Research article - Peer-reviewed, 2016
A systems analysis of biodiesel production from wheat straw using oleaginous yeast: process design, mass and energy balances
Karlsson, Hanna; Ahlgren, Serina; Sandgren, Mats; Passoth, Volkmar; Wallberg, Ola; Hansson, Per-AndersAbstract
Background: Biodiesel is the main liquid biofuel in the EU and is currently mainly produced from vegetable oils. Alternative feedstocks are lignocellulosic materials, which provide several benefits compared with many existing feedstocks. This study examined a technical process and its mass and energy balances to gain a systems perspective of combined biodiesel (FAME) and biogas production from straw using oleaginous yeasts. Important process parameters with a determining impact on overall mass and energy balances were identified and evaluated.Results: In the base case, 41% of energy in the biomass was converted to energy products, primary fossil fuel use was 0.37 MJ(prim)/MJ produced and 5.74 MJ fossil fuels could be replaced per kg straw dry matter. The electricity and heat produced from burning the lignin were sufficient for process demands except in scenarios where the yeast was dried for lipid extraction. Using the residual yeast cell mass for biogas production greatly increased the energy yield, with biogas contributing 38% of total energy products.Conclusions: In extraction methods without drying the yeast, increasing lipid yield and decreasing the residence time for lipid accumulation are important for the energy and mass balance. Changing the lipid extraction method from wet to dry makes the greatest change to the mass and energy balance. Bioreactor agitation and aeration for lipid accumulation and yeast propagation is energy demanding. Changes in sugar concentration in the hydrolysate and residence times for lipid accumulation greatly affect electricity demand, but have relatively small impacts on fossil energy use (NER) and energy yield (EE). The impact would probably be greater if externally produced electricity were used.Keywords
Lignocellulosic materials; Diesel; Biogas; Microbial oil; Systems perspectivePublished in
Biotechnology for Biofuels2016, volume: 9, article number: 229
Publisher: BIOMED CENTRAL LTD
Authors' information
Karlsson, Hanna (Karlsson Potter, Hanna)
Swedish University of Agricultural Sciences, Department of Energy and Technology
Swedish University of Agricultural Sciences, Department of Energy and Technology
Swedish University of Agricultural Sciences, The Department of Chemistry and Biotechnology
Swedish University of Agricultural Sciences, Department of Microbiology
Wallberg, Ola
Lund University
Swedish University of Agricultural Sciences, Department of Energy and Technology
Sustainable Development Goals
SDG7 Affordable and clean energy
UKÄ Subject classification
Bioenergy
Microbiology
Publication Identifiers
DOI: https://doi.org/10.1186/s13068-016-0640-9
URI (permanent link to this page)
https://res.slu.se/id/publ/79371