Hydrogen and its diverse applications


Environmentally-friendly energy technologies: Hydrogen and fuel cells

On Earth, hydrogen is usually found as a compound together with other chemical elements. In order to use hydrogen in its pure form, it must first be split from the compound it is combined with, by applying energy. The resulting pure hydrogen is a source of energy that can be used in many different ways. The most efficient method for converting hydrogen to electricity is the fuel cell. In turn, fuel cells can be used wherever power and heat is required – be it for mobility, heating or in combined heat and power systems.

Hydrogen is thereby a fuel for vehicles that are based on land (e.g. cars, buses, forklifts, trains), water (e.g. ships, submarines) and in the air (aircraft) as well as a fuel for heaters and combined heat and power plants. If pure hydrogen is used in fuel cells for applications such as above, no local pollutant emissions are produced. The only by-product is water.

Hydrogen is currently still mainly produced via the process of reforming natural gas. However, due to the use of natural gas, this method results in the emission of greenhouse gases (GHG). Future-oriented, climate-friendly hydrogen production therefore uses renewable energy from wind, sun, hydro or geothermal power instead. This is made possible through the use of electrolysers, which split water into its chemical element components of hydrogen (H2) and oxygen (O) using power from renewable sources. Hydrogen and fuel cells therefore enable a departure from fossil-based fuels (keyword: decarbonisation).


Hydrogen for the storage of renewable energy

Unlike electricity, which can only be stored to a limited degree, energy in the form of hydrogen can be temporarily stored for weeks and months on end. This attribute plays a vital role in an energy system that increasingly makes use of fluctuating renewable energy. Today, electricity is usually supplied as it is needed through fossil-based fuels in coal, gas or nuclear power stations.

In contrast, electricity from renewable sources, such as wind power and photovoltaic plants, is produced and available only when the wind is blowing or the sun is shining – irrespective of the actual demand. In order to enable the current power supply demands to be met with the expansion and ultimately the conversion to a renewable energy supply system, storage solutions are necessary in which large quantities of surplus electricity can be stored for long periods so that the power demands can still be met even during conditions with little wind or sunshine. Hydrogen is an energy storage medium.

 

It can be produced using an electrolyser at any time when surplus renewable energy is available. The hydrogen produced with this method can be stored, can be used as a fuel, and in periods during which too little electricity is available from renewable energy facilities can also be reconverted to electricity in fuel cells and fed into the electricity network.


Hydrogen facilitates a new, clean and integrated energy system

Fossil-based energy (oil, gas, coal) is primarily used in today’s energy system, which is divided into the power, heat and transportation sectors. These energy sectors largely possess their own distribution paths (electricity, heat and gas networks) and infrastructure (refineries, pipelines and refuelling stations). Production, provision and consumption are all aligned to the needs of the consumer in the respective energy sectors.

Thanks to the establishment and expansion of renewable energy, the power sector has developed into an increasingly environmentally friendly and sustainable sector. In contrast, the fossil-based fuels of oil and gas are still predominant in the heating and transportation sectors – along with the subsequent greenhouse gas emissions. In order to attain the global climate targets that have been set, fossil fuels must be virtually entirely replaced by renewable sources of energy. At the same time, the energy supply system must develop so that all energy sectors are integrated. Hydrogen connects these energy sectors.  

Besides its dual function as a source of energy and a storage medium, hydrogen is also a raw or basic material in numerous production processes (e.g. in the chemical industry, refineries, development of semiconductors). With the deployment of hydrogen from renewable sources of energy, industry processes can be decarbonised and emissions significantly reduced. Instead of fossil-based fuels, the underlying production process (keyword: Power-to-X) exclusively uses electrolysis hydrogen and existing CO2 sources to synthesise climate-neutral fuels – which can be used for mobility and heating just like their fossil-based counterparts, diesel and natural gas.