Life cycle assessment of biomethane from offshore‐cultivated seaweed

Abstract

Algae are a promising source of industrial biomass for the future. In order to assess if aquacultured seaweed (macroalgae) could be considered an environmentally friendly source of biomass for bioenergy, life cycle assessments were performed for European countries, comparing methane as a biofuel from the anaerobic digestion (A) of whole seaweeds, (B) of alginate extraction residues, and (C) natural gas as a fossil fuel reference. These results clarify that the sources of electricity and energy used to heat the anaerobic digesters have an important impact. Recycling of materials and use of greenhouses at the nursery stage also allow environmental improvements for system (A). Ecodesign can make algal biomethane competitive in several categories compared to natural gas: a decrease of 21.9% and 54.2% in greenhouse gas (GHG) emissions and 58.6% and 68.7% in fossil depletion for systems (A) and (B), respectively, decrease in ozone depletion, and last but not least, improvement in the marine eutrophication index for system (A). For system (B), benefits are more arguable and dependent on the allocation. To conclude, seaweed could become competitive with terrestrial feedstock for biofuel production in the near future. © 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

Golden Tides: Problem or Golden Opportunity? The Valorisation of Sargassum from Beach Inundations

“…The gasification of seaweed with wood-based biomass was also considered economically feasible. Conversely, the large-scale anaerobic digestion or gasification of seaweed alone was considered extremely challenging economically, and will require seaweed to be delivered to the processing plant at below £300 per tonne [171,172]. However, the biomass from golden tides has no cultivation cost, with the only costs prior to AD being for collection, sorting, and transport.…”

Offshore and Multi-Use Aquaculture with Extractive Species: Seaweeds and Bivalves

“…The aim of the project was to produce biomethane and bioproducts from macroalgae cultivated in the open sea next to offshore wind farm facilities (Langlois et al 2012). A life cycle assessment for the production of biogas from offshore-cultivated macroalgal feedstock in a European framework was carried out, as well as production optimization from hatchery phase to offshore (Marfaing 2014).…”

El potencial de la maricultura de laminarias como fuente para la obtención de biocombustibles y otros bioproductos en la costa atlántica de España

“…Sin embargo, la producción comercial de biodiesel a gran escala tiene como principal limitación los elevados costes del cultivo y de la cosecha de la biomasa microalgal (Chisti 2007;Gouveia and Oliveira 2009;Griffiths and Harrison 2009). Recientemente las macroalgas han despertado también un gran interés como fuente de biomasa para la producción de biocombustibles (Gosch et al 2012;Hughes et al 2012;Kraan 2013;Langlois et al 2012;Wei et al 2013). Estas grandes algas marinas presentan importantes ventajas respecto a otras materias primas vegetales, como son su rápido crecimiento, además de que su empleo no compromete el suministro de alimentos básicos u otros productos derivados de las cosechas.…”

“…La biomasa de las macroalgas marinas contiene polisacáridos (compuestos ricos en azúcares), lípidos y proteínas, entre otros componentes orgánicos, que se pueden utilizar para producir diferentes biocarburantes. Estos serían el bioetanol a partir de la fermentación de los polisacáridos (Kraan 2013;Nahak et al 2010;Wei et al 2013), el biodiesel derivado de los lípidos mediante un proceso de transesterificación (Aresta et al 2005;Gosch et al 2012;Maceiras et al 2011), y el biogás producido por una digestión anaerobia de los compuestos orgánicos de la biomasa (Chynoweth et al 2001;Hughes et al 2012;Langlois et al 2012). La idea de utilizar las macroalgas como fuente de biocombustible fue concebida por Howard Wilcox a principios de los años 70, después de la primera gran crisis mundial del petróleo.…”