Cultivation of algae with indigenous species – Potentials for regional biofuel production M. Odlare a,⇑ , E. Nehrenheim a , V. Ribé a , E. Thorin a , M. Gavare b , M. Grube b a School of Sustainable Development of Society and Technology, Mälardalen University, Box 883, SE-721 23 Västerås, Sweden b Institute of Microbiology and Biotechnology, University of Latvia, 4 Kronvalda boulevard, Riga, LV-1586, Latvia article info Article history: Received 25 August 2010 Received in revised form 28 December 2010 Accepted 3 January 2011 Available online 8 February 2011 Keywords: Energy Biofuel Cyanobacteria Green algae CO 2 -capture Eutrophication abstract The massive need for sustainable energy has led to an increased interest in new energy resources, such as production of algae, for use as biofuel. There are advantages to using algae, for example, land use is much less than in terrestrial biofuel production, and several algae species can double their mass in 1 day under optimized conditions. Most algae are phototrophs and some are nitrogen-fixing. Algae production there- fore requires only small amounts of amendments such as carbon sources and nutrients. In the present paper an experiment was performed using water sampled from Lake Mälaren in Sweden. The lake water is considered nutrient rich, has relatively neutral pH and is rich in organic compounds and suspended sol- ids. The idea behind this research was to enhance indigenous algae production rather than inoculate new species into the system. A simple experimental setup was designed where algae biomass growth was measured regularly over a 13 day period. FT-IR absorption spectra were evaluated in order to determine protein, lipid, carbohydrate and silicate contents of the algae. The algae community structure was char- acterized throughout the production cycle. Furthermore, the potential for energy supply for the transpor- tation sector in the Mälardalen region from algae cultivated as tested in the experiment was evaluated. Ó 2011 Elsevier Ltd All rights reserved. 1. Introduction A growing demand for energy has led to an increased interest in renewable energy sources, such as the extraction of biofuels such as biodiesel from algae. The advantages algae has over other biological sources of energy are many. For example, algae has far lower space requirements than land-based plant production and several algal species can double their biomass in 1 day. Most algae are photo- trophs and some are nitrogen-fixing, meaning that algae cultivation requires few additives such as carbon sources or nutrients. Algae can be cultivated in open ponds or in closed systems such as photobioreactors. The choice of reactor system depends upon a series of factors where there is a trade off between capital costs and rate and reliability of biomass production [1]. Commercial out- door systems mostly consist of large open ponds, tanks or raceway systems. The advantages of such systems are their simplicity and low cost, while their disadvantages are related to limited control of the growth conditions, water evaporation and invasion of undesired species [1]. One problem with open systems is that the optimal growth temperature is rarely attained and that the light availability is limited, which has also been shown to be a problem for phytoplankton growth in the Swedish Lake Mälaren [2]. How- ever, a combination of these systems, such as an in-lake basin with a flow through system and glass coverage, could be used to supply the algae with higher temperature and more stable growing condi- tions. At the same time, the nutritious conditions in Mälaren could be used to enhance growth, if the cultivation system was located close to a sewage treatment plant, for example. Mälaren is Sweden’s third largest lake and stretches from Stockholm on the Baltic coast to approximately 110 km inland. Mälaren has an area of 1120 km 2 , a maximum depth of 66 m and an average depth of around 13 m. This lake has become increasingly eutrophic as a result of the abundance of nutrients, particularly phosphorus. This has led to algal bloom, where algae and algae-like bacteria grow and form large plumes of biomass in the lake. The cultivation of algae for energy production requires efficient methods for quantifying and characterizing the composition of the biomass. Algal growth can easily be established through optical density (OD) measurements with a spectrophotometer [13]. One of the simplest and cheapest ways to monitor algal community development during the cultivation period is through microscopic assays of algae samples. As the macromolecular composition of the biomass is an integrated indication of the organisms’ physiological state and reflects the influence of cultivation conditions on cell regulatory mechanisms, it is important to accurately assess this 0306-2619/$ - see front matter Ó 2011 Elsevier Ltd All rights reserved. doi:10.1016/j.apenergy.2011.01.006 ⇑ Corresponding author. Tel.: +46 21 101611; fax: +46 21 101370. E-mail addresses: monica.odlare@mdh.se (M. Odlare), emma.nehrenheim@ mdh.se (E. Nehrenheim), veronica.ribe@mdh.se (V. Ribé), eva.thorin@mdh.se (E. Thorin), grube@lanet.lv (M. Grube). Applied Energy 88 (2011) 3280–3285 Contents lists available at ScienceDirect Applied Energy journal homepage: www.elsevier.com/locate/apenergy