The problem with a baseload power plant in New England is that a baseload powerplant is worthless without a fuel supply. The Marcellus gas fields in PA are loaded with natural gas but a decade ago there was a concerted effort to "starve" New England from getting additional major supplies of natural gas by stopping pipeline development into the region. It was quite successful. There was an attempt of a coalition of states to encourage new pipelines but it ultimately entailed each state signing "take or pay" contracts to cover the cost of building the pipelines. It all fell apart. The last major pipeline into the region was the PNGTS that runs from the Canadian Border through Coos county and then over to Maine using the Portland Pipeline right of way. The PNGTS ties into the tail end of the Canadian gas network which is higher priced than PA gas. PNGTS has offered to expand the capacity of the existing pipeline at least once by the installation of gas compressor stations but there are no takers as they would need to pay for the expansion and upkeep even if they did not need the capacity. There was hope that Sable Island Nova Scotia would pump gas into the New England network but the gas field fizzled. There was discussion of added additional LNG to the network but LNG sells for a premium over regular natural gas as its quite expensive to liquify it. Unlike parts of the US, the geology of much of New England is unsuitable for underground gas storage so it needs to be stored elsewhere and shipped via currently limited pipeline capacity. The best way to use it is direct from the well fields after its been processed, but as mentioned New England is limited on pipeline capacity into the region. There are two types of natural gas, firm and non firm. A firm gas contract owns space in the pipeline to get it into the region. Effectively the firm gas holder is paying for a share of the cost to build and maintain the pipe. A residential gas utility would be a firm gas owner. Most gas is Non Firm, the owners of firm gas capacity will look at their projected gas use and rent out the space to other entities on a day ahead basis. Big power stations all run on non firm gas, they or their broker has to bid on enough gas a day in advance to run the plant. If they do not use it they have to pay for the capacity in the line and frequently for the gas. If supply is plentiful things are great but in New England especially in the winter, its not plentiful and natural gas stations may have to curtail production if they cannot buy gas, this happens on cold days. ISO New England has been warning that New England is close to a cold day in winter where the choice is heat the houses or keep the lights on. Current firm price contract for January 23 are reportedly 6 to 7 times the current gas cost.
So natural gas generation is not the ideal baseload as the fuel supply makes it vulnerable to supply disruptions with no easy way to store it. Nuclear is darn good baseload as the fuel charge in the reactor last years (while the waste lasts 10s of thousands of years). The fuel cycle used by the current generation of nuclear plants was designed to be inefficient as a source of weapons grade fuel. There are other cycles that are more efficient that generate less waste. Many of these cycles were tested and developed by the US long ago but were abandoned. Given the current cost and timing to build a new nuclear plant, its likely the last large US nuclear power plant is going to be Vogtle in Georgia (if it ever opens). There are SMRs (Small Modular Reactors) proposed but they are 10 to 20 years out and suffer a lot of the issues of big plants.
Fossil fuel plants are great baseload plants, put in a few big oil tanks and they can run for weeks. Not very efficient although light distillates like jet fuel can be burned in combined cycle power plants very efficiently but emmissions are higher than natural gas and fuel cost is high. Cousins Island in Maine has one or two old school fossil boilers and steam turbines and they crank it up on occasion, that would be the oil fired generation that pops up on really hot or really cold days. So what is left?. Coal also can be stockpiled and is relatively cheap but unless its one of the few multibillion dollar IGCC (Intergrated combined cycle gasification) plants, its not very efficient and puts out a lot of CO2 per KW as well as lot of other air toxics plus a nasty solid waste stream. Biomass electric generating plants also can stockpile wood chips, the new Berlin plant can hold 30 days worth of fuel with room to spare. The fuel is relatively local but are not very efficient, no better than coal. They put out less toxics and the ash can be spread back in the woods. There were a lot of these plants built in NH and VT to supply Mass and CT but compared to natural gas combined cycle plants they cannot compete. The few left running are getting quite worn out and many are owned by the same bottom feeder firm.
So we are left with the problem that there really are no baseload plants that make a lot of sense in New England. Even if someone were to want to build one, financial institutions have no interest in funding them as they are worried that they will become financial albatrosses in the long run. The Berlin Biomass plant is one of the most technologically advanced biomass plants in the US yet it has consistently lost money and only runs with a state subsidy that was extended only at the last minute recently. Even as advanced as it is, it is not that efficient. The only way to make it really efficient is to start from scratch and build a IGCC version of a biomass fired power plant. To date I am not aware if anyone has built a wood IGCC as the required scale of such a plant would overwhelm a regional waste wood supply. Wet wood chips are low btu content and take up lot of space, haul a truckload full of wood over about 100 miles and the fuel used to haul it will exceed the btu content of the wood. Therefore all the biomass boilers in New England were built small and spread out so they could run on local chips from nearby. One of Berlin's issues is that its 75 MW and its fuel is coming from longer distances than it should. The other biomass plants do not have that subsidy and can only afford cheap local wood so there is a glut in the region of low grade wood but the cost to haul it to Berlin is prohibitive. Whenever I see trucks of chips going up and over Pinkham notch from the south, I know that there was probably as much btu content in the diesel required to haul it up than in the wood btu content in the trailer. Far better to burn it in the Tamworth plant but Tamworth does not get a subsidy.
So the choice is now that New England has shut down most (but not all) nukes what will the power system look like and where will the money go?. One option is to pay HQ to deal with the problem and pay dearly in the long run plus be very vulnerable to supply interruptions (a couple of locals took out the existing DC Canadian line through NH about ten years ago by target shooting insulators, it took a couple of days to correct the problem and put it back on line). If that had occurred now, the potential impact would be much greater as the regional power margin has dropped precipitously. The alternative is to build out local renewables including a big investment in offshore wind and storage.