Daniele Spinelli

Life-Cycle Assessment of Microalgal-Based Biofuels

Abstract Fossil-fuel depletion and attempts at global-warming mitigation have motivated the development of biofuels. Several feedstock and transformation pathways into biofuel have been proposed as an alternative to the usual fuels. Recently, microalgae have attracted a good deal of attention because of the promise of reduced competition with food crops and lowered environmental impacts. Over the last years, several life-cycle assessments (LCAs) have been realized to evaluate the energy benefit and potential global-warming reduction of biofuel and bioenergy produced from microalgae. This chapter presents a bibliographic review of 15 LCAs of microalgae production and/or transformation into biofuel. These studies often differ by the perimeter of the study, the functional unit, and the production technologies or characteristics. Methods for environmental impact assessment and the energy balance computation also diverge. This review aims to identify the main options and variations among LCAs and concludes with some recommendations and guidelines to improve the contribution of an LCA and to facilitate comparisons among studies.

Comparative life cycle assessment study on environmental impact of oil production from micro-algae and terrestrial oilseed crops

In this study the LCA methodology is applied in order to satisfy two goals: i) to evaluate the hot spots in site-specific production chain of biodiesel from terrestrial and micro-algae feedstock; ii) to compare quantitatively, utilizing primary data, the impacts of the first generation in respect to the third generation bio-fuels. Results show that micro-algae are neither competitive yet with traditional oil crops nor with fossil fuel. The use of renewable technologies as photovoltaics and biogas self production might increase the competitiveness of micro-algae oil. Further investigations are however necessary to optimize their production chain and to increase the added value of co-products.

Biosynthesis of ethyl butyrate with immobilized Candida rugosa lipase onto modified Eupergit ® C

Abstract Lipase from Candida rugosa was immobilized onto the modified Eupergit®C. The support was treated with ethylenediamine and subsequently activated with glutaraldehyde. Enzyme immobilization efficiency was 85%. The optimum pH was close to 6.5 for both the free and immobilized lipase. Immobilized lipase retained its maximum activity in a temperature range of 55 – 60°C. Subsequently, ethyl butyrate synthesis was investigated using immobilized enzyme by esterification of butyric acid with ethanol in solvent-free conditions (23% product yield) and using hexane as a solvent (65% product yield). The acid-alcohol molar ratio and different enzyme amounts were tested as efficient reaction parameters. The biocatalyst maintained 60% of its activity when reused in 8 successive batch reactions in organic solvent. Therefore, the immobilized lipase has demonstrated its potential in practical applications such as short-chain ester synthesis for the food industry. Graphical Abstract