What’s a fossil fuel utility to do in a rapidly warming world? That was the question posed by a study the City released jointly with Philadelphia Gas Works (PGW), the country’s largest municipally-owned gas utility, in 2021.
The answer? Diversify and decarbonize. The study recommended that PGW pilot three strategies: expanding its weatherization services, converting methane harvested from sewers or landfills into “renewable natural gas” and providing networked geothermal energy.
Experts with the Natural Resources Defense Council who analyzed the study weren’t too impressed with the first two strategies. They found that weatherization is “important” but that its “decarbonization potential is limited.” Renewable natural gas, they claimed, has “no promise as a scalable and affordable decarbonization solution.” Geothermal energy, however, could “hold the most promise, both for the city and Pennsylvania.”
Specifically, the City’s study highlights the potential of networked geothermal district heating systems, which connect ground-source heat pumps from multiple homes to a central infrastructure of pipes that pull heat from deep underground. In the summer, the system can provide cooling by pulling heat from inside homes and pumping it into the ground. According to the study’s authors, the infrastructure required for networked geothermal systems is similar to natural gas infrastructure, which means that PGW’s existing workforce could be retrained to build and maintain them.
“With all of the talent and expertise in Philadelphia, the City is well positioned to take on a leadership role in developing a playbook for equitably decarbonizing a gas utility,” says Devin McDougall, a lawyer with Earthjustice who represents POWER Interfaith, an advocacy organization that has been calling for PGW to decarbonize. “There’s a real role for good union jobs in building out geothermal networks at scale. With the expertise of its union workforce, PGW has the opportunity to lead in that space — if they act.”
Philadelphia already has at least 40 geothermal installations, which provide heating and cooling at institutions including Bartram’s Garden, the Enterprise Center and the Ronald McDonald House. According to Geodelphia, an advocacy group that promotes the technology in Philadelphia, more than 1,000 schools across the country — including Kensington Creative and Performing Arts High School and the Community College of Philadelphia — have geothermal systems in place.

Some gas utilities are starting to experiment with geothermal systems, thanks in part to regulatory changes. Since 2021, at least seven states have passed legislation that either allows or requires utilities to undertake thermal energy network pilot projects. Pilots are in various stages of development in several states, including New York, Massachusetts and Minnesota. In Framingham, Massachusetts, the utility company Eversource launched the country’s first gas utility-led networked geothermal system this summer, which now cools and heats 36 buildings without fossil fuels.
In 2022, PGW took the first step toward a geothermal pilot of its own. That summer, the Philadelphia Gas Commission approved a fiscal year 2023 operating budget for PGW that included $500,000 for a geothermal feasibility study — a historic milestone that activists celebrated. “This is just one step in a long journey,” said Rabbi Julie Greenberg of POWER Interfaith at the time. “This was a building block towards the energy future we need.”
The journey, it turns out, has been longer than advocates had expected. More than two and a half years since the gas commission approved the geothermal feasibility study allocation, no geothermal study has been released. Progress on the study, meanwhile, appears to be stalled, while the utility is tight-lipped about its timeline and findings. (Neither the five members of the commission nor the mayor’s office returned a request to comment for this story.)
In its first quarterly report about the study from December 2022, PGW reported having completed its “Due Diligence Phase 1,” which included conducting a market survey of current “best practice” geothermal technologies, identifying potential pilot sites and developing an initial scope and work plan. The report also enumerated tasks still on the to-do list: identifying a final targeted project site, completing a technical evaluation and performing a final legal and regulatory analysis, among others. An undefined “decision point” about the project, the report noted, was planned for July 2023.
That deadline came and went. PGW’s most recent quarterly report, from the fourth quarter of 2024, shows no further progress on the study, and the “decision point” has been deferred to the first quarter of fiscal year 2025. When asked for information about the delay and the current status of the project, PGW spokesperson Dan Gross declined to comment. “As PGW’s efforts move forward to explore options like geothermal and other alternative energy sources to help expand our current greenhouse gas emissions reductions portfolio and promote a more sustainable future, we will be sure to keep you apprised,” he says.
Patrick Houston, a climate justice organizer with POWER Interfaith, says he’s disappointed but not surprised that PGW hasn’t made much progress in exploring potential clean energy solutions. “PGW has been slow-walking this geothermal feasibility study ever since the public pushed for it to be funded three years ago,” he says. “I don’t think it matters the intensity of climate-fueled L.A. fires and Philly drought, or how much Philadelphians pay for gas — PGW won’t get serious about clean and affordable alternatives until the Philadelphia Gas Commission that oversees them truly holds them accountable to the public interest.”