Air Pollutant Emissions and Regulatory Implications of a Biorefinery Producing Raw Bio-oil

摘要

Pyrolysis oil, also referred to as bio-oil, has attracted considerable attention because of the high carbonaceous matter and high heating value compared to the original biomass before conversion.1–3 Utilizing the existing fossil fuel infrastructure by introducing raw bio-oil in the fluidized catalytic cracking (FCC) unit in petroleum refineries to produce renewable hydrocarbon fuels (i.e., repurposing existing assets) offers a promising opportunity to reduce the carbon intensity of transportation fuels and would present a relatively low capital requirement to existing facilities.1,4 However, a facility (biorefinery) producing raw bio-oil is considered a chemical process plant under the Clean Air Act (CAA)5 permitting program and is expected to emit air pollutants that could pose threats to the environment and public health. Based on the type and magnitude of the regulated pollutants emitted, the biorefinery may be subject to regulations under the New Source Performance Standards (NSPS) or National Emission Standards for Hazardous Air Pollutants (NESHAP) for New Source Review (NSR) and/or Title V program.6,7 This paper examines the potential regulatory implications (in terms of emissions and federal regulations) of a biorefinery producing raw bio-oil. In this analysis, we examine the air pollutant emissions (preliminary potential to emit (PTE)) and evaluate the potential air pollutant regulatory and permitting implications for a biorefinery utilizing an ex situ fast pyrolysis process, with a design capacity of 2,000 dry metric tons of biomass per day to produce 4,200 barrels of raw bio-oil.8 The raw bio-oil produced from the biorefinery can be blended with petroleum-based intermediates (vacuum gas oil) in the FCC units of existing petroleum refineries to produce gasoline and diesel blendstocks with renewable content. We also discuss selected emissions control technologies, which could be used to further reduce potential emissions (alternative PTE) and help biorefineries avoid being subject to the major source permitting requirements (e.g., prevention of significant deterioration (PSD)) if desired. This analysis is expected to provide insights for new bio-oil project developers to identify opportunities to mitigate emissions and develop strategies to overcome challenges and risks associated with air permitting. Our previous analysis investigated permitting ramifications of co-processing partially upgraded bio-oil in petroleum refineries while this analysis looks into regulations and permitting classification for a biorefinery producing raw bio-oil.