Many of us now believe that global warming is real and want to reduce our dependence on fossil fuels. We have switched to compact florescent light bulbs, sealed our homes, and wonder what else we can do short of spending money on a solar heating system. If you are heating your air or water with electricity, the answer is: plenty.
Using electricity for heat is a waste of resources and money. It is also bad for the environment. Ads for electric water heaters and space heaters tout the efficiency of electric heat. True, the efficiency of electric water heaters can be as high as 95% compared to 85% for the best gas water heaters. However, these numbers are misleading. The problem is that inefficiency is hidden in the generation of the electricity.
The national average efficiency of fossil fuel power plants is 35%, according to the U.S. Department of Energy.
Modern power plants achieve efficiencies of no better than about 55%. These fossil fuel power plants consume two to three times as much energy from fossil fuels as they output in electricity. Also, transmission losses consume 9.5% of the power generated. Thus, the average electricity user gets less than one third of the energy that was in the fossil fuel.
The overall efficiency of our electricity providers is improved by their use of renewable energy sources if one considers hydro, wind, and solar generated electricity to be 100% efficient. Unfortunately, the present percentage of our power generated by renewable energy sources is only between ten and fifteen percent.
What do these numbers mean to you? Heating water using an electric water heater is less than 33% fuel efficient. Heating directly with natural gas (or propane) in an efficient gas water heater is 85% fuel efficient.
Even if the natural gas efficiency is reduced another 10% to take into account the distribution cost (in energy), gas heat is at least twice as fuel-efficient as electric heat. The same numbers hold true for electric space heaters, cooking stoves, and clothes dryers. If the only source of energy is the plug in the wall, the total energy efficiency is less than 33%.
The bottom line; heating with electricity uses two to three times as much fuel as heating directly with natural gas.
The environmental impact of heating with fossil fuel derived electricity is even greater than these numbers indicate. The new power plants on the drawing board are nearly all fired by coal.
Coal is cheap, but also dirty. Its energy is primarily derived from its carbon content. Coal plants emit mercury, nitrous oxides, sulpher oxides, and vast quantities of the greenhouse gas, carbon dioxide.
Natural gas, on the other hand, is the cleanest of the fossil fuels. A significant fraction of its energy is derived from burning hydrogen rather than carbon. For the same amount of energy, natural gas emits 45% less carbon dioxide than coal.
If enough people switch from electric heat to natural gas so that they prevent the construction of new coal-fired power plants, they doubly help the environment.
First, these people use half the fossil fuel that the power plant would use for the same amount of heat. Second, because these people use natural gas rather than coal they reduce their carbon emissions by 45% for the energy they do use. The net result is a reduction in carbon emissions of about 70% compared to coal derived electric heat.
Furthermore, if people save enough energy that the power companies start shutting down older less efficient power plants, the reduction in emissions is even greater.
No, I don’t work for the natural gas industry. I see natural gas heat as the (much) lesser of two evils. The ultimate solution is solar heat which requires no fossil fuel and is a mature technology. But, if you are not ready for solar, switching from electricity to gas for heating saves as much energy as switching from gas to solar. Try it.
Craig Van Cleve is a mechanical engineer, a long-time solar energy advocate, and a member of the American Solar Energy Society. He lives in Lyons.
