Why aren't we harnessing waste heat?
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The typical power plant uses only one-third of the energy produced by burning fuel (usually coal) to generate electricity. The remaining two-thirds of that energy escapes as waste heat. Mr. Casten says that we easily could — and should — harness this heat to warm water or even cool buildings. (You can cool with a heat source by using an absorption chiller.)
By harnessing waste heat, the same fuel would do twice the work. We'd have doubled efficiency.
The simultaneous production of heat and electricity is called cogeneration.
Electrical generation is not the only heat-wasting culprit. Various industries — the production of metals, glass, and silicon, among other things — release waste heat as a byproduct. In these cases, heat could turn turbines and generate electricity.
Indeed, Casten estimates that industrial waste heat alone could supply about 200,000 megawatts of electricity in the US. That's 20 percent of the US's electricity needs, or 95 nuclear power plants not built.
In other words, we could burn fewer fossil fuels, spend less money, and fight global warming simply by harnessing the heat now flowing out of the country's collective flues and smokestacks.
So why don't we?
In a word, outdated laws. The near monopoly on electrical transmission by utility companies doesn't help either. In most states, for example, it's illegal for all but a utility to erect electrical transmission lines across a public thoroughfare. So if you generate electricity with the heat coming out your smokestack, you can't get it anywhere. There goes the incentive to do something with the waste heat.
A new, in-depth article by the New Republic's Bradford Plumer explains how things got this way:
Because they were shielded from competition, most utilities saw little reason to innovate or upgrade their lumbering fossil-fuel plants, since they’d just be forced to pass on any savings to consumers. A Fortune article in 1969 savaged utility executives as “generally unimaginative men, grown complacent on private monopoly and regulated profits.” After the OPEC crisis in the ’70s exposed the industry’s clumsiness in the face of adversity, Congress tried to promote competition on the generation side in some states. But deregulation was only partial, and most Americans still have little, if any, choice of utility.
One problem: utility companies have little incentive to change. Plumer writes:
Perhaps the most urgent state-level reform would be to alter how electricity rates are structured, so that utilities’ profits don’t just hinge on pumping as many electrons as possible through their wires. After all, there’s broad consensus that the cheapest, fastest way to reduce carbon-dioxide emissions is to use power more prudently. Lawmakers have usually tried to do that through a blizzard of government mandates—from building codes to appliance standards. But these mandates only do so much if utilities are constantly trying to sell more power. So, a handful of states have tinkered with an approach called “decoupling,” in which utilities are guaranteed a fixed revenue each year, and can increase profits by cutting costs and selling less power. In California, which pioneered decoupling back in 1982, energy use per capita has flattened (even as it’s ballooned in most states), and utilities spent nearly $1 billion in 2008 on things like helping customers trade in their creaky, power-hogging fridges or promoting green buildings. Yet many utilities and regulators are wary of abandoning a business model that has persisted for nearly a century.