(365a) Technoeconomic Analysis of a Microalgae-Based Biorefinery Network for the Production of Advanced Biofuels

The establishment of a circular bioeconomy that satisfies the increased energy demands of a growing population has become a key focus of current governmental policies and initiatives. In Europe, for example, the recast directive 208/2001/EU mandates Members States to reach a minimum 20% share of renewable fuels in the transport sector by the year 2030. The latest statistics, however, indicate that up to 92% of the transport energy consumed in Europe (EU-28) is still satisfied by oil and petroleum fuels (e.g. gasoline and diesel, with only 5.11% deriving from renewable sources [1]. Therefore, the search for more sustainable biomass-derived fuel alternatives and efficient production routes continues to be a challenging but critical bioeconomy target.

Microalgae biomass is a promising production platform for advanced biofuels, although the single fuel conversion strategy has been deemed unfit for commercial applications. Due to their rich chemical composition, microalgal biorefineries are instead regarded as a more economically viable approach for the co-production of fuels and value-added chemicals through the full exploitation of biomass conversion and waste valorisation scenarios [2,3]. Therefore, it becomes necessary to identify those optimal conversion routes leading to reduced processing costs and increased productivity. For example, whilst the feasibility of producing microalgal biodiesel (via transesterification) has been widely evaluated, the co-production of biodiesel along with biobutanol (via fermentation) from microalgae can provide a more favourable outlook for biofuels production through the combined exploitation of microalgal sugars and lipids [4]. Evaluating the economic potential of such a biorefinery network can focalise research developments on critical processing stages, and identify areas of opportunity leading to improved process performance [5].

This work presents a technoconomic analysis of an integrated biorefinery network for the co-production of microalgal biodiesel (via transesterification of lipids) and biobutanol (via fermentation of sugars) along with additional products acetone, ethanol, and glycerol. The biorefinery is comprised of three major areas: i) feedstock pre-treatment, involving acid hydrolysis (AH) and solvent extraction (SX), ii) biodiesel production and purification, and iii) biobutanol production and purification. Two biorefinery configurations were evaluated (Configuration 1: AH followed by SX, Configuration 2: SX followed by AH) and compared against the single-fuel biodiesel or biobutanol conversion scenarios. In addition, a sensitivity analysis was carried out in terms of the Minimum Fuel Selling Price (MFSP) to identify those critical parameters with the greatest effect on fuels price, thus generating insights on the potential effect of process variables (e.g. solvent usage, fuel yield) and market uncertainties (e.g. feedstock costs, biofuel demand, fuel quality standards).

References

[1] European Commission, Energy Balance | 2020 edition, Luxembourg, 2020.

[2] G.M. Figueroa-Torres, J.K. Pittman, C. Theodoropoulos, Optimisation of microalgal cultivation via nutrient-enhanced strategies: the biorefinery paradigm, Biotechnol. Biofuels. 14 (2021) 64.

[3] J. Rajes Banu, Preethi, S. Kavitha, M. Gunasekaran, G. Kumar, Microalgae based biorefinery promoting circular bioeconomy-techno economic and life-cycle analysis, Bioresour. Technol. 302 (2020) 122822.

[4] G.M. Figueroa-Torres, W.M.A. Wan Mahmood, J.K. Pittman, C. Theodoropoulos, Microalgal biomass as a biorefinery platform for biobutanol and biodiesel production, Biochem. Eng. J. 153 (2020) 107396.

[5] C. Sun, C. Theodoropoulos, N.S. Scrutton, Techno-economic assessment of microbial limonene production, Bioresour. Technol. 300 (2020) 122666.