The relative obscurity of the race to improve power density in a fuel cell stack doesn't mean it's not important, since that's one of the keys to the future of our most promising alternative propulsion systems.
So GM's announcement that it has raised the industry's volumetric efficiency standard by some 60 percent is of more than passing interest, even though it's still a long way from where it needs to be for real-world consumer use.
According to GM, it has a fuel cell stack that generates 1.75 kilowatts (kW) per liter, which measures the stack's power output in kilowatts versus its volume. That beats the highest power density announced by any other fuel cell manufacturer, says GM, which is the 1.1 kW per liter mark claimed by Ballard Power Systems of Vancouver.
"Reducing the size and weight of the fuel cell stack while maintaining or improving its power output is important for packaging, design and affordability," says Matthew Fronk, chief engineer of fuel cell systems for GM's Global Alternative Propulsion Center (GAPC).
Fronk says smaller stacks create more space for other components and allow their use in smaller vehicles and stationary units. They also require less material, which provides an opportunity for further cost savings.
They also allow a greater stack volume, which is critical to the ability to deliver greater performance in a vehicle.