Energy systems seen as vulnerable; Brittle Power, by Amory B. Lovins and L. Hunter Lovins. Andover, Mass.: Brick House. 486 pp. $17.95.

The basic message of ''Brittle Power'' is compellingly simple: Don't put all your eggs in one basket. The ''eggs'' in this case are our energy resources. The ''basket'' is a highly centralized energy-distribution system for electricity, oil, gas, and so forth. If anything happens to the system, millions of people could find themselves shut off from the power source, as when the breakdown of a single electric grid caused the near-total blackout of New York City.

Authors Amory and Hunter Lovins argue that our current energy systems are dangerously brittle - when subjected to stress of any kind, they tend to break rather than bend. In the first two sections of their book, the husband-and-wife physicist-and-lawyer team document how things can go wrong, from mechanical failure to sabotage.

The solution proposed in part three is decentralization of energy technologies, utilizing a variety of smaller energy facilities located as close as possible to the site of consumption. In practice, this means rejection of giant new pipelines or nuclear reactors and greater emphasis on alternatives such as solar, biogas, and conservation.

The study, based on a report originally researched for the Federal Emergency Management Agency (FEMA), does not recommend massive federal planning to make these changes. Instead, it urges local communities to take the initiative by financing small energy projects, helping to retrofit existing houses with energy devices, and revising land use regulations.