Atop a 45-acre hillside along Black Bridge Road, a tall, earthen plateau is capped by layers of clay and topsoil that cover a former city of Janesville landfill cell.
The expanse is a quiet section of the city of Janesville’s landfill that has been retired since 2006 and has been growing tall grass and wildflowers ever since.
The old landfill section basically sleeps; it’s idle except for regular burps of landfill methane that the city of Janesville traps using underground collector pipes that convert the gas to generate energy that is then pushed to a private electric utility’s power grid.
But the swath of slumbering landfill could see more active use in sustainable energy production in the coming years. It is one of several sites at the city landfill that the city is considering for possible development of a solar energy farm.
The city this summer plans to hire a consultant to launch a feasibility study to learn whether some parts of the city’s landfill property off Black Bridge Road would be well-suited for solar power generation.
The Janesville City Council last year approved spending for a solar study at the landfill, and the newly seated city council this week authorized spending up to $30,000 on a consultant.
The city is now shopping for a consultant that City Operations Director Maggie Darr said will investigate a range of unknowns as the city eyes solar energy prospects at its landfill.
Just one factor, Darr and city environmental technician Matt Robinson said, is whether there is enough flexibility to develop and operate arrays of solar collecting panels on some of the crests of the capped, retired landfill cells given that some of the sites have years of regulatory obligations and environmental monitoring requirements that remain.
Other questions are whether the city, or a private partner, might develop or operate the solar farm—and whether the city might lease the solar farm property or hatch a revenue and energy-sharing agreement with another entity, such as an electric utility or another owner.
It’s also not clear how much former landfill space would be immediately usable for such a project or whether the amount of land that is suited for solar infrastructure could support a solar project at a scale that might draw private development interest.
Darr said the city for the past few years has wanted to launch a solar energy suitability study at the landfill.
This year, the city council set a 30-year goal to become “carbon neutral.” While Darr said the concept of a landfill solar farm predates the city’s energy goals, solar at the landfill could be an active step by the city toward cleaner energy.
Meanwhile, private utilities such as Alliant Energy over the past two years have launched development plans to expand solar energy production at half a dozen proposed locations around Rock and Walworth counties.
Those projects would be medium- or large-scale solar farms developed and run on leased farmland.
Janesville’s landfill property is distinct in that it is municipally owned and that it faces certain environmental monitoring and regulatory burdens, including routine checks of gas emissions, linings and water testing.
The size and prospective costs of a project aren’t determined, but a feasibility study would shed light on those elements.
Darr points out that capped sections of the landfill have limited short-term reuse prospects, and as such, have been underused pieces of real estate.
Locally, Alliant Energy a few years ago developed a small-scale solar farm at a similar site—on top of a former coal ash landfill in the town of Beloit.
“I think it’s not ‘Can it be done?’ It’s ‘How can it be done? And is it in our interest to proceed with it?’” Darr said.
The city in the past has communicated with Alliant on the concept of solar panels at capped-off sections of the city’s landfill. The concept would not be unlike private utilities using landfill gas collection to generate power.
What would be different would be how the land might be leveraged. Arrays of solar panels tend to have larger above-ground infrastructure than gas collector systems, and they would be placed on parts of the landfill for probably 25 to 30 years of use, complete with infrastructure that would wire solar energy out of the panels, possibly underground.
That means sections of the city’s landfill that need ongoing, routine monitoring work would need to be reviewed to help the city decide whether the physical footprint and operations of solar infrastructure would be workable.
As Robinson, the city’s environmental technician, eyed the long hilltop along Black Bridge Road, he noted it is one of four sites the city would review in the solar study, which the city hopes to have completed later this year.
Another landfill area the study would review is the city’s clean fill landfill, a 10-acre site that is unlined with clay and is scheduled to be closed out in 2024. The clean fill site is smaller than the other sites but likely will have fewer monitoring requirements. However, it wouldn’t become capped and available for use for a few years.
Robinson said a study might show it’s easier to develop solar on the clean fill site than on other capped sites at the landfill that must operate under a more intensive, prolonged regulatory checklist.
“There’s less regulatory issues (at the clean fill site), like no gas system. A lot of solar installations that you see pop up (on landfills), it’s on former landfill areas like that, where there are less (regulatory) considerations, no (landfill) gas pipes and things like that,” Robinson said.