The energy emitted from testing engines has found a powerful, second life at a General Motors facility.
Since 2008, more than 26.7 million kW·h of regenerated energy has supplied electricity for laboratory lights, air-conditioning, as well as the fuel pumps and coolant pumps used for engine testing purposes at GM's Pontiac, MI, engineering center. It's enough energy to meet the electricity needs of 2326 U.S. households in one year.
"Essentially, the engines are acting like a generator," Dave Gunnels, Engineering Manager for GM's Pontiac test facilities, told AEI. "The power goes to an ac motor in a test cell that is driven by a controller. That controller is firing back on the power bus, which is connected to the rest of the facility's electrical system. The loads for the lighting and air-conditioning pull power from that bus."
The entire Pontiac facility encompasses 1.675 million ft² (155,613 m²). Wings added to the main building four years ago account for approximately 35% of the overall footprint and are the beneficiary of the regenerated energy.
"When certain wings of the center were built from scratch, engineers were able to take advantage of the upgrade by baking in energy-efficient practices. If we would have tried to retrofit the existing architecture with energy-efficient projects, the costs would have been too high," Gunnels said.
Since the facility's overall energy requirements were downsized by 30% during building renovation work, the ripple effect was the downsizing of the facility's power transformers and power grid.
"Everything we came up with when designing the upgraded systems was based on this availability of regenerative power," said Gunnels.
The disposal process for engine exhaust is another example of the environmentally focused work that occurs at Pontiac. Before the exhaust is released into the atmosphere, the vast majority of hydrocarbons and other emissions are removed via thermal oxidizers inside the plant.
Depending on the number of engine tests occurring on a particular day, only two or three of the facility's four thermal oxidizers might be operating, as "we don't want to consume more energy than we need to consume," said Gunnels.
Other energy-conservation measures, such as reduced lighting levels and lowered building temperatures during off-peak work hours, are addressed via a building management system program.
On a yearly basis, technical specialists at the center conduct thousands of tests—ranging from 1 h to 1200 h in duration—on engines with displacements ranging from 1.0 to 7.0 L.
Among GM's 16 worldwide powertrain engineering centers—all of which have a certain level of testing capability—the Pontiac engineering center is unique.
"Pontiac is the only GM facility regenerating energy," said Gunnels, adding, "So the specific benefit is that we spend less money on energy production, and we reduce our carbon footprint."