Wood to power Savannah River operations

By James T. Hammond
jhammond@scbiznews.com
Published February 2012

Sometime this month, 50 trucks a day will begin delivering wood chips to the new biomass steam and electricity generating station at the Savannah River Site, moving the federal reservation closer to green self-sufficiency and lower costs for energy.

The semi, tractor-trailer rigs back up to a lift that tilts almost vertical and disgorges 40 tons of wood in six minutes.

Tractor-trailer disgorges wood chips
Sometime this month, 50 trucks a day will begin delivering wood chips to the new biomass steam and electricity generating station at the Savannah River Site. The trucks can disgorge 40 tons of wood in six minutes.
Already, 800 truckloads of wood are stockpiled at the 34-acre site of the $795 million energy plant, which fired up its boilers for the first time last month. Initially supplying about 10 megawatts of electricity to SRS, it will boost output to 20 megawatts when fully operational.

The biomass plant, which also uses shredded automobile tires in its fuel mix, is a project of Ameresco Inc., a national renewable energy provider. The company has 10 other such plants at federal installations, but the one at Savannah River is the largest such facility.

George Sakellaris, president and CEO of Ameresco, announced the project in 2009 and said, when completed, the new biomass facilities would reduce energy and water consumption and cut air emissions dramatically.

“In the first-year alone the energy and operational cost savings alone will be in excess of $34 million,” Sakellaris said.

With its corporate headquarters in Framingham, Mass., Ameresco has 55 offices in 30 states and in Canada. Ameresco, which had an initial public offering about a year ago and became a publicly-traded company, has experienced substantial growth in recent recession-troubled times.

In 2010, Ameresco reported $681.2 million in revenue, an increase of 44% over 2009. In its latest earnings report, for the first nine months of 2011, revenue was $539.7 million, an increase of 23% over the same period a year earlier.

Biomass economics

The biomass power station was built using energy savings performance contracting, an arrangement under which Ameresco pays all costs of installing new or upgraded energy-efficient equipment.

The energy upgrades are paid for by a portion of the savings from the improvements over the term of the contract. At the end of the contract, the customer owns the improvements and receives all of the continuing savings. The project created about 800 construction jobs, and will account for 125 permanent jobs.

Ken Chacey
Ameresco’s site manager Ken Chacey, front, explained on a plant tour that wood chips and shredded tires are mixed and fed into a fire box where the fuel is almost instantly incinerated in an 800-degree maelstrom of sand that is kept in suspension by a blower.
Ken Chacey, Ameresco’s site manager for the biomass project, explained on a tour of the complex that wood chips and shredded tires are mixed and fed into the fire box where the fuel is almost instantly incinerated in an 800-degree maelstrom of sand that is kept in suspension by a blower.

The ash and steel reinforcing wire from the tires settles onto a conveyor and is collected for transport to a landfill. Eventually, he said, ash residue might become an ingredient in the huge volume of concrete used at SRS in its environmental cleanup operations.

A national leader

Ameresco is one of the largest vendors of energy-efficient power solutions in the nation.

BMW contracted with Ameresco to develop a landfill gas-to-energy plant that produced enough renewable energy to cover 25% of the automaker’s electricity and almost all of its cooling and thermal needs.

The project at Savannah River is the largest wood-chip biomass plant in South Carolina and the largest energy-efficiency project in the federal government’s history, according to the Department of Energy.

The Savannah River wood biomass plant will replace aging coal-fired boilers currently in use. Ameresco designed, built and will operate, maintain and fuel the new plant, with no up-front cost to the Department of Energy.

By switching to renewable fuels from coal, greenhouse gas emissions are expected to be reduced by 100,000 tons a year, with these specific changes:

  • Particulate matter will be reduced by more than 400 tons a year.
  • Nitrous oxide will be cut by more than 2,500 tons a year.
  • Sulfur dioxide emissions will drop by more than 3,500 tons a year.

Switching to biomass power will eliminate the burning of coal by 161,000 tons per year. And the amount of water drawn from the Savannah River for use in power plants will decrease by more than 2.8 billion gallons per year.

Previous coverage

Ameresco’s main biomass plant and two satellite plants are expected to provide 30% of the electric power needed at SRS and 100% of the steam required.

Meanwhile, the 50 trucks per day — one about every 15 minutes — will create a major new market for the forest products industry around Aiken. Ameresco already has lined up five suppliers and about 30 trucks and drivers.

Fuel consumption

The plant will buy as much as 325,000 tons of wood chips a year. At current prices, the fuel cost is $20-$28 per ton. That’s about $9.1 million a year at the higher end of the price range for area growers. Most of the wood chips will be supplied from a 50-mile radius of the plant.

Wood consumed in the plant usually will arrive in trucks already chipped for use in the biomass burner. In case the plant can’t get chips, Ameresco equipped the plant with a chipper that can reduce whole logs to chips at 100 tons per hour.

That rate of wood consumption for power production is easily sustainable with the current rate of new biomass power plant development. According to state and federal authorities, there are 20.9 million tons per year of sustainable biomass available in the state’s forests. Agricultural biomass could add another 1.2 million tons of potential fuel annually.

The plant is coming online at an advantageous time in South Carolina. According to the state Forestry Commission, both hardwood and softwood forests are growing significantly more wood than is being harvested.

Softwood growth rates are double pre-Hurricane Hugo rates. With a current annual growth rate of 866 million cubic feet per year, pine growth is the highest ever recorded. Hardwood annual growth, meanwhile, is 412 million cubic feet per year, approaching a record.

Reach James T. Hammond at 803-401-1094, ext. 201.

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