A new regulation taking effect later this year will cost electricity customers about $120 million annually, according to the state agency responsible for overseeing how the money is spent.

But the bill could go higher, a spokesman for a trade group of energy producers warned.

The $120 million is the price tag for the state's participation in a group of nine other Northeast and mid-Atlantic states that plan to limit emissions of greenhouse gases to try to slow down global warming. The state plans to start selling permits to energy producers to emit carbon dioxide into the atmosphere in December.