Supersize It!

Sylvia Earle

PHOTO COURTESY OF THE SCIENCE MUSEUM OF MINNESOTA

You’ve probably heard of small-scale options for improving energy efficiency: insulating your home, installing fluorescent lights or natural skylights, driving high-MPG cars. But what can be done to improve energy efficiency on a large scale?

Plenty, says Twin Cities consulting engineer Dave Solberg. Solberg is working with businesses around the world to apply the principles of exergy—essentially, advanced heat recovery—as a tool for dramatically enhancing energy efficiency on a commercial scale. Tapping exergy helped Minnesota-based Cypress Semiconductor reduce natural gas consumption 98 percent. By incorporating exergy-utilizing features into the design of a new facility in Malaysia, solar energy panel manufacturer SunPower reduced construction costs $4.5 million.

The Science Museum of Minnesota is among the latest to give exergy a shot. Currently, the SMM uses cold water piped in from nearby District Energy to cool and dehumidify outside air to 50 F, then reheats the air to room temperature using hot water. Under the new process, the water warmed by the hot air it cooled will also be used to reheat the room air—not only saving energy, but decreasing water use as well.

Power electronics offer another option for increasing energy efficiency in corporate and industrial settings.

“Motors consume approximately two-thirds of the electricity that we use,” says Ned Mohan, professor of electrical and computer engineering in the University of Minnesota’s College of Science and Engineering. As a result, improving the efficiency of motor technology—used in appliances, computers, HVAC systems and renewable energy conversion devices, to name a few—could make a big dent in energy use.

Mohan says power electronics, which control and convert electric power with the goal of zero energy loss, can greatly improve efficiencies of motor-driven systems. Say you want to use your air conditioner on a hot summer day. You choose the “low” setting to save energy. But because the air conditioner’s motor only runs at full force, you’re not actually saving anything: The extra air is simply diverted with throttles and flaps. Power electronics can control the motor so only the amount of power needed is delivered.

By better matching the amount of energy a device receives with what it needs to operate, power electronics can improve energy efficiency across the board, from the smallest computer to the largest building—and everything in between.