Large-scale production of biofuels from algae is currently unsustainable according to the conclusion of a report from the National Research Council of the US National Academies. Published in October 2012, the outcome is based on the water, energy and nutrient requirements of existing technologies to produce enough algae to meet 5% of the US transportation fuel needs.
Aiming to address this issue, the Integrated Sustainable Algae (InteSusAl) project was launched on 1 May 2011. Led by The Centre for Process Innovation (CPI, UK), the consortium plans to demonstrate an integrated approach to generate biofuels from algae in a sustainable manner on an industrial scale.
Although algae cultivation has a major advantage over other biofuels by not competing for agriculture land, the low concentrations that phototrophic growth can support means large amounts of water are required for cultivation. There are then large power requirements to separate the cultivated algae from the water. This limit of phototrophic growth is mainly due to the self-shadowing of the cells. To overcome this barrier, InteSusAl will use heterotrophic technologies to increase the cell densities.
The project, co-funded by the European Commission under the 7th Framework Programme, has now carried out screening of algae strains for optimal growth and oil production within the different production technologies. CPI is designing a novel low cost fermentation system that aims to allow an economic production of algae from bio-diesel glycerol. From laboratory trials each 1kg of glycerol used will produce 0.8kg of biomass. This biomass can, after extraction, obtain triglycerides for bio-diesel production and the remaining cellular material used as feed to bio-ethanol fermentation. The majority of the biomass is made via the heterotrophic module reducing the water usage by an order of magnitude. Use is made of the other nutrients that are present in the bio-diesel glycerol. Heterotrophic growth of algae overcomes the low cell densities caused by slef shaowing by feeding a carbon source to the algae in the fermentation system. Cell densities of 50g/l have been achieved compare to a photo bio-reactor reaching densities of 4g/l.
InteSusAl will consider sustainability across the whole process, in terms of both economic and environmental (closed carbon loop), implications including optimum use of algal biomass resources to enable commercialisation. To demonstrate the project’s integrated and sustainable approach, InteSusAl will operate a production unit on a 1 hectare site, growing 90-120 tonnes of dry algae per year. The current activities also include the commissioning of an industrial scale low cost fermentation unit for location on the production site.
The InteSusAl consortium is composed of six partners coming from four European countries, whose complementary expertise will enable successful delivery of the projects. The Royal Netherlands Institute for Sea Research (NIOZ, NL) provides expertise in algae strain selection and growth. The Wageningen UR Food and Biobase Research (DLO-FBR, NL), is developing harvesting techniques to minimise energy usage and additives such that the majority of the water can be recycled. The demonstration unit will be hosted in Portugal by Necton, alongside with their existing commercial photo bio-reactors. The National Renewable Energy Centre (NAREC, UK) is carrying out a life cycle analysis to compare the sustainability of this approach to the other European co-funded projects in the Algae cluster and to fossil fuels. Dissemination and exploitation of results are being led by the European Renewable Energy Research Centres Agency (EUREC, BE).