MASHANTUCKET, Conn. (AP) – The Mashantucket Pequot Tribal Nation is spending millions to retool its power system, generating electricity while heating and cooling Foxwoods Resort Casino.

The tribe in eastern Connecticut says it will start testing the $34 million project this spring and will bring it online in June.

Initially, it is expected to provide nearly 60 percent of the tribe’s electricity needs and heat and cool the casino.

Two 10,300-horsepower jet engines will power the system, which will convert natural gas into electricity and steam. The system is designed to produce 15 megawatts of power and burn cleanly and efficiently while easing demand on the regional power grid.

The new system is expected to cut the tribe’s electricity bill of $24 million a year.

Charlene Jones, a former tribal councilor and chairwoman of the tribe’s utilities authority, said it should pay for itself in three years.

“It just made sense in terms of value and the environment,” she said.

Mike Collins, sales manager for Yankee Gas, the Northeast Utilities company that supplies much of the tribe’s natural gas, said cogeneration also is better for the environment.

“It’s a way of going green, though it’s not totally green like wind or solar power – it’s light green,” he said.

The Mashantuckets’ cogeneration system would be among the five biggest in the state, he said.

Robert Birmingham, the tribe’s planning director, said the tribe eventually intends to ramp up the system to provide all of the electricity consumed on the reservation, including the casinos. The consumption ranges from as little as 18 megawatt hours a month in the winter to as much as 26 to 28 megawatt hours a month in the summer, he said. The reservation consumes 180 to 190 megawatt hours of electricity a year.

ISO New England, manager of the region’s power grid, said one megawatt of power can provide the energy needs of 1,000 typical New England homes at one time.

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