clipped from www.nytimes.com

Mrs. Showalter compared prices in 13 states and Washington, all of which have adopted market pricing for industrial users, with the rest of the nation. The 13 states are California, Connecticut, Delaware, Maine, Maryland, Massachusetts, Michigan, Montana, New Hampshire, New Jersey, New York, Rhode Island and Texas. Montana is returning to regulated pricing.

Under the rules of these markets, every electric power generator whose bid is accepted gets the highest price paid to supply power, called a clearance price or single-price market. In most auctions, each supplier gets the price at which they offered to sell, known as an as-bid market.

One result of clearance pricing is that nuclear power plants, which must run at a steady rate even when demand for power is minimal, have at times collected $990 per kilowatt-hour for power they had offered to give away during low-demand hours.