installed in the vehicle, electric power is generated from hydrogen by reversing electrolysis. The hydrogen and oxygen from the air react to form water, producing heat and electrical energy. In this process, a battery serves as a temporary storage unit to cover peak loads (for example, during acceleration). It also stores kinetic energy during braking.5

The storage system of a fuel cell vehicle is fundamentally different from that of passenger cars with conventional drives. The reason is that hydrogen is stored either in gaseous form under high pressure or in liquid form at minus 253 degrees Celsius. Because hydrogen therefore achieves a very high energy density, it requires specially insulated tanks for its storage.

The principle of hydrogen propulsion: advantages and disadvantages

The combustion of hydrogen leaves behind virtually no exhaust gases, making it an environmentally friendly alternative to oil, coal and natural gas. So if you consider the problems of gasoline and diesel drives in terms of pollutant production and energy consumption, hydrogen vehicles hold a clear advantage. A disadvantage for private consumers is the low density of hydrogen filling stations in Germany: While there are around 15,000 conventional filling stations in this country, there are only around 100 hydrogen filling stations so far. The nationwide expansion of the infrastructure is desirable, of course, but at the same time very expensive – which is why investors have so far shied away from it.4

Hydrogen drives are also ahead of gasoline and diesel drives: While the calorific value of one kilogram of hydrogen is 33 kilowatt hours, that of one liter of gasoline or diesel is only about 10 kilowatt hours. What’s more, hydrogen can be stored for any length of time.

A disadvantage for private consumers is the low density of hydrogen filling stations in Germany: While there are around 15,000 conventional filling stations in this country, there are only around 100 hydrogen filling stations so far. The nationwide expansion of the infrastructure is desirable, of course, but at the same time very expensive – which is why investors have so far shied away from it.

If we look at energy efficiency, another disadvantage of hydrogen drive compared to alternative drive types becomes apparent. This is because other electrically powered vehicles consume much less electricity than is the case with the hydrogen detour. Hydrogen drives are therefore particularly useful in applications such as heavy-duty transport, for which conventional batteries would be too large and too heavy. These include buses and trucks, for example, but also train, air and ship traffic.

Hydrogen drives possible applications

Hydrogen already has numerous fields of application today. For example, hydrogen drives are used for cars, buses, trucks and trains. In Leipzig, the Heiterblick company is building Europe’s first hydrogen-powered streetcar. And the fuel is even used in some aircraft – for example, in the four-seater "HY4" plane from the German company H2Fly, which was launched in 2016.2

At the same time, efforts are being made to make entire cities more environmentally friendly using hydrogen as an energy source. The Japanese company Toyota, for example, is currently developing the "Woven City," a hydrogen model city whose main energy source is hydrogen.

However, not only the economy, but also politics sees hydrogen as the drive of the future: The Paris Climate Agreement of 2016, for example, provides for the production and distribution of hydrogen to be expanded worldwide. The vision of politicians and experts is to convert both the transport sector and major industries such as steel and chemicals to hydrogen as an energy supplier.

The future of hydrogen drives

As an energy carrier, hydrogen offers the opportunity of 100 percent clean energy storage. After all, the exhaust air from a hydrogen car consists of pure water vapor – and is thus considered to be locally emission-free. Whether hydrogen drives really protect the climate, however, always depends on the conditions under which the hydrogen was produced. Only if the energy for hydrogen production is obtained from renewable sources such as wind power and photovoltaics can a neutral climate balance be achieved.1

If fossil fuels are not used in the production of hydrogen, hydrogen cars are extremely environmentally friendly. Instead of gasoline or diesel, a hydrogen vehicle simply fills up with hydrogen and benefits from a powerful electric motor. The only emission generated by the fuel cell during energy production is water vapor. For those looking for a long-term alternative to fossil fuels, hydrogen and fuel cell cars offer exciting opportunities.

Further information on hydrogen drives

Many people still fear that hydrogen will diffuse out of storage systems over time, resulting in losses for the user. However, these concerns are considered outdated by experts. Experiments with 700-bar pressure tanks, for example, show that the losses are now marginal. The hydrogen tanks installed in cars today have multi-layer walls made of different materials. This means that even tiny hydrogen atoms cannot escape through the walls.6

Things to know about the hydrogen fuel cell by SFC

SFC uses hydrogen technology and has developed the EFOY hydrogen fuel cell. This is based on the globally popular polymer electrolyte membrane (PEM) technology, which is suitable for both mobile and stationary applications. Polymer electrolyte membrane fuel cells have a high power density of up to 20 kilowatts. They also score with a comparatively low operating temperature of 80 degrees Celsius – which makes them interesting for mobile applications.7

The "EFOY Hydrogen" hydrogen fuel cell incorporates SFC’s many years of experience. Its high power density is already being used, for example, as an emergency power generator in critical infrastructures such as mobile phone masts.

For power requirements from 40 watts to 2.5 kilowatts, SFC offers the EFOY and EFOY Pro series of direct methanol fuel cells. These work similarly to hydrogen fuel cells, but instead of water they convert liquid methanol directly into electrical energy. There is hardly any loss of efficiency. A positive feature is the effective cold-start behavior.