Energy Source of the Future?

No chemical element occurs more frequently in the universe than hydrogen. One proton in the nucleus, one electron in the shell - that's all there is to the simplest isotope of the lightest of all elements. On earth, it is mostly bound in water. And it can be separated from this with electrical energy. The process is called electrolysis and provides us with both an energy source and a basic raw material.

But why take the "diversions" of hydrogen when electricity generated from renewable sources can also be used directly? "We're often asked that," says Guido Jansen. He's the spokesperson for the Institute for a Sustainable Hydrogen Economy (INW) at the Jülich Research Centre. The institute forms the heart of the Helmholtz Hydrogen Cluster. "We then like to respond with a comparison of strawberries and strawberry jam," he adds with a grin. "It's certainly more efficient to eat the strawberries straight away than to process them into jam in many stages. However, strawberries aren't always available and can't be stored for a particularly long time. That's why strawberry jam also works as a business model." It's the same with electricity and hydrogen. Of course, it's best to use the electricity directly, says the expert. But that won't work without storage in the future. And he sees hydrogen as an ideal energy source. "We don't want to compete with batteries in any way," he says. "We think that every technology has its justification and its application."

What these applications look like and what technical challenges need to be solved are currently being intensively investigated in Jülich. "One of our projects is to supply a hospital with electricity and heat," explains Guido Jansen. "To this end, we're testing a new type of solid oxide fuel cell from our project partner Bosch Energy together with an innovative form of hydrogen transport." In the final stage of the project, the hydrogen won't be cooled down or delivered under high pressure, but will instead be bound to a liquid organic carrier. During storage, these Liquid Organic Hydrogen Carriers, or LOHC for short, incorporate the hydrogen into their molecular structure via a chemical reaction. This is hydrogenation. The liquid can then be transported and stored in the tank truck. Part of the waste heat from the fuel cell is used to extract the hydrogen from the carrier medium. This is dehydration. The remaining heat from the fuel cells is available for use. "We chose a hospital because there is a continuous need for electricity and heat around the clock," he says. "In principle, this can also be transferred to other applications and sectors."

For example, the food industry. And they've long been familiar with the gas. For example, hydrogen is used to harden fats. In this process, known as hydrogenation, the hydrogen saturates the double bonds of the fatty acid residues. That changes the melting point. Oils that are liquid at room temperature become spreadable fats. Margarine is a very prominent example of this. The gas is also listed as a food additive with the number E 949 and is used as a packaging or propellant gas. Hydrogen is also indispensable when considering the very beginning of the process chain in the food sector - agriculture. This is because the gas is combined with nitrogen in the Haber-Bosch process to produce ammonia. And that in turn is the starting point for the most important fertilisers.

In these applications, it's therefore not a question of whether hydrogen will find its way into the market. On the contrary, they offer a good starting point for decarbonising the industry. This is because the vast majority of hydrogen still comes from fossil fuels. For example, 99.06 percent of the 94 million tonnes of hydrogen produced worldwide in 2021 were made from natural gas, coal, oil and refinery by-products. By increasing the "green" share - i.e. hydrogen from solar and wind-powered electrolysis - they could make today's hydrogen consumers in the food industry sustainable without additional investment in existing systems.

But hydrogen also has potential in other areas of the food industry. This is because many processors also have a high demand for electricity and heat without major fluctuations throughout the day. As in the Jülich researchers' hospital project, fuel cells are the method of choice here as well. These systems are actually commonplace. The principle has been known since 1838 and was later primarily used in space travel. In a fuel cell stack - as the smallest unit of the systems is called - hydrogen and oxygen combine within an electrolyte to form water. This releases energy that can be extracted as electricity. The SOFC systems already mentioned are particularly suitable for industrial applications. SOFC stands for Solid Oxide Fuel Cell. Here, the electrolyte is a special ceramic. This type of cell operates at temperatures of several hundred degrees Celsius. That makes it possible to utilise heat as well as electricity. This can either be extracted and fed into the company's own heating network or converted into a refrigerating system using absorption chillers. When using electricity and heat, modern systems operate with an overall efficiency of around 90 percent.

In a hydrogen economy, however, the food industry need not only act as a consumer. This is because it has excellent prerequisites for producing the energy source and raw material itself or providing the raw materials for it. That's because hydrogen can't only be produced by splitting water. It can also be obtained from organic substances. For example, organic waste. Or plastics. Both are produced in large quantities in the food industry and previously had to be disposed of at great expense. This is why there are now companies that specialise in converting waste streams into raw materials.

The much-touted hydrogen economy is still in its infancy. There is no shortage of potential starting points. But where should investments be made first? "There are certainly areas in which hydrogen can make a huge contribution to achieving climate targets. In the steel industry, for example. Or in glass production," says Guido Jansen. "However, we believe that the technologies should be introduced as broadly as possible across all relevant sectors. It wouldn't be wise to wait until we have enough hydrogen and then start thinking about using it." One country that seems to have recognised this is China. The People's Republic is investing heavily in hydrogen projects and aims to cover ten percent of its final energy consumption with renewably produced hydrogen by the end of the decade.

And what about Germany? "In the field of hydrogen research and technology, we are very well positioned in an international comparison," he says. "Other countries are currently often faster when it comes to implementing projects." He has observed that German companies are rather hesitant in this regard. People often wait and ask whether a retrofit would be profitable. "Showing companies other options is one of the objectives of the Helmholtz Hydrogen Cluster," he says. "With our demonstration projects, we want to show that many technologies have already left the research stage and are proving themselves in practice."