Cost-effective large-scale production of Chlorella vulgaris-based biodiesel and bioethanol: A comparative assessment

Abstract

Background

Microalgae-based biofuel production is a promising alternative to conventional renewable energy sources, despite its economic viability at industrial scale remains unrealized. The present study is the first to present a novel evaluation of large-scale biodiesel and bioethanol production from Chlorella vulgaris, integrating the cost analysis of chemicals and energy demands, to identify the most viable production route for real-world implementation.

Methods

Three biofuel production routes, namely, biodiesel via two-step transesterification and bioethanol from whole and defatted biomass through acid hydrolysis, were systematically assessed, with a functional unit of 1000 kg (dry biomass) of C. vulgaris.

Significant findings

Total costs associated with chemicals and energy demands were $ 2.30/L, $ 95.52/L, and $ 0.73/L to produce biodiesel, bioethanol, and defatted biomass-based bioethanol, respectively. Consequently, the most profitable biofuel production using defatted C. vulgaris biomass has a profitability ratio of 1.01 (>1). Moreover, biodiesel production demonstrates the most renewable system with a net energy ratio of 6.28 and a net energy balance of +29.93. Nonetheless, the production viability of biodiesel and bioethanol (whole biomass) could be enhanced by incorporating cost- and energy-effective strategies. Additionally, the valorization of defatted biomass for bioethanol production would be a promising strategy, facilitating a circular bioeconomy and enhanced sustainability.