Algae is proving itself as one of the most productive sources of biofuel. Frank Rogalla of Aqualia reveals EU demonstration projects being undertaken to enhance efficiencies in the process
But if all the world's current consumption of diesel, close to 700Bl/yr, were to come from biofuel, the annual need of phosphorus would triple to 120Mt/yr of P2O5 - reducing the reserves to a mere 100 years. Recovery of phosphorus is therefore critical.
Analysis done by Professor Kroiss of the Technical University of Vienna has shown that about half of Austria's phosphorus needs for agriculture can be found in sewage sludge, and an equivalent amount is lost by run-off through surface waters. To capture the phosphorus, wastewater nutrients could be converted to biofuel - hence the sudden popularity of green algae, which can contain up to 50% in oil, as one of the most promising renewable fuel feedstocks.
Microalgae are among the fastest growing photosynthetic organisms, with carbon fixation rates significantly higher than those of landgrown plants - allowing a continuous harvest with cycles ranging between one and ten days. The produced oils could be converted into biodiesel and carbohydrates, in turn fermented into ethanol - while the biomass residue can be used for further energy production, such as anaerobic treatment, combustion in combined heat & power applications, or synthetic biofuels via gasification and pyrolysis.
First experiments on small-scale in reactors of 200l, in Almeria, Spain, or 100l, in Firenze, Italy, animated by the craving for new, sustainable energy sources, report algae productivity of around 20,000l/ha/yr of oil. This promises a yearly yield three to five times higher than conventional sources of biofuels:
- Palm oil - 3000 to 6000 l/ha
- Sugar cane - 4000 to 7500 l/ha
The conclusions showed that algal biodiesel production cost would be close to around US$1/l, based on the best long-term projections for the performance of the technology. Even with assumptions of US$50 per tonne of CO2 as a carbon credit, the cost of biodiesel never competes with petroleum diesel, which has a production cost including operations and capital, of about one order of magnitude less, averaging around US$0.1/l, ranging from US$5/barrel in Saudi Arabia and Iraq to US$30-40/barrel in offshore production in Nigeria or Angola.
While the initial algae-to-fuel research failed to deliver convincing results then, recent concerns for issues such as climate change and the impacts of fuel crops on food production and land use change have broadened the search for alternative feedstocks and rekindled the interest in algae. The EC is participating in the funding of three large-scale industryled projects aimed at demonstrating the production of algal biofuels along the whole value chain, covering strain selection to algae cultivation and production, oil extraction, biofuel production and testing in vehicles.
The Seventh Framework Programme (FP7) for research and technological development provides the structure for reaching the EU goals of growth, competitiveness and employment, with a €51B budget for the seven-year period, of which 5% is earmarked for energy-related projects. The EU has issued calls for demonstration projects that put particular emphasis on biofuel production from lignocellulosic biomass and addresses the complete value chains from raw resources to a final marketable biofuel.
The 2010 call topic of Algae to Biofuels is aimed at large-scale demonstration of biofuels production from algae with ambitious, but achievable targets:
- Minimum plantation area of 10ha
- Minimum productivity of 90t dry solid (DS) / ha/yr
- energy efficiency;
- economic viability; and
- environmental sustainability.
The InteSusAl consortium is comprised of nine partners, including academic, industrial and public sector representation, and is coordinated by the Centre for Process Innovation in north-east England, which will provide key background research and development to the project. Partners include the Brussels based European Renewable Energy Centers Agency, process equipment manufacturer GEA Westfalia Separator, Wageningen University in the Netherlands, the Netherlands Institute of Ecology, the UK National Renewable Energy Centre, the Turkish research enterprise Ege Biyoteknoloji, and the public authorities and bus operators of the Turkish municipalities of Seferihisar and Bornova.
Through the integration of novel, enclosed raceways and photobioreactors, powered by stored renewable energy sources, optimised algal growth was estimated to yield more than 1500t dry algae on 10ha in a period of 18 months. From this dry mass, 580t will be converted of biodiesel, to be used in Turkey in public transportation fleets with control vehicles operating within the same fleets.
Glycerine from the biodiesel process will be used to provide a carbon source to enhance the microalgal growth in the cultivation phase. In addition, and as part of the integrated sustainable approach to this work, the fermentation of biomass to produce methanol to catalyse the transesterification reactions will be assessed.
The All-Gas project aims to demonstrate the sustainable production of low-cost biofuels from algae, based on the reuse of wastewater and other residues, taking into account that:
- Providing microalgae with synthetic fertilizer as a nitrogen source could already account for up to one-third of the theoretical energy content of the produced biomass, estimated around 5kWh/kg. Freshwater algae in high growth conditions can contain up to 10% nitrogen, leading to an external energy input in the form of nitrogen of 1.5 kWh/kg of algal biomass
- Wastewater treatment plants (WwTP) today do not take advantage of the energy content of organic matter in municipal effluents, estimated at 2.5kWh/m3, or five times the energy used in its treatment. On the contrary, nitrogen fertilizer is lost into the atmosphere as gas within the treatment process, in order to meet the nutrient discharge limits
If the target productivity of the algae cultures - 3,000kg DS/d - is reached, with algal oil content of 20%, enough biodiesel to run about 200 cars could be generated. The bio-methane production from the anaerobic digestion of raw wastewater and biomass residues should yield an equivalent amount of bio-methane for another 200 cars. Wastewater flow of around 5,000m3/per day would be treated to a level allowing for reuse, minimizing emissions, energy consumption and wastewater process residues.
The project will be implemented in twostages at a WwTP in southern Spain, starting with a prototype facility to gather the main design parameters for the full-scale plant during the first two years. Once the viability and sustainability of the concept has been verified in full-scale ponds of 1,500m2 each, 10 hectares will be developed and operated during the following three years.
Spanish water and wastewater company Aqualia leads the consortium of the All-Gas project, consisting of seven partners: the Netherlands-based FeyeCon Group, Turkish manufacturer MTD Turkbiodiesel, BDI - BioEnergy International of Austria, Dutch gas handling specialist Hygear, The University of Southampton and the Fraunhofer Umsicht Institute in Germany.
The BIOfuel from Algae Technologies (BIOFAT) project targets both biodiesel and ethanol production, based on optimised growth and starch and oil accumulation, with CO2 from industrial fermentation used as a renewable carbon source. Coordinated by Abengoa Bioenergía Nuevas Tecnologías (ABNT), the other nine partners include the Department of Agrarian Biotechnology at the University of Florence and its spin-off company Fotosintetica & Microbiologica, Algal Fuel (A4F) of Portugal, Israel's Ben Gurion University, Dutch company Evodos, Algosource Technologies (AST) of France and US company Hart Energy Consulting.
The BIOFAT process will be based on a technology hybridisation approach. The process is on photobioreactors, operated under culture stress conditions to allow for high productivity, followed by a raceway stage for bulk biomass production, modifying the culture conditions in order to induct oil and starch accumulation.
The final step includes the harvesting and unit operations focused on algae fractions separation for ethanol and biodiesel production, plus other co-products (the 'algorefinery' concept). The project will be implemented in two phases: first, strain selection and process optimisation in a one hectare demo-scale facility, and second, economical modelling, including scale up to a 10ha demo facility, pursuing the following scientific and technology objectives to reach competitive and sustainable algal biomass production.
Because of the dual product approach, BIOFAT aims to develop and cultivate algae maximising oil and starch content. Algae oil will be dedicated to biodiesel production, while biomass (starch) will be available to produce second-generation ethanol through traditional fermentation processes.