LONDONDERRY — Liberty Utilities presented a new economic analysis of its Granite Bridge project Friday maintaining it is the lowest-cost option for expanding natural gas in the region.

The Public Utilities Commission had delayed its review of the 27-mile underground project along Route 101 so that the utility could complete this update on its estimate for construction costs and economic forecasts.

The plan calls for building a new pipeline carrying liquefied natural gas (LNG) from Stratham to Manchester with a plant to store gas in Epping.

Company officials underlined Friday its assertion that buying gas in the summer and storing it in Epping would lead to significant savings for Liberty customers who buy gas during the winter months when it's typically more expensive.

“After over a year of extensive development work, Granite Bridge continues to be the lowest-cost, least disruptive way to meet the natural gas needs of New Hampshire customers,” said Susan Fleck, Liberty Utilities president.

“With all the market volatility we have seen in recent years, LNG would provide considerable benefit to our customers. We looked at our actual natural gas purchases over the past five years and calculated that if the Granite Bridge LNG facility had been in service during that time, our customers would have enjoyed over $120 million in savings on their natural gas costs.”

During its review utility executives have made design changes for the pipeline moving some of its route to avoid environmentally sensitive areas.

This latest report maintains those changes raised the cost of construction by 30 percent, officials said.

The energy purchase savings should permit Liberty Utilities to keep its earlier forecast that construction of the pipeline would increase the average customer's bill by about $2 per month.

The so-called Customer Benefit Guarantee requires efficiencies and these savings would be used to lower the up front capital cost for Liberty's customers.

“Granite Bridge is a long term solution to New Hampshire’s energy needs. We are committed to helping residents and businesses in the area take advantage of clean, low cost natural gas through the efficient management of our resources,” Fleck said. “The Customer Benefit Guarantee is simply further evidence of Liberty Utilities’ commitment to deliver stability in supply and cost to our customers.”

The project has attracted strong support from business groups and organized labor, but many environmentalists maintain Liberty Utilities has aggressively made moves in the energy market to create more demand in the state for natural gas.

The PUC's consumer advocate had called for more transparency into the company's finances and warned this project could lead to a significant increase in the rate base passed on to customers.

Last week the town of Epping overwhelmingly approved a non-binding resolution at its Town Meeting to compel the utility to seek local approval of the storage plant site.

Currently the project only requires state approval from the PUC for its finances and then review from the state Site Evaluation Committee.