AUGUSTA – Mainers will have to pay $300 million more for electricity over the next four years as the result of a decision by the Federal Energy Regulatory Commission.

Maine Public Utilities Commission Chairman Kurt Adams said the state will appeal in federal court.

“Commercial and industrial customers that are in the market will see a 5 to 6 percent increase right out of the block,” Adams said. “This order takes effect December first.”

He said residential customers will not see an immediate impact because of the way the Maine PUC has structured its “standard offer” plan for the next two years. The standard offer is the default source for the actual electricity used by customers and is a separate charge on electric bills from the distribution costs charged by utility companies.

“But by the end of the four-year period, residential and commercial customers will see about a 10 percent increase in their bills as a result of this decision, ” Adams said. “It’s a very, very bad decision for consumers.”

In a statement, FERC Chairman Joseph Kelliher defended the decision. He said there need to be investments in new generating and distribution facilities in New England and that will not occur without some increased costs to ratepayers.

“This order marks final commission action to help assure that New England has an adequate electricity supply in the future,” he stated. “I commend the parties for entering into this settlement and taking steps to make sure the region has reliable electricity supplies at a just and reasonable cost. The region acted to prevent a crisis, and for that they should be applauded.”

Maine was one of eight of the 115 parties to the case that refused to agree to the rate increases and the new FERC plan for allocating the costs of power distribution in the region. Power generators will be able to bid for the right to build power plants, transmission lines and supply electricity to companies that distribute power, such as Central Maine Power Co. and Bangor Hydro-Electric Co.

Adams agrees there are capacity needs in New England, but argued that the improvements should be paid for by those that will benefit from the improvements. He said the FERC action is aimed at improving capacity in parts of Connecticut and Massachusetts.

“We’ve got plenty of capacity in Maine,” he said. “We are exporters of electricity, and we certainly are not part of the problem FERC is talking about.”

The issue has been simmering for a year. Adams was so angry with discussions last January that he walked out of a meeting called to negotiate a settlement among the 115 parties to the FERC proceeding.

After the initial FERC decision last June, Gov. John Baldacci called the decision “unbelievable” and “unacceptable” and urged FERC to reconsider. The agency denied that request, and the rate increases begin in December

“We will appeal in federal court,” Adams said. “But that won’t stop the increases from taking effect.”

He said if the state wins in court, and he believes it has a good legal case, the court could order rebates to customers.

Lawmakers approved legislation Baldacci submitted earlier this year that directs the PUC to study whether Maine should continue as a member of the New England Power Pool or ISO-New England, the Independent System Operator for the region.

Adams said the study ordered by the Legislature is well under way, and he predicted the FERC decision will make the issue “front burner” when the new Legislature takes office next month.

When the decision first was released last June, it raised concerns with Maine’s business community. David Clough, Maine director of the National Federation of Independent Businesses, said commercial customers had increases in rates earlier in the year. He said Maine is already a “high energy cost” state and any further increase in energy costs would hurt the ability of Maine businesses to compete.