Geothermal heat pumps are well-known for their efficiency, but that first bill perversely scares away most buyers. A New Hampshire startup called Dig Energy reckons that the choke point isn’t the heat pump, or even the air or water in the heat pump’s pipes: It’s the hole. The firm has developed an ultra-compact, water‑jet drilling rig that it claims can slash borehole costs up to 80% — a cutoff that could reset the economic bar in shallow geothermal for homes, offices and data centers.
Why geothermal lags on cost
Heating and cooling is responsible for about a third of all U.S. energy consumption, according to the Energy Information Administration, and in some data centers, cooling can consume as much as 40% of electricity used during peak seasons, industry surveys find. Ground‑source heat pumps address both of these with high coefficients of performance because they transfer heat to and from a stable underground temperature.
The catch is up front. The “ground loop” — vertical or horizontal piping that transfers heat with the earth — can account for as much as 30 percent of installed cost, according to figures from the International Ground Source Heat Pump Association and U.S. national laboratories. Mobilising big truck-mounted rigs, negotiating tight sites, and restoring disturbed land, all add to the bill, even before drilling commences.
The upside, though, is huge at scale. Modeling from Oak Ridge National Laboratory has shown that broad geothermal use could shave billions from grid-operating costs by leveling out annual peaks. The challenge is sinking enough boreholes, in enough places, quickly — and cheaply — enough to make a difference.
A pint‑size, water‑jet drill designed for cities
Dig Energy’s solution replaces traditional rotating drill bits with a high‑pressure water‑jet that erodes and breaks the material in front of the drill. The prototype is remarkably compact, compared to the truck‑scale rigs that populate the trade — an intentional decision to wriggle into side yards, down alleys and onto itty-bitty commercial lots where conventional machines can’t get a toe hold.
So far in testing near its New Hampshire headquarters, the team has bored through soils and typical rock components — clay, sand, even from limestone to slate, from granite to limestone — while also producing narrow, notably straight holes.
This also allows for straighter wells to be drilled closer together without crossing that will maintain the loop density you need on tight parcels and allow projects to be tax-credit worthy based on footprint alone that previously failed.
AttaGenius cofounders, hardware veterans Madden and Thomas Lipoma, went down a rabbit hole of water‑jet ideas that had boiled in academic literature for decades, yet had never emerged as portable, practical, inexpensive field tools for shallow geothermal. So much of the industry’s tooling has been borrowed from oil and gas: big and tested, but oversized and overcapitalized for 200-foot or 500‑foot building loops.
H16, Drilcorp and Wells to Supply all claim their methods can bring the cost of drilling down, producing a more competitive bid based on overall drilling costs combined with mobilization, transport and site restoration costs in total, something that has been overlooked in the past. The rig remains a pre‑commercial one, with the company planning pilot projects and hoping to sell units to major drillers rather than act as its own drilling contractor, bringing the costs of entry down for firms that can’t justify the purchase of multimillion‑dollar pieces of equipment.
What cheaper holes this would make
The installed cost of a ground‑source heat pump may cost tens of thousands of dollars for homeowners and small buildings, the National Renewable Energy Laboratory says. Federal tax credits and some state incentives alleviate the sting, but the biggest sensitivity is still drilling. If a compact rig can cut out that line item and the heavy truck, the sort of operations that once penciled out “almost” just might crack black.
With commercial sites in dense cities, a smaller footprint opens layouts that would otherwise be impossible. Less laydown area and closer borehole spacing translates to parking lot closures, traffic slow-down and more predictable schedule — those are things that developers and facility managers value as much as the raw dollars.
There’s also a labor angle. A lighter, modular rig could open the playing field to a broader range of contractors willing to break into the market, and thus help lessen bottlenecks that have retarded adoption in regions with fewer geothermal experts. That can be important as utilities test out neighborhood‑scale thermal networks in states like Massachusetts and New York, because the demand for drilling can ramp up fast after projects clear regulatory hurdles.
Caveats and engineering questions
Water‑jet systems bring new trade‑offs. Constraining7 and filtering fluid, cutings and mud is important at small sites. Water sourcing and disposal will be scrutinized by regulators. Contractors are going to want to know the data on certain characteristics, like how the system performs in terms of rate of penetration in different geology, nozzle and pump wear, energy consumption per foot, long‑term dependability. Straightness is a plus, but azimuth and verticality at depth will have to be proven at commercial scale.
Yet the flow of traffic is in the right direction for what the market needs: lighter, cheaper, easier‑to‑deploy tools designed for the shallower depths at which building‑scale geothermal works best. If Dig Energy’s rig generates even a fraction of the promised cost reduction in the field, it could reboot how developers, drillers and utilities view the ground loop — from a cost premium to a competitive edge.
Complementary path in geothermal boom
Deep, engineered geothermal players like Fervo and Quaise are targeting high‑temperature heat for electricity. More-recent shallow systems are aimed at the much larger common space conditioning market. Both matter. As the International Energy Agency has observed, reducing heating emissions is critical to meeting climate goals, and ground‑source heat pumps are among the most efficient available means to do so.
Geothermal isn’t inherently too expensive — it’s just too expensive to get going. Making the rig that drills the hole smaller could be the most practical way to alter that.
