Ciaran John Forde, Marie Meaney, John Bosco Carrigan, Clive Mills,

Susan Boland, Alan Hernon*

AER BIO, National Institute for Bioprocessing Research & Training (NIBRT), Blackrock, Co. Dublin, Ireland

Corresponding author email: alan. hernon@aer-bio. com

OUTLINE

Introduction 185

Sources of Biolipids 186

Plant-Derived Biolipids 186

Edible Lipids 186

Nonedible Lipids 187

Waste Edible oil 187

Animal-Derived Biolipids 188

Microalgae and Other Oleaginous Microorganisms — Derived Biolipids 189

Supply and Projected/Purrent Volume 190

Energy Balance 192

Processing of Biolipids and Properties of

Biolipid-Derived Biofuels 193

Extraction 193

Steam Distillation 193

Maceration (Solvent Extraction) 193

Enzymatic Hydrolytic Maceration 193

Expression (Cold Pressing) 194

INTRODUCTION

Biolipids have been an important source of energy since prehistoric times. While the term "biofuel" is now often synonymously used with "biodiesel", the first biofuels used were wood or other plant materials, which were burnt to provide heat, light, protection from
predators and for cooking. The earliest lamps recorded were made using plant material that was soaked with animal fat, such as lard. Later lamps, which used oils, were introduced in the eighteenth century, with early lamp fuels being oils from fish, whale and a variety of nut and other plant sources. Whale oil was much sought after for a lamp fuel as it produced a cleaner flame with

Bioenergy Research: Advances and Applications

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less odor and smoke. Another source of light was candles, which were made from tallow and other oils rendered from animal waste. These fuels are known as primary biofuels, fuels that are used without any signif­icant processing in contrast to secondary biofuels where significant processing is required before the raw prod­ucts can be used as fuels. As they were discovered, coal, gas and petroleum products (kerosene in partic­ular) slowly replaced tallow and other animal-based fuels. Similarly, the use of biolipids as transport fuel is not novel; in fact, in 1900 when Rudolf Diesel showcased his internal combustion engine at The Exposition Universelle in Paris it was fuelled by peanut oil (Stauffer and Byron, 2007). However, advancements in the use of petroleum as fuel at the turn of the century resulted in the selection of this abundant, cheap and efficient hydro­carbon as the fuel of choice for transport. It was not until the oil crisis of 1973 when oil became expensive and the security of supply became paramount that biolipids were investigated again; however, this interest was short lived as the supply of crude oil from the Organization of Arab Petroleum Exporting counties was restored in 1974. Now over 100 years after Diesel’s invention we are almost completely dependent on this finite, expen­sive and polluting hydrocarbon (petroleum) as a trans­port fuel. Consequently, the use of petroleum-based products has resulted in a significant number of envi­ronmental issues including global warming via the greenhouse gas (GHG) effect. Also, in an era when it is generally accepted that we have reached peak oil production and it is projected that the demand for trans­port fuel will increase globally by 39% in the next 10 years interest in the use of biolipids as fuel has reached new heights. Recent years have seen significant research, investment and advances in sustainable en­ergy technologies such as solar, wind, geothermal, tidal and hydroelectrical. It should be noted, however, that these energy sources, along with nuclear power, relate to the generation of electricity. Currently electricity only accounts for about 33% of the world energy market, whereas liquid fuels account for the remaining 67% of global energy consumption. These figures, along with the finite nature of crude oil stocks, illustrate the need to drastically increase the production of sustainable liquid fuels (Schenk et al., 2008). Alternative liquid fuel sources are continually being sought (Bereczky, 2012; Singh and Singh, 2010) and while the obvious solution is to revert to the use of vegetable oil used in 1900, there are several problems with that approach. Most notably is the need to use arable land to feed the world’s exponen­tially growing population. Land use for the production of liquid biofuels has become a hotly debated topic since 2007 when a combination of poor harvests and alloca­tion of vast quantities of land for the production of biofuel (mostly corn ethanol) resulted in a spike in world food prices (Tenenbaum, 2008). The ease in supply of food to the world market in 2007/2008 acted at an indi­cator to what will happen in the future as the world’s population increases beyond 8 billion people and we struggle to meet the nutritional needs of humankind. It will simply be impossible to grow enough terrestrial crops to meet the worlds nutritional and energy needs. It is therefore necessary to explore the use of biolipids from all sources including lipids from plant, animal and microalgae sources. Recovering lipids from waste products like recovered vegetable oil and beef tallow will also have a role to play in meeting our insatiable demand for energy. Therefore, it is important to judicially select biolipids that require the minimum land usage (maximizing ton of oil per hectare) and lipids with good fuel properties, as discussed below. In addi­tion, the energy consumed in growing and recovering the biolipid is also an important consideration when selecting a biomass for the production of biofuel.