A TALE OF TWO BIOMASS BOILERS

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1 A TALE OF TWO BIOMASS BOILERS What could be better than using energy grown locally to heat your facility? Two school districts in Pennsylvania are using biomass boilers to provide thermal energy: The Benton Area School District biomass boiler was constructed in 2009 and is using locally grown switchgrass for fuel. The East Lycoming School District biomass boiler construction will finish in 2010 and they are planting hybrid willow on their property for fuel. Richard Skinner, Energy Engineer McClure Company rd World Energy Engineers Conference, Washington, D.C. Dec. 8-10,2010 1

2 Biomass Boilers Uses a clean burning, solid fuel combustor and traditional boiler technology to produce thermal energy Has a large fuel storage area and impressive fuel handling system of belts and augers Can burn a variety of fuel: wood chips, switchgrass, corn, manure, etc. Reasons for Considering a Biomass Boiler: Uses renewable fuels Locally produced fuels reduce dependence on foreign energy sources Significant cost savings to oil and gas Considered carbon neutral Is a well established technology 1 in 10 students in Vermont attends a biomass heated school. 2

3 $/MMBTU Biomass Can Save Up To 75% On Cost Of Fuel $25.00 $20.00 $15.00 $10.00 $5.00 $0.00 Fuel Cost Btu Content $/MMBTU Wood Chips $34/ton 5,000 Btu/lb $4.25 Switchgrass $60/ton 7,500 Btu/lb $5.00 Coal $120/ton 25 MMBtu/ton $6.00 Oil $2.50/gal 140 MBtu/gal $22.32 Natural Gas $1.25/therm 100 MBtu/therm $ st year wood chip cost from East Lycoming; Switchgrass cost from Benton; Boiler efficiency 80% for all fuels. 3

4 Benton School District Biomass Boiler heats High School and Elementary School Fueled by switchgrass grown locally Received $700k in grants; cost $2.1 M About 13 year payback with $3.25 oil The 7.5 MMBtu/hr input boiler at Benton operated for an abbreviated heating season in 2010 and saved 17,177 gallons of oil and consumed 210 tons of switchgrass. An addition was constructed on the Maintenance Building located between the High School and Elementary School to house the biomass boiler and fuel storage. About 2,100 feet of underground pipe was installed to connect the three buildings. 4

5 Switchgrass A native, warm season grass Requires minimal fertilizer and water Can grow on marginally productive land Harvest with traditional agricultural equipment Switchgrass will yield 3-4 tons per acre Low density, benefits to densifying Immature market Photos courtesy of Ernst Seed Specialized machinery creates densified switchgrass pucks that are four times as dense as ground switchgrass. Switchgrass pucks provide more fuel in the storage bin, are less costly to transport, and easier to handle. The Benton fuel pit will hold about 40 tons of switch grass pucks and at a typical burn rate of 3 tons per day, can last for 13 days. 5

6 East Lycoming School District Biomass boiler will provide heat & domestic hot water to High School Biomass boiler will handle about ¾ of thermal load and displace all oil usage Biomass boiler portion of project: $2.1 M Received $800k in grants Project has 15 year payback Planting hybrid willow The biomass boiler, rated at 130 boiler hp, is housed in an addition to the rear of the High School and adjacent to the existing boiler room. 6

7 Hybrid Willow Fast growing with high planting densities Can grow on marginally productive soils Harvest every three years Plants have a 21 year life; 3 years to mature Cut, chip and burn, no additional processing 1 year growth on mature root system. Photos courtesy of Double A Willow East Lycoming intends on planting about 60 acres of hybrid willow that will yield about 600 tons of 50% moisture content wood chips. This will supply nearly all of the projected tons per year of wood chips needed for the biomass boiler. 7

8 Fuel storage and handling Biomass Boiler Challenges Biomass fuel energy contents that range between btu/lb require relatively large storage volumes. Solid fuel handling is more challenging (belts and augers) than liquid or gaseous fuels. Ash handling and removal Air permitting Cost of system Shoulder season heating Biomass fuels create ash that must removed, typically on a weekly basis. The complex air permitting requirements in Pennsylvania necessitated the use of an environmental consultant; future national standards are expected to increase. The cost of a biomass boiler can be significant ; cost evaluations should include building additions and fuel storage. A biomass boiler will rely on traditional heating systems during the shoulder heating season due to limited turndown ratios. 8

9 Conclusions Biomass boilers are a proven, successful technology Uses Renewable Energy Reduces dependence of foreign energy Up to 75% savings on cost of fuel Significant installation cost It will take several years to determine the cost effectiveness of using switchgrass and hybrid willow at these locations. While these two schools are pleased with their biomass boiler decisions, only time will tell whether it makes more sense to produce your own, or buy commercially available fuel such as wood chips. 9