Drive systems for compressors for hydrogen filling stations: Scalable, robust and compact

Within the next six years, several thousand hydrogen filling stations will go into operation worldwide, making an important contribution to the decarbonization of the mobility sector. Together with partners from the hydrogen industry, Bosch Rexroth has developed a scalable portfolio of servohydraulic drives for compressors in the power range between 10 and 280 kW. A new cryopump for example directly compresses liquid hydrogen to 875 bar and thus allows heavy commercial vehicles to be directly refueled within a few minutes.

Long service life and start-stop operation, high efficiency with low hydrogen losses and low operating costs: OEMs and operators are looking for solutions that can be implemented quickly in technological terms to ensure the economical operation of hydrogen filling stations. Based on its decades of experience in electrohydraulics, Bosch Rexroth has developed customized solutions for an economical hydrogen infrastructure, working together with partners.

The company relies on servohydraulic drive technology with an infinitely variable hydrostatic transmission. The robust hydraulics has a long service life. Long-stroke, ATEX-certified drive cylinders for compressors increase delivery rates thanks to end position-optimized control. The portfolio covers the power range between 10 and 280 kW as well as various applications.

New cryopump: 100 kg of hydrogen in 10 minutes

Bosch Rexroth developed the new electrohydraulically driven cryopump in collaboration with FirstElement Fuel, the market leader for the commercial operation of hydrogen filling stations in the USA. With a connection rating of 280 kW, it compresses liquid hydrogen to 875 bar for the direct refueling of heavy trucks. The aim is to refuel vehicles with 100 kg of hydrogen within 10 minutes. With direct refueling, there is no need for temporary storage tanks at filling stations. The first filling stations will be equipped with the new system from 2025.

Bosch Rexroth also offers variants developed together with partners for medium and smaller outputs. The 75 kW CytroCore compressor drive can be used to compress both liquid and gaseous hydrogen. In the lower output range of 10 kW, a ready-to-connect self-contained actuator CytroForce drives the compressor cylinders. No specific hydraulics know-how is required for either of the solutions.

Standard modules finely scalable in hardware and software

For optimum energy efficiency, Bosch Rexroth relies on so-called displacement control. In contrast to throttle control which is used in most industrial hydraulic systems, position and force control is achieved by means of servohydraulic pump control. This control concept reduces energy consumption by approx. 75 %. In addition, the drive system for compressors require less than one square meter of installation space and are much quieter than conventional drive systems. After a one-off parameterization, they are ready for immediate use. They communicate with the control system for the hydrogen filling station via open interfaces. All modules continuously record operating data, thus putting in place the conditions for systematic condition monitoring and predictive maintenance for maximum availability with the digital service CytroConnect Solutions.

Bosch Rexroth can configure the standard drives in its portfolio in hardware and software to suit specific applications and thus precisely meet the requirements of users. The drive systems for compressors simplify the system architecture and operability of hydrogen filling stations and are suitable for both established companies in the hydrogen industry and newcomers.