You can heat homes with gas, propane, oil or electricity.
Or you can make use of the virtually endless supply of clean energy that lies right beneath your feet.
The South Side nonprofit Blacks in Green is pursuing the latter option, with a plan for a multibuilding geothermal system that will tap steady, year-round underground temperatures of about 55 degrees.
In step one of the project, workers will send plastic pipes 450 feet into the ground beneath Chicago alleys. The pipes, which circulate a fluid that absorbs and releases heat, will loop back to up to 69 buildings in a four-block area of West Woodlawn, powering heating and central air.
The $10.8 million project is one of only five community geothermal heating plans nationwide selected for full funding by the Department of Energy in December, and it is moving forward at a time of growing interest in neighborhood geothermal among states, utilities and energy experts.
“It will be an example for the entire country,” said Tugce Baser, an associate professor of civil engineering at Saint Louis University and a member of the Blacks in Green project team.
It’s unclear whether the project will be affected by President Donald Trump’s attempts to freeze funding for clean energy programs, but Blacks in Green founder and CEO Naomi Davis said her team is assuming the best and continuing its work on the project.
Multibuilding geothermal heating and cooling has been used for decades, often at college campuses and military complexes, with documented cost and energy savings.
But now interest in systems spanning existing neighborhoods is growing, due to factors such as ambitious state clean energy goals, growing demand for electricity and the slow pace at which new power sources are being added to the grid.
At the New England utility Eversource, which launched the nation’s first utility-run neighborhood geothermal pilot project in Framingham, Massachusetts, last year, clean technologies manager Eric Bosworth said dozens of utilities from across the country have called with questions.
Interest is growing on the state level as well. Since 2021, seven states have passed laws allowing or requiring utilities to develop neighborhood geothermal pilot projects, according to the Building Decarbonization Coalition.
“For me, it’s a no-brainer,” Baser said of geothermal, in which heat from the core of the earth moves toward the surface, constantly replenishing the heat that’s used to warm a building.
“(The heat) is there, it’s constant and it’s available any time you want it. Why not use it?” Baser said.
The Blacks in Green pilot was selected for $10.8 million in Department of Energy funding before Trump took office and moved to freeze funding for many clean energy projects.
Davis declined to discuss the federal funding controversy but said, “We’re moving ahead, come what may, because we’re dedicated to doing the work.”
Physics or magic?
For Blacks in Green, the geothermal project is part of a larger vision for West Woodlawn, a majority Black neighborhood on the South Side.
“We are creating what we call a Sustainable Square Mile, which is where African American neighbors can walk to work, walk to shop, walk to learn and walk to play,” said Davis, an attorney and activist who has lived in the neighborhood since 2010.
“We own the businesses in the walkable village. We own the land. And we live a conservation lifestyle,” she said.
Locally owned clean energy is part of that vision, and when the Department of Energy made its community geothermal grants available, Blacks in Green applied.
“This is a very unique opportunity to have a community-owned utility, essentially,” Davis said. There was also the chance to create good jobs in the neighborhood, lower participants’ utility bills — and even reach children at neighborhood elementary schools.
“How do we get into those classrooms?” Davis mused. “How do we get into those children’s heads and hearts and get them excited about a career in energy?”
Neighborhood geothermal, which could theoretically be extended to entire regions, hasn’t gotten as much attention as wind and solar, but it has its advantages, including the ability to produce a steady supply of clean energy, regardless of whether the sun shines or the wind blows.
“When you’re looking at the energy system as a whole, having that (continuous) energy is really critical. It’s part of reliability, it’s part of resilience, it’s part of affordability because the infrastructure gets used for a long time and continuously,” said Magavi.
Geothermal heating and cooling systems can draw warmth from hot springs or even a lake or pond, but in the Midwest plans for multibuilding geothermal systems generally rely on the mild temperatures below the earth’s surface.
That’s the kind of system used in Framingham, and it’s the kind envisioned for West Woodlawn.
At deeper than 20 feet, the temperature is a pretty constant 55 degrees, according to Andrew Stumpf, a geologist with the Illinois Geological Survey who worked on an initial study for the Blacks in Green project.
In cold weather, the fluid circulating through the geothermal system’s underground plastic pipes absorbs the relatively warm temperature of the earth and brings it back to home heat pumps, which concentrate the heat and send it into homes.
In the summer, the fluid in the pipes — often water and food-grade glycol, a synthetic liquid used in salad dressing — brings heat from the homes down into the earth, where the heat is released.
The heat pumps, which run on electricity, are highly efficient because most of the energy they use comes from the steady temperatures in the ground, not the electric grid.
In fact, geothermal heat pumps deliver more energy (in the form of heat) than they draw from the electric grid (in the form of electricity), often three to five times as much.
“It’s kind of like magic, but it’s actually physics,” Magavi said.
Lower energy bills
That adds up to some clear advantages over current heating systems, supporters say.
A 2023 analysis by the Oak Ridge National Laboratory looked at what would happen if geothermal heating and cooling were widely used in homes and commercial spaces, and affected single family homes underwent weatherization (a common practice when installing heat pumps).
The study found that such large-scale geothermal deployment would lower national electricity demand by up to 13% by 2050, and could decrease planet-warming carbon emissions by more than 7,000 million metric tons through 2050 — or as much CO2 as 640 million homes would emit in the course of a year.
Consumer energy costs would fall too, a finding consistent with real-world studies.
For instance, the first phase of a multibuilding geothermal heating and cooling system at Ball State University in Muncie resulted in an annual energy cost savings of 30%, or $764,200, according to a 2016 report by Oak Ridge National Laboratory.
But if geothermal is a promising technology, there is a catch: high upfront costs.
For an individual homeowner, an initial $10,000 to $30,000 price tag for geothermal (before government and utility incentives) can be a dealbreaker.
The good news is that for a utility, geothermal’s 10-year or 12-year payback time — or period in which the energy cost savings pay for the system — is very attractive, according to Magavi.
Also in the good news column: Geothermal networks are a good fit with traditional gas utilities, which use similar underground pipeline networks and employ workers with similar skill sets.
In Massachusetts, Magavi developed a plan for utilities to start installing neighborhood geothermal, gradually building out a larger clean-energy heating and cooling network.
“We really have an amazing opportunity,” she said. “We can increase our energy independence, improve access to heating and cooling and really create a lot more stability over the long run for our energy system.”
In 2017, she started pitching the concept of neighborhood geothermal to utilities — including Eversource, which is now operating the Framingham pilot project.
Today, there’s a “huge increase in excitement” about neighborhood geothermal said Magavi, who quipped, “I’m measuring it by my exhaustion.”
“There are so many more people randomly reaching out and calling. There’s more projects starting,” she said.
High-tech alleys
The basic structure of the Chicago pilot project is similar to Framingham’s, but with a twist.
When it comes to drilling deep holes for the pipes, the Blacks in Green project makes use of a well-known feature of the local landscape: the Chicago alley.
The 16- to 20-foot wide strips of land are public rights-of-way, and typically don’t have a lot of underground infrastructure, according to Andrew Barbeau, president of the Accelerate Group consulting firm, and the technical lead for the Blacks in Green geothermal project.
In contrast, streets have water, sewer and gas mains, as well as adjacent sidewalks, trees and parkways.
“Not only is that a lot of infrastructure to work around, but it’s very expensive to dig up streets,” Barbeau said.
The four-block pilot project will require drilling about 120 holes, each 450 feet deep, and will serve up to 69 residential buildings and up to 240 households.
Households can choose whether or not to participate, as they did in Framingham. Participants will need to get heat pumps installed, and many homes will require related renovations such as ductwork.
On the plus side, the Department of Energy grant and government incentives will cover the cost of the heat pumps and related renovations. And heat pumps provide central air as well as heat, a big bonus for those currently making do with window air conditioning units on sweltering summer days.
There are also potential financial benefits. In Chicago, pilot program participants are expected to see a 30% reduction in total gas and electric bills, Barbeau said.
In Framingham, the response from residential customers was good, with roughly 80% of of those eligible opting in, Bosworth said. In Chicago, which is at an earlier stage in the process, Davis said people are “curious and they’re open.”
The goal is for the Chicago geothermal system to be completed in 2 ½ years, but already Davis is looking ahead.
“Getting it right, so that we can do it again and again and keep scaling — that’s our plan,” she said.
nschoenberg@chicagotribune.com
