Hydrogen is intended to contribute to the energy transition. The gas can cut emissions and thus minimize global warming. But so far, no country in the world is pursuing a hydrogen economy. It seems too expensive, too complex – and too dangerous.
Green hydrogen to reduce CO2 emissions
Only a Green Hydrogen Economy, many believe, will achieve so-called decarbonization, where CO2 emissions are reduced through the use of low-carbon energy sources. In Europe, 9.8 million metric tons of hydrogen are currently produced each year primarily through the use of fossil fuels. The EU Commission has set a target for clean hydrogen production to increase to one million tons by 2024, rising to ten million tons by 2030.
Producing hydrogen with electrolysis
Hydrogen occurs in nature mainly in bound form. The element is available in almost unlimited quantities in the water molecule, but it is not easy to obtain. If you want to use the gas, you have to split the compound of hydrogen and oxygen. But this so-called electrolysis process, which chemically separates hydrogen and oxygen, requires a lot of energy. If electricity from solar plants or wind turbines is used for this, then we call it green hydrogen. If it comes from fossil fuels, it is called gray hydrogen.
Two processes: electrolysis and fuel cell
Electrolysis is used to produce hydrogen. The hydrogen is then stored in tanks and, if necessary, brought back together in a reverse reaction in a fuel cell. During this electrochemical reaction, energy is released. Water, electricity and heat are created. Two processes are therefore necessary for the production and use of hydrogen as an energy carrier.
Hydrogen and oxygen are brought back together in the fuel cell. The chemical reaction creates energy and water.
Competition between fuel cells and batteries
You fill up with hydrogen and the fuel cell converts the fuel into electrical energy. The electric motor is driven with this energy. There are no exhaust fumes, as is the case with battery-powered electric vehicles. In these vehicles, the electricity comes directly from the battery. A few decades ago, hydrogen vehicles were celebrated as the drive system of the future. In the meantime, battery-powered electric cars have caught up and are cheaper than hydrogen cars in terms of purchase price.
Advantages and disadvantages of hydrogen vehicles
But there are advantages and disadvantages to both vehicle drives.
- filling the tank with hydrogen, which can be done in a few minutes, but there is not a comprehensive infrastructure at filling stations.
The advantages of fuel cells over batteries are particularly evident in large vehicles. The hydrogen provides enough energy for buses and trucks to heat or cool sufficiently, but without sacrificing range. There is also no need for additional batteries for power supply. Many research projects confirm the strengths of hydrogen propulsion.