Budding engineers compete to build more efficient, greener cars

The 17 Chevrolet Equinox sport utility vehicles that pulled up to the US Department of Energy headquarters on 21 May were identically equipped when they came off the assembly line in 2005. Four years later all resemblance ended at the exterior. In the intervening time, teams of students from 17 universities had torn the guts out of their donated crossover SUVs—those built on a car frame—and installed radically new drive systems of their own design. The goal of the makeover contest, sponsored by DOE, General Motors Corp, and others, was to improve the fuel economy and reduce the tailpipe emissions of the SUVs without sacrificing vehicle safety or performance.

For GM and other US automakers, the Challenge X: Crossover to Sustainable Mobility competition got a new generation of engineers and scientists to work on “sustainable and innovative solutions” to reducing the country’s dependence on oil, GM vice president for environment and energy Beth Lowery told the crowd at the ceremonial finish line. GM is beginning to move to electric-powered vehicles, she said, adding, “There has never been a more exciting time to be involved in the auto industry.”

The winning team, from Mississippi State University, achieved a 38% gain in mileage over the stock vehicle with a “through-the-road parallel” hybrid system powered by a turbo-diesel engine running on 20% biodiesel fuel. Through-the-road parallel hybrids, the architecture selected by 13 teams, feature one set of wheels powered by the engine and the other set driven by electric motors. Ryan Williams, an MSU mechanical engineering undergraduate, said his team used computer-aided design software to help marry the drive train to the vehicle. Team members fabricated the one-of-a-kind brackets and other necessary structural components using computer numerical control tools available in the university’s machine shop. Like many other participants in the Challenge X, Williams said he hopes to go on to a career in the automotive industry.

Bells and whistles

The University of Wisconsin—Madison team won second place with a virtually identical drive architecture, adding a few bells and whistles that included an expensive stereo and an infrared camera that can spot a deer on the road ahead. Ben Fjellanger, a UW mechanical engineering student, said that several members of his team will be interning this summer at the GM assembly plant in Janesville, Wisconsin.

In addition to supplying the vehicles, GM put up $10 000 in seed money and up to $25 000 worth of additional production parts, including the GM engine of its choice, to each team. Ten teams, including the top three scorers, opted for a 1.9-liter direct-injection turbodiesel, which ironically isn’t available in the US market. Universities were required to match the seed funding, grant release time of one course per semester for a faculty adviser, and provide an auto shop and computer lab. Institutions also committed to granting course credits to at least a core subgroup of the team members.

A Canadian entry, from the University of Waterloo, was the only vehicle with hydrogen fuel-cell propulsion. A major challenge was to get the cell, which was made for stationary applications, to fit under the car’s hood, explained Charles Hua, a chemical engineering graduate student. Although it was the only zero-emissions vehicle in the competition, its range was limited to 150 miles per tank by a contest rule that restricted the liquid hydrogen storage to 5000 pounds per square inch, half the pressure that is currently practical. There’s also the matter of finding hydrogen fuel, although Hua said he knows of at least two filling stations in Ontario.

A belt-driven motor paired with a flexible-fuel engine was the Texas Tech University entry. To reduce the load on the engine, the eleventh place team fitted a small fuel-cell and hydrogen tank in the trunk to power the lights, air conditioning, and other electric accessories. Team member Stephen Barrett explained that hydrogen can be injected to boost engine combustion under full acceleration conditions. Barrett has already landed a job with National Instruments Corp, a contest sponsor; his work on the vehicle’s electronics package won a $700 prize from NI, which supplies electronic control equipment to automakers and others.

Hydraulic drive

Arguably the most exotic drive train was a hydraulic hybrid system designed and built by last-place finisher University of Michigan. Its engine does not supply power directly but drives a pump that pressurizes hydraulic fluid in two onboard “accumulator” tanks. That stored energy is used to drive hydraulic motors turning the front and rear axles. The drive system requires no battery or transmission, explained team member Javier Somoza, who said that he’d “definitely” be looking for a career in hybrid propulsion R&D once he’s completed his master’s in mechanical engineering.

Teams were initially instructed to follow the development process GM uses when introducing a new model. After a year of modeling, simulation, and testing of the selected drive trains, teams were given two years to integrate them into their vehicles. The final year was devoted to ensuring customer acceptability and proving vehicle reliability in real-world conditions. Teams were graded periodically on their progress, their outreach efforts, and metrics such as acceleration, emissions, and fuel economy. More esoteric criteria included “well-to-wheel” greenhouse gas emissions reductions, well-to-wheel petroleum use, and “dynamic consumer acceptability.”

Awards totaling $79 500 were doled out to top-ranking competitors in various categories. As first overall, MSU won $7000.

A 300-mile road rally from New York to Washington, DC, marked the end of the road for Challenge X, but DOE, GM, and Natural Resources Canada have already selected the 17 teams for a three-year contest that kicks off this fall. Argonne National Laboratory, which managed Challenge X, will also manage the new program, in which Saturn SUVs will be reengineered to meet California’s tough zero-emissions standard. Most of the schools from Challenge X, including the top three finishers, will be back.