A 2008 law gave Massachusetts utilities the same mandate to obtain more renewable power. But the two largest came back with vastly different deals, especially in price.

National Grid estimates its 15-year deal with the Cape Wind offshore wind project will cost ratepayers $1.2 billion above the projected market price of comparable energy.

NStar says its contracts with three smaller land wind farms total $111 million below market price.

The $1.3 billion gap has fired up Cape Wind foes, who say it proves National Grid paid way too much for Cape Wind power.

But National Grid says its deal with the Cape Wind is a good price for its many benefits, including its proximity to an energy-hungry area.

©2011 The Associated Press. All rights reserved.