Dr Christoph Stiller – Head of Energy Production and Storage, Linde Innovation Management
Hydrogen is an environmentally sound energy carrier. It is also an ideal medium for storing energy from renewable sources such as the wind and the sun. Pioneering the latest hydrogen technologies, Linde is working on a range of projects to turn our vision of sustainable energy and clean transport into reality.
»How can we best store the increasing amounts of energy we are producing from renewable sources?«
Dr Christoph Stiller
Looking ahead, one of the biggest questions society is facing is how to secure a clean supply of electricity to meet future energy needs. Should we harness the power of the sun, wind or water? Dr Christoph Stiller, Head of Energy Production and Storage at Linde Innovation Management, is already ahead of the game. For him, the big question is: “How can we best store the increasing amounts of energy we are producing from renewable sources?”
As Stiller stands in front of a wind farm to the south of Berlin, the blades of the hundred-metre turbines swoosh in the autumn wind and energy flows at top speed. Yet that is not always the case, since wind and solar power, by their very nature, are subject to fluctuations. The wind doesn’t always blow and when it does, it is never at a consistent speed. Similarly, the sun only shines during the day – and not always at that – and in more temperate climates it is only strong enough in the summer months. Demand-driven distribution of energy from renewable sources such as these thus hinges on effective storage solutions. And that is where hydrogen (H2) comes into the picture. “Hydrogen is the key to our future energy landscape,” declares the engineer. “It has a high energy density and is easy to transport.” As an industrial-scale storage solution, it also tops the economy ratings. “If you store energy in a battery, you’re looking at an investment of around 400 euros per kilowatt hour. Storing the same amount of energy as hydrogen in underground caverns costs well under a euro.”
Hydrogen-based options also compare favourably to pumped-storage hydroelectric plants, which only have limited capacity. In Germany, for instance, just 40 gigawatt hours can currently be stored in this way. Meanwhile, experts estimate that around forty terawatt hours would be required to meet the country’s entire energy needs solely from renewable sources – so a thousand times the current capacity. Another benefit of hydrogen is that, unlike batteries, it does not run down over time, so is still available even if it has been stored for an extended period.
Hydrogen-powered fuel-cell vehicles can easily cover 400 kilometres and more on a single tank.
State of charge and power flow are displayed on the on-board computer.
The process of using electrolysis to convert energy to a gas such as hydrogen for easier storage is referred to as power-to-gas. The resulting green hydrogen can then be used in a number of ways. “At times of peak demand, the hydrogen can be turned back into electricity by gas-fired power plants, or used by combined heat and power stations,” explains Stiller.
Alternatively, it can be fed into the natural gas network – either directly, with the gas grid able to absorb up to five percent hydrogen – or indirectly following methanation. Here the volume of hydrogen that can be fed into the natural gas network is unlimited. Methanation entails adding carbon dioxide to the hydrogen to produce synthetic natural gas. “Hydrogen is enabling completely new connections across the energy landscape,” Stiller confirms. “It is both a storage medium and a highly versatile product in its own right.”
Clean energy expert Dr Christoph Stiller at the new hydrogen refuelling facility at Berlin airport. Linde and its partners are committed to expanding the filling station network.
A special dispenser fills vehicles with the hydrogen, cooled to temperatures as low as minus 40 degrees Celsius.
This potential is set to drive demand for facilities that convert electrical energy into hydrogen. Linde’s Innovation Management team plays an important role here, evaluating relevant products and technologies, designing implementation measures and ensuring smooth execution. One such project is currently under way at the “Energiepark Mainz” in the German city of Mainz.
Supported by the German federal government’s Energy Storage Funding Initiative, Linde, Siemens and municipal utility company Stadtwerke Mainz are investing a total of 17 million euros in the construction of a hydrogen facility. This will be able to absorb up to six megawatts of electrical power – roughly the output of three wind energy plants – and produce up to 200 tonnes of hydrogen per year. Part of this will be fed into a local natural gas pipeline and converted back into electricity on demand at a modern gas and steam power station.
Power-to-gas is shaping up as a key technology not only in the transition to a greater share of renewable energies, but also in the move towards eco-friendly transport options. That is why Mainz will also be home to a filling station for hydrogen trailers, which in turn will supply hydrogen refuelling facilities. This system will have the capacity to power 1,500 fuel-cell vehicles running on hydrogen. Industrial customers will also be able to obtain green hydrogen for their production operations from Mainz. “Energiepark Mainz is the most ambitious lighthouse project for hydrogen energy storage to date. We are combining several new technologies here – and, for the first time, on a scale that could make a real difference to our energy landscape,” reveals Stiller. The plant is scheduled to go on stream in early 2015.
Once converted to hydrogen, renewable energy can be placed in temporary storage. An ionic compressor – no bigger than a container – increases the pressure prior to refuelling.
Outside the wind farm to the south of Berlin, Christoph Stiller gets into a car and accelerates to over fifty kilometres per hour in just a few seconds – without a sound. The Linde expert is sitting in a Mercedes F-Cell, a hydrogen-powered fuel-cell vehicle. “It just goes to show – hydrogen and electric mobility are by no means at odds,” he remarks. “Like a battery-operated vehicle, this car is also electric and produces zero emissions.” Combining hydrogen with a fuel cell gives the Mercedes model a range of 400 kilometres, and it takes just three minutes to refuel – almost the same as a conventional combustion-engine car.
The in-car hydrogen is stored in pressurised gas tanks integrated in the floor beneath the passenger compartment. From here it flows to a fuel cell, where it reacts with oxygen from the air to produce electricity and power the motor, which drives the car via the front axle. An additional high-voltage battery absorbs kinetic energy on braking, which in turn enables powerful acceleration. The journey to the capital’s new main airport generates no emissions. If Stiller accelerates hard, the exhaust pipe emits a few drops of water, and otherwise just water vapour – whether in stop-and-go traffic around town or doing 100 mph on the German motorways. “This car is a lot of fun to drive,” exclaims Stiller, as he pulls onto the site of the newly opened Total filling station at Berlin airport. “It ticks every single box for the perfect modern vehicle.”
After just a few minutes at the hydrogen dispenser, not far from the kerosene tank for aircraft fuel, the car is already full up. Stiller replaces the hose, the handle slightly cold as the hydrogen flows into the car’s compressed gas tank at temperatures as low as minus 40 degrees Celsius. And without a hint of an odour. The hydrogen used for road transport has to be 99.999 percent pure, so for every million hydrogen molecules, a maximum of ten other molecules is permitted. Linde ensures this at every process step, directly at the airport. The hydrogen available here is currently delivered from Leuna, where it is manufactured from raw glycerine or biogas. However, from mid-2014, it will be produced by an electrolysis facility at the airport itself. As part of the H2-BER project, Linde is working with Total, Enertrag and McPhy to demonstrate how power-to-gas can already change the face of everyday mobility. The project is supported by the German national innovation programme for hydrogen and fuel-cell technology (NIP).
Demanding requirements: hydrogen for electric vehicles must be 99.999 percent pure.
The digital display on the fuel dispenser shows the price: 9.50 euros per kilogram, so just under 40 euros for a full tank. Stiller pays by card, as do all members of the Clean Energy Partnership, which includes companies such as Total and Shell, Daimler, BMW, Volkswagen, Toyota and Hyundai, Siemens and Linde. Their mutual aim is to advance widespread adoption of clean hydrogen technology.
At the rear of the building, Stiller meets Alexander Zörner, Linde’s project manager for hydrogen applications in northeast Germany. “This filling station is in a league of its own,” confirms Zörner. “We have linked up the entire hydrogen chain here – from the initial energy source right through to the point of use.” Indeed, the H2-BER project is like a one-stop mobility shop, extending from hydrogen production to fuel sales at the pump. The energy from the wind is converted into hydrogen by a 12-metre electrolysis system. The gaseous hydrogen then flows into a state-of-the-art ionic compressor developed by Linde, initially at a pressure of around 50 bar. This increases many times over inside the compressor, since the in-car hydrogen needs to be stored at 700 bar. Leading vehicle manufacturers are now turning their attention to hydrogen power. And in several countries, the necessary infrastructure is gradually expanding towards nationwide coverage. By the end of 2015, there should be fifty hydrogen fuelling stations in Germany and a hundred in Japan, for instance. Linde is already supplying components for these pioneering hydrogen stations to the European, Asian and American markets. “Market maturity is now a given,” concludes Stiller. “The important thing is to gain experience from pilot projects so that we can commercialise hydrogen technology cost-effectively, ensuring widespread coverage as soon as possible.” Berlin airport seems a promising start.
Networked hydrogen economy
Wind farms produce large volumes of renewable energy. Depending on requirements, this might be fed directly into the grid, used to power electric cars or stored in the form of hydrogen. There are many different applications for hydrogen generated from wind power. It can be used to power fuel-cell vehicles, co-fed into natural gas pipelines or converted into synthetic natural gas by means of methanation. It can even be used as a fuel in heating and power plants.