Fuel-cell technology is gaining traction at an increasing number of vehicle manufacturers around the world. Following initial advances by Asian manufacturers, European OEMs are putting more resources into researching into and developing hydrogen-powered fuel cells.
“We are seeing increasing interest on the part of manufacturers,” says Dr. Michael Becker, Director for Predevelopment at Pierburg and coordinator of the company’s fuel cell activities. “This applies, on the one hand, to larger passenger cars, and increasingly to trucks and buses”.
His company is now receiving inquiries from all over the world, including for stationary systems that use fuel cells in the form of co-generation systems such as those used for heating and energy on buildings. Pierburg is an integral development partner and supplier of components and systems in the Rheinmetall Automotive competence pool.
The appeal of fuel cells is that they do away with time-consuming recharging, while having the advantages of electrically-powered vehicles. The only emission from the electrochemical reaction between hydrogen and oxygen in the fuel cell is water vapor discharged from the exhaust, which can be a simple plastic pipe.
Systems complementing each other
Although fuel-cell vehicles require a battery, this can be smaller than the conventional array installed in all-electric cars. After starting, the battery is used for accelerating and energy recovery when the brakes are applied. Due to their weight, batteries are not seen as viable alternative power sources for long-haul trucks and buses. This is where the fuel cell comes into its own: low weight and small footprint coupled with short refueling times.
Within the fuel cell, the presence of de-ionized water and hydrogen places special demands on the materials used, particularly with regard to resistance and the hydrogen tightness of the components. Pierburg is applying its combustion engine expertise in pumps and valves to provide a range of products for fuel-cell vehicles.
The range includes a leak-free control valve, a coolant pump and a hydrogen recirculation blower. The pump and blower are both suitable for both low- and high-voltage vehicle electrical systems of 12/24 and 400/800 volts.
The control valve, MPV (Multi-Purpose Valve), has a particularly compact package with low weight and is suitable for use on the cathode side of the fuel cell. It is resistant to de-ionized water and hydrogen and allows proportional and precise control. It combines low leakage with a high flow rate and low-pressure loss at the same time. The valve operates as an air diverting or bypass valve for the compressor or can be used as a pressure control valve as well as an isolation valve or shut-off valve for the fuel cell stack.
The proven coolant pump range has been specially redeveloped for fuel-cell applications, and can run off 400 volts or up to 800 volts. These high-voltage coolant pumps are driven by a brushless EC motor with sensorless control. They are equipped with LIN / CAN bus communication and corresponding diagnostic functions. The pumps are rated for up to 2.2 kilowatts. They are suitable for use with de-ionized water and various coolants.
Fuel cell systems have a recirculation system for unused hydrogen on the anode side. An active blower is often used for this purpose, which must function safely and efficiently even at high concentrations of hydrogen. To ensure this, Pierburg has developed a hydrogen recirculation blower (HRB) based on a side-channel blower without dynamic sealing elements to ensure ultimate hydrogen tightness over lifetime.
The blower is very compact has excellent NVH characteristics. It has a rating of 0.7 to 2 kilowatts or up to 400 watts in the low-voltage version. It is driven by a brushless motor with sensorless control; LIN / CAN bus communication and diagnostic functions are also available.
The company was recently commissioned by a vehicle producer to develop a cathode flap for a low-volume series. The electric flap systems, developed at the Pierburg plant in Berlin, will be used to control the fresh and exhaust air mass flows as well as the ultra-tight shut-off of the fuel cell stacks.
Automotive Industries (AI) asked Becker what is driving the interest in fuel cell technology.
Becker: There are certainly many and varied reasons for this. The current development focus is shifting toward larger passenger cars and includes trucks and buses. This is certainly due in no small part to the new legislation for trucks in Europe. CO2 emissions must be lowered 30% by 2030. This cannot be achieved without new technologies, and fuel cells are in themselves ideal for commercial vehicles. In addition, there is local public transport. Here, trains and buses with fuel cells are already in use on various routes.
AI: Do you see any varying levels of interest in fuel cells on the part of manufacturers?
Becker: No, we receive inquiries from all over the world and it can be said that almost all manufacturers are interested in the technology. This is especially true of manufacturers of heavier cars and SUVs, of commercial vehicles and buses, but also of producers of stationary systems. We are therefore in dialogue with many OEMs.
AI: How will fuel-cell sales develop in the near future?
Becker: Market experts are predicting that we will see large annual gains from the middle of the next decade from the currently low baseline. For 2030, it is conservatively estimated that approximately two million fuel-cell vehicles will be produced worldwide. Lead markets will be Asia and Europe. By the way, the projected transport infrastructure of the Olympic Games in Tokyo and in Beijing is largely based on hydrogen. Even though the Tokyo games were postponed for the known reasons, Japan will keep pushing fuel cell technology in a structured and sustainable way.
AI: In your opinion, what advantages does the fuel-cell offer over BEVs?
Becker: Apart from the short refueling time, the fuel cell has further advantages over pure BEVs. It enables long ranges, is significantly lighter and occupies less space, especially in heavy duty vehicles. And in winter it works without limitations even at sub-zero temperatures. In a fuel-cell car, you can finally switch on your air conditioning and heating again without having to panic about the range. So the fuel-cell vehicle is safely ahead of the BEVs in these respects.
AI: Where do you see any still unresolved central issues in improving the marketability of fuel cells?
Becker: From my point of view, three things are necessary. Firstly, the production of hydrogen must be regenerative throughout in order to achieve the desired ecological effect. Hydrogen can and should also serve as an energy accumulator if, for example, electricity generated by wind turbines is used, especially in times when general consumption is so low that they would otherwise be switched off.
Furthermore, work must be done on the infrastructure of the hydrogen filling stations, which is in fact happening as part of various publicly funded initiatives. Finally, of course, there is also a need for a reduction in costs in order to make fuel-cell vehicles more affordable for consumers. With the corresponding economies of scale, there will certainly be a lot happening here in the future.