The firm just wrapped work on a heating and cooling system for a Boston office. It says its rig makes drilling cheaper, quieter, and less water-intensive.

Dig Energy, a startup on a quest to vastly improve geothermal drilling, has completed its first commercial project, digging seven boreholes for a geothermal heating and cooling system at the headquarters of Boston general contracting firm Suffolk Construction.

Dig first stepped into the public eye almost exactly a year ago, when it announced a $5 million funding round after some five years of developing its technology behind the closed doors of a barn in New Hampshire. At the same time, Dig was selected to participate in Boost, an accelerator program run by Suffolk Technologies, the venture capital affiliate of Suffolk Construction.

Dig’s innovation: a rig purpose-built to drill geothermal boreholes with less noise, less water usage, and far lower cost than conventional drilling equipment.

Geothermal systems, which use all-electric heat pumps to tap into thermal energy stored underground, are widely hailed as the most efficient way to warm and cool buildings. However, the upfront price of accessing this clean source of energy can be a major barrier. The expense of installing a geothermal system can be up to five times that of an equivalent air-source heat pump. Only about 1% of buildings in the United States use geothermal systems for heating and cooling, estimated Dig Energy co-founder and CEO Dulcie Madden.

Dig says its technology could upend this math, cutting the cost of drilling by up to 80% as compared to conventional geothermal drilling. The companies declined to share specific numbers, but Dig ​“put some early proof points out there that, from a cost and schedule perspective, they’re going to be very competitive in the market,” said Parker Mundt, a partner at Suffolk Technologies.

In the standard process, the borehole is drilled first, typically with a metal bit or compressor, and shored up along the way with a casing to prevent collapse before a heat exchange pipe is inserted.

Dig’s system, by contrast, uses a high-pressure nozzle that sprays water at 10,000 pounds per square inch to bore through soil and rock. The approach was explored by the oil and gas industry decades ago, but never gained traction because it didn’t increase productivity in those sectors, Madden said. She and her partners saw an opportunity to adapt the idea for geothermal and spent years honing the technology.

“It’s a known industry practice that’s being adopted in a novel way for the first time,” Madden said.

The team engineered a drill string — the long vertical pieces that connect the surface equipment to the drill tip — that stays in the ground once the hole is complete, becoming the heat exchanger that transfers thermal energy to and from the surrounding earth. The nozzle stays behind as well; it was designed to be cheap enough that it is still economical to use a new one each time.

That innovation means the hole can have a smaller diameter than in conventional geothermal systems, because no extra room is needed for casing and the insertion of the heat exchanger. This process reduces debris and, perhaps counterintuitively, even water usage, because standard drilling uses large amounts of water to lubricate and cool the drill bits, as well as to turn displaced earth into mud that can be more easily removed from the hole.

Drilling at the Boston jobsite last month used one-tenth the water that the conventional drilling would’ve used and created 75% less material to be carted away, Madden said.

The process was also much quieter than standard drilling operations, which Madden likened to a demolition site. Dig’s equipment operated at such a low volume that workers could hold a conversation right near the rig and people in nearby buildings couldn’t hear a thing, she said. Also, the rig’s small size — about the same footprint as a parking spot, Mundt said — made it easy to maneuver in a dense urban environment.

“You can have people working around the rig without any disruption,” Mundt said.

Dig has several more jobs lined up after its inaugural success; the company is booked until mid-summer 2027, Madden said. And work is underway on a new version of the rig that aims to cut down on drilling time, she said.

Already, though, Dig’s performance on its first outing bodes very well for its future, Mundt said.

“The results from this initial commercial project at our headquarters were incredibly exciting for us,” he said.

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The solar-plus-storage project faced no opposition despite growing pushback to clean energy in the state — likely because of its brownfield location.

Clean energy scored a rare win in Ohio last month when state regulators unanimously approved a permit for 149 megawatts of solar and 149 MW of battery storage at the Hamden Energy site in Vinton County, located in the southeast quadrant of the state.

In contrast to most of the state’s solar permitting cases, no parties in the case opposed the project, proposed by developer Recurrent Energy, at the Ohio Power Siting Board — largely because it will be built on reclaimed coal mine land.

“Developing a solar project on reclaimed land is an excellent opportunity to harvest another one of the area’s abundant resources to power Ohio while providing supplemental tax revenue to support a legacy energy community,” said Ali Trunzo, a senior development manager for Recurrent Energy.

Like much of the rest of Appalachian Ohio, Vinton County has a history of hosting extractive industries — particularly coal, iron, and clay — whose production has plummeted over the last century. Although its economy has grown over the past 20 years, roughly 19% of the county’s residents live in poverty.

The county’s board of commissioners did not block the project, which they could have done under a 2021 law that erected extra hurdles for solar and wind power, but not fossil fuel generation.

Opponents of other solar farms in Ohio have frequently raised concerns about projects taking farmland out of use, although solar occupies less land than golf courses in the state and can coexist with some farming practices.

Projects on former mine lands and industrial brownfields, like Recurrent’s, tend to draw less opposition, although they have their trade-offs. Namely, they can be more expensive to develop than greenfields because of conditions at the location and the need to accommodate remediation, according to RMI, a clean energy think tank.

Trunzo declined to provide cost information about Recurrent’s Hamden Energy project, although she noted that specialized methods and equipment may need to be used to adapt to the site’s soils and terrain.

The roughly 25 people who commented in the case docket or spoke at a June 10 local hearing voiced mixed opinions. The most common concern was whether ongoing reclamation would be finished before construction started on the solar and battery project.

That remediation work is the responsibility of Cheyenne Resources, which holds the surface mining permit for the property, confirmed Andy Chow, a spokesperson for the Ohio Department of Natural Resources. Recurrent Energy has agreed to begin construction only after reclamation is done.

The Recurrent project is not the first coal-to-solar farm greenlit by the state. Regulators approved the Vinton Solar Energy Center in 2018, and the project remains under construction by developer Invenergy. Other states are siting solar at former mine lands as well.

More projects will likely follow in Ohio because of recent policy changes.

Under a 2025 law, House Bill 15, former mine lands and industrial brownfields are eligible for treatment as priority investment areas. Ohio has more than 70,000 acres that might fit that definition, RMI data shows. Rules from the Ohio Department of Development for designating such places took effect two months ago. Agency spokesperson Brian Bohnert told Canary Media the state has started to identify its first areas under the program. One of the two sites designated through late August includes both former coal mine land and an industrial site.

“The reuse of former mining land for new energy production is a win-win for Ohio consumers and the environment,” said Rebecca Mellino, associate director of climate and energy policy for The Nature Conservancy.

The Nature Conservancy’s view, Mellino said, is that HB 15 not only creates priority areas but also lets counties host solar on former mine sites and brownfields despite exclusions that might otherwise apply under Senate Bill 52, the 2021 enactment that added hurdles for renewable energy developments.

In many cases, solar energy is cheaper and can come online quicker than natural gas generation. Yet as projections call for the state’s electricity demand to grow, clean energy developers continue to face bans or project vetoes under SB 52. Beyond the statute’s terms, state regulators have often blocked projects on the basis of unanimous local government opposition, regardless of whether opponents’ arguments were based on opinion or grounded in fact.

A bill passed by the Ohio Senate this spring could make it even harder, if not impossible, for many solar and wind projects to get built. SB 294 is now in the Ohio House of Representatives.

“Projects like Hamden Energy are vital to bringing sustainable, affordable, and dependable energy online,” said Chris Tavenor, general counsel for the Ohio Environmental Council, which was a party in the case.

But, Tavenor cautioned, ​“without reform to the energy siting process, energy costs will remain high, and we will continue to see energy prices rise along with demand. We acknowledge this win, while also recognizing that we have much more work ahead.”

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NextEra Energy is one of three U.S. energy companies to win backing from the Department of Energy to revive shut-down nuclear plants to meet soaring power demand.

A third shuttered U.S. nuclear power plant is set to attempt a comeback with hefty support from the federal government.

On Tuesday, the U.S. Department of Energy said it closed a loan of up to $1.9 billion to NextEra Energy to help finance the restart of the Duane Arnold Energy Center in Iowa, which shut down six years ago. The company aims to begin producing electricity from the 615-megawatt power plant by early 2029.

The loan was finalized by the department’s renamed Office of Energy Dominance Financing, known as the Loan Programs Office under past administrations. The office previously closed a $1 billion loan to restart Constellation Energy’s Crane nuclear plant in Pennsylvania and a $1.52 billion loan to revive Holtec International’s Palisades plant in Michigan.

All three of these decades-old nuclear plants shut down in recent years owing to the high costs of repairing and relicensing the facilities. Competition from natural gas and increasingly low-cost renewable energy also soured operators and utilities on atomic power.

But with electricity demand surging across the U.S., due in large part to the data center boom, power plant owners are looking to give their mothballed facilities a second chance — something that’s never been done before in the U.S.

Holtec’s Palisades plant is poised to become America’s first nuclear restart as early as this year. The firm has hit several snags along the way on the first-of-a-kind project, causing it to miss its original target of early 2026. But in July, it reached a ​“watershed moment” by completing all major renovations for its reconstruction of the plant’s single 800-MW reactor. Last week, Holtec said it achieved another historic milestone: beginning the process of loading nuclear fuel into the reactor vessel. It faces a contractual deadline to complete the restart by March 2027.

If Holtec is successful in getting Palisades back online, it could help pave the path for reviving the country’s other shuttered reactors.

NextEra Energy, for its part, is still working to secure licensing approvals from the U.S. Nuclear Regulatory Commission to return Iowa’s only nuclear plant to service. Last fall, the company signed a 25-year agreement with Google to supply electricity from Duane Arnold, which will help power the tech giant’s growing cloud-computing and AI infrastructure in the state.

“By bringing new generation online to serve new demand, we can strengthen the grid, create hundreds of good-paying jobs and help ensure Iowa families and businesses are not asked to bear the costs of growth,” John Ketchum, president and CEO of Florida-based NextEra Energy, said in a Tuesday news release.

While federal loans for nuclear restarts began under the Biden administration, the Trump administration has leaned heavily into supporting nuclear, even as it cancels funding and blocks development of other clean energy sources. In June, the Office of Energy Dominance Financing announced a $17.5 billion loan initiative to help energy companies buy nuclear equipment and build 10 new large-scale reactors in the next few years.

The moves come amid growing bipartisan support in the U.S. for nuclear power, which can provide carbon-free electricity around the clock. Several Democratic-led states with moratoriums on nuclear power have in recent months walked back their restrictions as they seek low-emission sources of electricity that can supplement solar and wind and reduce strain on the grid.

The Duane Arnold reboot is expected to supply enough power for nearly 500,000 homes and create nearly 1,500 jobs during construction, while supporting over 400 permanent positions during operations.

“New nuclear development and the restart of Duane Arnold will meet our growing energy demand while also providing hundreds of good-paying jobs throughout the state,” Iowa’s Republican Gov. Kim Reynolds said on Tuesday.

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