Case study: Stäubli's connection to a greener future

The ongoing transition to renewables and green energy has been underway now for decades, with a focus on wind power in the 1990’s, solar power in the 2000’s and in recent years much of the focus has been on battery power and electromobility. In parallel with this has been the ongoing development and investment in the production and use of hydrogen as a clean fuel.

The potential of hydrogen as a sustainable future energy source is further reinforced by the fact that in recent years many countries have developed national hydrogen strategies.

It may be the smallest molecule in the universe, but hydrogen holds immense potential as a clean energy source as part of the global energy transition. It is a gas that can be burned in an engine or used in a fuel cell to power vehicles, generate electricity or provide heat. 

The potential uses of hydrogen are many and varied, and span across multiple market sectors including, rail, aerospace, on and off-road vehicles, marine and energy generation. A key function which is common across all applications, whether it’s in the production of hydrogen, transportation of hydrogen, or the use of the gas as a fuel source, is the need to be able to connect the production, storage, and transportation mediums reliably and safely to the trains, ships or vehicles which will use the fuel. 

This is where the global expertise of Stäubli, and the company’s reputation for producing the highest quality coupling solutions, will make a valuable contribution to the development and acceptance of hydrogen as a key fuel source, whilst at the same time, enhancing the potential of achieving the all-important environmental targets.

Stäubli is active at all levels within the hydrogen sector, including participating as part of the ISO body (ISO T/C 197 Hydrogen Technologies) responsible for the standardization in the field of systems and devices for the production, storage, transport, measurement and use of hydrogen.  Specifically, Stäubli’s contribution surrounds the definition of the standard for the refueling connector. By participating, Stäubli plays a key role in defining the standard that will then be implemented worldwide. Stäubli is also recognized as experts in the field by the French Standardization Body, AFNOR, and as such deemed qualified to participate in these important industry working groups.

Stäubli has for many years been an innovator within several highly regulated sectors where the company’s couplings and connectors satisfy the most stringent demands for performance, quality, and safety. The cross-sector expertise gained by Stäubli has been instrumental in developing unique solutions for petrochemicals and motorsport, where Stäubli’s refueling solutions have been established as the standard in certain sections of the sport. 

The knowledge gained in developing these solutions is at the heart of the product offering for the hydrogen sector. Stäubli is a key participant in all areas of the hydrogen industry from the production phase, to logistics, moving the hydrogen from one place to another, and finally wherever the hydrogen is being used. The nature of the product, its volatility, and the pressures with which it is held and dispensed pose some unique challenges for the connection solutions. 

The hydrogen fuel cell is being seen as a possible alternative to BEV’s (Battery Electric Vehicles) or Hybrid’s. The hydrogen fuel cell works by feeding the hydrogen to the anode, and air to the cathode. A catalyst at the anode separates hydrogen molecules into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity. This is used to power the vehicles electric motors. The potential advantages of the hydrogen fuel cell for vehicular transport is the short refueling time, which is very similar to that of a conventional petrol or diesel vehicle. The differences and challenges, however, relate to the safety, security and high pressures used when refueling.

Unlike a conventional vehicle where the pump nozzle is just held manually within the tank aperture, refueling the hydrogen fuel cell requires a sophisticated and safe connection solution, capable of handling the high pressures, which can be between 350 and 700 bar, and which must also be leak free. 

A further requirement is the electronics which regulates and ensures the safety of the refueling operation. Infrared communications are used to monitor the pressure and temperature within the storage tank in the vehicle. This information is passed to the nozzle being used to fill the tank and from there to the dispensing system. Depending upon the pressure and temperature information received, the dispenser will adjust the flow to prevent overheating the tank. All this technology must be an integral part of the connection solution.

With a conventional petrol or diesel fuel nozzle, if the user mis-handles it or drops it, there is little to go wrong. As one might imagine, which such a sophisticated arrangement for hydrogen refueling, it is essential that the connection solution is both robust and reliable, as the failure of any one part of this system, mechanical or electronic, will render the refueling station inoperative. Given the limited number of hydrogen refueling stations currently available, it is essential therefore that reliability is built into the system. Stäubli coupling solutions for the hydrogen sector meet the required standard of 100,000 operational cycles without failure and have also passed drop tests, replicating real world operation and events. Another mandatory requirement for the hydrogen refueling system, which is unique, is interoperability, meaning that the manufacturer of the coupling on the station side must be able to connect to its counterpart on the vehicle side. 

Safety Guaranteed During Refueling

As we will have seen with conventional petrol or diesel refueling systems, there are instances where the vehicle has moved, either during refueling or at the end of the operation but where the user has failed to remove the nozzle from the vehicle. Whilst this can cause physical damage to both sides of the connection, overall, there is a minimum risk of serious consequences from such an event. When refueling a hydrogen powered vehicle, given the volatility of the fuel and the high pressures involved, any unexpected movement of the vehicle and subsequent damage to the connection could have significant consequences.  To ensure maximum safety during refueling and to address possible safety issues should the connection between the fueling station and the vehicle be accidentally broken, Stäubli coupling solutions incorporate a safety breakaway feature.

Typically installed between a fixed point and a hose line, Stäubli’s industrial breakaway couplings prevent the risk of spills and leaks. Separation occurs when force is applied axially or up to 90° in any direction to the plane of the coupling, and safety is maintained thanks to the instantaneous closure of both flows. These systems have already proven to be a valuable asset during fluid transfer operations within the chemical, petrochemical and rail sectors.

Ergonomics and Economy

Two additional key factors must be considered in relation to the use of couplings and connections for the hydrogen sector. The total cost of ownership for the fuel operator is important. Not only must they have total confidence in the product, the reliability and maintenance requirements of the product will be influential in determining cost effectiveness. 

From both the fuel operator and end user perspective, the refueling system must also to be intuitive, ergonomic, and easy to operate. All of these factors were a priority for Stäubli when developing the connection solutions for the hydrogen sector. A major contributing factor, in terms of performance and reliability, is the design and the materials used in the manufacture of Stäubli’s solutions. The net result is a range of solutions which are industry compliant, incorporate essential safety features and which will ultimately deliver the highest performance at an attractive and low overall cost of ownership.