LYNN – Salem Mayor Kimberley Driscoll says the clock is ticking on a plan to replace an aging Salem Harbor power plant with a new facility she said will provide energy security and jobs for the city and neighboring communities, including Lynn.Driscoll supports New Jersey-based Footprint Power?s plan to replace the coal-fired plant on the harbor which occupies 60 acres with a smaller-scale natural gas plant on about 12 acres that will employ about 80 people. Footprint?s proposal has secured local and state permits but faces opposition from the Conservation Law Foundation, an environmental organization, and state Rep. Lori Ehrlich, D-Marblehead.?It?s being sold to us as a necessary evil. It?s overkill,” Ehrlich said.Conservation Law wants the Footprint plant proposal weighed against Massachusetts requirements for reducing air pollution outlined in a 2008 law entitled the Global Warming Solutions Act.?This is the strongest law in the country attempting to do something about global warming,” said foundation senior attorney Shanna Cleveland.Driscoll said there is room for compromise between environmental concerns and her views of Footprint?s plan as a jobs and property tax generator. But the mayor said an agreement must be worked out soon: Footprint?s complicated schedule for the $250 million project requires additional planning steps to begin next month in order for the firm to meet a June 2016 deadline for connecting the proposed plant to the power distribution network.Built in 1950, the existing Salem power plant generates electricity as well as $4.75 million in property tax revenue annually to help pay for the city of Salem?s $135 million budget. The plant is scheduled to close next June.Driscoll notes that power distributor ISO has warned power shortages could affect Northeastern Massachusetts if the Footprint plant is not built. Without Footprint, Driscoll said the region will continue to rely on less efficient and older power plants, including ones in other countries, for local power.She called Footprint?s plant “better for the environment.”?We need the reliability. This is so much more efficient,” Driscoll said.Cleveland said the proposed plant?s long-term environmental impacts through 2025 – even longer – need to be much more thoroughly reviewed so they can be compared with the 2008 law?s air pollution reduction standards.The foundation filed an appeal with the state Supreme Judicial Court in November asking for the state Energy Facilities Siting Board to review Footprint?s plans for a second time.?We want analysis of the plant?s climate impact through 2056,” she said.Notwithstanding ISO?s warning, Ehrlich said there are other ways to ensure power supplies are met without building another Salem Harbor plant.?I take issue with the size of the project and reliance on gas, which is a fossil fuel,” she said, adding Marblehead residents endured decades of air pollution from the Salem plant without realizing any of its tax benefits.Driscoll said the Footprint plant is only one use envisioned for the power plant site, with a cruise ship dock, recreation area and marine-related industrial uses also proposed.?If this doesn?t happen, we?ll be looking at a desolate property for decades,” she said.Driscoll is scheduled to talk about the Footprint plan Thursday morning with Marblehead Chamber of Commerce members even as she tries to strike a compromise on the project between supporters and opponents.Cleveland said compromise is not out of the question.?We need to see a serious proposal that would provide for compliance with the Global Warming Solutions Act,” she said.