“Lots of trucks today, pretty much steady,” said the shift leader at Ameresco’s new biomass cogeneration plant at Savannah River Site.
From a control room high above the forested landscape, Trammel monitors conveyors, boilers and turbines that provide steam and electricity for the sprawling nuclear site.
“The primary goal is steam – enough to satisfy 100 percent of the site’s needs,” said Ken Chacey, Ameresco’s on-site manager. “We also make 30 percent of the electricity for the entire site.”
The technology revolves around a simple ingredient: wood chips that arrive by truck each day from forests and farms within 50 miles.
Since the plant went into service in January, it has produced about 1 billion pounds of steam pressure and 60,000 megawatts of electricity.
Its completion enabled the U.S. Energy Department to shut down its previous power source: a coal-fired power plant from the 1950s that generated air pollution along with electricity.
Biomass power production is growing rapidly, along with the demand for green energy and development of better technology, Chacey said.
The SRS plant was created under a $795 million “Energy Savings Performance Contract” in which Ameresco designed and built the plant and will operate it for 19 years, but will be paid over time through money saved on energy costs.
The wood chips that fuel the plant are often trucked to SRS the day they are harvested, and in many cases turn logging waste into revenue.
“A lot of it is off-spec wood – not good for pulp or saw timber,” Chacey said. “If you look at the industry as a whole, it’s a relatively small
amount of the wood that’s being used.”
The plant’s daily importation of 30 to 40 truckloads is much smaller than the 600 to 700 trucks per day needed to serve a major paper mill.
The plant also burns a small percentage of shredded tires processed at a separate plant near Jackson. The “tire-derived fuel” helps stabilize the temperature inside the plant’s twin boiler system, making it more efficient.
Procurement of the 322,000 tons of fuel needed at the plant each year also creates jobs – about 25 at the plant and nine more at the tire-shredding site, Chacey said. If you take into account the impact on loggers, truckers and others involved in fuel acquisition, the impact is 200 to 300 jobs.
The plant’s design allows great variability in the balance between steam and electricity.
“If the site’s needs increase with new missions – or even decrease – the amount of electricity can be raised or lowered,” Chacey said. “It was designed to be versatile.”
The biomass power industry is growing rapidly in Georgia, especially among companies that make wood pellets for overseas markets.
“We act as the forestry specialists for the state Department of Economic Development – and we’re doing a lot of projects,” said chief forester Nathan McClure of the Georgia Forestry Commission’s Utilization Department.
Georgia, already No. 1 in the nation for its volume of private timber land, is adding more wood pellet sites – including a $60 million pellet mill announced last week that will be constructed in Sandersville.
“The market for wood pellets is being driven almost totally by renewable energy in Europe,” McClure said, noting that energy producers in those nations are under pressure to use less coal.
Though export-quality wood pellets are drier and denser than the newly chipped material used in power plants such as the one at SRS, both create an opportunity to use some wood products that otherwise might be left as waste.
“A lot of these places use fuel chips, so it can include tops and branches of trees that would not otherwise be used for pulpwood or lumber,” McClure said.
Small trees thinned from timber stands to allow remaining trees to grow larger can also provide fodder for power generation or pellets.
“In many cases this helps the landowners to clean up the site and prepare for the next generation of trees,” McClure said.
As demand evolves with economic trends, state officials want to make sure there are always new markets for Georgia trees.
“The concern is that if landowners don’t have a market for their wood, then they would sell or develop their land or find an alternative use to forestry,” McClure said.
“There are a lot of ecological benefits to having lots of forests: clean air and clean water, and we’d like to keep it that way.”