For all the talk of solar as an important renewable energy source in Florida, there's another in abundance across the state: trash.

One of the country's leaders in generating electricity from biowaste is Covanta Energy, which operates a plant in Hillsborough County. It is one of 10 plants across the state.

Because biowaste is considered a source of "clean energy," the Hillsborough plant was certified this year to receive so-called carbon credits. The credits mean that as the plant produces energy, it leaves behind a minimal carbon footprint on the environment — so low that more significant carbon producers can buy Covanta's credits and reduce their overall scores.

We spoke with Joseph R. Treshler, the vice president of business management and development at Covanta, to learn more about the operation.

Here's what he told us:

What is Covanta Energy?

We build and operate energy waste facilities. We have 41 facilities around North America.

How long has Covanta operated in Hillsborough County?

It went into operation in 1987. We just completed the expansion in 2009. The original unit was 30 megawatts. We added a 17-megawatt unit. This facility generates 47 megawatts.

That would provide enough power for … ?

Forty-seven megawatts would probably power about 30,000 houses.

How many people work at this facility?

We're currently at 51, and these are not exportable jobs. In addition to these 50 jobs, there's probably another 60, 70 jobs in the community that support this facility. So it's a pretty good economic engine. Its annual impact is about $20 million a year in terms of local impact.

How does the plant produce electricity?

First of all, we produce some of the cleanest electricity available. The waste itself is fuel. You may have unexpected plastics or whatever burns. We're actually recovering that energy. The burning heats the water, which produces steam that turns the turbines like in any other power plant to produce electricity.

Does this also replace recycling?

No. We're very pro-recycling. We just say, "Give us what's left. Don't put it in the ground." There sometimes are some plastics that don't get recycled, and they come here. We also have a machine that extracts metals. Magnetic metals are extracted and sold to scrap companies. We can take mercury out of the waste, too.

Where does the electricity go?

We power the wastewater treatment plant next door. They're probably going to use the electricity to run the jail (in the future). And we sell electricity to Seminole Electric Co.

How much does it cost to build a biomass facility?

This facility would probably cost about $400 million. This is capital intensive. The state built 10 of these facilities between 1980 and 1991. They could easily build another 10 of these.

How long does a facility like this last?

It's already in the 24th year of its operation. The expected life is 40, 50, 60 years.