Unknown costs, unanswered questions: Issues swirl around Cape Wind, especially its ultimate cost to consumers 

By now, Governor Deval Patrick should have only good answers to tough questions about Cape Wind.

He doesn’t. And, that’s no laughing matter for Massachusetts rate payers, who will be subsidizing the plan to put 130 wind turbines in Nantucket Sound.

Patrick got off one funny line during this week’s gubernatorial debate on clean energy: “It’s amazing, only in Massachusetts would a project that has taken 10 years [to be approved] be seen as rushed,’’ he said, to appreciative audience chuckles.

Now, here’s the unfunny part.

As the Big Dig proves, government-funded projects take a long time around here, and the longer they take, the more they cost. The wind farm is a private venture, which relies partly on government subsidies that come directly from rate payers. So, the potential for “Big Wind’’ – as Jill Stein, the Green-Rainbow Party candidate dubbed it – is cause for legitimate concern.

Patrick’s rivals – Stein, Republican Charlie Baker, and Independent Tim Cahill – pressed him hard about the contract between Cape Wind and the utility National Grid, which is purchasing half its power, at 18.7 cents per kilowatt hour. But most of Patrick’s answers to serious questions about an energy project that government plays a role in regulating and financing ranged from vague to prickly.

Asked by Baker to explain why his opposition to no-bid contracts for racinos did not extend to a no-bid contract for Cape Wind, Patrick said Cape Wind was treated “like any other energy project’’ and that the racino-to-wind farm analogy is “hardly comparable’’ – although he didn’t explain why not.

Pressed by Stein to justify campaign contributions that the Stein campaign said he accepted over the past five years from Cape Wind principals and their affiliates, as well as from assorted energy companies and their lobbyists, Patrick replied, “I’m satisfied I kept an appropriate arm’s length’’ distance from special energy interests.

He also said he took no money from contributors connected to the wind farm project “while I was sorting out my own views.’’

To Cahill’s query about the huge gamble of having rate payers subsidize the future unknown costs of buying power from Cape Wind, Patrick dismissed concerns over what he said would add only “a buck and quarter to our monthly rate payer bills.’’

However, in an interview after the debate, Ian Bowles, the secretary of energy and the environment, acknowledged that the cost-per-month to rate payers could, theoretically, go up.

The cost of subsidizing Cape Wind relates to fossil fuel pricing, down from where it was two years ago because of a sluggish economy and increased supplies of natural gas. “The $1.25 could go up, if energy prices inexplicably went down below where they are today,’’ said Bowles. That is unlikely, he said.

Bowles dismissed questions about transparency and pricing as a “rhetorical red herring’’ and said Patrick’s opponents are foolishly turning an energy project other states covet into a “political football.’’

Wind farm calculations are based on a complicated cost-to-benefits ratio and that’s a problem for Patrick.

When he embraced Cape Wind during his 2006 gubernatorial campaign, he set himself apart from rivals as an independent “green’’ thinker. The project faced years of regulatory hurdles and immense political opposition, which was led by the late Senator Edward M. Kennedy. Since winning election, the Patrick administration, led by Bowles, has pushed hard for what would be the first offshore wind farm in the United States.

Last April, US Secretary of the Interior Ken Salazar announced that he was granting the final federal approval needed for the project. Patrick celebrated the decision as a path to thousands of new “green’’ jobs and the way to position Massachusetts as a national and global leader in the field of alternative energy.

Cape Wind opponents have been cast as wealthy landowners who did not want their priceless ocean views marred by steel turbines. For some, that’s true.

But it’s also true that Cape Wind’s ultimate cost to consumers is still very much up in the air.