Drilling for the 500-foot-deep geothermal field is set to start later this year as part of a larger $70 million infrastructure upgrade already underway at the 138-year-old Capitol. While it will cost nearly $4 million upfront, officials estimate geothermal will save the state $300,000 a year on heating and cooling costs and pay for itself in roughly a decade.
It will mean “utility independence, cost savings and clean, green energy,” said Tim Bowlin, chief financial officer and project manager for the Michigan Capitol Commission. “The wells have a 50-year guarantee, but we’re anticipating 100-plus years.”
The geothermal project will entail a major drilling operation, with plans calling for 224 individual “bores” that reach 500 feet below the state Capitol lawn. The holes will house vertical loop piping that carries vegetable-grade glycol transfer fluid deep underground, where it will be naturally cooled or heated and then used to do the same inside the building.
The liquid is the same type of food-safe glycol that is used in McDonald’s milkshakes, said facilities director Rob Blackshaw, but “we don’t anticipate any leaks.”
