E-Flex Hydrogen Fuel Cell continues move toward electric drive automobiles
By Mike Hanlon
April 20, 2007
April 21, 2007 The number of significant announcements coming out of the Shanghai Motor Show underlines the growing importance of the Chinese Auto market on the world stage, and fittingly, given that the Chinese Government seems far more committed to sustainable personal transport than its American equivalent, the star of the show in technological terms was the next iteration of the General Motors’ E-Flex electric architecture, configured with the company’s newest, most efficient hydrogen fuel cell system to date. This second variant of the E-Flex system uses GM's new fifth-generation fuel cell propulsion technology and a lithium-ion battery to provide up to 300 miles (483 km) of electric driving. The fuel cell E-Flex is a true Zero Emission Vehicle (ZEV) and operates all-electric from both hydrogen fuel cell-generated electricity and grid electricity. It is plug-in capable, adding up to 20 additional miles (34 km) each time it is charged, further reducing trips to the refueling station.
The E-Flex system is a flexible all-electric production vehicle architecture that can be configured to run on electricity from a number of sources. It was first shown in January at the North American International Auto Show in the Chevrolet Volt concept vehicle. The Volt is a battery electric vehicle with 40 miles of all electric-range and uses a small bio-fuel engine with a generator to extend its range to 640 miles (1030 km).
"The beauty of our E-Flex strategy is that it allows us to package various propulsion systems into the same space depending on what energy is available locally," said Larry Burns, GM's vice president of Research and Development and Strategic Planning. "It also provides flexibility in the sources of energy. We can obtain hydrogen or electricity from a myriad of renewable sources - wind, solar, geothermal, hydroelectric and biofuels - or from traditional sources such as natural gas, clean coal, nuclear or even gasoline.
"E-Flex provides flexibility in two ways: in the propulsion systems that can be used, and in the sources of energy that can be commercialized to compete with oil and meet global transportation growth in a sustainable way."
Independent studies indicate hydrogen fuel cell vehicles offer superior overall efficiency and fewer greenhouse gas emissions compared to internal combustion engines running on gasoline, when considering both the creation of the energy and its use in the vehicle.
GM's fifth-generation fuel cell system is half the size of its predecessor, yet it provides the same power and performance. The fourth generation currently powers the Chevrolet Sequel concept vehicle. The Sequel stores 8 kg of hydrogen and delivers a range of 300 miles (483 km). The fuel cell Volt will also deliver 300 miles of range, but with only 4.0 kg of hydrogen (75 miles / kg).
GM's advancements are a strong indication that our fuel cell technology has the potential to be a competitive alternative to the internal combustion engine - in size, performance, durability and cost.
"Our progress has made us increasingly confident that our fuel cell propulsion system will be automotive-competitive," said Burns. "But before this technology can be made widely available, governments, energy suppliers and infrastructure companies around the world need to collaborate with GM and the auto industry to develop a market for fuel cell vehicles and hydrogen fuel."
A variety of technological advancements and lightweight materials contribute to the efficiency of the Volt. With an estimated curb weight of 3,500 pounds (1,588 kg), it weighs 30 percent less than the Sequel. The fuel cell propulsion system is packaged entirely under the hood and is equivalent in size to a four-cylinder engine with automatic transmission. The Volt also features molded GE plastic panels on the fenders, window glazings, instrument panel and steering wheel, which offer between 30 percent and 50 percent weight reduction per part.
The E-Flex fuel cell variant also showcases GM's third-generation wheel hub motors, packaged inside the rear wheel to add considerable torque for all-wheel electric drive capability. The new coreless motor technology reduces mass and produces more power compared to the first generation shown in 2003.