Production of liquid fuels from biomass by pyrolysis and fermentation

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  1. Introduction

Energy makes all life possible. However, after the industrial revolution, carbon dioxide () emissions, as a result of energy production, have risen dramatically. Since 1990, temperatures globally have risen by 0.2 ۫C and the  concentrations in the atmosphere have increased from 354 parts per million (ppm) to 380 ppm and still increasing.  If no action is taken, average temperatures globally could increase by 5.8 ۫C by 2100 and sea levels from 0.09 to 0.88 meters (Institution of Mechanical Engineers, 2009). According to a report produced by World Energy Outlook (WEO) in 2009 “to avoid the most severe weather and sea-level rise and limit the temperature increase to about 2˚C, the green house-gas concentration needs to be stabilised at around 450ppm  equivalent” (International Energy Agency, 2009). Similarly, a recent report by the Institution of Mechanical Engineers claimed that if no action is taken, sea levels will increase by 7 meters by 2250, flooding much of London, East Anglia and other coastal areas. In the same report it is stated that “Our climate is changing so unless we adapt, we are likely to face a difficult future” (Institution of Mechanical Engineers, 2009). Moreover, the International Energy Agency, estimates that energy demand across the world will increase by 50% to 60%, between 2004 and 2030 (International Energy Agency, 2009). Because of these facts, concerns globally have increased, and people seek alternative methods of producing energy, more sustainable and less harmful for the environment and for all leaving organisms. One such renewable energy resource in Biomass.

Biomass, although its combustion emits  like fossil fuels, its considered a renewable form energy. The reason for this is that the amount of  that is released to the environment during the combustion was previously absorbed from the air, while the biomass plant was growing, over a short period of time. Thus, the biomass combustion system is considered to be Carbon Neutral. Furthermore, there is a major difference between biomass and fossil fuels. In contrast, burning fossil fuels releases  which had been locked up for millions of years in the ground, and will require millions of years to return back there. Replacing fossil fuel with a solid biomass fuel will typically reduce net  emissions by over 90% (nearly carbon neutral) (Liu, 2010). However, it should be noted that, some  emissions do occur, during its cultivation and combustion.

  1. Defining Biomass

According to Biomass Energy Centre (BEC), biomass can be defined as “the biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material […] (It) is composed of a mixture of organic molecules containing hydrogen, usually including atoms of oxygen, often nitrogen and also small quantities of other atoms, including alkali, alkaline earth and heavy metals.  These metals are often found in functional molecules such as the porphyrins which include chlorophyll which contains magnesium” (BEC © Crown Copyright, 2008).

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However, biomass is not a new source of energy, on the contrary, is considered as one of the oldest sources. Burning wood, for example, to cook, produces energy from biomass. Humans have been using this source of energy for more than 400,000 years, and in some less economic developed countries, still do.  As shown in Figure 1, biomass is one of the world’s most used alternative energy resource.  Yet, a great part of its usage is unsustainable, contributing this way to the global warming (Thomas, 2008).

Biomass for use as fuels can be either gathered or grown. The main biomass ...

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