Biomass Co-firing with Coal and Natural Gas

Ezinwa U Agbor
Biomass fuels have long been accepted as useful renewable energy sources, especially in mitigating greenhouse gases (GHG) emissions. Fossil fuel-based power plants make up over 30% of the GHG emissions in Alberta, Canada. Displacement of fossil fuel-based power through biomass co-firing has been proposed as a near-term option to reduce these emissions. In this research, co-firing of three biomass feedstocks (i.e., whole forest, agricultural residues and forest residues) at varying proportions
more » ... rying proportions with coal as well as with natural gas in existing plants was studied to investigate different co-firing technologies. Whole forest biomass refers to live or dead trees (spruce and mixed hardwood) not considered merchantable for pulp and timber production; agricultural residues are straws obtained as the by-product of threshing crops such as wheat, barley, and flax; and forest residues refer to the limbs and tops of the trees left on the roadside to rot after logging operations by pulp and timber companies. Data-intensive models were developed to carry out detailed techno-economic and environmental assessments to comparatively evaluate sixty co-firing scenarios involving different levels of the biomass feedstock co-fired with coal in existing 500 MW subcritical pulverized coal (PC) plants and with natural gas in existing 500 MW natural gas combined cycle (NGCC) plants. Minimum electricity production costs were determined for the co-fired plants for the same three biomass feedstocks and base fuels. Environmental assessments, from the point of harvesting to delivering electricity to the customers, was evaluated and compared to the various co-fired configurations to determine the most economically viable and environmental friendly options of biomass co-firing configuration for western Canada. The results obtained from these analyses shows that the fully paid-off coal-fired power plant cofired with forest residues is the most attractive option and has levelized cost of electricity (LCOE) ranging from $53.12 to $54.50/MWh; and CO 2 abatement costs ranging from $27.41 to $31.15/tCO 2 . Similarly, the LCOE and CO 2 abatement costs for whole forest chips range from iii $54.68 to $56.41/MWh and $35.60 to $41.78/tCO 2 respectively. When straw is co-fired with coal in a fully paid-off plant, the LCOE and CO 2 abatement costs range from $54.62 to $57.35/MWh and $35.07 to $38.48/tCO 2 respectively. This is of high interest considering the likely increase of the carbon levy to about $30/tCO 2 in the Province of Alberta by 2017. iv
doi:10.7939/r3dj58t7f fatcat:qvltxgtcjfhptbpmwzwtxgolh4