ST. PETERSBURG — Almost as certain as death and taxes is that landfills grow and grow.
But that no longer holds in Pinellas County, where for the past couple of months garbage trucks have been carting more tons of trash out of the Bridgeway Acres Landfill than have been dumped into it.
Roughly 13,000 tons of trash have been hauled from the landfill this year and delivered to the county’s waste-to-energy plant, where it was burned to produce electricity.
The garbage was part of 45,000 tons diverted from the WTE plant to the landfill in the fall when the plant was under capacity or offline for maintenance. In previous years, that’s where the trash would have stayed, taking up valuable landfill space and releasing greenhouse gases as it slowly decayed.
But this year, the county for the first time stockpiled the trash so it could later haul it out of the landfill, extending the landfill’s lifespan and generating income for the county through the sale of electricity to Duke Energy.
“Our hope will be we can recover all the stuff we dumped in the landfill in the fall,” said Kelsi Oswald, Pinellas waste energy section manager. “That’s the only landfill we have. By taking that material back out of the landfill, we save that space for the future.”
Hundreds of trucks haul an average of 17,000 tons of trash a week from across the county to the waste-to-energy plant on 110th Avenue just south of Ulmerton Road. The 10-story facility is the largest mass-burn energy plant in the United States.
Inside a foul-smelling receiving warehouse, dumped trash is bulldozed into a pit. Crane-operated grabbers lift 5-ton piles 70 feet into the air before dropping them into a hopper.
The trash slides into one of three furnaces, where it is incinerated at temperatures of more than 2,000 degrees, producing steam that turns a turbine and generates electricity.
Every two tons of trash burned generates roughly 1 megawatt of energy for which the county receives $30 from Duke Energy. That may not sound like much, but burning the seemingly inexhaustible supply of garbage produces enough energy to power roughly 45,000 homes for a day and earn the county about $1 million a month.
The energy company also pays the county a monthly $3.5 million capacity payment. Tipping fees paid by cities and private firms add on $2.75 million a month.
But revenue takes a hit when the furnaces are offline for cleaning tubes and grates. The cleaning schedule is staggered so at least two furnaces remain in operation. But once a year, the plant is shut down for several days for maintenance on the electric switchyard and transformers.
During that period, most trash ends up at Bridgeway Acres, the only operational landfill in Pinellas County. The landfill is estimated to reach capacity in about 75 years.
“It used to be a horrible thing if we had to divert to the landfill because it was taking up space and would be there forever,” Oswald said.
Part of the reason the WTE plant can handle the county’s daily trash and extra deliveries from the landfill is the county is producing less garbage, a combination of the recession and an uptick in recycling, Oswald said. From a peak of 1.2 million tons of trash in 2006, the amount of solid-waste garbage handled by the county fell to about 925,000 tons last year.
The increase in recycling is something of a mixed blessing. The U.S. Environmental Protection Agency considers recycling better for the environment than burning trash, but it also means less electricity generated from the WTE plant. The facility employs about 85 people and is managed by Green Conversion Solutions, which in 2013 was paid $20 million to run it.
The plant uses scrubbers and other technology to remove particulates before fumes are released into the air. Ash from the furnaces is used to cover the county’s landfill.
Green Conversion Solutions President Marc McMenamin said emissions from the facility meet Environmental Protection Agency standards for air quality.
It costs the county about $12 per ton to haul trash from the landfill, but more importantly it prevents rotting garbage from releasing methane, a more potent greenhouse gas than carbon dioxide released by burning. Electricity generated by burning trash also means less need to burn so-called dirtier fuels like coal or gas at traditional power plants.
The county plans to continue to stockpile new trash when the plant is offline, benefitting the county and residents, McMenamin said.