Flattening the Peaks

For a while, the little black box changed Emma Breen's life. As soon as the box was installed, Mrs. Breen, 64, switched her morning bath to the evening, washed her dishes before bedtime instead of after lunch and posted signs in her South Burlington, Vt., home admonishing guests not to use the hot water during certain hours. Down the street, the Dennis Cole family got a little black box too, but they used their hot water whenever they wanted.

Those little black boxes at Mrs. Breen's, the Coles' and in 98 other homes in the Burlington area are part of an experimental energy-conservation method called "ripple control" that is being tested by Vermont's Green Mountain Power Corp. with a grant from the Federal Energy Administration.

Ripple control is aimed at saving generating costs by turning off water heaters twice a day during periods of peak consumer demand, when electricity is most expensive to produce. So far, ripple control has worked: according to test results, the system has saved roughly $60 a year per heater in electricity costs, a saving that Green Mountain Power (G.M.P.) has returned to participants in the experiment in the form of monthly $5 rebates.

No Complaints. The figures suggest that if every water heater in the G.M.P. customer area were ripple-controlled, the utility could reduce its peak power load by 10%. Moreover, in the nine months since G.M.P. installed ripple control, not a single customer has complained. Indeed, since the water in the heaters stays hot for about four hours, and the heaters are rarely shut off for more than three hours at a time, ripple-controlled customers evidently have all the hot water they need available at any time. "Goodness," said Emma Breen as she took her signs down, "I've been cheating myself all this time."

In Western Europe, where electric power has always been expensive, ripple control has been in use for 30 years. But in the U.S., rising fuel prices and increased construction and operating costs have only recently forced utilities to earnestly consider what utility company engineers call load management--controlling the amount of electric power delivered to the customer--as a way of reducing the need for repeated expansion of generating capacities. In Michigan, for example, the Detroit Edison Co. is testing a method of shutting off water heaters by radio control. One of the early difficulties with some systems using this approach--now ironed out--was interference: electric garage-door openers were shutting off people's heaters. Another method under study by G.M.P. is thermal storage, which involves storing water heated to 280DEGF. in the home in pressurized tanks (to keep it from boiling away) for use during peak hours.

Aside from ripple control, so far the most feasible system for managing electrical load may be one developed by a firm based in Cambridge, Mass., called American Science & Engineering Inc. Its method, a bidirectional power-line carrier, is currently undergoing testing in homes in New Jersey and Wisconsin. The system costs $175 per installation, v. $79 for the ripple controller. But it allows for two-way communication between a utility and a household with two apparent advantages over ripple control: meter information can be conveyed directly through the system, thus obviating the need for an extra meter and someone to come and read it. More important, perhaps, the utility can also manipulate the customer's load by computer to arrive at maximum efficiency. A. S. & E. Marketing Manager Ralph Abbott believes such load-management systems will be in nearly universal use in the U.S. within ten years. There is at least a chance that Abbott could be right. Across the country, dozens of utility companies are currently experimenting with little black boxes and other methods of load management to find the most economical--and acceptable--way of controlling electric power use.

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