Hydrogen is one of the basic building blocks of the universe. It is found, chemically-bound, in every living organism and possesses enormous potential. Hydrogen is an excellent source of energy, permitting electrical power to be obtained from water. It owes its perfect energy-storage properties to its perfect versatility, an attribute shared by REHAU, the polymer specialist.
The future energy source
Hydrogen, chemical symbol ‘H’, is the first and lightest element of the periodic table and it has a very high energy content. It is a gas that is not found in its pure form in nature. Instead, it is always in compound form. Most hydrogen is found in water, H2O. Splitting water into its hydrogen and oxygen components means the resulting hydrogen can be stored and burned as required to provide electricity and heat, used in fuel cells or as fuel for carbon neutral mobility. And the energy to weight ratio is impressive: 1 kg of hydrogen contains as much energy as 2.1 kg of natural gas or 2.8 kg of petrol.
Hydrogen is a hot topic with REHAU, too. For years, the company has been developing a hydrogen tank for vehicles of the future, getting involved in fuel cell construction and developing solutions for hydrogen distribution infrastructure.
Ralf Winterling, Technical Head of Infrastructure at REHAU, is sure that hydrogen will assume a crucial energy-storage role in the future. At the moment, in his view, three separate areas of technology are extremely promising. “In Germany, further expansion in the field of pumped-hydro power plants is unlikely. But in countries such as Switzerland, Austria or Norway more use of these will be seen in the future. Heat accumulators for ‘Power-to-Heat’ technology for converting excess electrical power into heat and storing it, also has enormous potential. REHAU has built borehole thermal energy stores (BTES) in Braedstrup (Denmark), Crailsheim (Germany) and Drake Landing (Canada). These make use of the ground beneath our feet as the storage medium with REHAU ground source probes circulating water heated up to 85ºC by solar power at a depth of around 50 meters. The ground around the probes heats up to become a gigantic heat storage system. In winter, this heat feeds back into the circulating water. In Braedstrup more than 1,200 residential units as well as municipal buildings and businesses are serviced with this heat by the district heating system. The heat stored in the ground can also originate from power plants or industrial processes.
Hydrogen storage systems for ‘Power-to-Gas’ technology will also play an important part in the future, Mr. Winterling believes. In Argentina, REHAU is currently working on a hydrogen storage facility intended to be taken into service in 2014. Surplus electricity from renewable sources can be stored by converting water into hydrogen or synthetic natural gas. Large storage facilities are available in the natural gas network or in underground caverns. Special multi-layer pipes are intended to transport hundreds of thousands of cubic meters of pure hydrogen gas. The idea of using hydrogen is not at all new. Without hydrogen flight into space would be impossible. Hydrogen gas has been the fuel of space travel ever since the sixties. “We consider the energy transition as an opportunity we wish to seize. Germany has positioned itself and intends to get away from its dependency on fossil fuels. We are witnessing enormous growth in a mix of renewable energies, worldwide”, Mr. Winterling explains. “Suitable storage for energy obtained from renewable sources is an essential part of this. And hydrogen is certainly a crucial component.”
Natural gas pipeline networks can be used for hydrogen. The challenge is dealing with permeation, i.e., preventing very small and volatile hydrogen molecules diffusing through the walls of polymer pipes. REHAU is researching the concept of a hydrogen-compatible pipe system that solves this problem by incorporating barrier layers.
In the end, Mr. Winterling believes, the three technologies will exist in a mix. “The ‘raison d'être’ of each will depend on system costs.” What type of plant is located where will be dictated by local circumstances. “The major advantage of hydrogen is that it is suitable for transportation as well as for producing electricity and heat. This makes hydrogen the most universal of all”, Mr. Winterling thinks. The enormous potential of hydrogen in relation to renewable sources of energy is of particular significance. Hydrogen produced by wind power or solar power will be “green crude oil” – in limitless supply, infinitely renewable and completely emission-free when converted back into electricity and heat.
Ralf Winterling is Technical Head of ‘Traffic Route Engineering’ and has worked for REHAU’s construction division since 2001. Since 2011 he has been primarily concerned with the development of new products related to “Energy Transition”, also known as the German “Energiewende” (thermally activated tunnels, underground high voltage cables and heat / hydrogen storage facilities).