Jun 23, 2006. /Lesprom Network/. Forest products producer Weyerhaeuser Co. on Wednesday, June 21 said it plans to use biomass fuel to cut its greenhouse gas emissions by 40% by 2020. Biomass fuel is made of bark and lignin, the substance that binds wood fibers. Weyerhaeuser said its pulp and paper mills currently pull 72% of their energy from biomass. Increasing its use of biomass fuel will temper the effects of volatile oil and gas prices, the company said. The reduction in greenhouse gases will be measured relative to Weyerhaeuser's emissions in 2000.