Introduction of biomass Cofiring in coal fired boilers
One of the most attractive and easily implemented biomass energy technologies is cofiring with coal in existing coal fired boilers. In biomass cofiring, biomass can substitute for up to 20% of the coal used in the boiler. The biomass and coal are combusted simultaneously. When it is used as a supplemental fuel in an existing coal boiler, biomass can provide the following benefits: lower fuel costs, avoidance of landfills and their associated costs, and reductions in sulfur oxide, nitrogen oxide, and greenhouse-gas emissions. Other benefits, such as decreases in flue gas opacity, have also been documented. Biomass cofiring is one of many energy- and cost-saving technologies to emerge as feasible for federal facilities in the past 20 years. Cofiring is a proven technology; it is also proving to be life-cycle cost-effective in terms of installation cost and net present value at several federal sites.
Biomass cofiring in coal fired boilers savings
Biomass cofiring projects do not reduce a boiler’s total energy input requirement. In fact, in a properly implemented cofiring application, the efficiency of the boiler will be the same as it was in the coal-only operation. However, cofiring projects do replace a portion of the nonrenewable fuel—coal—with a renewable fuel—biomass.
Overall production cost savings can be achieved by replacing coal with inexpensive biomass fuel sources—e.g., clean wood waste and waste paper. Typically, biomass fuel supplies should cost at least 20% less, on a thermal basis, than coal supplies before a cofiring project can be economically attractive.
Biomass cofiring application in coal fired boilers
Biomass cofiring can be applied only at facilities with existing coal-fired boilers. The best opportunities for economically attractive cofiring are at coal-fired facilities where all or most of the following conditions apply: (1) coal prices are high; (2) annual coal usage is significant; As a rule, boilers producing less than 35,000 pounds per hour (lb/hr) of steam are too small to be used in an economically attractive cofiring project.