Daimler Truck and Linde Engineering have reached an important infrastructure breakthrough on the path towards decarbonizing transportation with H₂. Over the past few years, engineers from both companies have jointly developed sLH₂, a new process for handling subcooled liquid H₂. When compared to gaseous H₂, this innovative approach allows for a higher storage density, a greater range, faster refueling, lower costs and superior energy efficiency. Refueling takes around ten to fifteen minutes for a 40-ton heavy-duty truck, carrying 80 kg of liquid H₂ for a range of 1,000 kilometers and more. At the same time, the new sLH₂ technology lowers the required investment for a H₂ refueling station by a factor of two to three, and operational costs are five to six times lower. Today, liquid H₂ can be supplied reliably throughout Europe.

Compared to regular liquid H₂ refueling technology, the new process uses a new innovative sLH₂ pump to slightly increase the pressure of the liquid H₂. With this method, the H₂ becomes subcooled liquid H₂ (sLH₂). H₂ in this state, facilitates a very robust fueling process that also keeps energy losses during refueling to a minimum. Furthermore, no data transmission between the refueling station and vehicle is necessary, which further reduces the complexity of the solution. At the same time, refueling capacity is increased to new levels. The pilot refueling station has a capacity of 400 kg of liquid H₂ per hour. In comparison to regular liquid or gaseous H₂ refueling concepts, sLH₂ is considerably simpler while delivering increased performance.

Aiming to establish a common refueling standard for H₂-powered trucks, the technology is made openly available to all interested parties via an ISO standard. In the presence of Rhineland-Palatinate's Secretary of State for Economic Affairs, Petra DickWalther, and international media, Andreas Gorbach, Member of the Board of Management of Daimler Truck, and Juergen Nowicki, CEO of Linde Engineering, today inaugurated the first public sLH₂ pilot station in Wörth am Rhein, refueling a Mercedes-Benz GenH2 Truck prototype.

Andreas Gorbach, Member of the Board of Management of Daimler Truck AG, responsible for Truck Technology said, “Zero-emission transport needs three factors: the right battery-electric and H₂-powered vehicles, the required infrastructure network and cost parity for ZEVs compared to diesel trucks. In terms of vehicles, the transformation is in full swing. In terms of H₂ infrastructure, we are reaching a major milestone today: With sLH₂, H₂ refueling becomes as convenient as today’s refueling with diesel. It takes about 10 to 15 minutes to fuel our Mercedes-Benz GenH2 Truck for a range of more than 1,000 kilometers. We now call on other OEMs and infrastructure companies to follow our approach and jointly make this technology an industry standard.”

Juergen Nowicki, Executive Vice President Linde plc and CEO of Linde Engineering said, “Subcooled liquid H₂ considerably increases the efficiency of H₂ refueling systems. The required investment is reduced by a factor of two to three, and operational costs are five to six times lower. This and further advantages make sLH₂ a practical, CO₂-neutral alternative to diesel in the heavy-duty vehicle sector. The technology we have developed with Daimler Truck will help pave the way for the development of a robust refueling network, which is essential to keep vehicles moving and supply chains intact.”

Linde Engineering sLH₂ refueling station sets efficiency benchmark. The new public sLH₂ refueling station in Wörth am Rhein, Germany, sets a benchmark in terms of energy efficiency and performance. With energy consumption of only 0.05 KWh/kg, it requires approximately 30 times less energy compared with conventional gaseous H₂ refueling. The refueling station has a small footprint of just 50 square meters (not including the dispenser) and allows for configurations where several dispensers for parallel refueling of trucks are possible, as well as back-to-back refueling. The liquid H₂ storage tank has a capacity of four tons, sufficient for approximately ten hours of non-stop refueling. Meanwhile, the capacity of the sLH₂ fuel station can be increased to over eight tons per day with refilling. A lower initial investment and operational costs for the sLH₂ technology is expected to ultimately result in lower total cost of ownership.

Aim: Setting the industry standard for liquid H₂ refueling. Daimler Truck and Linde Engineering aim to make sLH₂ the leading H₂ refueling technology for heavy-duty trucks. As a result, both companies offer a high level of transparency and openness around the relevant interfaces of the jointly developed sLH₂ technology. The technology has been standardized in an open ISO process and is available to all interested parties. Now Daimler Truck and Linde Engineering call upon other OEMs, infrastructure companies and associations to apply the new liquid H₂ standard and thereby establish a global mass market for the process.

Safe, fast and simple refueling with H₂. In contrast to current LH₂ refueling, the sLH₂ process is similar to the convenience of current diesel refueling technology. Due to robust insulation the refueling hose and the design of the interfaces between the nozzle and fuel tank, the process is safe without the possibility of spillage. Therefore, the protective measures required for sLH₂ refueling are comparable to those required for diesel. During the refueling process, cryogenic liquid H₂ at –253°C can be filled into two connected 40 kg tanks mounted on either side of the truck chassis without the need for special safety gear. The sLH₂ technology allows for high flow delivery of more than 400 kg of H₂ per hour and filling 80 kg of liquid H₂ can be completed in ten to fifteen minutes. Finally, the new process avoids what are known as boil-off effects and “return gas” (gas from the vehicle’s tank returning to the filling station) and therefore only one nozzle is needed to fill the tanks, making sLH₂ technology easier to handle. The new refueling station in Wörth will be provided with liquid H₂ by Linde, which has the largest liquid H₂ capacity and distribution system in the world.

Liquid H₂ enables a range of 1,000 kilometers and more. Daimler Truck prefers liquid H₂ in the development of H₂-based drives. In this aggregate state, the energy carrier has a far higher energy density in relation to volume than gaseous H₂. As a result, the tanks of a fuel-cell truck using liquid H₂ are more cost efficient compared to the carbon tanks used for gaseous H₂. And due to the lower pressure, they are also significantly lighter. The technology thus enables a higher payload, and at the same time, more H₂ can be carried, which significantly increases the trucks’ range. This makes the Mercedes-Benz GenH2 Truck, like conventional diesel trucks, suitable for flexible and demanding long-haul transport. This was demonstrated in September 2023, when a prototype of the Mercedes-Benz GenH2 Truck approved for public roads completed Daimler Truck’s #H2RecordRun, covering 1,047 km of distance driven on one fill of 80 kg of liquid H₂. The company aims to introduce the series version of the fuel-cell truck in the second half of the decade.

sLH₂ to be implemented in Mercedes-Benz GenH2 Truck customer-trial fleet. From mid-2024 onward, five companies are expected to take part in initial customer trials to gain first experience in CO₂-free long-distance transport with Mercedes-Benz GenH2 Trucks. The semi-trailer tractors will be deployed in different long-haul applications on specific routes within Germany, and they will be refueled at the now open public sLH₂ refueling station in Wörth am Rhein and at a refueling station in the Duisburg area. Daimler Truck and its partner companies are thus creating a lighthouse project with the aim to demonstrate that decarbonized transport with H₂-powered trucks is already possible today. However, for the transformation to succeed, it will be necessary in the coming years to ensure the buildup of an international refueling infrastructure and a sufficient supply of green liquid H₂.