Thesis L Garcia Alba

ALGAE BIOREFINERY: AN EXPERIMENTAL STUDY ON LIQUID FUELS PRODUCTION AND NUTRIENTS RECYCLING AN EXPERIMENTAL ALGAE BIOREFINERY: ISBN: 97890-365-3552-6 INVITATION Hier komt de tekst voor de rug; hoe dikker rug, groter tekst de tekst Hier komt It is my pleasure to invite you to the defense of my PhD thesis on st June 21 , 2013 at 16:45. University of Twente - Waaier Prof.dr. G. Berkhoff-zaal ALGAE BIOREFINERY An experimental study on liquid fuels production and nutrients recycling ALGAE BIOREFINERY At 16:30, I will give a brief introduction to An experimental study on the content of my thesis. liquid fuels production and Laura Garcia Alba nutrients recycling [email protected] +31611531976 Laura Garcia Alba Laura Garcia Paranymphs: Laura Garcia Alba Pavlina Nanou [email protected] +31638303692 Rens Veneman [email protected] +31625037462 ALGAE BIOREFINERY An experimental study on liquid fuels production and nutrients recycling Promotion Committee: Chairman: prof. dr. G. van der Steenhoven University of Twente Promotor: prof. dr. S.R.A. Kersten University of Twente Assistant promotor: dr. ir. D.W.F. Brilman University of Twente Members: prof. dr. G. Mul University of Twente prof. dr. ir. H. van den Berg University of Twente prof. dr. P.E. Savage University of Michigan prof. dr. D. Fabbri University of Bologna dr. ir. A.M. Verschoor Duplaco/Wetsus The research described in this thesis was financially supported by the province of Overijssel via the Green Energy Initiative of the University of Twente. Cover design: “Un paseo por la playa” by Angel Garcia Vela (coast of Noordwijk, NL). Design by Cenk Aytekin (http://www.cenkaytekin.com/). Algae Biorefinery: An experimental study on liquid fuels production and nutrients recycling ISBN: 978-90-365-3552-6 DOI: 10.3990/1.9789036535526 URL: http://dx.doi.org/10.3990/1.9789036535526 Printed by Gildeprint, Enschede, The Netherlands © 2013 Laura Garcia Alba, Enschede, The Netherlands ALGAE BIOREFINERY AN EXPERIMENTAL STUDY ON LIQUID FUELS PRODUCTION AND NUTRIENTS RECYCLING DISSERTATION to obtain the degree of doctor at the University of Twente, on the authority of the rector magnificus, prof. dr. H. Brinksma, on account of the decision of the graduation committee, to be publicly defended on Friday 21st of June 2013 at 16:45 by Laura Garcia Alba born on September 26th, 1985 in Tarragona, Catalonia, Spain This thesis has been approved by: Prof. dr. S.R.A. Kersten (promotor) Dr. ir. D.W.F. Brilman (assistant promotor) A mis padres Dulce y Angel por todo vuestro amor y paciencia “Celebro que estéis bien” (Francisco Alba Lago, mi abuelo) Contents Chapter 1 Introduction 1 Chapter 2 Hydrothermal treatment (HTT) of microalgae: Evaluation of the process as conversion method in an 25 algae biorefinery concept Appendix A 63 Chapter 3 Hydrotreatment of hydrothermal liquefaction oil from 97 microalgae: Preliminary results Appendix B 121 Chapter 4 Experimental and economical evaluation of supercritical 133 CO2 extraction of oil from microalgae Appendix C 175 Chapter 5 Microalgae growth on the aqueous phase from 181 hydrothermal liquefaction of the same microalgae Chapter 6 Recycling nutrients in algae biorefinery 205 Appendix D 233 Chapter 7 Summary and Outlook 239 Samenvatting 253 Resum 259 Publications list 265 About the Author 267 Acknowledgments 269 Chapter Introduction ABSTRACT The research described in thesis deals with microalgae as renewable source for the production of liquid biofuels within a biorefinery configuration. In this chapter, first the research context is presented followed by a summary of the aspects that highlight the potential of microalgae for the production of biofuels and biochemicals. Subsequently, the concept of biorefinery is introduced showing how that has been defined for algae. In addition, we present a brief overview of the past and recent developments in the frame of algae-to-fuels to underline the commercialization potential of this type of biomass. Lastly, the scope and outline of this thesis are given. Introduction 1 Research context 1.1 The need for sustainable development In the context of sustainability, if we want future generations to remember us for our accomplishments, and not for our mistakes, drastic changes have to be made. Industry, academia and many other social institutions are joining efforts to lessen the self-created footprints which might not be drastically affecting today’s society, however will be the challenges of the near future. Society is facing the ongoing rise of three aspects that are closely linked to each other: The continuous growth of the world’s population and its economies increase in energy demand increased consumption of fossil fuels. Hence, conventional fossil fuels (coal, conventional natural gas and petroleum) reserves are decreasing and will eventually be exhausted. This results in a regular increase (on average) of fossil fuel prices and discussions on security of supply, which further contributes to more economical and political conflicts. In addition, the increase of 1 anthropogenic CO2 in the atmosphere and emissions is a proven fact, driven by the extensive use of fossil fuels together with deforestation. On the other hand, the recent “shale gas revolution” should not be overlooked.2 That term was given for the phenomenon that emerged in the United States and refers to the increased prospects of shale or unconventional natural gas supply (gas defined as unconventional in the sense of its less accessible location compare to that of conventional natural gas). Recently, in the U.S., shale gas has become available in larger quantities due to technological developments for its extraction and other legal aspects favoring its progress. Experts have indicated that reserves of this gas are very large and well distributed over the globe which would lead to a more diversified energy supply. However, environmental concerns have also grown regarding the hydraulic fracturing recovery process or also known as fracking. It requires large amounts of water and it also uses chemicals that can leak and lead to contamination of ground water. Moreover, its input on GHG emissions is still under debate since the real amount of methane that leaks during processing is not clear. It might be a solution in the short term, but it is still a finite source of which realistic prospects are still unclear. Additionally, there is a general disagreement between experts in the field on its sustainability. That general uncertainty could delay its deployment. If 3 Chapter 1 that happens and, in parallel, the investments on renewables are lessen due to the current shale gas revolution, it might be too late for a solution to climate change. Therefore, the development of renewable alternatives –for heat, power, transportation fuels and chemicals– is still essential and shall continue. Probably, the situation will be that both renewables and shale gas will contribute together to a greener future. The same as for the energy sector, linked aspects appear also for the food sector in the framework of depleting resources: The continuous growth of the world’s population and its economies increase in food demand increased consumption of fertilizers. Fossil fuels are not the only depleting natural source. Existing rock phosphate reserves, mined to recover phosphorous, could be exhausted in the next 50–100 years.3 At the same time, the production of nitrogen for mineral fertilizers (the Haber process) requires significant amounts of depleting fossil energy. Phosphorous, together with nitrogen and potassium, are combined into mineral fertilizers which are essential for food production. Therefore, both depletion of fossil fuels and phosphate rock reserves will contribute to the increase of food price. Yet an important difference exists between oil and phosphorus: oil can be replaced by other non-carbon forms of energy while, in food production, there is no substitute for phosphorus and, hence, it can only be reused to alleviate its depleting trend.3 All these highlight the importance of recycling and closing the material cycles. 1.2 The path towards sustainable development Production of heat and power in a sustainable manner can be achieved by the use of several renewable resources such as hydro, tidal, wind, geothermal and solar. Yet it is likely that for the coming decades there will be a demand for liquid fuels in the sector of long distance transportation (mainly aviation, shipping and trucks) as they are more efficiently stored and transported than any other energy source. Moreover, crude oil makes up a much larger share of the current global energy demand (∼41.2% as reported recently by the International Energy Agency4 for 2010), and it will remain like this unless new breakthrough technological developments emerge in the field of electricity. Among the alternative sources, biomass is the only renewable source that can directly store energy in the form of carbon containing molecules. The main building block of chemicals and fuels is carbon. Consequently, biomass can be an optimal source of carbon towards a more sustainable development for the production of bio-based fuels and 4 Introduction chemicals. With the utilization of biomass (or its products), greenhouse gas emissions are significantly reduced, and yet more, a carbon neutral cycle can be achieved when its consumption and production occur in short cycles. Biofuels production can contribute to diversify income and fuel supply sources thereby increasing the security of energy supply.5 Despite the abovementioned and many other benefits, biomass should be carefully managed to minimize the fossil energy input and environmental footprints (related to e.g. land and water use, and biodiversity) derived from its utilization. Clearly, we do not want to have the same negative impacts or create new ones as those we are trying to alleviate or avoid. There are different types of biomass from which both gaseous (e.g. H2 and CH4) and liquid biofuels (the focus of this research) can be produced.

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