Carbon Implications of Converting a Coal-Fired Power Plant to Combustion of Torrefied Arundo Donax

The production of electricity from energy crops in existing coal-fired power plants is a viable alternative to produce renewable baseload power and sequester carbon. The pulverization systems in coal plants can be easily adapted to grind biomass if the fibrous structure of lignocellulosic biomass is weakened by torrefaction. The objective of this paper is to evaluate the carbon implications of using torrefied Arundo donax as a replacement fuel for a combustion steam turbine generator. This assessment encompasses the carbon impacts of transportation, agriculture, torrefaction and combustion. Data derive from field measurements of Arundo agronomy, laboratory measurements of the torrefaction process and literature research of agricultural and transportation practices. Findings show that the agricultural machinery operations, agricultural inputs (fertilizer, irrigation, etc.) and transportation contributions to carbon emissions are minimal, contributing less than 1 % to total emissions. The vast majority of emissions arise from the biomass torrefaction and combustion processes. These emissions are largely offset by biomass farming, with carbon sequestration above ground and below ground driving net carbon emissions to very low levels. Below ground sequestration contributes to a net negative emissions profile, at least until saturation of soil organic content.