Let your driver’s license lapse and you’ve got a problem. You might get away with it for a while, but the first time you get pulled over, you’re in for an awkward conversation.<\/p>\n
Federal hydropower licenses work a little differently. The license for Northfield Mountain, a pumped-storage power plant dug into a mountain in Franklin County, Massachusetts, expired on April 30, 2018. The plant’s been running ever since, it’s all perfectly legal, and on November 2 it got a new owner.<\/p>\n
So how do you run a power plant for more than eight years on a license that’s expired?<\/p>\n
Basically, the law expects the paperwork to run late. Under the Federal Power Act, if a new license isn’t ready when the old one ends, the Federal Energy Regulatory Commission (FERC) has to give the operator a one-year license on the old terms. FERC’s 2018 notice for Northfield Mountain<\/a> says that first one ran through April 30, 2019, and after that it gets “renewed automatically” until the agency acts.<\/p>\n That’s eight automatic renewals so far, by my count. Frankly, that’s a long run for anything with the word “annual” on it. But there’s nothing shady going on here. FirstLight, which runs the plant, applied for a new license on April 29, 2016, two years before the old one ended. FERC’s still keeping an eye on the place too, and inspected it on July 15.<\/p>\n If you haven’t run into pumped storage before, think of it as a rechargeable battery that runs on river water. When there’s power to spare, the plant pumps water up to a high reservoir. When the grid needs more, that water falls back through the same machines and makes electricity.<\/p>\n Northfield’s bottom reservoir is the Connecticut River, specifically the 20 or so miles backed up behind Turners Falls Dam. Its top reservoir is man-made and sits on the summit, covering 286 acres when it’s full, with a main dam about a mile long and up to 140 feet high. Apparently that dam also has an intake built in case anyone ever wanted to send water over to the Quabbin Reservoir, one of Boston’s main water sources, which is a pretty fun thing to have lying around.<\/p>\n Engineers call the drop between the two reservoirs the “head,” and here it runs from 753 to 824.5 feet depending on water levels. So “about 800 feet” is a fair shorthand. We’ve looked at this kind of plant before: the Ludington plant in Michigan<\/a> lifts water 363 feet, and Grand Coulee’s pumps<\/a> manage 280.<\/p>\n The star of the show is the powerhouse. It’s a cavern measuring 328 by 70 feet, so a little longer than a football field without the end zones. Going by the elevations in FirstLight’s amended application<\/a>, it’s about 134 feet from the floor of the valve gallery to the roof. Four reversible machines live in there, and they spin one way to pump and the other way to generate.<\/p>\n One thing I can’t give you is a clean number for how deep the cavern sits. FirstLight’s application doesn’t state one, and I haven’t found it in what I’ve been able to read of FERC’s environmental statement. The closest thing I’ve got is that ventilation and emergency shaft. I’d really rather not find out how long those stairs take.<\/p>\n The top reservoir holds 12,318 acre-feet of usable water, or about 4 billion gallons by my math. An acre-foot is just what it sounds like, enough water to cover one acre a foot deep. FirstLight says that’s equal to about 8,729 megawatt-hours of stored energy.<\/p>\n I ran the plant’s maximum flows against the reservoir, and at full tilt you’re looking at about seven and a half hours to drain it and just under 10 to fill it back up. FirstLight’s website says up to 7.5 hours, so that checks out.<\/p>\n You’ll also see a few different figures for the plant’s output. FirstLight’s sale announcement says 1,168 megawatts, FERC’s listing says 1,166.8, and FERC’s final environmental statement recalculates that to 1,166.6. The 1,168 does show up in the application, in a table that gives the capacity at 820 feet of head and then falls to 840 megawatts at 768 feet. So that’s arguably a best-case number, but the gap between those three figures is under 2 megawatts.<\/p>\n On paper, this plant looks like a terrible idea. From 2011 through 2019, it generated an average of 889,845 megawatt-hours a year and used 1,189,640 megawatt-hours a year for pumping. That’s 34% more power going in than coming out.<\/p>\n It works for the same reason a store can make money on stuff it bought wholesale. The plant pumps during the slow hours when power’s cheap, then generates when demand’s high and power’s expensive.<\/p>\n An earlier version of FirstLight’s application breaks this down for 2013, which is the most detailed year I’ve been able to read. Northfield sold its power at $85.17 per megawatt-hour that year and paid $40.01 per megawatt-hour to pump. Even after losing about a quarter of the energy on the round trip, that’s a pretty healthy spread.<\/p>\n The energy trade apparently wasn’t the biggest check, either. That same breakdown leaves about $26.1 million after pumping costs, compared with $35.5 million in capacity payments and $14.9 million for reserves. Those last two are basically the grid paying Northfield to be ready. FirstLight puts the annual plant factor at about 9%, meaning it makes about 9% of what it could if it ran flat out all year. You don’t judge a fire extinguisher by how often it’s in use.<\/p>\n FirstLight’s earlier application also points to blackouts. It says grid operator ISO New England reconnected to New York’s grid at Northfield after the August 2003 blackout. It also says a September 2010 failure to recover from a lost power source likely wouldn’t have happened if the plant hadn’t been out of service. FirstLight isn’t exactly a neutral witness here, admittedly. But FERC’s staff also credits Northfield and Turners Falls with fast ramping and black start capability, meaning they can help restart a dead grid.<\/p>\n Mostly, it’s the river. FERC’s staff released its final environmental statement<\/a> on January 30, 2026, and it recommends relicensing both Northfield and the smaller Turners Falls hydro plant nearby. It also lists shoreline erosion, swings in water levels, fish passage, protected species and cultural resources as the main issues.<\/p>\n Fish are the easiest one to picture. Young American shad and American eels get pulled in when the plant pumps. Regulators call that “entrainment,” and you or I would call it getting sucked into a power plant. The plan on the table hangs a barrier net in front of the intake every year, from June 1 to November 15.<\/p>\n FirstLight also wants more room in the top reservoir, with a maximum drawdown of 84.5 feet instead of today’s 62.5. As I read it, FERC’s staff wouldn’t let that extra water be used for generating, and it’d limit pumping in the spring to protect spawning shortnose sturgeon.<\/p>\n Some locals would rather see the plant shut down for good. The Greenfield Recorder, citing FERC’s statement, reported that 49% of the comments FERC received opposed giving it a new license. Comment counts aren’t votes, but that’s still a lot of unhappy people.<\/p>\n Then there’s Massachusetts. Under the Clean Water Act, a state gets to sign off on water quality before FERC licenses a project like this. That sign-off is called a 401 certification. The state issued its certification in April 2025, and groups including the Franklin Regional Council of Governments, the Connecticut River Conservancy and American Rivers appealed it.<\/p>\n The latest I can find is that the appeal’s still unresolved, though that’s from earlier this year. Andrea Donlon, a planner at the council, told the Recorder in February that a license could be “another couple of years” away. She pointed to Bear Swamp on the Deerfield River, which got its license in December 2025 after a FERC environmental analysis in 2020.<\/p>\n All of that now belongs to Hull Street Energy, a Maryland private equity firm that closed on FirstLight’s US fleet<\/a> on November 2, and the announcement doesn’t say what it paid.<\/p>\n I went through FERC’s online docket for the project, and as of November 5 there’s no new license in it. The most recent entry is FirstLight’s October 23 statement of generation for annual charges. Unless that changes, by my reading Northfield Mountain’s current annual license runs through April 30, 2027, and then it renews itself again.<\/p>\n","protected":false},"excerpt":{"rendered":" Let your driver’s license lapse and you’ve got a problem. You might get away with it for a while, but … <\/p>\nSo what’s inside that mountain?<\/h2>\n
Why would you burn more power than you make?<\/h2>\n
So why’s the new license taking so long?<\/h2>\n