Razif Harun, Mark Doyle, Rajprathab Gopiraj, Michael Davidson, Gareth M. Forde, and Michael K. Danquah

Abstract With the current global drive towards a low-emission economy, countries need to take a stance. For example, Australia, which is one of the world’s largest polluters, has made a commitment that before 2020 its overall emissions would be reduced by 5-15% below the levels registered in the year 2000. To realise these targets, processes which capture carbon dioxide will prove critically important. One of such emerging processes is carbon dioxide capture for microalgae cultivation and subsequent downstream biomass processing for biodiesel production. This chapter will entail engineering scale-up, economic analysis and carbon audit to ascertain the viability of an industrial scale microalgal biodiesel production plant. This will involve the development of an industrial scale model to determine the feasibility of a real large-scale plant. Data from each process step (cultivation, dewatering, lipid extraction and biodiesel synthesis) will be presented individually and integrated into the overall process framework.

1 Introduction

Lack of sustainable energy resources currently threatens the survival of an increas­ingly globalised world economy. Due to the heavy dependence on limited fossil fuel resources, renewable alternatives which are able to compete with conventional energy options must soon be developed. Steady increases in the price of crude oil, for instance, are being observed, due to rising demands and the escalating scarcity of reserves. In addition, the increasing accumulation of CO2 in the atmosphere and

R. Harun • M. Doyle • R. Gopiraj • M. Davidson • G. M. Forde • M. K. Danquah (H) Bioengineering Laboratory, Department of Chemical Engineering,

Monash University, 3800 Clayton, VIC, Australia e-mail: michael. danquah@eng. monash. edu. au

J. W. Lee (ed.), Advanced Biofuels and Bioproducts, DOI 10.1007/978-1-4614-3348-4_30, 709

© Springer Science+Business Media New York 2013

its impact on climate change have provided a significant driver for change. Amid growing concerns, global agreements to limit greenhouse gas (GHG) emissions, such as the Kyoto Protocol, have been formed. Directly resulting from such agreements, many developed countries have adopted the “cap-and-trade” carbon trading schemes in efforts to curb emissions. Thus projects which capture CO2 to prevent release into the atmosphere will play a significant role in combating climate change.

Biofuels such as biodiesel and bioethanol are possible alternative fuels. Current biofuel production requires increasing amounts of arable land for biomass cultiva­tion, which compete with terrestrial fuel crops, thus heightening concerns over food affordability. Microalgae offer a unique alternative as it does not compete for culti­vation logistics with agricultural food crops. Microalgae could harbour a substantial amount of lipids for biodiesel production and carbohydrates for bioethanol production.

This chapter entails the engineering scale-up, economic analysis and carbon audit to ascertain the viability of an industrial scale microalgal biodiesel production plant. This will involve the creation of an industrial scale model that can be used to determine the feasibility of a large-scale plant. Four major stages are considered here: microalgal cultivation, dewatering, lipid extraction and transesterification (biodiesel production).