ST. PETERSBURG — In 2011, the city had a grand plan: reduce energy expenses and greenhouse gas emissions by producing renewable energy from biosolids.
For the uninitiated, biosolids is a polite term for treated sewage sludge. That's right, human waste.
But seven years later, the project faces severe scrutiny from City Council members after they recently learned that both the cost and benefits of the project are much different than what was originally pitched to them.
The $93.6 million project, set to be completed in April 2019, is designed to convert wastewater byproducts into methane gas at the Southwest Water Reclamation Facility next to Eckerd College. Under the original concept, that biogas could then be integrated into the natural gas distribution system for TECO Peoples Gas.
The city planned to send biogas to the utility, which in turn would set up infrastructure that would allow the city to use its own byproduct to power its sanitation trucks and the Southwest sewage plant. Doing so, city staff estimated, would save an estimated $31.6 million. City Council voted to move the project forward in January 2016, based on those projected savings.
That savings estimate has since dropped more than 50 percent, to $14.8 million.
What happened? Public Works administrator Claude Tankersley and staff are no longer sure whether the biogas can be used to power its sanitation trucks.
The ongoing biosolids issue resurfaced at Thursday's council meeting. Tankersley said the city is still figuring out how to deliver the biogas product to the trucks in a safe, reliable manner.
Using the biogas in the trucks generates the biggest revenue for the city, thanks to a federal credit earned for renewable energy. The city can then sell those credits to fuel refiners and importers.
The city had planned to partner with Peoples Gas to provide a pipeline for the trucks, but the energy company has yet to commit.
In fact, the utility rejected the request in 2013, according to Tankersley's presentation. The city considered compressing the biogas and delivering it by tube truck or building a city-owned fueling station. Both of those ideas were rejected as impractical, due to either cost, liability or other factors.
Then in 2016, Emera Inc. of Nova Scotia acquired TECO Energy and its subsidiaries, including Peoples Gas. So last year the city resumed negotiations with Peoples Gas in the hopes of feeding the biogas through the existing pipeline.
Several council members expressed concern that they still don't know whether Peoples Gas will commit to the project, and that the projected revenue the city could expect from running its sanitation trucks off the biogas to earn credits is also unknown.
"It changes almost a 50 percent piece of this project," council member Amy Foster said. "To me, that's a key question that needs resolution."
City Council chair Steve Kornell said he wished these questions had been addressed much earlier in the process. At this point, he said, it's unreasonable to stop construction, despite shifting details.
"There's some fairly major parts of it still up in the air, like whether (Peoples Gas) will accept the gas or not," Kornell said.
Tankersley could not say when the utility is expected to give St. Petersburg an answer, but said the city will be meeting with company officials in the coming weeks.
Apart from the trucks, the biogas can also be used to operate a new generator, which will burn off the extra biogas and produce heat and electricity for the Southwest plant.
"We need more than one way to expose of the biogas," Tankersley told council.
The project is expected to generate 840,000 therms of energy a year. The city expects its sanitation fleet will require about two-thirds of that, leaving about 300,000 to fuel the generator. The sanitation department expects to have 54 natural gas trucks by the end of 2018, which is about half of its fleet.
But the city needs more than 900,000 therms to run the generator, meaning it will need to purchase natural gas to cover about two-thirds of its requirement.
Tankersley and his staff did not know Thursday whether using biogas to run the generator would earn the city any credits that it could then sell for revenue.
Contact Caitlin Johnston at email@example.com or (727) 893-8779. Follow @cljohnst