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A podcast by GBH News reporter Ian Coss gives this notorious project a long-overdue reappraisal. Bonus: The show comes with lessons for climate infrastructure projects of the future.

If you’ve lived in Massachusetts at any point in the last 50 years, you’ve heard of the Big Dig. It’s infamous — a tunnel project that was supposed to bury an elevated highway in Boston to the tune of $2 billion that eventually ballooned in cost to $15 billion and took a quarter of a century to finish.
The Big Dig was more than just a highway project, though. It was a monumental effort that Ian Coss, a reporter at GBH News, calls a “renovation of downtown Boston.” The project built tunnels and bridges, yes, but it also created parks, public spaces, and mass transit options that transformed the city. In a nine-episode podcast series appropriately called The Big Dig, Coss dives into the long, complicated history of the project, making a case for why the Big Dig was so much more than the boondoggle people think it was.
I talked to Coss about how the Big Dig came to be and the lessons we can learn from it as we continue to adapt our built environment to a changing climate. Our interview has been edited for length and clarity.
I moved to Boston for college in 2010, and I remember going to the North End and being struck by how beautiful it was. I didn’t realize how recently that view had changed until I listened to your podcast — I mean, the Big Dig had only wrapped up a few years earlier.
It’s easy to forget how quickly it transformed. I grew up in Massachusetts, so when I would come into the city I would see [the Big Dig] being built — I have vague memories of the elevated artery. And when I moved to Boston Proper in 2013, which was less than a decade after the project wrapped, it was stunning for me to be like, “oh, this is what that project was,” because I definitely didn’t understand it at the time.
What made you decide to create an entire podcast about this “renovation” of Boston?
I think part of it was this disconnect where I grew up hearing about the Big Dig and mostly hearing bad things about it — it was behind schedule, it was a disaster, a boondoggle, etc. — because that really was the reputation of the project, nationally and locally. And then moving to the city and seeing the fruits of it, it was hard to reconcile those things. Like, this “disaster” created a greenway through the middle of the city. Now you can actually get to the airport.
What was driving that narrative of its being a disaster?
The Big Dig went on a very long emotional journey. It started as this kind of visionary, idealistic project championed by activists and supported by politicians of both parties. And then, after navigating the process of funding, permitting, contracting, managing, and designing, by the time it's in construction, it really is not a source of pride.
There are a number of technical things about the Big Dig that could have been done better, and we can learn lessons from it. The way it was contracted could have been done better. The management structure could have been done better. There were flaws in the design, including a fatal flaw that cost the life of a driver in the tunnel.
I think a lot of it is about the storytelling. Just to give one example, so much of the negative narrative around the Big Dig was around the cost. You often hear about how it started with an estimated cost of $2 billion and wound up costing $15 billion. But I think that narrative misses a few things.
One is that it was never going to cost $2 billion. That was not a realistic estimate. But in our country, it is so hard to get approval, political support, funding, and permitting in place that there is a very strong incentive all throughout the process to downplay the costs, downplay the risks, downplay the disruption, make it sound like this is going to be quick and easy and painless and cheap, just to get to the starting line. Because the paradox of it is that if we had known in 1983 or 1987 or 1991 that this was going to be a $15 billion project, it would have never happened. And yet, in hindsight, there are many smart people who told me that this project was a bargain at $15 billion because of what we got in terms of economic benefits, transportation improvements, and environmental improvements.
There’s almost an element of asking for forgiveness rather than permission here, but that forgiveness is inevitably laced with anger because of those expectations.
Right. If only it were just forgiveness.
The Big Dig had its roots in the National Highway Program. Were all those projects going constantly over budget?
There’s a great paper that I cite in episode four where the authors studied the cost of highway building per mile every year from the 1970s through the 1990s, and it’s actually a great sample set because we’ve built so many highways of different sizes in different states. Basically, what they found is that highway costs per mile really ramp up significantly in the 1970s. And that’s, of course, the period when the [Big Dig] was first getting conceived.
So the short answer to your question is, it was cheaper once. But there were other costs, in that those early highways in the ‘50s and ‘60s largely did not consider the impact on communities or on the environment. They did not make a lot of mitigation efforts to minimize the day to day disruption caused by those projects. So I think part of what the Big Dig captures is this really historic change in the way we build things in this country that was ushered in by the anti-highway movements, by citizen activism, and by the National Environmental Policy Act. Over the course of the 1970s we made it much harder to build things, for very good reasons.
I think the Big Dig — which some people describe as the last great project of the interstate era — captures an attempt to do a massive, ambitious infrastructure project that is also loaded with environmental mitigation and also has a robust community process. Part of what we learned through that is that you can have a project that’s cheap and efficient, you can have a project that’s democratic and humane, but it’s tough to have it all. And the Big Dig was trying to have it all, and we did get it all, but at enormous cost. That was the thing that could never be solved.
You make a connection between the Big Dig and climate change right from the first episode. What are the climate lessons we can learn from the Big Dig?
In some ways, it’s ironic to hold up the Big Dig as a case study for climate change because it’s a highway project. My point is not that the Big Dig is, like, the future of infrastructure. But what it offers is a recent case study on a massively ambitious building project. We have some distance, and you can see the whole arc of it, but it very much lives within our era. It’s not the Hoover Dam or the Golden Gate Bridge or any of those other big projects built in a different time under different conditions.
The way I see it is that in order to mitigate or prevent the worst effects of climate change — and you can feel free to disagree with me — we’re going to need to build a lot of stuff. This is not a problem that we’re going to solve by riding bicycles and growing vegetables in the backyard, both of which I do and hope everyone does. And of course, those projects might look different than the Big Dig because building a wind turbine isn’t exactly analogous to building a downtown tunnel. But I think there are relevant analogies, especially things like coastal mitigation in cities, improving mass transit, building high energy transmission lines — these large scale projects that will affect people but also are an important public good.
You talked on the show about the Big Dig as an attempt to make this process more democratic at some level. People on both sides had very strong feelings about it. This reminded me of the NIMBY/YIMBY dichotomy of climate projects. Did anyone mention any best practices that could be applied to future projects of this kind?
I’ve talked with Fred Salvucci [former Massachusetts Secretary of Transportation and driving force of the Big Dig] about this. He mentioned this biblical parable — he’s full of parables — about Jesus walking across the water and then turning to his disciples and telling them to follow. But they step into the water and fall right in, and when they get back out they say it’s impossible. And then Jesus says, “It’s easy to walk across the water. You just have to know where the stones are.”
And Fred said the lesson there is that, in order to navigate this kind of process, you have to know where the flashpoints are, what the issues will be. That way you can anticipate them rather than just going in and saying “this is my project, I’m going to do it this way and you can fight me on it.”
Part of what I think is really interesting about this, which I think speaks to present-day projects like offshore wind, is that in that fight, you have very well-intentioned actors who are trying to make the project better and using the environmental process to do that. And you also have bad actors who are weaponizing and manipulating the environmental process to their own personal ends. And those two things get all mixed up.
You know, I’m an environmentalist. I believe in environmental review. I don’t want to sit here and say that we need to get rid of all environmental permitting because it makes it too hard to build things. But I think it’s also important to recognize that these things can be weaponized.
Scheme Z, which proposed this big spiral loop of ramps and a bridge over the river, is a good example. Politically, that became very messy — they were trying to impose concentrated harm in the name of a public good. And I know, strategically, maybe there are things [Salvucci] could have done to mitigate that or circumvent that, but given the structures in place, the logical outcome is that it spends a decade in lawsuits and review committees and you wind up with something that’s okay, that everyone can live with.
The funny thing about that is that it turned into the Zakim Bridge, which is now a Boston icon.
Right. I mean, that’s part of the communication piece, too.
I was biking under the Zakim bridge the other day, and I biked through where there’s a nice pedestrian and bicycle bridge and this skate park that is always filled with people. Truly, that is maybe the best utilized public space created by the Big Dig.
It’s easy for me to play Monday morning quarterback and say “oh, you should have communicated that better, you should have told the story better.” I mean, he was saying all the right things. But then all you had to say on the other side was “it’s 18 lanes and five ramps,” and that sounded terrible and looked terrible on the page. And I mean, sure, I wish there weren’t all those ramps there, but like you said, ironically, the bridge became an icon of the city.
I think a big part of the lesson for me is how hard it is to build infrastructure democratically because the timescales are all wrong. These things have short-term costs and cause short-term disruption and bring very long-term benefits.
I was constantly struck by this issue of scale, both in terms of time and money. It’s hard to wrap your head around the idea of billions of dollars and projects that span decades. These are just things that are impossible for any regular person to really plan out.
I was talking to someone who said that their dad was in his 70s when the Big Dig was just getting started. And for him, it was like, “my city’s going to be torn up for the rest of my life,” right? That’s what this project meant for him — he would live with this mess of a project and never see the results. And he had to deal with that so that you could move to Boston in 2010 and never know the city another way. The cost of that benefit is borne by another generation.
And it’s the same thing with climate change. It moves on a scale that is so much longer than politics. The Big Dig took almost 40 years from conception to completion. So if you’re thinking about political capital, if you’re thinking about two- and four-year election cycles, it’s very, very hard to conceive, plan, and deliver a project on that kind of time scale.
The benefits and costs are almost inverted in climate change, in a way. We’re talking about future benefits, yes, but we’re also talking about future costs if we don’t do anything. But it’s so hard to make people think in a 40- or 50-year timescale.
If the Big Dig was so hard to make happen politically with what I think was a more genial political environment overall, it feels kind of impossible to think of building anything on that scale right now.
I gave a talk at City Hall a few weeks ago and I was talking with some of the young planners there, people who are in their 30s. Some of them have been listening to the series, and they told me they could not imagine what it would be like to get that kind of federal funding out of Washington, get all the local players on board, get it through the permitting process, and get it contracted. Because right now if they try to take away one parking spot and put in one bike line, they’re bogged down in meetings for a year.
I think climate change is also the inverse of projects like this because with the Big Dig, for example, you can feel the tangible benefits of a quicker commute and a more beautiful city. But with climate change, if the projects work, you’d actually feel nothing.
Exactly. Climate change is way, way harder. A road project or a rail project will have benefits. You get ribbon cuttings and photo ops. But if we make Boston resilient to flooding or something, you know, do some big project that would improve the shoreline or whatever ideally, that historic storm surge may never come, or it’ll come and we’ll be prepared for it and nothing will happen. But yeah, you’re working with long term counterfactuals.
It feels to me like climate change was designed in a laboratory to flummox institutions. It takes all of our cognitive biases, our ingrained social and biological blind spots and weak points and just flicks them all at us at once.
All nine episodes of The Big Dig are out now. You can listen on the WGBH website, Apple Podcasts, Spotify, or wherever you get your podcasts.
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SoftBank’s error and Nvidia’s scandal suggest data centers may have already peaked as an economic and energy trend.
This is Heatmap Daily, a weekday digest written by our executive editor. Subscribe here.
Covering energy and climate change sometimes means seeing certain stories in a different light than others. And a particularly vivid hue illuminated The Wall Street Journal’s report today that the Japanese conglomerate SoftBank Group is taking a $3.7 billion loss on several gigawatts’ worth of natural gas turbines.
For the Journal, the big news is that SoftBank and its billionaire founder, Masayoshi Son, are failing to capitalize on the artificial intelligence boom. But at Heatmap, we’re thinking about the turbines.
The data center boom and the return of electricity load growth has depleted the world’s supply of natural gas turbines. SoftBank had purchased reservations for about 13 gigawatts of turbines, according to the Journal. That’s a staggering amount of electricity — it could meet New York City’s maximum power draw on the hottest part of a summer’s day. The conglomerate now seems set to dump reservations for about four gigawatts’ worth. Keeping a reservation, it turns out, really is harder than making it.
Most of those rotors were reportedly from GE Vernova, one of the world’s largest producers of gas turbines. GE Vernova’s order list for gas turbines has been filled for nearly two years and the waiting list now stretches into 2031. That has led data center developers, hungry to get power as soon as possible, to reach for ever dirtier forms of electricity generation, including diesel generators and even old jet engines.
On that front, SoftBank’s failure to sell the turbines to a higher bidder suggests (albeit weakly) that demand for energy-producing assets might not be as strong as the AI boom’s backers once thought. SoftBank was already set to send about 9 gigawatts of turbines to the enormous Trump-backed OpenAI data center in Pike County, Ohio. The roughly remaining four gigawatts will be released back their manufacturers. (One thing this news can’t quite tell us, alas, is what type of turbine set-up will be used in the Pike County facility, which will be the world’s largest gas-fired power plant if it is build to completion. Recent public filings have suggested the facility isn’t planning on using any turbines in the more efficient combined-cycle configuration, which would mean the plant’s carbon intensity will be worse than most other new natural gas plants. But we’d love to hear any tips on this front.)
To zoom out for a second, I’m struck by how the AI bubble has been replaced by an AI muddle. As I wrote this, news emerged that Nvidia is preparing to fire its CEO, Jensen Huang, for his affair with a Chinese woman who is alleged to be a spy. (He had at least one more affair with another Nvidia executive, according to The New York Times.) Under Huang’s leadership, Nvidia has invested in a sprawling and sometimes circular network of energy-related companies, including Emerald AI, a startup that helps data centers flex their electricity consumption, and Redwood Materials, a battery recycler and producer led by the former Tesla executive J.B. Straubel. Huang has used Nvidia’s enormous balance sheet to buy down the risk of other AI and AI-related companies, propelling the overall AI trade to become the biggest story in American markets.
Now that balance sheet is in peril: Nvidia’s stock is already down 11% over the past five days, and it has fallen another 8% in after-hours trading since news broke of Huang’s ouster. If the chip designer’s financial network began to fray — or even if the next CEO had a lower risk appetite than Huang — then its demise could impact a much larger set of firms.
Even before the Huang scandal broke, companies at the center of the AI trade were showing signs of weakness. Alphabet, Meta, and Microsoft are all down on the month. Nvidia was already lagging by about 10% on the month before its hebdomas horribilis began, too. The memory and chip makers Micron and Applied Materials are both down more than 25% in about the same period, and GE Vernova and Oklo have fallen nearly 20%. Although the data center company Coreweave rebounded on an earnings beat today, it’s still down 24% on the month and nearly 50% since May.
The market rout isn’t total — Anthropic seems likely to enjoy one of the largest IPOs ever in the next week (although perhaps not with quite as large a valuation as its investors once imagined). And the underlying technology of AI seems to be getting worryingly better all the time. But even though the politics of data centers and AI seem set to dominate the new Washington, I’m wondering if data centers as a mainstream economic trend might have already peaked. Americans voted for a more subdued AI boom in the midterms. Now it seems like they might get it ahead of schedule.
Lunar Energy’s latest AI-powered system aims to integrate EVs into the automated demand response mix.
In theory, it’s straightforward to assemble the smart energy home: Solar panels, home backup batteries, and electric vehicles, plus smart thermostats, heat pumps, and water heaters — all the individual pieces can be had for the homeowner who can afford the up-front cost. The challenge is getting all those pieces to talk to one another.
Bay Area-based Lunar Energy is one of the tech firms that’s been trying to crack this problem. Today, it announced an upgraded version of its artificial intelligence-powered home energy control system, which not only integrates all those separate systems but also responds tactically to energy markets. CEO Kunal Girotra told me Lunar AI saves its users money by monitoring their home 24/7 and making decisions to charge, not to charge, or discharge so that they save the most money.
“Utilities are all moving to almost-real-time changes of rates,” he said. “You need software to handle that for you. I think that the race is on for who has the best AI machine learning algorithms to save the most amount of money. And so far, we seem to have a head start.”
Lunar’s first-generation system focused on generation, storage, and control. In other words, it connected elements like a home’s rooftop solar panels with the backup battery the residents might keep in the garage, using the AI to decide when to meet the home’s real-time energy needs with solar versus grid energy versus stored power. What it didn’t have was the ability to work with electric vehicles to manage charging and use the car’s battery as a bonus source of energy.
To fix this, Lunar has built its own bidirectional EV charger — one that can charge up the battery or discharge the car’s battery for a secondary use, like backing up the home’s power supply. Girotra, formerly the head of Tesla Energy, told me the problem with that functionality to this point has been the connection point between the car and the home electrical system. Carmakers and other companies in the space didn’t have the deep experience with electrical certifications to make the process seamless, he tells me. That led to setups like the original Ford Charge Station Pro, which required several different wall-mounted electrical boxes to connect the F-150 Lightning EV to the home.
Lunar’s charger is built to connect to its customers’ existing home Lunar energy system, which includes a microgrid interconnect device they call Lunar Bridge that islands the home in case of a power outage on the grid. In that way, the power stored in the EV battery is ready to back up the home in case of a blackout without any additional work — or to be optimized as part of a fully smart home that’s making money as part of a virtual power plant.
The company’s setup allows for another fun feature: “slow” charging that’s not slow at all, but actually two or three times as fast as the Level 2 charging most EV owners use to recharge their batteries overnight. Electric cars in the U.S. can typically take on only about 11 kilowatts of AC power from one’s home because of the limitations of their on-board hardware. Because Lunar’s system is fully DC, however, Girotra said the company decided to build a DC home charger, one that — like a Tesla Supercharger or other DC fast chargers out in the world — isn’t limited by that power cap. Lunar said it could use a combination of power from the grid, home solar, or home batteries to charge an EV at up to 25 kilowatts. That’s enough to recharge an EV in three to four hours rather than six to eight.
“If the standards get high, and if everybody sees cars can get charged in three hours, then all of a sudden people are like, ‘Wow, this is how I want it,’” he said. “Especially for 25% of the users who are like me, who always are running low on charge and they don’t mind a boost every now and then.”
Some of the other improvements in the second-gen system are more incremental. An inverter that’s 40% more powerful helps Lunar get its system up to enterprise scale. That’s crucial, as the world moves toward a place where more homes and businesses employ battery backup systems. Lunar’s new batteries come in modular 5 kilowatt-hour blocks ranging from 10 kilowatt-hours to 30 kilowatt-hours in a single unit and scale up to 300 kilowatt-hours for home or small commercial use; there’s also new pad-mounted configurations with capacity up to 1 megawatt-hour.
Batteries, though, are the simple part. Everyone from EV makers like Rivian to utilities like Octopus Energy is racing to make a person’s or a business’s batteries and solar panels and electric cars work for them, using the power of AI to account for moment-to-moment changes in energy prices and supply. Lunar’s new tech makes the case that the most important element is a single brain to integrate every last smart, electrified thing in your house.
The fundraise comes on the heels of a $50 million grant from the Department of Energy.
Almost all lithium-ion batteries on the market rely on graphite for their anodes, more than 90% of which is processed in China. That concentration has created a chokepoint in the Pentagon’s supply chain as the military increasingly turns to batteries to help its transportation network operate more quietly and reduce reliance on complex refueling logistics.
So when Congress passed the latest National Defense Authorization Act at the end of 2025, barring Chinese-linked battery materials from military use starting in 2028, Coreshell saw an opening. While the California-based silicon-anode battery startup had previously focused on automakers as its beachhead customers, it’s now shipping its first battery cells to the military for use on Navy ships and Army ground vehicles. On Wednesday, Coreshell announced a $30 million Series B to scale up manufacturing operations to meet the needs of this growing customer base.
“We’re entering a new stage where we’re no longer, I would say, demand limited,” Coreshell’s CEO Jonathan Tan told me. “This year we’ve had to put on second and third shifts, work nights and weekends, just to get the product out the door.”
Coreshell sets itself apart by going a step further than the NDAA requires. The law doesn’t make suppliers trace battery materials all the way back to the mine, which would be exceedingly difficult given China’s dominance across the battery supply chain. But Coreshell has nevertheless eliminated Chinese sourcing from its anodes by replacing graphite with silicon mined and refined in the U.S. by Ferroglobe, one of its Series A investors.
Ferroglobe and global investment firm Access Industries led the latest round, with defense contractor ADS also joining as a new strategic investor. The financing comes on the heels of a $50 million Department of Energy grant that Coreshell secured in August as part of a program to strengthen the domestic battery supply chain. That funding will support the company’s first commercial-scale facility, a 2-gigawatt-hour factory.
That’s about 20 times the size of the 100-ish-megawatt-hour plant the startup had originally envisioned, as the DOE grant has allowed Coreshell to “expand much further than we were originally expecting,” according to Tan. The company is now evaluating several potential U.S. sites and expects to announce its selection early next year. For now, it relies on unnamed contract manufactures, along with its small pilot line in San Leandro, to produce its cells. But once the gigafactory gets up and running, the startup plans to bring electrode production in house by 2028, followed by full cell assembly in 2029.
Building this plant will ultimately require significant additional capital. But Tan believes this latest vote of confidence from the federal government will help Coreshell to diversify its capital stack as it continues to fundraise. “That’s one of the great things about having such a notable DOE award is that it also allows us to attract multiple forms of capital,” he told me.
Silicon has long been recognized as a promising alternative material for battery anodes, as it can store far more energy than graphite. The catch is that it tends to swell during charging, causing it to break down quickly and ultimately leading to a much shorter cycle life. Coreshell says it’s extended its anode’s lifespan by giving it a proprietary coating, which Tan told me back in April essentially means “painting the inside of your battery” with an ultra-thin protective layer.
Other companies, such as Sila Nanotechnologies and Group14 Technologies, are also working to commercialize silicon anodes. But Coreshell says many of its competitors rely on more highly engineered, expensive forms of silicon, such as silane gas. By contrast, Coreshell uses metallurgical silicon, a cheap, raw commodity already widely used in aluminum alloys. That, Tan argues, gives the company a cost advantage not only over its competitors, but potentially Chinese graphite too.
Coreshell hasn’t yet demonstrated that its cells can meet the performance demands of the automotive industry, however. When the company raised its Series A in early 2025, it said it expected its automotive cells to exceed 1,000 charge cycles while retaining 80% of their original capacity. But Tan told me many defense applications don’t require such demanding performance targets, as Navy ships and ground vehicles are “not intending to have as many miles or missions or use cases on that same battery” as a consumer EV would.
That doesn’t mean the company is abandoning its automotive ambitions. As Tan pointed out, electric vehicles remain by far the largest source of global and domestic battery demand. “It’s natural for us to obviously utilize the security supply chain first,” he told me. “That allowed us to really get to commercialization, revenue, and production faster, because automotive qualification is this longer journey. But ultimately, we want to do both of those and more.”