Energy-intensive industries are confronted with the challenge of reducing their emissions. Natural gas, as a source of energy, could perform an important bridging function in this respect.
Deafeningly loud and oppressively hot: that is how the production of the passenger compartments of a motor vehicle in the context of automobile manufacturing could be described. In the automobile industry, natural gas is used, inter alia, as a fuel for industrial furnaces. With the aid of the hot working method, steel sheets are hereby first heated at very high temperatures before subsequently being shaped and cooled down. During this process the microstructure of the steel is altered in such a way as to be twice as hard as before.1
Hot working is an energy-intensive method. Such procedures, as do comparable ones, present a particular challenge to automobile manufacturers and other industrial companies. They are expected to, and wish to, commit themselves to the energy transition and reduce their CO2-emissions. At the same time it is almost impossible to avoid the high energy requirements of their production process and until now it has scarcely been possible to realise this profitably with the aid of renewable sources of energy alone.
One solution could be the increased use of natural gas: As the fossil energy source with the lowest CO2-emissions, the use thereof could reduce said emissions quickly and lastingly, whilst at the same time enabling traditional, energy-intensive, but tried and tests production methods to be retained in the medium term. This is the reason why natural gas, alongside the renewable sources, is already an important source of energy for the German industry today: in 2020, ca. 36 percent of natural gas sales were accounted for by the industrial sector.2 With a share of 50 percent, natural gas is at the same time the most important source of energy in the industrial generation of electricity.3
This figure could indeed increase still further in the future, especially in energy-intensive branches of industry such as the production of primary steel. In order to achieve extensive decarbonisation here, the currently standard carbon-based blast furnace routes would have to be replaced by the direct reductions procedure in which natural gas can be used for iron ore reduction in the short term and hydrogen, low in greenhouse gases, for the same purpose in the long-term. The term direct reduction describes a process in which iron ore is reduced to iron sponge. The basis of this procedure is usually a shaft furnace, which is filled from above with iron ore in the form of pellets and lump ore. In order that the oxygen in the iron ore might be able to dissolve itself out, carbon monoxide and hydrogen are used. These gases – other than in the case of the blast furnace process – are not produced from the burning of coke but are generated outside the shaft furnace by means of catalysis of natural gas. At a temperature of ca. 1000 degrees Celsius, both process gases are fed into the furnace, as a result of which the iron ores are perfused and the oxygen removed. This results in a cracked surface of the iron ores that resembles a porous sponge and is consequently called an iron sponge. The iron sponge is thereafter further processed into raw steel.4
Gas also has an important role to play with a view to the storage of energy. The share of renewable sources of energy in the production of electrical power will increase further in the future. One possibility for the storage of renewable electricity is to be found in the process “Power-to-Gas”.5 In this, water, through the use of surplus electricity, is split into hydrogen and oxygen by way of electrolysis. This (green) hydrogen can, to a limited extent, be fed directly into the existing natural gas grids or further processed to form synthetic natural gas, which may be added to the natural gas to an unlimited degree.
Many industrial enterprises today already pin their faith in the use of natural gas. The favourable CO2-balance of this source of energy, the role it plays in the transition to a functioning hydrogen economy and its storage capability could result in this source of energy soon being used yet more intensively by other companies as well – thus building a bridge to a more sustainable industry of tomorrow.
1 WINGAS GmbH: https://www.wingas.com/
2 BDEW: Sales of natural gas broken down according to customer groups: https://www.bdew.de/service/daten-und- grafiken/erdgasabsatz-nach-kundengruppen/
3 Destatis: Industry produced 53.4 thousand million kilowatt hours of electricity in the year 2019: https://www.destatis.de/DE/Presse/Pressemitteilungen/2020/10/PD20_410_43312.html
4 tec-science: Direct Reduction Process: https://www.tec-science.com/de/werkstofftechnik/stahl-erzeugung- herstellung/direktreduktionsverfahren/
5 Zukunft Gas: Power-to-Gas – Wind, sun and water are turned into natural gas: https://www.erdgas.info/energie/erneuerbares-erdgas/power-to-gas/strom-zu-gas