What Can Engineers Do About Global Warming?

By John Donovan, Editor-in-Chief, Low-Power Design

John Donovan

On November 17, 2007 the UN released the final report of its Intergovernmental Panel on Climate Change (IPCC), the group that won the 2007 Nobel Peace Prize for their work. Normally understated UN Secretary General Ban Ki-moon, described climate change as “the defining challenge of our age.” The ministerial meeting in Bali a few months later resulted in agreement that something needs to be done soon. The devil is in the details, of course, but it's finally possible to be cautiously optimistic.

The solution to global warming is both political and technical. Let’s leave the political issues aside for the moment and look at possible technical advances where EEs can contribute to the solution. I don’t mean obvious things like sell the Hummer, buy a Prius; switch from incandescent to mini-florescent light bulbs; and teach your kids to turn off the lights. I mean things you can incorporate into your next designs, or design areas you should consider embracing. Al Gore threw down the gauntlet at ESC 2007, when he challenged embedded designers to come up with innovative solutions to conserve energy. There’s a helluva lot of room for improvement there, with large short-term payoffs.

As John East of Actel pointed out in Portable Design’s October, 2007 cover story (“The Electronics Industry: The Power to Change”), more than 50% of the 4,055 billion kWh of electricity consumed in the United States each year is used to power electric motors. By simply adding intelligent load matching or variable speed control—and, in small appliances, simply switching from AC to brushless DC motors—efficiency can easily approach 95%. According to East, if implemented broadly these measures “could result in an annual reduction of U.S. energy consumption of as much as 300 billion kWh, saving billions of dollars and reducing greenhouse gases by more than 180 million metric tons.” Maybe then we could forgo a few dozen additional coal-burning power plants.

Even large 3-phase motors can benefit from better engineering. Modern 3-phase motors rely on pulse width modulators (PWMs) and power transistors, under control of MCUs, to adjust the speed and torque of the motors. Replacing rheostats or tapped switches, electronic drive systems greatly increase motor performance and power efficiency, often allowing the substitution of a much smaller motor into an existing design. They cost a little more, but the cost can often be recouped in a short time. On a macro level, the public good of the resulting power savings is considerable.

Then there is something as simple as the “wall warts” that power portable electronics devices when they’re not on batteries. I’ve got 14 of these things in my house alone. They reportedly consume four percent of the electricity used by the average U.S. home, or over one percent of total U.S. power consumption. If the energy usage were extrapolated to a national scale, the total would be about 52 billion kilowatt hours, or the energy produced by 26 average-size (coal-fired) power plants.

Wall warts are simple linear supplies with transformers that suck electricity 24/7 whether anything is connected to them or not. It would be dead-bang simple, and not expensive, to lose the transformers; go to a switching architecture; sense the presence of a load; and decouple from the mains in the absence of one, using just enough energy to be able to power back up quickly on demand. Portable designers are experts in power management. Just move a little of it closer to the wall.

Next, get on your company to look into alternative energy sources. Cypress and Google have led the charge in Silicon Valley to solar, getting them off the grid as far as possible. Austin has become a hotbed of wind power startups, since wind is one thing they have plenty of in the Panhandle and along the Gulf Coast.

With the federal government pushing a switch to alternative energy sources—and putting its money where its mouth is—the winds of change finally seem to have arrived. The devil is still in the details, but the trend line finally seems to be in the right direction.

An earlier version of this article appeared in the December, 2007 issue of Portable Design. Reprinted with permission.
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