Hydrogen cars have long ranges

RANGE: 700+ km. REFUELLING: In a few minutes. CHALLENGE: Few filling stations and expensive production method. ADVANTAGE: Hydrogen can store energy from renewable sources such as solar cells and wind turbines.

IMAGINE A CAR, whose exhaust you could drink. The only thing leaving the exhaust pipe is water. Just like with your old petrolpowered car, you refuel this one in a filling station in a matter of a few minutes. But you no longer need to worry about rising fuel prices due to dwindling oil reserves, as the car is powered by the most common material in the universe: hydrogen.

Moreover, the car does not break down very often, as the electric motor includes fewer moving parts than a clumsy combustion engine with pistons, valves, and gears. It can drive longer per litre, and there is no motor noise in the cabin. So, hydrogen cars have long been experts' preferred solution to the transport sector's problems with oil supply and environmental impacts. More and more manufacturers sell reliable hydrogen cars, and filling stations are established in several places. This has made hydrogen cars popular among car owners who prefer an attractive alternative to petrol and diesel.

Simple reactions power car

Hydrogen cars are powered by electricity generated in a fuel cell, and they involve

major advantages over petrol and diesel: there are no carbon dioxide and harmful particle emissions like with an ordinary car.

In a fuel cell, hydrogen atoms are divided into electrically charged ions and electrons, which move about the electric motor circuit to generate power for the motor. Moreover, oxygen is sucked in from the air outside, making the hydrogen ions combine with oxygen ions to produce pure water as the only waste product. Those are simple and harmless chemical reactions, and the energy is even used more efficiently than in traditional cars.

Hydrogen stores energy well

The major sales argument for hydrogen is its ability to store energy. Hydrogen contains 120 megajoules of energy per kg – compared to 44 for petrol. At best, batteries can store 23 megajoules per kg. So, a fully fuelled hydrogen car has a range of 6700 km, which is about the same as petrolpowered cars and much more than existing batteryfuelled cars. Theoretically, a hydrogen car could have an even longer range, but as hydrogen is a gas, it takes up more space than petrol does.

Hydrogen's energy density means that the gas can be used for many other things than powering cars. Experts consider hydrogen part of the future solution to storing surplus energy in a society, in which electricity is generated by unstable energy sources such as sunlight and wind.

In 2016, Stanford scientists tested a method for storing surplus solar energy as hydrogen. A wellknown hydrogen production method is electrolysis. Water consists of two portions of hydrogen atoms and one portion of oxygen atoms (H2O). By means of two electrodes in a water tub, electricity is sent through the water, which is split into hydrogen and oxygen ions. A few hydrogen ions will unite around one of the electrodes, combining into pairs to make up molecular hydrogen (H2), which bubbles out of the liquid and is collected in large tanks. So, it would be obvious to link a large electrolysis tub with existing solar cell systems, so surplus power could be used for hydrogen production. So far, scientists have had difficulties making it sufficiently energyefficient, but the Stanford scientists converted 30 % of the solar energy into hydrogen, i.e. twice as much as in previous experiments. Such methods are important, if hydrogen is to make its breakthrough. Today, electrolysis is still an expensive type of production. The most common method of

producing new hydrogen is splitting natural gas from the underground into smaller chemical constituents by means of vapour. Natural gas primarily consists of methane (CH4), and though the vapour process emits about half as much CO2 as petrol or diesel production, it still requires lots of energy, making hydrogen a less green energy source.

Hydrogen network spreads

The other challenge of a hydrogen-based society is lack of infrastructure. There are not enough filling stations – neither as compared to ordinary filling stations nor to power sources used by battery- powered cars. However, in recent years, hydrogen manufacturers have built hydrogen filling stations throughout the world, and unlike battery-powered cars, hydrogen cars do not require as many stations, as one tank of fuel will take them about twice as far.

In 2017, Germany opened 24 pumps, so the nation now has a total of 45 stations, but the expansion of the network of stations is meant to accelerate to 400 stations in 2023. In Scandinavia, there were only 12 stations in 2015, but the aim for 2020 is a total of 150 stations in Denmark, Iceland, Norway, and Sweden. In 2016, Denmark had 9 stations, which is sufficient for all corners of the country to be within reach of a station. Many stations have their own electrolysis plants, continuously filling up the stations.

Worldwide sales of hydrogen cars have also gradually begun to rise. Since 2013, about 6,500 hydrogen cars have been sold, but sales doubled in 2017 as compared to the previous year. Japan aims to have 40,000 hydrogen cars in 2020, when Tokyo hosts the Olympic Games – according to plan using only hydrogen cars for logistics.

As soon as hydrogen filling stations make up a c oherent, cross-border network, the demand wil l ris e. According to Hydrogen Mobility Europe, it will be possible to drive from Stockholm to Italy in a hydrogen-powered car in 2020 without experiencing any problems. Moreover, another analysis from Information Trends demonstrates that from 2050, hydrogenpowered cars will be the fastest growing vehicle category in the world.