Key technology represents an important milestone on the journey to climate neutrality
Fossil-free and no longer dependent on oil – around 40 years ago, that was the vision of energy supplies in the future. Leading research institutes were working on this topic at that time as part of funding programs organized by the German Research Ministry (now called the Federal Ministry of Education and Research). The solar hydrogen economy is therefore nothing new in Germany. So how does this explain the current hype regarding “green” hydrogen? What has changed over the last four decades? Professor Dr.-Ing. Manfred Norbert Fisch of the energieplus Steinbeis Innovation Center examines this question. He is convinced that one of the key technologies for a zero carbon footprint in Europe will be based on water electrolysis, which will be used to convert electricity surpluses resulting from renewable energy into green hydrogen. The name for this concept: power to gas.
Forty years ago, the key priority was to find alternative energy sources to replace petroleum in the chemical industry in order to enter a post-oil era. Using hydrogen as a secondary source of energy – produced through solar and wind energy – was seen as a panacea for the future. The technical means were already within reach, but producing electricity from renewables was far too expensive. In the meantime, the goal posts have shifted. The priority now is to optimize the costs associated with cutting anthropogenic carbon emissions and minimize the impacts of climate damage. There has also been a dramatic drop in the price of electricity generated by solar systems and wind parks. In Germany, green electricity can be produced for less than 5 ct/kWh; in Southern Europe it costs 3 ct/kWh.
Green hydrogen – key to the energy transition
According to Steinbeis expert Manfred Norbert Fisch, the goals of the green energy transition in Germany, which were drafted by the Federal Ministry for Economic Affairs and Energy in 2010, and the ambitious EU climate goals captured in the 2019 Green Deal are only just achievable, but only if there is a rapid expansion in the construction of photovoltaic systems and wind farms.
The required power plant capacity from renewable energy (RE) in Germany will rise by at least 500% (factor Five) by 2050 compared to the current level of approx. 110 GW. This is the same percentage as the rise in non-usable electricity surpluses resulting from fluctuating supplies of RE. As a result, green hydrogen is a key factor for the transition to alternative energy sources. Electricity surpluses should not be “regulated away,” as is currently the case, but converted into hydrogen for use as a chemical energy source (power-to-gas). This green hydrogen (H2) could replace carbon in many processes. For example it could be used as a reducing agent in steel production. Synthetic methane and synthetic fuels can be produced from H2. It can also be used in fuel cells for conversion back into electricity.
In addition, green hydrogen will be needed in the coming years to decarbonize industry and transportation. At around 33 kWh/kg, its energy density is roughly three times higher than that of diesel, so H2 offers significant potential as a fuel – for example in heavy goods transportation. To produce 1kg of hydrogen, 45-50 kWh of electricity are required for the splitting process in electrolysis. A considerable amount of tap water is also needed: roughly 16-20 liters. The heat that has to be dissipated, somewhere between 60 and 65°C, is usually released into the environment. The efficiency level of PEM and alkaline electrolyzers is about 60%. The key advantage of hydrogen molecules is that unlike electrons in batteries, they have zero-loss storage capabilities over long periods of time. This speaks in favor of medium- and long-term storage in green hydrogen, among other things in order to cope with feared “quiet periods,” when no energy can be produced by wind and solar energy farms due to a lack of wind or sunshine.
The time to act is now
The current hype surrounding green hydrogen is fueled by the German government’s National Hydrogen Strategy. Germany’s aim with this strategy is to become a world leader in hydrogen technology in the areas of electrolysis, fuel cells, H2 infrastructure, H2 filling stations, and H2 gas stations. It’s an ambitious goal and to achieve it, German engineering will be needed as well as innovative companies that are willing to take risks so that production capacity can be built up to provide many gigawatts of power in Europe. By 2030, €7 billion will have been earmarked to ramp up projects in Germany, plus €2 billion for investments in “sunnier” countries. To create future-proof jobs and export green electricity and hydrogen to central Europe, it would be necessary to use a large part of the EU’s €750 billion economic stimulus program as part of the Green Deal in order to develop industry and promote initiatives in Southern Europe. It’s less important how much of the estimated demand for hydrogen in 2050 (around 15 million tons of hydrogen) will be produced in Germany and Europe, or imported from abroad; it’s more important to understand that now is the time to act. Roadmaps and studies on various scenarios don’t move things forward, they only eat into the time we have left to start doing something. The technology we need to produce green hydrogen is already available, it just needs to be made use of.
The approach of asking how much green hydrogen should cost compared to conventionally produced hydrogen – €1.50 or €2 per kilo – is completely out of touch with future oriented thinking. Asking this question in the context of the German government’s climate protection plan gets us nowhere. Instead, the issue that should be addressed is which cost-effective measures can be applied to achieve the goal. Nevertheless, discussion is required regarding where and with which technologies the large volumes of green hydrogen will be produced, what prices will be offered to customers, and what impact can be expected on commodities that are produced with it.
Electrolysis – using electricity to decompose water
The cost of green hydrogen mainly depends on the cost of generating electricity, the operating time of electrolyzers, and the investment costs of electrolysis plants. Within years, it will be possible to produce green hydrogen for €3 to €5 per kilo. Manufacturing costs for hydrogen will drop by at least two-thirds by ramping up industrial production on a gigawatt scale and making targeted investments of under 500 euros/kW.
“A major proportion of hydrogen should be produced where the demand can be met directly,” says Fisch. Shipping on truck trailers has its limitations, because ultimately a 40-ton vehicle transports a few hundred kilograms of hydrogen (15-20 MWh). The gas grids in Germany are fundamentally suitable for distributing large volumes of hydrogen and conveying it from Southern to Central Europe. During the transition period before 2050, there will be mixed networks accounting for a two-digit percentage of H2. In parallel, dedicated hydrogen networks will connect industrial regions across Europe. How green electricity, green hydrogen and green fuel produced in North Africa or other sunny regions should be transported to Europe is a fascinating challenge in technological, economic, and engineering terms. Producing hydrogen in sunny, arid areas requires large quantities of water, which can mainly be extracted from marine sources, although that also places a major drain on energy. In addition, liquefaction is energy-intensive, transportation is costly and results in energy losses, and such arrangements have geo-political ramifications – monumental challenges for which solutions still need to be found. “According to my calculations, taking into account all downstream expenditures before reaching the customer in Germany, there are no significant price advantages between hydrogen from Germany or Southern Europe and MENA countries,” says Fisch. Also, this countries should decarbonize there one industry first, before they export green energy. The questions that then remain relate to space potential and acceptance among the population for building the required wind farms and photovoltaic installations in open areas. Expanding PV and wind farm capacity to 500 or 550 GW would not present space problems in Germany. There are sufficient roofs and empty spaces for PV systems. 250 GW of photovoltaic systems would cover the equivalent of only 2 or 3% of agricultural land, without taking usable roof areas into account.
Another advantage of integrated electrolytic hydrogen production in Germany is that it offers the possibility to use waste heat generated in the process of supplying buildings and neighborhoods. Around 30% of used electricity is converted into heat. This significantly improves system efficiency from around 60 to almost 90%. If only half of the green hydrogen required in 2050, i.e. around 7.5 million metric tons per year, is produced in Germany, this will result in usable waste heat of around 110 TWh/a. This is roughly equivalent to current district heating levels and is enough to supply heating to around 14 million energy-refurbished homes. There is therefore considerable potential on a number of fronts, which can be leveraged with existing concepts.
The journey to becoming a climate-neutral city
The climate neutral district “Neue Weststadt” in the Baden-Wuerttemberg city of Esslingen revolves around generating domestic power from renewable sources, local hydrogen production, and the waste heat generated in order to supply the city district with heat. The green hydrogen is fed into the city’s gas grid, thus contributing to decarbonization of the energy sector. Research will also be carried out into the technical and economic viability of making direct use of energy in the coming years in the transportation and industry sectors. This real-world laboratory (“Reallabor”) for researching the green energy transition in an inner-city area measures 12 hectares and will be inaugurated in June 2021.
Currently nearing completion, the district will span around 500 residential properties, offices, commercial buildings, and new buildings for the local university. The aim is to create an urban district that is almost carbon-neutral. Carbon-neutral for this project is defined as achieving annual carbon emissions for housing and travel of under one ton per capita. To achieve this, among other things energy consumption will be reduced, many roofs will be fitted with solar panels (approx. 1,500 kWp PV), waste heat will be recovered from hydrogen production, and imported biomethane will be used in combined heat and power plants (CHP). A key element of the system for supplying the district with energy is a hydrogen electrolyzer with an output of 1,000 kWel. Electricity used in the district will be supplied by PV systems installed on roofs, with a major share coming from generation plants supplying surplus renewable electricity from outside via the national grid. Waste heat from the electrolyzer will be used to meet around half of the heating requirements of housing units, commercial buildings, and the university via a local heating network. This will raise the annual efficiency of electrolysis to about 85 to 90%. Studies are already underway to assess further commercialization options for green hydrogen, such as filling trailers or laying H2 pipelines to nearby industrial sites.
The project is nearly ready and is one of six lighthouse projects under the auspices of the 6th Energy Research Program organized by the German Federal Government, as part of a funding initiative called “Solar Construction/Energy-Efficient City”. Between 2017 and 2022, the project is receiving a subsidy of around €12 million. The enterprise responsible for financing, operating, and marketing green hydrogen and waste heat from H2 production is Green Hydrogen Esslingen (GHE), founded in 2019. Depending on electricity prices (8 to 10 ct/kWh), it is currently working on the basis of a hydrogen price of 6 to 7 euros/kg. Trial operation is planned until May 2021, when a two-year monitoring phase will begin supervised by the energieplus Steinbeis Innovation Center.