Bioethanol potentials from marine residual biomass: an Emergy evaluation

Abstract

Different types and sources of biofuels were recently studied as potential energy issues. The aim of this work is to evaluate the use of new kinds of renewable and alternative feedstocks for producing bioethanol. In particular, the potential production of bioethanol from cellulosic material was analyzed considering two species of macroalgae (C. linum, G. longissima) as residual biomass from an eutrophic lagoon system. Besides chemical analyses and the evaluation of yields in producing bioethanol, accounting methods are necessary to understand the level of sustainability of the whole production process exploiting natural resources. An assessment was carried out based on the emergy approach, in order to evaluate the environmental performance of processes in the case study. Results showed that macroalgae are a good candidate for bioethanol production even if bioethanol conversion from macroalgae biomass was found to be not very efficient per se. Nevertheless, the feedstock may be involved in processes of biorefinery in systems with a high carbohydrate content, in which heat necessary to treat the feedstock and maintain the micro organisms performing the transformation are provided by external sources already existing (e.g. a combined heat and power plant).

Utilization of Microalgal Biofractions for Bioethanol, Higher Alcohols, and Biodiesel Production: A Review

“…Microalgae contain proportions of biocompounds similar to those of human food sources [39]. Microalgal proteins are mixtures of amino acids and peptides, and they can be converted to higher alcohols [40]. Studies on transforming amino acids to biobutanol have recently been conducted ( Figure 2).…”

Meeting the U.S. renewable fuel standard: a comparison of biofuel pathways

“…In the classical method, the oil is mixed with an alcohol (usually methanol) and a basic catalyst (usually potasium hydroxide (KOH), or sodium ethanolate (CH3COONa) and heated to approximately 70 °C (at 20 psi) for several hours in a process called transesterification. The products are biodiesel (67%) and glycerol (33%) (Chisti, 2007;Coppola et al, 2009;Gouveia et al, 2009;Meng et al, 2009). …”

An Overview of Algae Biofuel Production and Potential Environmental Impact

“…Carbohydrates such as starches and sugars can be fermented to produce ethanol. 18 If algal oil is extracted for production of biodiesel fuel, producing ethanol can facilitate this process by becoming a key component of the transesterification process. Transesterification of algal oil can be accomplished with ethanol and sodium ethanolate, which serves as a catalyst.…”

“…The catalyst sodium ethanolate and ethanol react with the algal oil to produce biodiesel and glycerol. 18 Microalgae belonging to several different families possess the ability to produce and accumulate a large fraction of their dry mass as lipids, as listed in Table 2. 7,17,19 In microalgae, high cellular lipid content is often achieved under environmental stress, which can be caused by limitations of nitrogen, phosphorus, silicon, salinity, and iron.…”

“…Once the lipids have been extracted, the leftover solids are composed of mostly carbohydrates and proteins. Carbohydrates such as starches and sugars can be fermented to produce ethanol . If algal oil is extracted for production of biodiesel fuel, producing ethanol can facilitate this process by becoming a key component of the transesterification process.…”