Hydrogen is the lightest gaseous chemical element, it is also the third most abundant element on Earth. Due to its high reactivity, it occurs almost exclusively as a compound in nature. A hydrogen atom consists of one proton in the nucleus and one electron in the shell. Hydrogen does not pollute the environment when it escapes, making it an emission-free energy source. Hydrogen is highly flammable but does not support combustion. Hydrogen was discovered in 1766 by Henry Cavendish, but at the time of its discovery, hydrogen had not found much use. One of the first uses of hydrogen in transportation came with the development of ballooning and airships, where hydrogen was used as a carrier gas alongside helium. As for the use of hydrogen propulsion today, we must distinguish between its use in fuel cells, or the discovery of the fuel cell itself, and in internal combustion engines.

The principle of the fuel cell was discovered in 1838 by the Swiss scientist Christian Friedrich Schönbein, and the first working prototype was built by the British scientist Sir William Grove. After the invention of the dynamo, the fuel cell fell into partial obscurity. "Its real "The fuel cell had its real renaissance in the 1960s. This was largely due to cosmic research, because the fuel cell has a more favourable ratio energy-to-weight ratio. For example, the Apollo spacecraft were equipped with them, but but they're also the power source for today's space shuttles." [3]

Although the hydrogen internal combustion engine was the first patented internal combustion engine, and as early as 1808, when a French patent was granted to retired Major Issac de Rivaz, its practical use dates back to a much later time. Hydrogen in Rivaz's engine was obtained by the electrolysis of water and "the design was ... unsettled and practically unworkable" [4]. The first working hydrogen internal combustion engine was not developed until a century after the first French patent, in the 1920. Its use was first tested in the airship engines of Ricardo and Maybach.

With efforts to reduce emissions in transport and the development of emission-free energy sources in transport, the use of hydrogen as an energy source is developing alongside electric mobility. To pump hydrogen into vehicles, special filling stations are required to ensure fast and safe filling of the car's tanks. Hydrogen is pumped in gaseous form and compressed to high pressure. The first hydrogen filling station was opened in 2002 in Reykjavik. [2] When Shell opened it in 2003, only one fuel cell car, a Mercedes-Benz Sprinter, and three Daimler Chrysler hydrogen buses were operating in Iceland as part of the European Union's first ever public transport programme.

Iceland was considered an ideal location for this pilot project because it has an abundance of cheap and clean hydro and geothermal energy that can be used to produce fuel by electrolysis with minimal carbon dioxide emissions. This made Iceland a pioneer in the transition to a hydrogen economy, with more than 40 vehicles on the road in 2007, mostly Toyota Prius hybrids, second only to California.

Japan currently has the largest number of hydrogen filling stations of any country in the world. In September 2021, there were 154 hydrogen refuelling stations in operation in the country. Japan's position as a leading provider of hydrogen automotive fuel is not surprising given that Japanese automakers Toyota and Honda are among only three automakers in the world that mass-produce hydrogen cars. [3]

There are approximately 136 hydrogen filling stations in the European Union. The first hydrogen refuelling stations began to be introduced in 2016, but their expansion stalled until 2019, when the number nearly tripled in a single year. Hydrogen is seen as a critical resource for achieving emissions reductions and its use in transport is supported by many governments. In 2020, the EU saw a drop of 10 refuelling stations due to the UK leaving the EU.

The first non-public filling station was opened in the Czech Republic in 1999 in Neratovice, followed by another one in ÚJV Řež in 2020. In 2022, the first public filling station was opened in the Czech Republic in Ostrava.

Global demand for hydrogen after the Paris Agreement and more recently after COP26, the world is trying to find innovative technologies to replace fossil fuels and reduce greenhouse gas emissions. Hydrogen has emerged as one such alternative, particularly for the transport sector. Global demand for hydrogen totalled 71 million tonnes in 2019, with the refining sector being the main consumer. The IEA forecasts that by 2070, total demand could reach more than 500 million tonnes, with the transport sector expected to be the largest consumer of hydrogen. Where current infrastructure is failing, not only does technology need to advance, but the necessary infrastructure also needs to be developed for countries to meet their net zero targets. Only three countries in Europe have met the EU requirements for a sustainable taxonomy for hydrogen production using electricity from national grids. Most countries would produce hydrogen with high carbon intensity if they used grid electricity. In addition to the carbon intensity of the product, the biggest global challenges for hydrogen technology, according to the 2021 survey, were its complex distribution and inconsistent supply and storage issues.

Refuelling takes place at filling stations. The whole process is very similar to refuelling traditional fossil fuels. After connecting the filling gun to the tank valve, you flip a lever and the system does the rest. Filling the tanks takes 5 minutes and will give the car full capacity. So refuelling is similar to CNG/LPG vehicles, except that in the case of hydrogen it is compressed not liquefied gas. This difference is due to the fact that a temperature of -253°C is required to liquefy hydrogen. Achieving such a low temperature would be economically and technically very challenging.