TACKLING ENVIRONMENTAL TOPICS WITH IRREVERENCE,INTELLIGENCE, AND A FRESH PERSPECTIVE

Tank You Kindly

Last spring, when our fifty-gallon hot water tank decided to give our basement floor a thorough cleaning, we had to scramble to find an energy- efficient alternative. After about a week of cold showers, we got an energy-friendly, natural-gas, heat-on-demand system. Planning ahead definitely would have saved us time, money, and goose bumps.

LIZ
Silver Spring, Maryland

Let’s jump into the wily world of water heat. Here are the (overwhelming) water-heating options: on-demand water heaters, storage water heaters, heat-pump water heaters, tankless coil water heaters, indirect water heaters, solar water heaters, and water heaters hooked up to the furnace in a strange symbiotic relationship.

Most folks have a cylindrical tube tank in the basement or a closet. While hardly an inspiring example of industrial design, the tanks are actually pretty good at heating water. Newer tank water-heater models are well insulated and thus have little “standby loss” (heat lost as the tank stands idly by waiting for you to bathe).

The water held in tube tanks can be heated either by electricity or natural gas. Good electric-tank water heaters are 90 percent efficient or more, meaning that 90 percent of the electricity heats the water and 10 percent is wasted. Gas-tank water heaters are 60 percent efficient or more. But in the gas versus electric smackdown, electric water heaters lose on the price of electricity and the environmental costs of electricity generation. Electricity is a secondary product, like meat: One natural resource is transformed into another, which we buy. Nuclear, coal, hydro, and oil-burning electricity plants are a primary reason to be grateful for the Clean Air Act and Clean Water Act. Also, as electricity travels to your abode, some of it falls by the wayside and goes to waste. Natural gas is nonrenewable, and the tube tanks are less efficient, but the gas exacts less of an environmental burden en route to your home.

Readers may have seen on-demand heaters in a foreign land or under someone’s sink. (I encountered my first one right next to my first yurt—in California, of course.) Small metal boxes mount­ed on the wall, they’re unobtrusive and tasteful. When hot water hears you call­ing, the boxy little heater fires up, heating only the water you use. From what I can piece together, on-demand heaters are cool, but not quite as cool as you would think. Electric on-demand heaters use large amounts of power in short bursts. Instead of giving you x watts over an hour, the electric company must give you x watts in ten minutes—requiring higher generating capacity back at the plant. Given the importance of reducing peak energy demand, that’s not an ideal solution. In fact, it’s enough to inspire a “no” vote on electric on-demand heaters.