Production routes of advanced renewable C1 to C4 alcohols as biofuel components – a review

Abstract

In 2018, the EU's revised Renewable Energy Directive came into force, increasing renewable energy targets for all energy sectors while limiting the use of first‐generation biomass as feedstock. Fuel components like methanol, ethanol, propanols, and butanols represent promising candidates to enable the targets for transportation to be achieved because they can be used with existing infrastructure and can be further processed to give additives and substitutes. A wide variety of feedstocks and processes are available for this purpose. In this review, the thermocatalytic and biological synthesis routes for C1–C4 alcohol fuels are summarized to illustrate the many alternatives. They include biomass and waste gasification and carbon capture and utilization to obtain syngas for catalytic conversion, fermentation of sugars from lignocellulosic feedstock, and novel, less developed pathways like syngas fermentation, glycerol conversion, and biogas reforming. The current state of technology is presented by discussing the advantages and technical hurdles, and by introducing recent scaled‐up approaches. This demonstrates the need for further research and development. The assessment of techno‐economic analyses in the literature illustrates the dominant factors affecting production costs and reveals the broad range of feasibility of the various production routes. The review shows that the routes most similar to conventional, well‐established syntheses bear the highest potential to be implemented in the short and medium term. The availability of cheap and abundant feedstock also plays a crucial role. Methanol synthesis from biomass gasification and ethanol, and acetone‐butanol‐ethanol fermentation from lignocellulosic biomass, are therefore considered to be very promising. © 2020 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd.

A Review on Supply Costs and Prices of Residual Biomass in Techno-Economic Models for Europe

“…An analysis of the sources cited showed that the spatial resolution used in the sources did not always fit the scope of the literature studied. This supports the assumption that suitable information on biomass supply costs or prices is not always available for use as input variables in the models, although assumptions about underlying supply costs and prices have a significant impact on model results [5][6][7]. Therefore, supply costs or prices are influenced by spatial effects, such as the amount of available biomass, as Brown et al [62] mentioned.…”

“…Techno-economic analyses are used, among other things, to evaluate whether it is economically feasible to employ products made from biogenic raw materials. The studies by Lepage et al, Schubert, and De Jong et al show that the input variables used in the analyses for the costs and prices of supplying the biogenic raw materials can have a significant influence on the models' findings [5][6][7]. For that reason, it is important for techno-economic models to use data on supply costs and prices for biogenic raw materials that are valid and fit the context of the research.…”

Semi‐Batch Hydrotreatment of Lignin‐Derived Phenolic Compounds over Raney‐Ni with a Continuous Regeneration of the H‐Donor Solvent

“…Propanols (n-PrOH, 2-PrOH) can be obtained by biochemical conversion of sugars and by catalytic hydrogenolysis of bioglycerol as an available by-product of biodiesel production that it is an attractive approach regarding sustainability and energy efficiency compared to the processes based on petroleumderived feedstocks. [42,43] However, the mixture of both propanols is formed in glycerol hydrogenolysis. The primary alcohols are poor H-donors in comparison with the secondary alcohols (Figure 5).…”

An overview of the obtaining of biomass-derived gamma-valerolactone from levulinic acid or esters without H2 supply

“…Alcohols are also products from a conventional refinery, but their use requires fewer precautions and lower equipment costs since the reactors require less complexity because of the lower pressures. In the future, it is expected that both molecular hydrogen and alcohols can be obtained in biorefineries (Campos 2018;Schubert 2020). LA or LE CTH involves Meerwein-Ponndorf-Verley (MPV) reduction (Johnstone et al 1985).…”