State regulators will hold a hearing on the request on Dec. 4 at the Public Utilities Commission headquarters, 21 South Fruit St., Suite 10, in Concord. Organizations and individuals that are stakeholders in this process will have a chance to comment at the hearing.

"Each year we have to provide to the Public Utilities Commission the real numbers of our costs over the past 12 months and the estimated costs for the next 12 months," said PSNH spokesman Martin Murray. "We supplied our original estimates in September and will update them in December."

Murray said the largest part of the costs based on the September figures was that of making and purchasing power for the approximately 490,000 customers the utility serves in New Hampshire. The utility needs approximately 1,800 megawatts of power to meet that need and gets about 1,140 from its own power plants and hydro facilities, Murray said.

"The rate has to be adjusted in January and could be adjusted again in July, if the one approved in January proves to be too high or too low," the PSNH spokesman said.

Part of the increase has to do with both the Regional Greenhouse Gas Initiative, designed to curb carbon emissions, and the Renewable Portfolio Standards, set up to move the state toward getting 25 percent of its power from renewables by 2025. Murray estimated that amount 20-30 percent of the increase can be attributed to those two programs, but indicated those costs haven't been completely determined yet.

"In terms of RGGI, this is all quite new to us," he said. "The cost will be based on what the price is at auction of the credits we need to meet our carbon requirements."

RGGI requires companies that emit carbon dioxide to purchase RGGI allowances, which are sold at auction by the 10 states in the RGGI region. The number of allowances available is reduced over time, thus reducing the amount of CO2 emitted in the region.

The states will use the auction revenue to implement energy efficiency programs designed to lower the overall demand for energy, thus reducing the need to produce power from CO2-emitting generators.

Murray noted that the first auction of those credits was held in September, with another planned for December, and that the amount PSNH will have to pay for credits still has not been fully determined.

As for the Renewable Portfolio Standards, while that program is in its second year, the cost of meeting those standards is still not clear either, Murray said.

The figures submitted to the PUC in September has PSNH paying the full amount of the penalty for not meeting those standards. However, the utility has reached a deal with the Lempster Wind Farm being built in Lempster.

Murray said that buying the credits from the wind farm could impact both the RGGI and RPS costs for the utility.

This has become an issue in the New Hampshire gubernatorial race, Forbes.com reported recently.

Republican gubernatorial candidate Joe Kenney criticized the RGGI component Friday as an unnecessary burden on ratepayers. Kenney said he would repeal the law intended to curb carbon emissions that Gov. John Lynch signed.

Pamela Walsh, Lynch's campaign manager, said the rate request still has to be reviewed and the final increase could be much less. She said New Hampshire's participation in RGGI will benefit the state in the long run.

PSNH is a subsidiary of Northeast Utilities of Connecticut.