Environmental, Economic, and Scalability Considerations of Selected Bio-Derived Blendstocks for Mixing-Controlled Compression Ignition Engines

Abstract

Economic and environmental favorability are vital considerations for the large-scale development and deployment of sustainable fuels. Here, we have conducted economic and sustainability analyses of pathways for producing bioblendstocks optimized for improved combustion for mixing-controlled compression ignition (MCCI) engines. We assessed 25 pathways for the production of target fuels from renewable feedstocks and conducted technoeconomic analysis (TEA) and life cycle analysis (LCA) to determine which bioblendstock candidates are likely to be viable given a slate of 19 metrics evaluating technology readiness, economic viability, and environmental impacts ranking each metric as either favorable, neutral, unfavorable, or unknown across a range of screening criteria. Among the results, we found that the economic metrics were largely favorable for most of the bioblendstocks. Of the near-term baseline cases, eight pathways offered the potential of a minimum fuel selling price (MFSP) of less than $5/gallon of gasoline equivalent (GGE). In comparison, under future target case scenarios, there is potential for seven pathways to reduce their fuel selling price to less than $4/GGE. Biochemically-based pathways struggled to achieve favorable target case MFSP under the processing approach taken here, but further economic improvements could be achieved when lignin valorization is included. Most of the conversion technologies were determined to be robust in that they would be minimally affected by the feedstock specifications and variations. However, given the early stage of development for most of the pathways, blending behavior and testing for regulatory limits are key data gaps as knowledge of how many of these bioblendstocks will perform when blended with existing fuels and how much can be added while still meeting fuel property specifications is still being assessed. Twelve pathways showed significant reductions in life cycle greenhouse gas (GHG) emissions greater than 60%, and 15 showed favorable fossil energy use reductions compared to conventional diesel fuel. Energy-intensive processes and the use of GHG-intensive chemicals such as sodium hydroxide contribute significantly to GHG emissions. Results from these analyses enable researchers and industry to assess the potential viability of MCCI bioblendstocks.

Screening and evaluation of biomass upgrading strategies for sustainable transportation fuel production with biomass-derived volatile fatty acids

“…The impact of avoided methane emissions is dramatic, as this gas traps heat more than 20 times as efficiently as CO 2 ; 31 these avoided emissions are credited as negative CO 2 -eq emissions in accordance with previous work. 2 , 29 Biogenic credits for the VFA upgrading pathways were between 69 and 73 g CO 2 -eq./MJ which were very similar to the combustion emissions during vehicle or jet fuel used for each product (70–75 g CO 2 -eq./MJ), offsetting these emissions. These emissions are accordingly omitted from Figure 7 , unlike those of the petrofuels.…”

“…Conversion of wet waste-derived VFAs to fuels also avoids methane emissions which would otherwise result from traditional waste management options such as landfilling of organic wet wastes, giving these processes low to negative life cycle carbon emissions; this is crucial as methane is more than 20 times as efficient at trapping atmospheric heat as CO 2 . 2 , 3 , 17 , 28 , 29 , 30 , 31 Alcohols and alkanes formed by these upgrading processes are promising blendstocks 18 for end fuel uses including gasoline, jet, or diesel. We approximate upgrading processes and blending capacity of upgraded molecules in petrofuels using a MATLAB script, the VFA Upgrading to Liquid Transportation fUels Refinery Estimation (VULTURE), written for this work.…”

Identification of Key Drivers of Cost and Environmental Impact for Biomass-Derived Fuel for Advanced Multimode Engines Based on Techno-Economic and Life Cycle Analysis

“…However, the furan mixtures and prenol–isoprenol mixture were categorized as unknown. As discussed by Kolodziej and Scheib, blending isobutanol with gasoline (up to 12.5 vol%) produces a similar gasoline at 2.7% O 2 content, which is acceptable by engine manufacturers; therefore, the U.S. EPA waiver (211b) could potentially allow isobutanol blending levels up to 16.1%, which produces a final fuel with the same oxygen content (3.5%) and heating value as an ethanol 10% blend (E10) . Finally, there are legal restrictions for blending these fuels such as limits on oxygenates (1-butanol, isopropanol, isobutanol, prenol, propanol/ethanol mixture) and olefins (prenol, diisobutylene).…”

Lignin for energy applications – state of the art, life cycle, technoeconomic analysis and future trends

“…Since the interest on lignin as an alternative to fossil-fuels based technologies has gained considerable attention recently, lignin-only LCA studies have emerged, which are either focused on lignin extraction [289][290][291][292][293][294][295][296][297][298][299] or lignin-based products (asphalt, [300][301][302][303][304] adhesives, [305][306][307] resins, 308 fine chemicals, [309][310][311][312][313][314] carbon fibres 315 and fuels. 287,[316][317][318][319][320] Lignin as a product from biorefineries is a new concept, therefore most of the LCA conducted are based on either well quantified extraction processes such as Kraft or based on experimental lab scale data which has been extrapolated. In the latest case, the LCA allows to evaluate the environmental impact of an upscaled biorefinery.…”

“…However, lignin is considered only as energy cogeneration in this study. 320 The LCA on bio-jet fuel from poplar biomass was performed by Budsberg et al 318 This study uses lignin as a source of H 2 using hog fuel as the alternative energy source.…”