Engineered Systems - February 2008 - (Page 31) Chipping Away At Emissions Advantages of Wood Biomass Equipment In a paper prepared for the USDA Forest Service, State and Private Forestry Technology Marketing Unit, Forest Products Laboratory, Madison, WI, chemical engineer Richard Bergman and wood technologist John Zerbe outlined some of the benefits of using wood biomass equipment: “Wood fuel has several environmental advantages compared with fossil fuels. Wood can be continually replenished, which leads to a sustainable and dependable supply. However, proper forest management must be practiced to ensure that growing conditions are not degraded during biomass production. “There is little net production of carbon dioxide from wood combustion, because the CO2 generated during combustion of wood equals the CO2 consumed during the lifecycle of the tree. Transporting the material using petroleum generates excess CO2. “Wood fuel contains minimal heavy metals and extremely low levels of sulfur; wood fuel is no threat to acid rain pollution. Particulate emissions from wood are controllable through standard emission control devices such as bag houses, cyclone separators, and electronic precipitators. Bottom ash is minimal. Usually, wood ash is less than 1% of the weight of the wood, and sometimes ash may be used as a fertilizer. “The principal economic advantage of wood-burning systems is that wood fuel is usually less expensive than competing fossil fuels. However, the price of wood for use as fuel can be extremely variable. Sometimes when surplus supplies of wood residues are available at nearby forest product manufacturing plants or municipal solid waste handling facilities, the cost can be very low or even negative. Transportation for delivering from the supply site to the wood combustion or wood processing unit is the primary expense of wood fuel. “At other times, mostly dependent on location of the wood power facility, the cost of wood fuel can be quite high because large volumes of fuel are needed to have a dependable and consistent supply of wood fuel. Because the market for wood biomass energy may be uncertain or uncommon in a particular area, potential wood biomass users may want to do a brief, informal feasibility study before undertaking a rigorous economic analysis.” HYBRID BOILER FILLS THE BILL La Sarre and Macamic Hospitals were built in the 1940s, and both still had their original boilers, which Fauteux pointed out were riveted, not welded. Most of the original boilers were disassembled and removed, although each hospital kept one existing boiler as a backup. Ironically, these boilers are not allowed to operate due to their excessive emissions, but they will remain in place until facility personnel become comfortable with the new biomass boilers. Fauteux installed Hurst multi-fuel “Hybrid Series” solid fuel-fired steam boilers at both hospitals, and back-up oil burners were installed on the 200-hp boiler at La Sarre and the 250-hp boiler at Macamic, just in case there is ever a problem in the fuel handling. The fuel is kept in a storage area that is located 30 ft down in the ground, which keeps the wood from freezing. Every few days, a truck delivers a load of wood waste — usually sawdust, wood chips, and bark — and dumps it into the reserve. Due to rising fuel prices, these fuel deliveries are getting more expensive, but they’re still less than the cost of buying oil or gas. “Years ago, it cost about $25/ton for the wood waste to be delivered,” said Fauteux. “Now it’s $65/ton undelivered. But the price Expand Your BACnet IP Network ® BAS Remote The RoHS Compliant Mode Modern biomass dern biomass ioma boil s come boilers come iler equipped with uipped with i po proven emissions emissio missions control devices that tl i s that h significantl redu significantly reduce gnificantly duce NOx and NOx and CO emission In emissions. In issions addition particulate addition, particulate dition, rticulat emissions are reduced through the use of cyclone separators, bag houses, or electronic precipitators, which catch almost all the ash generated during the combustion process. • Put your I/O directly on ctly the BACnet/IP network – NO router required • Universal I/O – Digital or Analog input or output all in a single point • Monitor and Control I/O using your web browser • BAS Remote now with PoE • B-ASC Compliant For more information visit www.BASremote.com or call 630-963- 70 call 630-9 630-963-7070 30-963 0 Over Years In Networked Controls FREE INFO: 22 w w w. esmag a zine . c o m 31 http://www.BASremote.com http://www.BASremote.com http://www.esmagazine.com
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