Hydrogen plays a significant role in the energy transition because excess energy on sunny and windy days can be used to produce hydrogen. This hydrogen is then available for use in mobility and industry, regardless of the sun and wind. Hydrogen can be stored more effectively than electricity, providing an alternative storage option for electricity from renewable sources. Additionally, green hydrogen enables emission-free mobility and reduced-emission industries (e.g., steel production).

Hydrogen can be produced in various ways. Currently, hydrogen is primarily obtained from fossil raw materials, mainly through steam reforming of natural gas. Green hydrogen is produced by electrolysis using electricity from renewable energy sources. In this process, water is split into hydrogen and oxygen using electricity. By using renewable energy for electricity generation, hydrogen can be produced completely emission-free. There are also other production methods, each assigned a different color (see the next question).

Hydrogen is a colorless gas, but the colors refer to the method of production. Green Hydrogen: Produced by electrolysis using electricity from renewable sources. Turquoise Hydrogen: Produced by methane pyrolysis, splitting methane into hydrogen and carbon. Gray Hydrogen: Produced through steam reforming of fossil fuels. Blue Hydrogen: Gray hydrogen where the resulting CO2 is captured and stored. Other colors include yellow (electrolysis with grid electricity), orange (various methods including biogas reforming), red (electrolysis with nuclear power), white (natural deposits), and brown (coal gasification).

Industry: Used for desulfurizing oil products, producing ammonia for fertilizers, methanol for fuels, hardening fats in food industry, plastics production, metal alloying, and as a shielding gas. Mobility: Used in forklifts, cars, buses, trucks, trains, and rockets. Buildings/Heating: Fuel cells produce both electricity and heat, increasing efficiency through combined heat and power generation.

Hydrogen can exist in various purity grades. Commercially available hydrogen: Typically 3.0 (99.90% purity). Higher purity requirements: For example, hydrogen 5.0 (99.9990% purity) used in the semiconductor industry. The exact composition of remaining gases is crucial, especially for applications like fuel cells, where certain impurities must not exceed specific limits.

Availability: Produced from water using electricity and stored efficiently in large quantities. Production Method: Produced using excess renewable electricity, serving as a flexible energy carrier. Comparison with Combustion Engines: No local emissions, quieter, less wear and tear, high efficiency. Comparison with Battery Vehicles: Short refueling times, lighter tanks, fewer problematic raw materials. Flexible Applicability: Suitable for remote areas and critical infrastructure. Transport: Fewer losses in pipelines, possibility to use existing natural gas networks. Storage: High energy-to-weight ratio, stored in natural gas caverns.

Hydrogen Buses: No local pollutants, quieter, higher ranges, suitable for multi-shift operations and hilly terrain. Heavy-Duty Vehicles (Trucks): Long ranges, comparable payloads to diesel trucks, shorter refueling times. Forklifts: No local emissions, suitable for indoor use, continuous multi-shift operation. Trains: Suitable for routes without overhead power lines, climate-friendly alternative to diesel. Passenger Cars: Locally emission-free, comparable range and performance to combustion engine vehicles.

Compressed Gas Cylinders: Transported by truck. Liquid Form: Transported by truck or ship for longer distances. Pipelines: Efficient for very large quantities, possibility to retrofit existing natural gas pipelines.

The calorific value of hydrogen is 33,000 kWh per ton. Converted into electricity using a fuel cell with 50% efficiency, it yields 16,500 kWh per ton. This amount of electricity could power a 60W light bulb for almost 31 years or run a 1.5 kW vacuum cleaner continuously for a year and 3 months.

Hydrogen is not oxidizing, toxic, radioactive, odorous, corrosive, carcinogenic, or hazardous to water. It is not a greenhouse gas and does not contribute to global warming. Hydrogen pressure tanks are subject to the highest safety standards. In rare cases of a leak, hydrogen dissipates quickly due to its low density. Hydrogen flames burn quickly, primarily upwards, with low radiant heat. Hydrogen is no more dangerous than gasoline when handled with appropriate care.

Hydrogen and fuel cell technology compete with established technologies and energy carriers. Further cost reductions require scaling and mass production. Increasing production volumes will lower prices, making hydrogen more accessible. Regulatory changes, especially regarding CO2 emissions, will affect competitiveness. Infrastructure challenges, such as the limited number of refueling stations, also hinder adoption. The industry and policymakers are working on building a foundational infrastructure to address these issues.