Summer's heat brings with it, as it did last year, the threat of massive power outages. Everyone who's suffered through them knows the disruptions they cause. But blackouts are also on the minds of operators of power plants and electricity distribution networks as they get ready for peak demand.

Lots of things can cause blackouts -- transformer failures, severe weather, human error and, of course, terrorism. But the power reliability story hinges on economic and technological choices made more than a century ago -- choices that structured and defined what the electric power distribution systems in the United States would look like.

In the 1880s, Thomas Edison created the first electrical distribution system. Basing it on direct current and small, local generating plants, he built it into a major industry. Shortly thereafter George Westinghouse challenged him with a new system. Based on alternating current, it involved building large power plants in out-of-the-way places and shipping the electricity long distances -- as is still done today.

Westinghouse's new system seemed clearly superior and quickly began to take business away from Edison. Edison, with a huge investment in his electrical distribution system, fought Westinghouse stubbornly. When it appeared he could no longer win by competing fairly, he tried playing up the dangerous aspects of alternating current. He arranged a series of grisly demonstrations at which fifty dogs and cats were electrocuted. He even tried to have the term"electrocuted" replaced by"Westinghoused." It didn't work, and he eventually lost out. Historians see this as the one case in which Edison backed the wrong horse.

Maybe, says energy expert Maurice Gunderson of Nth Power, a venture capital company in San Francisco, it wasn't so much that Edison was wrong as that he was ahead of his time. It's true that if Edison had had his way there would be small generating plants all over the place, for the effective reach of direct current in his day was limited to half a mile. Small plants all over the place may sound like a crazy idea. Yet if we want to guard against blackouts we may have to build them again, even if they  trigger the NIMBY (not in my back yard) reaction.

Thanks to new technology, the building of smaller, local plants -- sometimes called distributed generation -- is no longer a crazy idea. To some extent, it's already being done. Solar cells, wind machines and other"green" methods generate electricity locally or even on-site. There are also fuel cells that can generate clean electricity on a local scale, while at the same time accomplishing other tasks. Four sewage plants in New York state have installed fuel cells that convert waste gases to energy. A similar technique can be used at farms.

Cogeneration systems are another way of supplying on-site electric power. Their advantage is that rather than having to laboriously get rid of the waste heat that is generated along with the electricity, as is the case with centralized plants, they can put it to work on-site. Centralized plants are in fact the second largest user of water after agriculture.

Distributed systems are often cheaper than centralized power, which must include the cost of distribution. Problems with pollution will be another factor driving a move toward distributed generation. But the main driving force is continuing advances in technology. A century ago, we were very good at building bridges, buildings and dams. But if today we tried to use the available small power plant of that day, say the engine of a Model T Ford, to generate electricity, its cost would be astronomical.

It's only in the last decade or so that distributed generation has really become practical. The hybrid car of today is actually a rolling power plant. Using modern engine technology, we can now make cogeneration power plants in many sizes that are efficient and economical.

Still, though direct current can now be transported far more economically than it could in Edison's day, and though many of our electronic devices actually run on this form of current, it's not likely that our electrical system will change back to one based on it. But putting distributed generation to work would help reduce the huge investment required to bring the existing grid back up to where it should be.

We need to reduce grid complexity, or at least its propensity to collapse under pressure. In addition to more distributed generation, we'll see greater use of specialized direct current lines that can also act as a kind of shock absorber between electrical grids, to insulate them from disturbances that originate in neighboring grids.

Edison wouldn't feel completely vindicated by these developments, but were he around today he would surely have a big smile on his face.

This piece was distributed for non-exclusive use by the History News Service, an informal syndicate of professional historians who seek to improve the public's understanding of current events by setting these events in their historical contexts. The article may be republished as long as both the author and the History News Service are clearly credited.