An innovative concept of networked distributed generation sources that can create small power "islands" promises to improve reliability for the entire power system and allow utilities to defer new transmission projects.

Northern Power Systems, Waitsville, Vt., is proposing to build such a network at its home office park. It will pool several propane- and wind-fueled distributed generation sources totaling 350 kw to supply five commercial and industrial buildings and 12 residences. The system will be able to sustain itself in a power shortage, avoiding a blackout and relieving demand on the local utility, Washington Electric Cooperative. It will use existing WEC distribution lines, but could be isolated from the larger grid by a fast switch, creating an "island" and maintaining service for local users.

The project will be the first installation using networked distributed generation to create a separate subnetwork, says Ben Kroposki, senior engineer at the Dept. of Energy’s National Renewable Research Laboratory, Golden, Colo. "If we can build these internal islands, people will stay up and running in an emergency and the bigger utility has less problems to deal with," he says.

NREL is contributing $350,000 to the project, which still needs state approval and will take about two years to set up. Kroposki says the Institute of Electrical and Electronics Engineers has just issued new standards for interconnecting distributed generation to utilities, which could guide development.

Distributed generation faces plenty of regulatory and institutional barriers, including acceptance by utilities, "but we see a lot of places where it makes a sense," says Dan Reicher, NPS executive vice president. These include industrial and business parks where generation units are concentrated. Even a tiny system like that proposed by NPS can have a major impact on a small rural utility such as WEC, which has only 9,000 users and a 14-Mw peak load, Reicher notes.

Other companies offer systems to network scattered units to provide an energy reserve that can be sold into the local grid. Celerity Energy, Portland, Ore., has set up systems in Albuquerque and Denver. The networks link standby generators to provide peaking power to the local utilities. The system, designed by Sixth Dimension, Fort Collins, Colo., allows Celerity to control the units and send power to the utility. But it does not form a separate minigrid. The units remain available to the owners to provide reliability in blackouts. Celerity collects capacity charges from the utility for the service, which helps defray the cost to the owners of their generation units.

The system allows utilities to avoid dealing separately with small owners, says Dennis Quinn, Celerity senior vice president. He sees interest growing especially as owners replace older standby generators with new equipment and look for ways to leverage the investment.

The Bonneville Power Administration, Portland, Ore., has hired Celerity to review distributed generation on the Peninsula area of western Washington state. The goal of the Energy Web project is to eventually pool existing small generation to create a reserve and defer the need for new transmission lines.