After a two-year battle over whether Public Service of New Hampshire should install a sophisticated mercury and sulfur filtration system in its Merrimack Station in Bow, the utility company will finally be able to do it.

The state Legislature mandated in 2006 that PSNH install the wet scrubber to cut down on harmful emissions by the year 2013, but the high price tag had the New Hampshire Public Utilities Commission – the authoritative force in such endeavors – debating whether it was in the public’s best interest.

After the commission investigated its authority in superseding the Legislature’s decision, they found it was above their call to do so.

The PUC delivered their findings in a 14-page study released on Thursday, Sept. 19.

“This is a very exciting and important project,” said Martin Murray, senior corporate news representative for PSNH. “It may be the largest environmental project of its type in the entire country.”

The wet scrubber would ideally reduce the plant’s mercury emissions to about 20 percent of what the coal burned at the plant would produce on its own, without any filtration. The new technology would also reduce sulfur emissions by about 90 percent.

Northeast Utilities, which owns PSNH, has approved long-term funding for the scrubber, estimated to cost about $457 million.

The total brunt of installing the scrubber will fall on ratepayers, but Murray said PSNH has been trying to complete the project ahead of the July 1, 2013, deadline to qualify for potential incentives that could alleviate some of the cost.

That price tag has jumped significantly from the initial estimate of about $250 million, prompting the PUC to investigate in late August.

“The reason for the difference between the two prices is there have been some incredible increases in the prices of commodities and goods,” said Murray, including steel and other construction materials as well as transport.

In its final investigation report, the PUC said the finding was based that they did not have authority over whether the scrubber goes in, on the fact that the Legislature mandated a specific solution for reducing the sulfur and mercury emissions in addition to mandating PSNH’s adherence to a deadline.

The report also says that since the Legislature had already said the scrubber was in the public interest, it overrode their right to decide whether it actually was. The alternative to not install the wet scrubber would be closing the plant, which provides almost half of PSNH customers in the state with power. Sen. Ted Gatsas, representing Bow in the Legislature, has said such an action would be a detriment to the town of Bow and to PSNH ratepayers, who would see their rates increase even more drastically the longer the project was put off or if the plant were closed.

“The PUC has understood that they don’t have jurisdiction over the scrubber,” Gatsas said Thursday, Sept. 19, after hearing the news. “So that’s good news for the town of Bow and all the rest of the ratepayers in the state of New Hampshire because any delay would have increased costs.”

Gatsas added installing the scrubber may allow PSNH to purchase cheaper coal from West Virginia instead of what they now buy from Venezuela. The Venezuelan coal has significantly lower sulfur content, but costs a lot more.

The next step, Murray said, is to finalize things with the town before construction can get up and running.

Representatives from PSNH will meet go before the Bow Planning Board on Tuesday, Oct 11, in the hope of getting the approval on a final permit because of a new smoke stack that will be installed at the plant, Murray said.

The hope is to obtain all local and state permits in time to start construction before this winter, Murray said.

The PUC will keep an eye on costs in addition to conducting an official review following construction completion, the Sept. 19 report says, “In order to meet our obligations in that regard we will continue our review of the documents already provided by PSNH, require additional documentation as necessary, and keep this docket open to monitor PSNH’s actions as it proceeds with installation of the scrubber technology.”

“This is a significant potential obstacle that has been bypassed. At least we know now that there will be no more delay at the state or regional levels,” Murray said.