Review Article A critical look at the microalgae biodiesel Georgi Petkov, Albena Ivanova, Ivan Iliev and Irina Vaseva Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Sofia, Bulgaria The quantitative production of microalgae oil is often overestimated. The cost of the salts invested in the production of 1 kg algal diesel approximates the actual price of 1 kg mineral diesel. Total sum of electrical energy expenses for production of biodiesel from microalgae is several-fold higher than the energy income from combustion of the same quantity. The biological value of cultivated microalgae as food is much higher than as fuel. An opinion is shared that money ought to be invested in microalgal biomass production as a food additive, forage, and pharmaceuticals. The aim is to prevent making too hasty steps and investments in microalgal biodiesel. Keywords: Biodiesel / Microalgae Received: July 5, 2011 / Revised: November 2, 2011 / Accepted: December 15, 2011 DOI: 10.1002/ejlt.201100234 1 Introduction Production of oil from microalgae is an old idea which keeps cropping up almost every decade, for 50 years now [1–7]. Since the beginning of the new century, microalgae have persistently been considered as a possible good renewable source of diesel fuel. The algal fatty acids, converted into their methyl or ethyl esters, can be used as biodiesel [8–12]. The idea has been fostered all over the world and often under- pinned by wishful thinking proofs. Presently one can even find many e-books or other popular sources in the Internet selling the idea of algal biodiesel production ‘‘at home’’ or ‘‘in a garage’’. And indeed, there are not many technical hin- drances to produce biodiesel using almost any organism as a source. Being an interdisciplinary pursuit, the algae-diesel- idea requires theoretical knowledge as well as real life experi- ence in photoautotrophic biotechnology and industrial chemistry. In most of the cases, the experience is based on laboratory observations, and small outdoor devices, and the optimistic results are a consequence of extrapolation to much greater volume or surface. A look at the chart of Chisti [13] suggests that algal biomass should be extremely cheep and crude oil should be much more expensive in order to make the production of microalgal biodiesel economically reasonable. Research and development aiming at the prime cost decrease of micro- algae biomass is worth financing, but microalgal biodiesel production is nowadays a groundless venture, in particular, it can be disastrous for small and medium enterprises. This is in agreement with the opinion of Schneider [14], and with the results published by Carlsson et al. [15]. They both have referred to the words of Gerald Cysewski (Cyanotech Corp., Hawaii) about algal biodiesel: ‘‘Not from microalgae – I just can’t see it.’’ In a lecture, Venter [16] shared the opinion that genetically modified algae are perspective for biofuel production. However, a monoculture of a highly productive, preliminary selected strain cannot be easily cultivated in an open pond or a lagoon. The natural inhabitants of the basin will predominate and they will compete with the newly introduced algal strain. It is possible to increase the content of algae triacylglycerols via genetic manipulation but most probably the growth rate will remain a limiting parameter since it is inversely related to triacylglycerol content [17, 18]. High lipid-containing strains are already available. For some of them an oil content of 80% has been reported [13] without putting the focus on their extremely slow growth rate. Additionally a reasonable question arises: what has been referred to as oils in these highly pro- ductive strains: triacylglycerols or total lipids? We do not question the economical relevance of biodisel derived from other sources like higher plants, either usual or novel oil-bearing species. Just a century ago R. Diesel has conducted experiments with plant oils as fuel for his engines. Higher plants have the advantage of constant CO 2 supply, while algae need stirring in order to insure the access to this extremely important component. Plants receive and use direct, reflected, and dissipated light via the surface of their leaves, while algae can use only the light reaching water surface. Another disadvantage of algal cultivation is the longer time necessary to warm up the water layer in order Correspondence: Dr. Georgi Petkov, Institute of Plant Physiologyand Genetics, Bulgarian Academy of Sciences, G. Bonchev str., bl. 21, 1113- Sofia, Bulgaria E-mail: gpetkov@bio.bas.bg Fax: 359-02-873-99-52 Eur. J. Lipid Sci. Technol. 2012, 000, 0000–0000 1 ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com