GM Said It Has Developed The “World’s Most Powerful Fuel Cell Stack” – Brief Article
General Motors’ latest fuel cell stack sets a new world standard for power density that packs 60 percent more power than any competitor, GM said at a recent fuel cell technical conference in London. The new GM stack is said to generate 1.75 kilowatts (kW) per liter, setting an industry benchmark for volumetric efficiency — the measurement of the stack’s power output in kilowatts vs. its volume. The highest power density announced by any other fuel cell manufacturer to date is 1.1 kW per liter by Ballard Power Systems, according to GM scientists.
“Reducing the size and weight of the fuel cell stack while maintaining or improving its power output is important for packaging, design and affordability,” said Matthew Fronk, chief engineer of fuel cell systems for GM’s Global Alternative Propulsion Center (GAPC). Smaller stacks create more space for other components and allow their use in smaller vehicles and stationary units.
“We achieved this efficiency through further developments in materials, and improving how we form parts of the fuel cell and how the stack is put together,” said Gary Stottler, director of stack development at GAPC. The new stack has 640 cells with a continuous power output of 102kW (134 horsepower) and a peak power output of 129kW (173 hp), the company said. It weighs 82 kg (180 pounds) and measures 32 1/4 inches by 5 ` inches by 20 inches, or 82 cm by 14 cm by 50 cm (58 liters).
Continuous power is the power that systems are designed to run on indefinitely, while peak power is the power that systems are designed to support for brief periods. Continuous power is what engines and other propulsion systems run at the majority of the time. GM’s previous industry-best fuel cell stack — Stack 2000 — has a power density of 1.6 kW per liter and weighs in at 190 pounds. Stack 2000’s continuous power output is 94 kW (126 hp) with a peak power output of 129 kW.
As a point of comparison, Ballard’s top stack has been quoted at 75 kW of continuous power. As with Stack 2000, the membrane at the core of each cell in the new stack does not need external moisture to maintain its efficiency. This is accomplished with a unique and proprietary method of water management inside the stack. Fuel cells need humidification to properly function.
The new stack continues to have Stack 2000’s cold start performance: full power in 30 seconds at minus 20 degrees Celsius (minus 4 degrees Fahrenheit), the company said. This cold-start performance is critical in colder climates. Despite the ability to start quickly in extreme cold, GM said its engineers continue to improve the stack’s cold weather capabilities.
In conjunction with the announcement that it has developed a powerful fuel cell stack, General Motors said it expects to mass produce fuel cell cars by the end of the decade, according Matthew Fronk, a senior executive at the company. “We see a path to volume production within this decade, probably around 2008-2010,” Fronk, chief engineer of fuel cell systems at General Motors, the world’s largest carmaker, told the fuel cell conference in London.
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