Nova Scotians can expect to pay more for power as the province ramps up its green energy program.

The government announced Friday it plans for 40 per cent of all electricity to come from renewable sources by 2020. That would supply as many as 500,000 homes.

The NDP government has already set a goal of 25 per cent by 2015, and now plans to make that law.

Currently, only 12 per cent of Nova Scotia's power comes from renewable sources such as wind turbines. Most of the province's electricity is generated in coal-fired plants.

"These standards make Nova Scotia one of the most progressive energy jurisdictions in the world," said Premier Darrell Dexter. "There are costs but in the long run consumers will pay less than if we stay on the current path."

The province's plan, which includes a guaranteed price for community-based power producers, is expected to attract $1.5 billion in new investments and create hundreds of jobs.

Residential power bills are expected to climb. In five years, the average household could pay an additional $15 a year to help the province reach its goals.

Provincial officials said their aggressive plan will make Nova Scotia a global leader in green energy.

"I think they are stretch targets but they are achievable," said Robin McAdam, Nova Scotia Power's vice-president of sustainable development. "We aren't hamstrung if tidal [power] doesn't pan out."

Premier Darrell Dexter said it will mean more stable power prices for consumers and a more secure supply of energy.