The international community has set itself the goal of keeping the increase in global warming to below 2 degrees Celsius above pre-industrial levels. This may not sound very ambitious, but it will require a huge amount of effort from countries the world over. Global carbon dioxide (CO2) emissions play a key role here and will have to be drastically reduced. The transport sector accounts for 20 percent of global CO2 emissions. “We need to put a lot more zero-emissions vehicles on the road if we want to achieve this two-degree target,” explains Sebastian Fritz, Head of Market & Project Development for Hydrogen Solutions at Linde Gas. In future, absolute CO2 emissions produced by the transport sector will have to fall by 40 percent even though the number of people and goods in transit is set to rise drastically. This figure comes from the latest study carried out by the Hydrogen Council, an alliance of 19 companies, including Linde, committed to promoting a global hydrogen economy. This goal is not something that can be achieved with conventional combustion engines.
Climate-friendly way to go
“The only thing vehicles equipped with hydrogen-powered fuel cells emit is water vapour,” says Linde expert Fritz. This makes hydrogen (H2) an climate friendly option, ideal for supporting the transition to low-carbon mobility choices. Linde offers all technologies required to produce hydrogen, transport it efficiently to refuelling stations and fill up fuel-cell vehicles. The company is the world’s largest manufacturer of H2 production plants and a leading provider of equipment for hydrogen refuelling stations. “Linde Engineering covers the full gas treatment spectrum. And Linde Gas masters the entire downstream technology portfolio required to enable a fully functional hydrogen economy,” adds Anton Jell, Vice President Business Development for Hydrogen and Synthesis Gas Plants at Linde Engineering.
Liquid Hydrogen trailer
Increasing energy density
With hydrogen, cooling and compression processes play a vital role in transport, storage and fuelling. This is because hydrogen has a low energy density under normal pressure and temperature conditions. 3,000 litres of gaseous hydrogen, for example, contain the same amount of energy as one litre of petrol. “Hydrogen has to be heavily compressed to increase its energy density and allow it to be efficiently stored and transported,” explains Jell. This means that gaseous hydrogen either has to be compressed to produce CGH2 (compressed gaseous hydrogen) or cryogenically liquefied to produce LH2 (liquid hydrogen). Linde offers powerful technologies to convert hydrogen to both of these aggregate states. “There are a number of factors that determine whether it makes sense to compress of liquefy, including the volume of hydrogen to be transported and the distances involved,” explains the Linde expert.
Pressurised storage tanks
Liquefied hydrogen has a very high energy density. This is an advantage as it means that more hydrogen can be transported by truck to refuelling stations. Up to five tonnes of LH2 can fit into Linde’s specially designed transport tanks. “However, liquefying hydrogen requires a lot of energy,” says Jell. “The gas first has to be cooled to minus 253 degrees Celsius.” Refuelling stations also have to be equipped with special, insulated cryogenic containers for the LH2 to ensure as little hydrogen as possible evaporates during storage. However, transporting and refuelling with LH2 is actually very cost effective, and the benefits of a liquid supply scheme rise in synch with demand for H2 at the filling pumps.
High-pressure H₂ on the go
“Compressed gaseous hydrogen can also be delivered to refuelling stations,” continues Fritz. In these cases, the hydrogen is transported at different pressure stages. Around one tonne of hydrogen, for example, can be transported at a pressure of 500 bar. To withstand the highest pressures, the H2 storage elements are equipped with high-performance plastics and a carbon fibre shell.
CcH2 Trailer at Linde Hydrogen Center, Unterschleissheim
Storing and refuelling hydrogen
At fuelling stations, the H2 is then stored in 45-bar gas storage tanks, 200-bar tubes, which can also be installed underground, or in liquid storage tanks. The hydrogen must then be compressed to a specific pressure for dispensing at the pumps as it is injected into fuel-cell vehicles in a compressed gaseous state. As such, the compression unit is one of the core pieces of equipment at a H2 refuelling station. “The compressor brings the gas to the required pressure, which is either 350 or 700 bar depending on the vehicle in question,” adds Fritz. “Linde offers two powerful, innovative technologies for refuelling: the cryopump for liquid hydrogen and the ionic compressor for compressed hydrogen.” Both technologies keep refuelling times at stations to under three minutes. This is all it takes to fully refuel a car with high-pressure H2. Once full, it can travel just under 600 kilometres before the next pit stop. “Hydrogen cars have a similar range to vehicles with combustion engines,” comments Jell. To date, Linde has notched up over a million H2 fill-ups. “These were carried out across the globe at over 100 refuelling stations equipped with our technologies,” elaborates Fritz.
H₂ for cars and trains
Today, more and more car manufacturers have launched hydrogen vehicles or are already manufacturing small-series models. In 2016, Linde affiliate Linde Hydrogen Concept launched BeeZero in Munich, the world’s first car sharing service made up solely of hydrogen-powered fuel-cell vehicles. This fleet of fuel-cell cars has been in service for nearly two years now, giving the Group valuable insights that will help it further develop hydrogen technologies and expand the H2 infrastructure.
Hydrogen fuelling station OMV Vienna Austria
Hydrogen is also making an impact on rail transport. From 2021 on, fourteen fuel-cell trains will be used to replace diesel locomotives in the German state of Lower Saxony. These Coradia iLint trains will be produced by railway vehicle manufacturer Alstom. The trains can cover around 1,000 kilometres on a single tank with top speeds of up to 140 kilometres an hour. “Linde has been asked to supply the hydrogen,” enthuses Linde expert Jell. The company will be building and running the world’s first hydrogen refuelling system for trains to support this project. This climate friendly fuel is also generating interest in other areas. “We have received multiple queries about whether H2 can be used as a fuel for trucks, ships and even aircraft,” explains Fritz.
The climate-friendly choice
Hydrogen can play a key role in achieving the world’s two-degree climate mitigation goal. This is backed up by another finding from the Hydrogen Council’s latest study, which shows that vehicles powered by hydrogen produced conventionally from natural gas already emit 30 percent fewer CO2 emissions than cars with diesel engines. “An even better option would be to use hydrogen generated with renewable energies such as wind, hydroelectric and solar power,” summarises Jell. Linde’s engineering and gas specialists are working closely to develop technologies and concepts for sustainable hydrogen production. After all, every mode of transport and every kilometre travelled that saves CO2 – whether by land, water or air – bring us closer to our two-degree climate mitigation goal.