Mark
Holtzapple, left, describes his StarRotor engine. (Photo courtesy of Texas
A&M Engineering.)
(College Station)—The StarRotor engine being developed by Mark T. Holtzapple, a professor of chemical engineering at Texas A&M University, seems too good to be true. It is expected to last about a million miles, go 1,000 miles between fill-ups, and up to 100,000 miles between oil changes. It produces virtually no pollution, and runs on a variety of fuels—even olive oil.
It’s basically a jet engine for cars, so it may lead to the development of space cars, a la “The Jetsons.”
The only drawback? So far, the StarRotor engine exists only on paper. But with half of the engine—the compressor—successfully created and tested, Holtzapple is confident that it’s only a matter of time before the StarRotor engine will be standard equipment on a wide range of motorized devices.
“I really do believe it is the perfect engine,” Holtzapple said. “We just have to get enough funding to build it.”
Holtzapple believes that the engine can be mass-produced in the next few years “if the stars are aligned properly.” Its initial applications will probably be in electric power generation; Holtzapple’s company is negotiating with a Texas power company to install a StarRotor expander that captures wasted energy to make electricity.
Its use in cars will depend on the automotive industry, Holtzapple said.
“Once we demonstrate a high-efficiency engine in a vehicle and it appears in magazines such as Popular Science, it will be hard for industry to ignore,” he said. “Consumers will demand the performance of the StarRotor engine once they know it is possible.
“If the American car industry is smart, it will adapt new technology to gain market share. Wouldn’t it be great if U.S. cars were three times more efficient than those of our foreign competitors?”
Holtzapple said that because the StarRotor engine is smaller than the engines now used, car designers would have more flexibility in creating body styles. Storage space could be added to the front of the car as well as the traditional trunk, for example.
Holtzapple
is optimistic that the StarRotor engine can be mass-produced in the next
five years. (Photo courtesy of
Texas A&M Engineering.)
Holtzapple developed his love of machinery as a child, when he and his machinist grandfather “made stuff in his basement” using lathes, band saws, drill presses and other machine tools. While in the U.S. Army in the 1980s, Holtzapple performed research on water desalination and helped develop a Stirling engine-powered backpack cooling device for soldiers wearing chemical protective clothing.
When he joined the Texas A&M faculty in 1986, he decided to pursue engines and air conditioners as a hobby and focus on biomass work in his professional career. (In his “real job,” he developed a process that converts biomass—any organic waste, from sewage sludge to garbage to crops—into a mixed-alcohol fuel that is economically feasible and burns cleaner than fossil fuels. He holds ten patents in this area.)
He built a liquid-piston Stirling engine/air conditioner with his own money, but when it didn’t work the way he had hoped, he commiserated with his colleague, Dick Davison.
“In about 30 minutes—a 'Eureka' moment—he and I developed the thermodynamic cycle for a water-based air conditioner that met many of the goals of the Stirling system,” Holzapple said. “The problem was that it needed a large compressor that worked efficiently under vacuum conditions, and there was nothing on the market that satisfied the need.”
His quest to find the perfect compressor led him to Christian Burger, a professor of mechanical engineering at Texas A&M. Burger assigned the design of such a compressor to one of his graduate classes, where Holtzapple met a “brilliant” master’s degree student, Andrew Rabroker, now a co-founder and design engineer with StarRotor Corporation.
“We hit it off and worked on the project long after the class was over,” Holtzapple said. “We were trying to find a pump to circulate the liquid water. I had identified a gerotor pump, which appeared to be a good solution.
“The next day, Andrew informed me that the gerotor would be a good compressor. At first, I was skeptical, but Andrew did a great job of explaining it to me. He won me over to it,” Holtzapple said.
Holtzapple happened to be working on another project at the time, a thermodynamic cycle that could make engines much more efficient.
“This activity took many years of thoughtful, hard work,” he said. “I knew the required thermodynamics,but could not figure out the hardware to make it work. As soon as Andrew figured out that the gerotor would work on an air conditioner, I realized it could be used in an engine—another ‘Eureka’ moment.”
The result is a compressor, called the Generation 5, that has achieved an energy efficiency of 81.8 percent, a finding that soon will be tested by an independent research group. The compressor’s closest competitor is a screw compressor, which typically has an energy efficiency of 70 to 80 percent and costs three times more to manufacture.
“We believe that Generation 5 is the compressor we’ve been striving for,” Holtzapple said. “It has the characteristics that make it commercially viable and superior to the competition in many ways. Nonetheless, we will always seek ways to refine, improve, and explore.”
Holtzapple’s company received its first order for a Generation 5 compressor, from a major oil company, this March, and the second, from Aggie-owned Gooseneck Trailer Manufacturing Co., in May.
The next step, according to Holtzapple, is getting the word out about the new compressor and raising significant capital to ensure that supply can meet customer demand.
“It doesn’t help to get customers excited and then not be able to deliver our product,” he said.
In the meantime,
Holtzapple’s accomplishments have attracted attention. In addition to
receiving an A&M System Spirit of Innovation Award for Ingenuity and being
the first engineer in 31 years to participate in the Texas A&M Distinguished
Lecture Series, he recently was selected to receive the inaugural Walston Chubb
Award for Innovation from Sigma Xi, the scientific research society. He will
receive the award and present the 2006 Walston Chubb Lecture on Innovation
at the society’s annual meeting in Detroit this November. 