Governor Deval Patrick announced today a goal of building enough wind turbines in the state by 2020 to supply energy to 800,000 homes.

Currently, the state has about 6.6 megawatts of wind power capacity generated by nine wind turbines. The governor's new target to develop 2,000 megawatts of wind power capacity is about 10 percent of the state's current electricity demand.

Officials say the target is intended to guide the incentives and policies made by state agencies. "It helps to motivate the bureaucracy," said Ian Bowles, the secretary for energy and environmental affairs. About one-tenth to one-quarter of the governor's wind power target could be reached with municipal-scale projects, Bowles said. "Offshore wind is going to need to make up a substantial part of it."

But the offshore wind farm proposed for Nantucket Sound that proponents say would fulfill three-quarters of the electricity demand of the Cape and Islands continues to face opposition from groups concerned about the impact of the 130 turbines on views, property values, navigation, and historical sites.

In late December, the federal agency responsible for evaluating Cape Wind released a report showing that the wind farm would have an "unavoidable" adverse effect on views from 28 historical sites, including the Edgartown Harbor Lighthouse and Nantcuket Cliffs, as well as a negative impact on the ceremonial practices of the local Wampanoag Indians because the turbines would be visible on the horizon.

The report's findings will be included in a final environmental review of the project expected to be released soon, said Nicholas Pardi, a spokesman for the Minerals Management Service, the federal agency.

"This report to us is another example of why Nantucket Sound is a poor site for an industrial size wind plant," said Audra Parker, executive director of the Alliance to Protect Nantucket Sound, the central opponent to Cape Wind.

Mark Rodgers, spokesman for Cape Wind, said the report's findings are not new. "All that it really means is that in certain conditions you will be able to see wind turbines from these sites. We don't dispute that you would be able to see wind turbines."