Hydrogen as an energy carrier for use alongside wind and solar power
Hydrogen is one of the great new hopes of the energy transition. The element is found on the Earth in almost inexhaustible quantities, can easily be stored including for long periods of time and can be transported over long distances. But how suitable is hydrogen actually as an energy carrier?
For some years now, the topic of hydrogen as an energy carrier has been gaining momentum in business and science circles. In 2015, thirteen partners from politics, business and science joined forces as part of the “Hydrogen and Fuel Cell Germany” initiative to promote hydrogen as the fuel of the future. Among them are the automotive groups BMW, Daimler and Toyota. Together, they want to use hydrogen and fuel cell technology to make sustainable mobility and environmentally friendly energy storage possible in Germany in the near future. The initiative is pursuing the concept of sector coupling. This involves linking the fields of electricity, industry, heat and transport within an intelligent supply network in such a way that hydrogen is generated on a large scale in a sustainable way and then optimally redistributed.
Politics is also driving the issue more strongly at present. With its National Hydrogen Strategy, the German Federal Ministry for Economic Affairs and Energy (BMWi) intends to create the framework conditions for the necessary investments and innovations so that the production, transport, use and further application of hydrogen can take place in a sustainable manner in the future. As part of the 2020 National Reform Program, the German Federal Government set the goal of using “green” hydrogen, supporting a rapid market start-up for this and establishing corresponding value chains. Green hydrogen is produced by water electrolysis, with the necessary electricity coming from renewable sources. Politicians therefore want green hydrogen to become established on the market as quickly as possible. This is an important step, because at the moment hydrogen as a sustainable energy carrier is not yet really worthwhile, neither ecologically nor economically, and especially not for end users.
Still nothing for private users
End users can use hydrogen in two main areas – to generate heat and energy at home and as an alternative fuel for cars. There are currently two ways of producing hydrogen for private energy generation using private CHP plants equipped with fuel cell technology. The first is by generating “gray” hydrogen, which is achieved by steam reforming natural gas. This method uses fossil fuels and also produces CO2. The majority of hydrogen used industrially is also generated in this way to date. The second method is to use a CHP plant equipped with water electrolysis technology and coupled with a PV system. Green hydrogen could be generated using this combination. However, the costs for this are still very high, as such heating systems have not yet been produced on a large scale. However, this could change in the future.
Fuel cells are still not particularly attractive in the automotive sector either. This is due both to the higher acquisition costs and the poor infrastructure – there are hardly any hydrogen filling stations in Germany. Although the number of hydrogen filling stations is set to be increased to 400 in 2023, compared with over 17,000 battery charging stations and over 14,000 fossil fuel filling stations, the supply remains limited for the time being. However, according to the German Federal Ministry for Economic Affairs and Energy, this will soon change. As soon as a corresponding infrastructure is in place, end users’ interest in fuel cell cars is likely to increase. Fuel cells offer clear advantages in terms of range, storage time and refueling time, especially as batteries and fuel cells have a similar life cycle assessment.
The best alternative for commercial vehicles so far
In the transport sector, however, the future looks a little brighter. Although hydrogen only achieves an efficiency of 20% to 30% due to the relatively high energy consumption during production (compared with 70% for batteries), the short range and high weight of batteries pose a problem if heavy loads or lots of people need to be transported over long distances. So far, hydrogen is the best alternative to fossil fuels such as diesel, and the technology pays for itself much sooner than in the private sector as a result of the high vehicle utilization. According to the “Hydrogen and Fuel Cell Germany” initiative, for example, each diesel bus replaced by a fuel cell bus could save 50 tons of CO2. A train using hydrogen technology would emit as much as 700 tons less CO2 than a diesel train. In terms of efficiency, hydrogen and diesel are about the same.
Lots of future potential
According to the German Federal Ministry for Economic Affairs and Energy, hydrogen not only has energy potential, but it is also slated to create 5.4 million jobs in the hydrogen industry by 2050 and generate annual sales of €800 billion. Although the development of hydrogen as a comprehensive energy carrier is still in its infancy, the political groundwork for strong growth has been laid with the 2020 National Reform Program. The topic of hydrogen is therefore expected to gain considerable momentum in the coming years. If the technology and infrastructure can be advanced accordingly and synergies between sectors can be exploited, hydrogen will indeed soon become a sustainable energy carrier to be used alongside wind and solar power.
Hydrogen can be produced in four different ways. Each method of production is assigned a color:
Green hydrogen
“Green hydrogen is produced by the electrolysis of water, where only electricity from renewable energies is used for electrolysis. Regardless of the electrolysis technology chosen, the production of hydrogen is CO2-free, because the electricity used comes wholly from renewable sources and is therefore CO2-neutral.” (German Federal Ministry of Education and Research)
Gray hydrogen
“Gray hydrogen is produced from fossil fuels. During its production, heat is used to convert natural gas into hydrogen and CO2 (steam reforming). The CO2 is then released unused into the atmosphere, thereby intensifying the global greenhouse effect. The production of one ton of hydrogen produces around 10 tons of CO2.” (German Federal Ministry of Education and Research)
Blue hydrogen
“Blue hydrogen is essentially gray hydrogen, but where the CO2 is captured and stored as it is produced (carbon capture and storage, CCS). The CO2 produced during hydrogen production does not escape into the atmosphere and hydrogen production can be considered CO2-neutral on balance.” (German Federal Ministry of Education and Research)
Turquoise hydrogen
“Turquoise hydrogen is hydrogen that is produced by thermal cracking of methane (methane pyrolysis). Solid carbon is produced instead of CO2. For the process to be considered CO2-neutral, the heat for the high-temperature reactor must be supplied from renewable energy sources and the carbon needs to be permanently bound afterwards.” (Federal Ministry of Education and Research)
“Today, we must lay the groundwork for Germany to become the world’s number one in hydrogen technologies.”
Peter Altmaier, Federal Minister for Economic Affairs and Energy at the “Hydrogen and Energy Transition” stakeholder conference on November 5, 2019 in Berlin