By: Susan Kraemer
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.