Industry Insight What is Hydrogen and How Can it Help Us?
The increasingly relevant climate change coupled with the worldwide static increase in energy consumption by industry and private households requires us to rethink. New climate-neutral alternatives are being promoted more and more. One of the biggest hopes in the field of climate neutrality is hydrogen. But what is hydrogen? How can we produce it and where can it help us?
Hydrogen is the most common element in our universe. It is present in bound form in almost all organic compounds. However, hydrogen (H2) only occurs in bound form. For example, combined with oxygen (O2) as water (H2O). The main component of natural gas, methane (CH4), and crude oil are also important hydrogen-containing compounds, so-called hydrocarbons. In addition, more than 50 % of all minerals known to date contain hydrogen. Hydrogen is also present in the earth's atmosphere.
But how is hydrogen transformed into an energy carrier? The electrolysis process is used for this purpose. What this is, you will learn in the next paragraph.
Different Types of Hydrogen
Like electricity, hydrogen is a secondary energy and must be produced. This requires raw materials such as water, methane or natural gas as well as energy, which are supplied. Although hydrogen is always a colorless gas, colors in the designation provide information about the type of production. A distinction is made between green, blue, gray and turquoise hydrogen.
Green hydrogen is produced exclusively from renewable energy sources. For this purpose, the process of water electrolysis is primarily used. Electrolysis is the splitting of a chemical compound under the influence of electric current. The water particles are decomposed into oxygen and hydrogen with the help of electricity. An electrolytic cell is used for this purpose (see diagram). This contains two carbon electrodes (platinum or graphite), which are immersed in a liquid salt. The current causes an electron surplus at the cathode and an electron deficiency at the anode.
Hydrogen accumulates at the cathode due to the application of electricity. The anode, in combination with electricity, causes the oxygen to separate from the water.
Turquoise hydrogen is produced by methane pyrolysis, in which methane is broken down into solid carbon and hydrogen in a thermochemical process. The carbon material can be used here in industry, e.g. for battery production. If the heat supply for the high-temperature reactor is provided by renewable energies, this is a CO2-neutral process. Likewise, the permanent bonding of the carbon material is crucial for CO2-neutrality.
Gray hydrogen is obtained from fossil fuels. During its production, coal or natural gas is split into hydrogen and carbon dioxide (CO2) under heat. The CO2 is then mostly released unused into the atmosphere, thereby increasing the global greenhouse effect. Approximately 10 tons of CO2 are produced per ton of hydrogen. Thus, it can be said that gray hydrogen does not support our environment in any way.
The production of blue hydrogen is identical to the production of gray hydrogen. The difference in the color coding is that the released CO2 is stored underground using CCS technology (Carbon Capture Storage) or it can be further processed in industry. As a result, blue hydrogen can be considered CO2-neutral in balance sheet terms.
What Can Hydrogen be Used for?
Hydrogen can be used in different areas. The following two ultimately have shown numerous research advances.
Because of the many ways in which hydrogen can be used, it can make a significant contribution to a clean industry and to our future on this earth. Especially the keyword decarbonization plays a key role here. This means the way to a future with fossil-free manufacturing and energy production.
More and more new projects are being initiated to reduce corporate emissions. The steel industry, for example, wants to use green hydrogen to significantly reduce greenhouse gas emissions. Thyssenkrupp, for example, has set itself the goal of reducing emissions by a third by 2030. By 2050, it wants to produce climate-neutral steel.
The petrochemical industry and the upstream oil and gas industry also have a great need for hydrogen. Here, however, the gas is needed as a cleaning product. Crude oil and natural gas, as well as the refinery products derived from them, contain sulfur-containing compounds. These must be removed as carefully as possible for two reasons: when these compounds are burned, for example in fuels, toxic and environmentally harmful sulfur oxides are produced, which is why environmental regulations only permit low limits. In addition, sulfur compounds are typical catalyst poisons, so they damage the catalytic converters both in motor vehicles and in other processing operations of petrochemical raw materials.
So-called hydrodesulfurization is used here. This means desulfurization with the aid of hydrogen. In this process, added hydrogen reacts with the sulfur on a catalyst to form hydrogen sulfide. This in turn can be isolated, and from it a considerable proportion of the sulfur produced worldwide is obtained, another important basic chemical. The hydrogen used thus also contributes indirectly to sulfur chemistry.
Hydrogen as a raw material
Hydrogen has long been an important raw material for the chemical and petrochemical industries. It is mainly used for the production of ammonia. This is mostly followed by fertilizers and plastics. It is also used to process crude oil into fuels and high-grade chemical products. In addition, hydrogen is needed for reduction processes in metallurgy, as a coolant in electrical generators, as a protective gas in electronics, for welding and cutting in mechanical engineering, and for fat hardening in the food industry.
Mobility (hydrogen fuel technology)
Battery driven vehicles are not profitable in every situation. In heavy-duty traffic in particular, a lot of energy is needed due to the weight of the vehicles. Accordingly, a relatively large amount of electricity would be needed to cover the required ranges. Hydrogen can also be processed in further steps to produce synthetic fuels, which are then used in internal combustion engines. These would make emission free driving possible in situations electric motors have little to no use.
More and more automotive companies are turning to hydrogen as an alternative to electric motors. Siemens is working on a hydrogen train together with the Deutsche Bahn. This should be able to be refueled in the same time as the current diesel-powered trains. Shipping is also expected to benefit from hydrogen. The French inland shipping company “Compagnie Fluvial de Transport” has been working on the first commercial cargo ship powered by hydrogen since 2018. This is scheduled to enter service in 2021.