In June, Massachusetts Attorney General Maura Healey asked the state's Department of Public Utilities to open an investigation into the future of natural-gas companies in the state. Healey’s request was prompted by the recognition that Massachusetts cannot meet its legally binding emission reduction targets unless it abandons the use of fossil gas in buildings.

The attorney general’s office asked utility regulators to explore the potential for a range of alternatives to decarbonize heating, including building electrification, energy efficiency and “geothermal network applications.”

The last option is a nod to work by the Cambridge, Massachusetts-based nonprofit Home Energy Efficiency Team (HEET) to advance a concept called the GeoMicroDistrict, which would see heat pumps in individual buildings transferring thermal energy between a shared district water loop and their own heating and cooling distribution systems.

In such a system, gas companies could deliver thermal energy instead of gas — minus the carbon, says Audrey Schulman, HEET’s co-executive director.

“Can gas companies change from just sending gas out in one direction through that gas tree to being able to manage thermal energy — bidirectional — in an efficient way through something as simple as water?” Schulman asks.

Other emerging gas-displacing thermal energy management solutions include the geothermal-based heating and cooling system for homes offered by the Google spinout Dandelion Energy in New York state and E.ON’s ectogrid, a system that balances thermal energy flows in a building cluster, which the German utility giant is building at Medicon Village in Sweden.

The GeoMicroDistrict concept

HEET has briefed key stakeholders, including the attorney general’s office and natural-gas companies, on the concept, which it describes as “networked geothermal boreholes, connected by a shared loop in the current gas right-of-way that provides thermal energy to customer buildings.”

HEET sees GeoMicroDistricts as Lego-like blocks that can be scaled from a single residential street up to mixed-use residential and commercial neighborhoods. GeoMicroDistricts could operate as standalone segments or be interconnected to create larger, more efficient networks.

The GeoMicroDistrict concept for transferring heat between buildings and even neighborhoods. (Image: HEET)

“The hardest one to build is that first one; then you can begin to connect more segments,” says Zeyneb Magavi, HEET's other co-executive director. “As the thermal grid gets larger and more diverse, it can become more efficient and with more potential for energy storage, load sharing and load canceling, and the more opportunities for the utility to play the role of thermal manager, optimizing heating and cooling.”

The GeoMicroDistrict concept is available for use by interested parties under a Creative Commons license. “This allows open sourcing of all our innovation and materials and data, with acknowledgment and the requirement to share back any iterations or improvements,” Magavi said.

A feasibility study conducted by the international consultancy Buro Happold Engineering for HEET found that GeoMicroDistricts could meet 100 percent of the heating and cooling load in low-density residential and medium-density mixed-use settings. Greenhouse gas emissions from heating, cooling and hot water for connected buildings would fall by 60 percent today and by more than 90 percent by 2050 assuming Massachusetts reaches its long-term renewable energy targets.

HEET is working to launch three GeoMicroDistrict pilots in partnership with the utility Eversource in the greater Boston area.

Eversource is seeking approval from the Department of Public Utilities for cost recovery from ratepayers for the pilots, for which it would be repaid within five years if performance-based metrics are met. If approved in November, work on the GeoMicroDistrict pilots could begin next year.

“We could substantially complete customer acquisition, zoning, engineer/contractor selection, technical design, ground loop and pumping station construction, geothermal network testing and commissioning, and customer HVAC installation and retrofits within approximately 16-18 months,” Eversource spokesperson Reid Lamberty said in an email.

“We do see geothermal technologies as a potential solution to provide low-carbon heating,” Lamberty said.

Is Eversource ready for the transition?

Eversource’s willingness to participate in the GeoMicroDistrict pilots suggests the utility’s leadership is open to new solutions. Then again, the old way of doing things may not be an option for much longer.

In testimony before a Massachusetts legislative committee in November 2019, Bill Akley, Eversource’s president of gas operations, said the utility was confident enough with HEET’s presentation of the GeoMicroDistrict concept that it had agreed to the pilots.

“We now have to get our hands dirty and really try this to see what works, what doesn’t work, all the economics around it, all the feasibility around it,” Akley said.

State Senator Michael J. Barrett, chair of the Joint Committee on Telecommunications, Utilities & Energy, asked Akley how Eversource reconciles its existing business model with a scenario in which a majority of Massachusetts’ 2.8 million residential units have to get off fossil gas entirely.

“We don’t get to 2050 unless the lion’s share of those — 75 percent, 80 percent — are off natural gas entirely. Speculate with me about how Eversource, and the natural gas division, is going to deal with the necessity of a movement off natural gas of that magnitude,” Barrett asked.

Akley responded by mentioning Eversource’s commitment to explore renewable natural gas, to procure third-party certified “responsibly sourced” gas, and to continue to reduce methane leaks and replace aging pipes across its gas distribution system.

Barrett wasn’t satisfied. “The problem I see with an aggressive leak repair program is you wind up with new natural gas infrastructure — and that’s what we want to work away from,” he said.

“Help me understand,” Barrett went on, “why [we are] putting in new infrastructure into the ground. […] It’s there for another 30 years and has to be paid for by the ratepayers. How does that help us transition off natural gas altogether?”

Akley said aggressive leak mitigation in the short term would provide public safety benefits as Eversource continued to explore transition options.

“If you’re not accelerating the replacement of this infrastructure, your leak rate will go in the reverse direction. For the time being, this replacement program is ensuring we’re at the right pace, getting ahead of corrosion and leaks, reducing leak rates," Akley said.

“If GeoMicroDistricts or other things work,” Akley continued, “we absolutely have the ability to turn and alter those programs. But I think you cannot underestimate the value to public safety of continuing these accelerated programs at the current time.”

Akley said the FUTURE Act, the subject of that day’s hearing, could facilitate the evolution of Eversource’s business model. The legislation, which is pending in the Massachusetts Legislature, would permit gas utilities to bill customers for renewable thermal British thermal units (Btu) instead of gas.

The evolution of natural gas utilities

Eversource’s footprint in Massachusetts is poised to grow. On July 2 Attorney General Healey announced a $56 million deal with Columbia Gas, a unit of Indiana-based utility group NiSource, to resolve her office’s investigation into Columbia's role in the September 2018 Merrimack Valley gas explosions. Columbia Gas agreed to leave Massachusetts by the upcoming heating season.

Cash in the deal will clear $15 million in accumulated debt from the accounts of 26,000 low-income customers and fund a heat pump pilot in the Merrimack Valley. Columbia Gas’ new owner, Eversource, agreed to hire an independent consultant to “prepare a case analysis outlining potential decarbonization strategies for its gas business.”

According to HEET’s Magavi, the deal also allocates $4 million for a “networked geothermal pilot” in the Merrimack Valley. The project is likely to move forward before the three pilots pending in Eversource’s rate case and could be the first GeoMicroDistrict in the ground in Massachusetts.

Schulman recounted that Columbia Gas was the first gas utility to hear HEET’s GeoMicroDistrict pitch.

“The first time we showed it was to the president of Columbia Gas before the Merrimack Valley gas disaster,” she said. “He began to tell us exactly how our ideas could help him. He said, ‘We should do it for places where we have to do expensive infrastructure replacement or where the pressure on the system is too low.’ He just got really excited about the possibilities.”

Magavi said a geothermal-based solution offers natural-gas companies a way forward that plays to their strengths and maintains their payrolls.

“We see it as a very high potential option for transforming gas utilities into renewable thermal management utilities in a way that would save their jobs, their structures, their customers, and benefits and accelerates the transformation of the electric grid,” she said.

If we instead attempt to shut down the legacy gas utilities, she added, “it’s a much slower and more difficult challenge to transform and use the existing financial structure, space, rights-of-way in the street, and employees to deliver renewable energy, just as we’re transforming our electric utilities from fossil fuels to renewable energy.”

“It’s novel for them," Magavi said. "I don’t dismiss the novelty and the challenge."