Hydrogen-Based Electricity Supply for the Infrastructure

Proton Motor develops and produces products for energy supply based on customized hydrogen fuel cells. This technology is one possible solution for a grid-independent, or decentralized, electricity and emergency power supply.

Key component of a zero-emission hydrogen application: the fuel cell stack

No matter what the actual application, and no matter what performance level is required: at Proton Motor, every hydrogen solution starts with a cell stack.

A cell’s active surface determines the electrical energy the cell stack is able to supply by the number of simultaneous reactions. The corresponding voltage is the result of the number of connected cells.

Based on this principle, Proton Motor’s stack modules are able to supply a capacity of 1.8 to 42.6 kW. The company is planning to increase the potential power output even further – mostly by using multistacks.

Highly leak-tight, maintenance-free KNF diaphragm pump recirculates hydrogen gas

The operating principle of the fuel cell systems is recirculation. Feeding more hydrogen into the anode input than the process consumes prevents deficient supply of the anode even when the power load is fluctuating.

Proton Motor currently uses type N 838.1.2 diaphragm gas pumps from KNF for systems of up to 10.6 kW output to transfer excess hydrogen gas back into the fuel cell stack.

At the anode outlet, the N 838.1.2 gas pump takes up the unused hydrogen, while the condensate remains in the separator. The remaining hydrogen gas mixture is compressed to the required anode input pressure by the N 838.1.2, and recirculated into the stack.

The KNF recirculation pump ensures that the hydrogen can be almost fully used. This optimizes hydrogen utilization and has a positive effect on the system’s efficiency.

The requirements of hydrogen on the diaphragm pump

Hydrogen is an energy source that sets specific demands on the recirculation pump.

All of the pump components that come into contact with the medium – the pump head, the connection and the connecting plate – are made from 316L stainless steel. This prevents unwanted embrittlement of the material and leaching of hazardous components.

Hydrogen has a low density, which actually changes depending on the operating point. The pump head has been adapted to cope with the characteristics of hydrogen and to stay reliably sealed.

The series model’s IP 20 protection class has been raised to IP 44 for this application. To make this possible, the motor has been equipped with an additional flange, special motor screwed cable glands and a separate terminal box. Another quick and cost-efficient adjustment enabled by the KNF modular system is the gastight screw joint.

Dynamic pump curves for various operating states

The operating modes start-up, normal operation and shut down or stand-by all cause different amounts of hydrogen gas needing to be recirculated.

The KNF recirculation pump has been equipped with a motor from the “Digital Customization” series. This finely controllable motor gives the maintenance-free recirculation pump the flexibility to provide any anode gas flow rate with the best possible energy efficiency.

The system pressure is up to 400 mbar g, an inlet pressure that KNF’s brushless DC motor, an inhouse development, is easily able to cope with. Gentle start-up is possible and the operating current is always under control, avoiding peak loads.

Modular fuel cell systems demanding compact hydrogen pumps

When selecting the anode gas pump, Proton Motor pays close attention to the size of the device. The diaphragm gas pump N 838.1.2 series model is intrinsically compact. Modifications to the connection of the pump head have made the recirculation pump even smaller, so that it takes up even less space. This option perfectly supports modular design the CleanTech company relies on.

Hydrogen for off-grid and emergency power supply

Proton Motor’s scalable fuel cell solutions are suitable for either stationary or portable applications. They can be used indoors as well as outdoors as turnkey cabinet solutions.

Apart from their use as backup system, another important area of application is the emergency power supply for critical infrastructure. One of Proton Motor’s recent projects is the emergency power supply for the Deutsche Bahn (DB) interlocking center in Sömmerda, Germany. The company has developed a container solution for uninterruptible power supply in cooperation with the DB Bahnbau Gruppe and DB Netz AG, which replaces the previous diesel generator with their HyModule^® S8 zero-emission fuel cell system with an output of 7.8 kW.

Hydrogen – an energy source with potential

Fuel cells are building blocks for a sustainable energy supply. The compact design of the stack module makes it easy to assemble them to a higher-level, tailor-made system for a particular application. If the hydrogen is generated by electrolysis from water using renewable energies such as photovoltaics or wind energy, energy generation with fuel cells is carbon-neutral.

KNF diaphragm gas pumps ensure the controlled, continuous recirculation of the hydrogen within the fuel cell stacks.