Hydrogen is a key resource for lower-carbon mobility choices. It has an even higher energy density in liquid form. Linde’s technology innovation lies at the heart of liquid hydrogen fueling stations.
Instead of harmful fumes, the tailpipes of hydrogen-powered vehicles emit nothing other than pure H2O – more commonly known as water. This key feature makes hydrogen (H2) not only a popular source of energy for fuel-cell vehicles, but also a key stepping stone in the move towards a climate-friendly energy economy. The hydrogen in fuel cells produces clean electricity when it reacts with oxygen (O2) to form water. This process does not create any harmful exhaust gases. It is an attractive idea that has been around for some time now. In fact, the writer Jules Verne foresaw a hydrogen-based energy economy as far back as 1874. “Water will be the coal of the future,” wrote Verne at the time. Now, almost 150 years later, Verne’s vision is slowly taking shape. Producing H2 is still a cost- and energy-intensive process. However, excess electricity from renewable energy sources that is not required during off-peak periods is an excellent way of producing green hydrogen.
Approximately 55 kilowatt hours of energy are required to generate one kilogram of hydrogen. “This is enough to power a fuel-cell car for around 100 kilometers,” calculates Thomas Schaefer, Global Market Development Manager at Linde Hydrogen FuelTech. In 2017 alone, 5.5 terawatt hours of energy were reported to have gone unused in Germany alone. This would have been enough energy for hydrogen cars to travel ten billion kilometers – without producing any emissions at all.
Hydrogen can be produced in a number of different ways. Depending on the method, the end product will be either grey or green hydrogen. Grey hydrogen is a by-product of various processes in the oil and gas industry such as natural gas steam reforming. These proven processes are based on mature technologies. However, they all release carbon dioxide (CO2). In contrast, green hydrogen is carbon-neutral, which makes it the preferred option for the transition to a more sustainable energy economy. Green H2 can be generated from renewable resources through biological processes such as biomass gasification or biogas reforming. Another option is to use solar, wind or water power to electrolyze water (H2O), splitting it into H2 and O2.
The production capacity for green hydrogen is increasing worldwide – driven by the transition to more sustainable energy systems. More and more of Europe’s energy is sourced from increasingly efficient solar farms, ever-bigger wind farms and hydropower plants. In 2018, energy from these sources accounted for 16.8 percent of all energy consumed in Germany. Scandinavian countries are even further ahead here, with renewables accounting for 40 percent of the energy mix in Finland, over 50 percent in Sweden and 70 percent in Norway.
The key challenge with renewable energy, however, is the fact that it fluctuates. In strong winds, for example, wind farms produce more power than the grid needs. The same applies to solar farms on sunny days. “If we use this green energy for electrolysis, we can store it as hydrogen and transport it too,” explains the Linde expert. The green hydrogen can be distributed to hydrogen fueling stations, for example, of which there are already more than 80 in Germany. The H2 Mobility Deutschland initiative aims to expand this network of fueling stations to 400 sites by 2023, creating an extensive infrastructure for fuel-cell cars across Germany. Linde is also an active member of this project.
Today, hydrogen is typically transported to fueling stations as a gas. Linde’s custom-developed, patented ionic compressor uses five hydraulic pistons to gradually compress the hydrogen to a pressure of 900 bar so it can be used to fuel vehicles. For passenger cars, for example, the gas must be at a pressure of 700 bar while larger vehicles such as buses and trains require 350 bar.
Complementing this compressed gas fueling solution, Linde also offers a refueling concept that enables hydrogen to be stored as a liquid. The major benefit here is that liquid hydrogen has a much higher energy density. “One tanker filled with liquid hydrogen contains as much energy as seven gas tankers,” adds Schaefer. This is because liquid hydrogen (LH2) takes up one seventh of the volume of hydrogen in the gaseous state (GH2). This makes LH2 a particularly interesting option for densely populated areas where there is limited space for building or expanding fueling stations. It was against this backdrop that Linde developed its CP90 and CP50 cryopumps for LH2 fueling stations.
The first CP90 on US soil has now opened in Oakland, California. The new plant has three times more capacity than existing hydrogen fueling stations in California. Twelve other stations are set to follow shortly, securing the supply of hydrogen in this southwestern US state. California wants to have five million vehicles with carbon-neutral drive systems on the road by 2030 – and it needs to be able to supply these with green fuel. “Hydrogen is being massively incentivized in California. The capacity of hydrogen fueling stations is a particular focus here. So, we will need fueling stations that can serve a much higher volume of vehicles per day than before,” continues Schaefer. “The LH2-based CP technology is our answer to this challenge. These stations can store up to 800 kilograms of hydrogen on site. The CP itself can compress up to 40 kilograms per hour, which is enough for around 200 to 300 cars a day.”
“The newly developed cryogenic pump greatly enhances fueling efficiency for fuel-cell buses.”
Other countries are also investing heavily in efforts to build out their hydrogen infrastructure. In South Korea, the “HyNet” consortium aims to install around 100 H2 fueling stations by 2022. Following Germany’s example, Japan has founded “Japan H2 Mobility” – a company that aims to build 170 hydrogen fueling stations in Japan by 2021.
“All of this activity is really driving demand. With decades of expertise, Linde is a pioneer in the H2 space,” continues Schaefer. Numerous projects in recent years confirm this status. As part of a two-year pilot project, for example, Linde gathered valuable experiences in hydrogen mobility with its BeeZero car-sharing service. And the next tour de force is just around the corner: Linde has developed a new, more powerful cryopump. “This CP model can refuel up to 100 kilograms of hydrogen per hour,” explains Schaefer. This will allow buses equipped with climate-friendly fuel-cell drives to be refueled more efficiently than ever before. Innovations such as these from Linde are giving a turbo boost to the future of eco-friendly mobility powered by hydrogen.
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Germany already has over 80 hydrogen fueling stations like this one here in Berlin. Linde is a member of H2 Mobility Deutschland, an initiative that aims to expand the German network of fueling stations for fuel-cell cars to 400 sites across the country by 2023.
Following Germany’s example, Japan has founded “Japan H2 Mobility” – a company aiming to build 170 hydrogen fueling stations in Japan by 2021.
Hydrogen is typically transported as a compressed gas to fueling stations such as this one in Stavanger, Norway.
Linde’s patented ionic compressor uses five hydraulic pistons to gradually compress hydrogen to the right pressure. The gaseous H2 can then be used to fuel vehicles – at a pressure of 700 bar for passenger cars or 350 bar for larger vehicles such as buses and trains.
H2 is transported by tanker to most fueling stations as a compressed gas. Linde also offers a concept that enables hydrogen to be stored as a liquid (LH2), capitalizing on the advantageous fact that LH2 has a much higher energy density.