Grec Comes On

Commercial Operation

 

In 2002, community discussions began about the possibility of a new power source in Gainesville through Gainesville Regional Utilities. Studies were conducted over several years to consider the city’s baseload electrical generating options, including coal, natural gas, biomass and purchasing power from other utilities.

In 2007, the city and utility became serious about biomass power as an option, especially to bring much needed diversity to the GRU power generation portfolio, and awarded the contract to the American Renewables development team for the development of the plant and the power agreement. Following more project analysis from the state, site approval and getting permits and logistics in place, construction on the Gainesville Renewable Energy Center (GREC) began in June 2011 and was substantially completed in October 2013. As of mid-December, the $500 million, 100 MW facility, which is adjacent to a GRU coal plant, is open for business and in commercial operation. It is built to supply enough renewable power for approximately 70,000 homes. GREC has a 30-year, $3.1 billion power purchase agreement with Gainesville Regional Utilities to sell all of the electricity from the facility to the utility.

Today GREC is owned by Energy Management, Inc., BayCorp Holdings and Starwood Energy, as well as by certain principals of Fagen, Inc., the contractor that built the facility. Starwood and Fagen became owners during the course of the construction project. Late last year the city made an offer to purchase the plant, reportedly $400 million, which was turned down.

EMI’s Mark Rodgers says they remain open to a sale, but are “also open to the possibility of long-term ownership.”

GREC will utilize approximately 1 million tons of woody biomass annually as fuel, making this operation environmentally friendly, cost-effective and reliable, and bringing a new source of electricity to the region while reducing dependence on fossil fuels, and lifting GRU’s renewable energy portfolio to more than 20%.

Over the nearly three-year construction period, up to 900 construction workers helped build GREC at a time when unemployment in the region had risen and good jobs were hard to find. Today, 45 employees operate GREC. GREC is also spending approximately $30 million annually for wood fuel, and creating 160 forestry and trucking jobs to handle the once discarded wood, process it, and deliver it to the facility.

Richard Schroeder is the president and founder of BioResource Management, Inc. and his company has worked closely with the GREC. The company was formed in 2005 and Schroeder has over 30 years’ experience in the biomass and forestry industry. Schroeder’s company was acquainted with the owner through previous biomass development efforts in New England and other parts of the country.

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BioResource Management maintains an office at the power plant and they are responsible for all aspects of the wood supply including verification that the supply meets the sustainability standards and quality standards required by the plant. The company employs a full-time forester to monitor all forest harvesting to ensure that the wood delivered meets all criteria and standards for best management practices and sustainability. BioResource Management is contracted to supply the plant through 2019. Approximately 40% of the raw material used in the plant is urban wood waste (tree debris and landclearing), 40% in-woods chips and 20% mill residues (such as bark and sawdust) and logging residuals.

The company used its contacts and experience from working the supply area for over 30 years when they went about rounding up a list of logging suppliers and other raw material suppliers. “As with any project, the supply is never finalized; existing and potential suppliers are evaluated on a continual basis,” Schroeder says. Approximately 12-20 suppliers deliver to the facility on a regular basis, from within a 75 mile radius of the plant.

Schroeder reports that he received positive reactions when he approached potential wood suppliers. “Everyone in the wood business was enthusiastic about the project. This represented a new market, for forest materials previously not used, and enabled wood suppliers and landowners to increase their productivity in their existing lands and equipment,” Schroeder says.

The plant only receives material that is in “chip” form. The specification is that all material be size reduced so that 95% by weight will pass through a 2 1/2 in. round hole screen and no material can be longer than 7 inches. The GREC is a unique biomass plant according to Schroeder. “This plant is much larger than most stand-alone biomass generating facilities,” Schroeder notes. “It also incorporates the latest in both combustion and emissions control technology, meeting all current and anticipated future regulatory requirements.”

GREC hired Fagen Inc. as the engineering, procurement and construction contractor. Metso supplied the 100 MW biomass boiler island, flue gas cleaning system and plant automation system. The boiler is a 930,000-pound per hour bubbling fluidized boiler, while the 116.1- MW Siemens turbine provides low combustion and low-excess air, which results in minimal emissions.

The operation requires approximately 130 truckloads of fuel daily. To accommodate peak delivery periods, three drive-through Airoflex truck dumpers are capable of unloading around-the-clock.

Wolf Material Handling Systems provided the fuel handling solution and they were tasked with supplying every component in the wood yard from the time the delivery drivers weighs in at the gate to the metered delivery of fuel to the boiler house. As a complete solution provider for the GREC system, Wolf designed and manufactured an innovative sampler system at the scale house and over a half mile of conveyors incorporating one fixed stacker, two wood hog chain feeders, and two Wolf-designed, underpile reclaimers with the associated chute work and dust collection system. The system also included the Airoflex drive-over truck dumpers, inbound and outbound scales, RID fuel tracking system, and dual hog and screen systems.

After unloading, the biomass fuel passes under a metal detector and magnet to remove ferrous metals upstream of the disc-screen/hammer hog sizing system.

WSM Bioprep fuel preparation machinery includes a WSM model 72-18 disc screen with dual drive and WSM model 5472 vertical feed hog/grinder. The WSM disc screen features incoming orientation rolls and a dual drive system for high capacity screening of pre-processed fuel. Acceptable fuel passes through the disc screen, and over-sized material is gravity fed to the WSM 5472 vertical feed hog/grinder (54 in. diameter x 72 in. wide rotor).

WSM’s vertical hog/grinder is specifically designed for high volume processing of boiler fuel materials, and to reduce operating and maintenance costs with design features that include pivoting housing for access, reversible/replaceable hammer tips, and modular screens.

The Wolf Radial Stacker/Reclaimer is capable of automatically building a million cubic foot pile at a rate of 600 TPH while simultaneously reclaiming at a rate of 200 TPH. It is the largest stacker/reclaimer Wolf had provided to date.

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Biomass fuel will have an average moisture content of 45%. Generally, the yard operates on a first-fuel-in, first-out basis.

The BFB boiler technology involves combustion of biomass fuel in a dense, fluidized sand bed located at the bottom of the furnace as well as above the bed.

To further control the NOX air emissions, the plant uses a selective catalytic reduction system. To mitigate particulate matter, Fagen constructed a 20-module baghouse, which offers better filter control. Gainesville Regional Utilities also holds itself to strict environmental standards as its site is a zero-liquid-discharge zone, meaning that all industrial wastewater is recycled and reused and will not leave the site.

Steam generated by the boiler is sent to the steam turbine generator for the production of electricity, which is transmitted from the STG to a switchyard to increase the voltage. The electricity is then transmitted through aerial transmission lines to the electric grid.

The evolvement of the project included considerable feedback from the public over various issues, one of which was noise emissions. The site is eight miles northwest of downtown Gaines­ville. According to EMI’s Rodgers, there were concerns from neighbors about the noise, but the plant has been able to decrease the level of noise through the implementation of acoustic panels in the main stack.

One of the biggest challenges now, Rodgers says, is that natural gas prices have fallen. He adds, “In the long run the community will be able to see the value of using renewable energy.”