Gray Power

by Richard T. Stuebi

The distinction between “green power” — electricity without any carbon emissions, usually from renewable energy sources such as solar and wind — has been clearly drawn vs. “brown power” — electricity generated from fossil fuels.

In a recent article in The Nation, author Lisa Margonelli writes about “The Case for ‘Gray Power'”. “Gray power” is the term that Ms. Margonelli uses for a concept called “energy recycling”, wherein electricity is generated from capturing waste heat from burning fossil fuels. So, gray power is not as “green” as renewables, but given that the fuel is being burned anyway, generating more electricity from the same amount of fuel burn is surely a good thing.

Ms. Margonelli makes the point that there are huge untapped opportunities for capturing waste heat to generate electricity in the U.S. — especially in the Midwest and South, with the plethora of coal-fired powerplants in the region. This message has been pounded home loudly and frequently by such people as Thomas Casten of Recycled Energy Development.

So what’s preventing this opportunity from being captured? Ms. Margonelli argues that there are two main impediments. First, various electric utility and state regulatory practices impair the economics of those who might pursue gray power opportunities. Second, the U.S. Clean Air Act is written in such a way to discourage major modifications of powerplants — even if they are modifications that improve economic and environmental performance.

Her proposed remedy is the creation of a federal Clean Power Authority, analogous to an organization like the Tennessee Valley Authority or Bonneville Power Administration, whose mission would be to recycle wasted energy from powerplants in the South and Midwest.

While I agree that the two issues she identified are in fact real impediments to recycled energy, Ms. Margonelli misses a third critical one.

In Europe, waste heat recapture is much more prevalent than in the U.S. Why? Because the waste heat often can’t be economically converted into electricity, but must remain as heat — and Europe’s infrastructure is much more optimally configured to economically use this heat.

Given that Europe is so compact and densely populated, pretty much every powerplant is within 20-30 miles of a sizable town, and many of these towns have central district heating systems that can make direct use of the waste heat piped in from the powerplant. In contrast, most major powerplants in the U.S. heartland are situated hundreds of miles away from any city center with a district heating system that can use waste heat. Lacking an economically proximate market for waste heat, it just goes up the stack — poof!

No question that opportunities to capture gray power in American urban centers are non-trivial, and they should be diligently pursued. But what’s needed to make gray power in the U.S. more of a widespread reality is not so much a federal Clean Power Authority, but technology that can economically convert low-grade (and low-value) waste heat into higher-value electricity. And that is exactly what firms like Akron-based ReXorce Thermionics are working to develop.

Richard T. Stuebi is a founding principal of the advanced energy initiative at NorTech, where he is on loan from The Cleveland Foundation as its Fellow of Energy and Environmental Advancement. He is also a Managing Director in charge of cleantech investment activities at Early Stage Partners, a Cleveland-based venture capital firm.