There May Be Gigawatts Of Power Leaving The Tennessee Valley As Hot Air

TVA’s combined cycle natural gas plants essentially function like a combined heat and power system. Credit: TVA

Several gigawatts of potential power – enough to power hundreds of thousands of homes – are leaving the Tennessee Valley in the form of hot air, according Department of Energy estimates. And now TVA has approved at least one new project to put the heat from industrial plants to work.

The broad term for capturing wasted heat to generate power is “co-generation,” also known as “combined heat and power.” There are many kinds of set-ups, but they all revolve around recycling excess heat. They work well for everything from college campuses to chemical plants.

TVA counts 32 customers with some kind of co-generation project. The DOE keeps a running state-by-state list, though there haven’t been many additions in recent years. And most are simply producing power for their own facilities. A few produce enough to sell electricity back to TVA.

A Weyerhaeuser pulp and paper plant in Columbus, Miss., generates enough electricity to sell back to TVA.

“Every one of these is a little different,” says TVA spokesman Duncan Mansfield.

Late last week, TVA’s board authorized spending $157 million on a co-generation deal, though few details were revealed, citing competitive interests. Director Marilyn Brown is pushing for more of these arrangements as TVA shuts down many of its coal plants.

“I’m hoping that we’re going to continue to take a look at those opportunities and to be ready to negotiate,” Brown said at a TVA board meeting. “Each of these situations is unique. The business case has got to be good for all sides.”

President Obama has challenged utilities to generate 40 gigawatts of combined heat and power by 2020.

From the EPA: Gas turbine or reciprocating engine CHP systems generate electricity by burning fuel (natural gas or biogas) to generate electricity and then use a heat recovery unit to capture heat from the combustion system’s exhaust stream. This heat is converted into useful thermal energy, usually in the form of steam or hot water. Gas turbines/engines are ideally suited for large industrial or commercial CHP applications requiring ample amounts of electricity and heat.