Energy Efficiency

Published on August 9th, 2010 | by Susan Kraemer


Nearly 200 Gigawatts of US Energy is Wasted

August 9th, 2010 by  

Heavy industries like steel mills, paper mills and cement mills have by far the largest untapped potential for energy generation in the wasted heat they generate but do not tap to make electricity. It is not just heavy industries that wastes this potential.

Coal-fired power plants lose as much as 51% of their energy in conversion loss, according to the EIA. Most have made no efficiency gains since the 1950s. The typical power plant burns three units of fuel to generate just one unit of electricity, and then vents wasted potential power to the sky as steam. Nuclear plants waste 21%.

A Department of Energy study, cited by Dick Munsen, author of From Edison to Enron, found untapped potential for 135,000 Megawatts (135 Gigawatts) of cogeneration in the U.S. In addition, a Lawrence Berkley National Laboratory study identified another 64,000 Megawatts (64 Gigawatts)  that could be obtained from industrial waste energy recovery.


One example is the ArcelorMittal steel plant, retrofitted by a company that builds Combined Heat & Power units, Recycled Energy Development. The mill is in Indiana, a state that gets 90% of its electricity from coal. A series of waste heat recovery projects turn the plant’s smokestack emissions into clean electricity and useful steam — utilizing an energy source that would otherwise simply be vented.

They actually generate as much electricity from just  their own waste heat as a 200 MW gas-fired power plant.

Not only do these technologies reduce the steel plant’s carbon dioxide emissions by 800,000 tons each year, and save the company $100 million a year in energy costs.  But for every steel plant supplying that much power, that’s one less gas-fired plant that needs to be built.

However, these vast numbers don’t tell the whole story. As a percent of energy costs to the steel plant this huge number is well under a 10% reduction in energy use. So the incentive is relatively low, from the point of view of heavy industry, itself, to reduce energy costs 10% with a large capital expenditure. There needs to be an economic incentive.

In Finland 30% of the electricity on the grid is produced by the forestry industry and paper mills, due to a law like our Public Utility Regulatory Policy Act (PURPA) that is near expiration, that gave an economic incentive to harness waste energy.

The PURPA law that was passed in 1978, after the oil shocks, began to create a market for non-utility-produced energy. That resulted in about 7% of the energy on the grid being produced by heavy industry as a byproduct, creating a secondary revenue stream for industries, but as subsequent laws clamped down on competition with utilities, it stalled there. But the potential is for a much higher percentage, as much as 20%, according to Sean Casten of Recycled Energy development.

But when as a nation we first started on electricity production in the 19th century, we did not waste this kind of energy. Thomas Edison began the largest district heating project in the world with the Pearl Street power station in 1882, by harvesting the waste heat in electricity production, and selling the heat to neighboring buildings.

Now in Manhattan, ConEd supplies 100,000 buildings with 350 degrees °F steam from waste heat from three of its seven gas-fired electric power stations, creating the largest district heating project in the world, with a staggering amount of power.

The city inherited the clean energy district heating system set up by Thomas Edison in the 19th century as a byproduct of the first electric power plants that made electricity using coal-fired steam.

Image: Flikr User Musiquegirl

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About the Author

writes at CleanTechnica, CSP-Today and Renewable Energy World.  She has also been published at Wind Energy Update, Solar Plaza, Earthtechling PV-Insider , and GreenProphet, Ecoseed, NRDC OnEarth, MatterNetwork, Celsius, EnergyNow, and Scientific American. As a former serial entrepreneur in product design, Susan brings an innovator's perspective on inventing a carbon-constrained civilization: If necessity is the mother of invention, solving climate change is the mother of all necessities! As a lover of history and sci-fi, she enjoys chronicling the strange future we are creating in these interesting times.    Follow Susan on Twitter @dotcommodity.

  • Mark

    “Coal-fired power plants lose as much as 51% of their energy in conversion loss… Nuclear plants waste 21%.”

    These figures refer to percentage of generating source rather than heat loss for each of the sources.

  • Peter Wilson

    Sounds all well and good but you need to do a bit of reading on entropy and exergy to understand why so much heat is “wasted” The quality of this energy and the heat difference you have available to extract useful work from this energy is very low.

    As for saying little research has been done since the 1950’s that is plain wrong. Power companies have spent a lot of money extracting energy from the coal and oil they burn in order to reduce costs, bump profits and executive salaries. The materials they use, the pressures they now operate at and the fuel burners they use are all a result of research over many years.


  • The numbers are a little off here. Conventional thermal power plants – be they coal, gas or nuclear powered – routinely all waste upwards of 60% of the energy put in as heat. That’s this flow chart: A few percentage points are lost in transmission and distribution as well.

    Coal provides about half of the electricity in the U.S., gas 17%, nukes about 20%, and renewables about 9%. (That last percentage is rapidly increasing.) See this chart to illustrate how energy is generated and consumed.

    The important point remains, as your post notes: we can do a tremendous amount with the energy we throw away at these plants. Tom and Sean Casten are, of course, visionaries in this regard. At the end of the day, though, we want to be using “micropower” – renewable energy, generated locally, with massive amounts of cogeneration in play. We’re getting there.

  • They make a product here in the USA to recycle waste heat to electricity.

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