Abstract
BackgroundDespite the recognition that feedstock composition influences biomass conversion efficiency, limited information exists as to how bioenergy crops with reduced recalcitrance can improve the economics and sustainability of cellulosic fuel conversion platforms. We have compared the bioenergy potential—estimated as total glucose productivity per hectare (TGP)—of maize cultivars contrasting for cell wall digestibility across processing conditions of increasing thermochemical severity. In addition, exploratory environmental impact and economic modeling were used to assess whether the development of bioenergy feedstocks with improved cell wall digestibility can enhance the environmental performance and reduce the costs of biomass pretreatment and enzymatic conversion.ResultsSystematic genetic gains in cell wall degradability can lead to significant advances in the productivity (TGP) of cellulosic fuel biorefineries under low severity processing; only if gains in digestibility are not accompanied by substantial yield penalties. For a hypothetical maize genotype combining the best characteristics available in the evaluated cultivar panel, TGP under mild processing conditions (~3.7 t ha−1) matched the highest realizable yields possible at the highest processing severity. Under this scenario, both, the environmental impacts and processing costs for the pretreatment and enzymatic saccharification of maize stover were reduced by 15 %, given lower chemical and heat consumption.ConclusionsGenetic improvements in cell wall composition leading to superior cell wall digestibility can be advantageous for cellulosic fuel production, especially if “less severe” processing regimes are favored for further development. Exploratory results indicate potential cost and environmental impact reductions for the pretreatment and enzymatic saccharification of maize feedstocks exhibiting higher cell wall degradability. Conceptually, these results demonstrate that the advance of bioenergy cultivars with improved biomass degradability can enhance the performance of currently available biomass-to-ethanol conversion systems.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0479-0) contains supplementary material, which is available to authorized users.
Highlights
Despite the recognition that feedstock composition influences biomass conversion efficiency, limited information exists as to how bioenergy crops with reduced recalcitrance can improve the economics and sustain‐ ability of cellulosic fuel conversion platforms
Commercial forage maize cultivars display substantial diversity in cell wall composition and cell wall digestibility Entries evaluated in this study comprised forage maize cultivars bred for Northern-European markets
We postulate that if breeding would allow for the combination of the best characteristics available in the entry panel, maximum total glucose productivity per hectare (TGP) at low-mid conditions (~3.7 t ha−1) would correspond to 100 % of the highest realizable yields
Summary
Despite the recognition that feedstock composition influences biomass conversion efficiency, limited information exists as to how bioenergy crops with reduced recalcitrance can improve the economics and sustain‐ ability of cellulosic fuel conversion platforms. Techno-economic and life cycle assessments of cellulosic fuel refineries have minimized the role of biomass feedstocks to cost, productivity, and availability considerations [9,10,11,12,13,14] These comparative analyses often imply that the profitability and sustainability of cellulosic fuels can be primarily attained through innovations in process engineering or advances in the yield productivity (per hectare) of biomass species. Under these provisions, advancing lignocellulosic crops with increased cell wall degradability could prove detrimental to the industry, since alterations in cell wall composition may lead to concomitant reductions (albeit, of varying degrees) in yield productivity [15]
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