As the aftershocks spread from Tuesday’s announcement by owners of the Pilgrim nuclear power plant in Plymouth, Massachusetts, that they will close down in June 2019 and possibly as soon as spring 2017, electric customers and policymakers now are wondering: What does it mean for New England's power supply and the economy?

About 300 of Pilgrim's 633 current workers are expected to lose their jobs when the plant shuts down and switches over to securing the site and radioactive waste on site, and preparing for a decommissioning process that could cost over $1 billion and take decades.

Pilgrim does supply enough power for over 500,000 homes, about 5 percent of the total demand of New England's power grid. Energy industry leaders generally think there's enough extra capacity to cover that, as long as there’s no major disruption in natural gas supplies.

"New England’s power generators stand ready to continue providing safe, environmentally-responsible, reliable and competitively-priced electricity for consumers. Already, more than 1,800 megawatts of new power plants, enough to serve approximately 1.3 million households, are under construction and under development including nearly 1,000 megawatts in Massachusetts alone," said Dan Dolan, president of the New England Power Generators Association.

In terms of what happens to the price of electricity, that depends heavily on what the price of natural gas is in 2019 or 2017 or whenever Pilgrim closes. That's because most often gas-powered plants establish the wholesale price of power in New England. Pilgrim's owners, Entergy Wholesale Commodities, predicted that gas is likely to be cheap and nuclear uneconomical for years to come when they concluded the only economically viable decision was to shut down.

Massachusetts House and Senate leaders have been working all year on a potentially far-ranging energy bill that would address raising current limits on solar energy production, offshore wind power, and possibly natural gas supplies. Gov. Charlie Baker is urging them to also add in his plan to explore the possibility of importing more cheap hydropower from Quebec as well, and has said Pilgrim’s shutdown makes that issue even more urgent.

House Speaker Robert DeLeo said in a statement that "Pilgrim's closing will certainly play a major role in the House’s energy policy discussions moving forward." But he and other House leaders are not predicting how soon, if at all, an energy bill could emerge from the Legislature. Baker's Quebec hydro gambit also faces opposition from many legislators who say local energy would produce local jobs – while Baker says the high cost of electricity generally in Massachusetts is killing thousands of other jobs, and no one can really predict whether Quebec hydro is a net job-killer or job-gainer for Massachusetts.

Pilgrim's closing does means huge challenges for Massachusetts' commitment to reducing carbon dioxide emissions. The state's Global Warming Solutions Act commits the state to a 25 percent cut, from 1990 levels, of CO2 by 2025, and an 80 percent reduction by 2050. Pilgrim today represents 84 percent of all non-carbon-emitting Massachusetts electric production, so losing Pilgrim moves the state a giant step backwards on CO2 goals.

Environmentalists are bullish on more solar and also on offshore wind, particularly the newly federally designated and leased offshore wind areas several miles southwest of Martha's Vineyard.

"The Pilgrim closure was both expected and presents an important opportunity," said George Bachrach of the Environmental League of Massachusetts Action Fund.

If fully developed, Bachrach said, off-shore wind could supply two and a half times as much power as Pilgrim does, and the state could also get twice what Pilgrim generates from hydroelectric and solar, even before accounting for the value of more energy efficiency, closing gas pipeline leaks, and other steps.

"Pilgrim's clean energy must be replaced by clean energy – not fossil fuels," Bachrach said.

With videographer Justin Mintzes