Lauro A. Ribeiro, Patricia Dias, Luis Felipe Nascimento and Patricia Pereira da Silva

Abstract Despite the challenges, depending on the local conditions and practices, renewable energy sources are already a significant contribution to the energy mix. Although this is true for electricity generation, the same does not apply for the trans­portation sector, where the available renewable sources are limited and still have a modest impact in the overall consumption. In this context, advanced biofuels such as microalgae are worldwide believed to be a better choice for achieving the goals of incorporating non-food-based biofuels into the biofuel market and overcoming land — use issues. Compared to other biofuel technologies, the most favorable factors for the cultivation of microalgae for the production of biofuels are they can be grown in brackish water and on non-fertile land, and the oil yield production is far supe­rior. Main challenges are currently the feasibility of large-scale commercialization, since the majority of economic and financial analyses rely on pilot-scale projects. Environmental issues are most likely to diverge opinions from experts. This chapter presents a review of microalgae cultivation (species, usage, processes, and culture) and biofuel production, highlighting advantages and challenges of algae biofuel.

L. A. Ribeiro (*)

School of Sciences and Technology, University of Coimbra and INESCC, R. Antero de Quental, 199, 3030-030 Coimbra, Portugal e-mail: lribeiro@inescc. pt

P. Dias • L. F. Nascimento

Management School, Federal University of Rio Grande do Sul, Av. Washington Luiz, 855, 90010-460 Porto Alegre, Brazil e-mail: patricia. dias@ufrgs. br

L. F. Nascimento

e-mail: nascimentolf@gmail. com

P. P. da Silva

School of Economics, University of Coimbra and INESCC, R. Antero de Quental, 199, 3030-030 Coimbra, Portugal e-mail: patsilva@fe. uc. pt

A. Domingos Padula et al. (eds.), Liquid Biofuels: Emergence, Development and Prospects, Lecture Notes in Energy 27, DOI: 10.1007/978-1-4471-6482-1_12, © Springer-Verlag London 2014

1 Introduction

Innovative technologies and sources of energy must be developed to replace fossil fuels and contribute to the reductions of emissions of greenhouse gases associated with their use. Biofuels are particularly important as an option by means of trans­portation that lack of other fuel options (especially trucks, ships, and aircrafts). However, alternative sources of biofuel derived from terrestrial crops such as sugarcane, soybeans, maize, and rapeseed impose pressure on food markets, con­tribute to water scarcity, and precipitate forest devastation. In this way, the sustain­ability of biofuels will depend on the development of viable, sustainable, advanced technologies that do not appear to be yet commercially viable.

In this perspective, algal biofuels are generating substantial awareness in many countries. In the United States, they may contribute to achieve the biofuel produc­tion targets set by the Energy Independence and Security Act of 2007. Likewise, in the European Union (EU), they may assist to the achievement of goals established in the recent Renewables Directive. In order to address the technical-economic barriers to the further development of this type of bioenergy, it is thus necessary to contribute with a study that incorporates biomass feedstock availability assess­ment, production, management, and harvesting in support of the upscaling of this promising technology.

Biodiesel and bioethanol are the two liquid biofuel options currently looked upon with more attention and under more vigorous development, since they can be used in today automobiles with little or no modifications of engines, for replac­ing diesel and gasoline, respectively. The Directive 2009/28/CE also targets the transportation sector fuels; in particular, each member state should reach a mini­mum 10 % share of renewable energy by 2020. Complementary, the Directive also states that this must be possible by using electricity and sustainable biofuels (i. e., based on a sustainable production). It also mentions that correct sustainability cri­teria should be adopted for biofuels, so that the rising world demand for biofuels does not destroy or damage land biodiversity and establish many others’ recom­mendations to ensure total sustainability of biofuels. An interesting point of this Directive is that, it recommends member states to incentive and support the use of biofuels that add supplementary diversifying benefits, such second — and third-gen­eration biofuels (e. g., biodiesel from microalgae or bioethanol from lignocellulosic materials). Some changes were recently proposed to the Directive 2009/28/CE (EC 2012), in particular dealing with the calculation of the carbon footprint, namely how to account for the ILUC (indirect land-use changes), and setting new goals deemed more adequate to promote the growing European biofuels industry.

In this context, the overall purpose of this literature review is to provide an inte­grated assessment of the potential of microalgae as a source to produce biofuels, while confronting it with competing emerging biofuel technologies. It is intended to provide a comprehensive state of the art technology summary for producing fuels and coproducts from algal feedstocks and to draw some insights into the fea­sibility and techno-economic challenges associated with scaling up of processes.