National-Level Infrastructure and Economic Effects of Switchgrass Cofiring with Coal in Existing Power Plants for Carbon Mitigation

Abstract

We update a previously presented Linear Programming (LP) methodology for estimating state level costs for reducing CO 2 emissions from existing coal-fired power plants by cofiring switchgrass, a biomass energy crop, and coal. This paper presents national level results of applying the methodology to the entire portion of the United States in which switchgrass could be grown without irrigation. We present incremental switchgrass and coal cofiring carbon cost of mitigation curves along with a presentation of regionally specific cofiring economics and policy issues. The results show that cofiring 189 million dry short tons of switchgrass with coal in the existing U.S. coal-fired electricity generation fleet can mitigate approximately 256 million short tons of carbon-dioxide (CO 2 ) per year, representing a 9% reduction of 2005 electricity sector CO 2 emissions. Total marginal costs, including capital, labor, feedstock, and transportation, range from $20 to $86/ton CO 2 mitigated, with average costs ranging from $20 to $45/ton. If some existing power plants upgrade to boilers designed for combusting switchgrass, an additional 54 million tons of switchgrass can be cofired. In this case, total marginal costs range from $26 to $100/ton CO 2 mitigated, with average costs ranging from $20 to $60/ton. Costs for states east of the Mississippi River are largely unaffected by boiler replacement; Atlantic seaboard states represent the lowest cofiring cost of carbon mitigation. The central plains states west of the Mississippi River are most affected by the boiler replacement option and, in general, go from one of the lowest cofiring cost of carbon mitigation regions to the highest. We explain the variation in transportation expenses and highlight regional cost of mitigation variations as transportation overwhelms other cofiring costs.

Regional Allocation of Biomass to U.S. Energy Demands under a Portfolio of Policy Scenarios

“…A fraction of the coal used as fuel in existing steam turbine plants can be substituted by either cofiring biomass with coal or by using 100% biomass, by retrofitting the boiler to allow biomass input. 17 Retrofitting results in a small (assumed 10%) loss of efficiency. The costs of retrofitting are discussed in the section that follows.…”

“…In the electricity sector, biomass has the potential to displace coal. A fraction of the coal used as fuel in existing steam turbine plants can be substituted by either cofiring biomass with coal or by using 100% biomass, by retrofitting the boiler to allow biomass input . Retrofitting results in a small (assumed 10%) loss of efficiency.…”

“…Wahlund et al, Wilson et al, Zhang et al, , Eriksson et al, and Spatari et al each address some choice between feedstocks or end uses, together covering all of the feedstocks and end uses covered in this study. Kocoloski et al, Elia et al, Morrow et al, − and You et al additionally construct spatially explicit optimization models to choose feedstock type/end use, as well as infrastructure location. However, none of these studies considers as many feedstocks and as many end uses simultaneously in a spatially explicit way, as are modeled in this study.…”

Torrefaction of Healthy and Beetle Kill Pine and Co-Combustion With Sub-Bituminous Coal

“…Recent analyses have shown that, in order to achieve high levels of emissions reductions at minimal additional cost, transportation of biomass over significant distances should be avoided and local biomass resources should be considered for regional energy needs such as electricity [6]. Numerous studies have explored the use of biomass resources, including forest residues and dedicated crops like switchgrass, for co-firing with coal in power plants with an emphasis on local resources [2,7,8].…”