The object of this report is to consider if current and possible future biofuel technologies can be used to reduce dependence on liquid fossil fuels and to determine the potential impacts of biofuels on greenhouse emissions, food production and the global environment. The political and economic implications of changes are reviewed and the increased role of biofuels in transport is summarised from both the short-term and long-term view.
Biofuels are derived from organic material, commonly known as biomass and they can be classified as either ‘first generation’, ‘second generation’ or more recently ‘third generation’ fuels.
First-generation fuel is generally the edible part of plants which includes grains, sugars or seeds. This is currently the most commercial but also possibly the most controversial fuel.
Second-generation fuel is generally made from lignocellulosic biomass, the non-edible parts of feedstock, which includes purpose grown grasses, trees and the waste or crop residue. This technology is relatively new and underdeveloped.
Third-generation fuel is algae that can be cultivated more or less anywhere and can produce large quantities of lipids (plant oils). This technology has the potential to produce large amounts of cleaner, affordable biofuel but mass producing algae is still a few years away (Goldenburg 2010).
Potential of biofuels to reduce dependence on liquid fossil fuels
There is much potential for biofuels to reduce dependence on liquid fossil fuels.
The two most common biofuels used in the transport sector are ethanol and
Biodiesel. These can be used as substitute fuels or mixed with fossil fuels. In the UK Tesco sells E5 or 99 RON super-unleaded and B5 biodiesel this is used in unmodified vehicles (Oilgae 2006). To use higher concentrations of bioethanol E85 or B30 biodiesel, vehicles need to be either purposely manufactured such as the “flex-fuel” or be modified (The AA 2010). This all costs extra money and currently in the UK there are limited options to reduce dependency on fossil fuels.
i. Alternatives to Petroleum Fossil Fuel
Bioethanol is basically made in the same way as alcoholic beverages by fermenting the sugar components of the biomass to produce alcohol (see figure 4). Bioethanol is a clear flammable liquid that can be used in its pure form as in Brazil where E100/E95 ethanol is called ‘alcool’. In colder climates pure ethanol can increase emissions and cause starting problems due to viscosity, so E85 a mixture of 15% petroleum and 85% ethanol is generally used (Cleanairtrust 2009).
Ethanol can be produced from any biological feedstock that contains sugar (carbohydrates) or materials that can be converted into sugar such as starch or cellulose (BTH 2007).
Sugar Feedstock (1st generation) includes sugar beets, sugar cane and sweet sorghum. These feedstocks contain high percentages of sugar and are known as simple sugars that are easily turned into ethanol via fermentation and distillation.
Figure 1: examples of sugar feedstock used for ethanol production (BTH 2007)
Starch Feedstock (1st generation) includes corn, maize, wheat, barley, oats, spelt, triticale, rye, sorghum grains, cassava and potatoes. Starch has complex sugars and to produce ethanol from starch it takes much more effort than from sugar crops. First it needs to be converted into sugar and then into ethanol. According to Fritsche (2008) many crops such as maize produce almost as much greenhouse gas in production as using fossil fuels.
Figure 2: examples of starch feedstock used for ethanol production (BTH 2007)
Cellulosic Feedstock (2nd generation) includes willow, hybrid poplar trees, eucalyptus, miscanthus (elephant grass) and switchgrass. To produce a fuel from cellulose it is more costly than producing ethanol from sugar or starch but as more large-scale production facilities are introduced the costs will come down (Techpulse 2010).
Figure 3: examples of cellulose types of feedstock for ethanol production (BTH 2007)
There are two fundamental reactions in converting biomass to bioethanol these are:
Hydrolysis – is the chemical reaction that converts complex polysaccharides in the feedstock to simple sugars. To convert biomass to bioethanol, acids (generally diluted sulphuric acid) and enzymes (fungal produced amylase) are used to catalyse this reaction (Janssen and Rutz 2007).
Fermentation – is currently the most used technology in biofuel production. It involves an anaerobic breakdown of sugars caused by yeast or bacteria which feed on the sugars. Ethanol and carbon dioxide are formed as the sugar is expended. The fermentation equation for the 6-carbon sugar, glucose, is:
(Glucose) C6H12O6 à (Ethanol) 2C2H5OH + (Carbon Dioxide) 2CO2
Figure 4: Fermentation equation
ii. Alternatives to Diesel Fossil Fuel
Biodiesel can be produced from plant oils (lipids), animal fats, algae and waste cooking oil which are biodegradable and renewable. Vegetable oils and animal fats are triglycerides esters of glycerol with three fatty acid chains (Strath 2006). The process used to convert these oils to Biodiesel is called transesterification see figure 5.
Figure 5: Transesterification process
Biodiesel feedstock use photosynthesis to convert solar energy into chemical energy. When the plant is burned the stored chemical energy is released (Beyer 2008). Oilseed crops are the main feedstock for biodiesel these include rapeseed, sunflower seed, soybean, palm, coconut, jatropha oil. There are hundreds of other potential species currently being researched but one potentially exciting feedstock is algae.
Figure 6: Lipid feedstock sources (BTH 2007)
Biodiesel production (see Biodiesel above)
Biodiesel is mainly produced from straight vegetable oils (SVO) or waste vegetable oils (WVO), these fats and oils are filtered and heated to remove contaminants and water (Garbett 2010). If free fatty acids are present, they can be removed by increasing the amount of potassium (calculated by titration). The pretreated oils and fats are then mixed with methanol and a catalyst potassium (producing ‘methoxide’). The oil molecules (triglycerides) are broken apart and reformed into methyl esters and glycerin these are separated and purified (AFCD 2010).
Figure 7: Biodiesel production schematic AFCD (2010)
iii. Alternatives for Aviation Fossil Fuel
Kerosene and Avgas are currently the main fuels used in aviation (BP 2010). Companies like Virgin Atlantic are conducting biofuel flights using a mixture of 25% biofuel from babassu nuts and coconut (Bradley 2008). Many of these new fuels need to be high-grade synthetic fuel and the Fischer Tropsch technology is an excellent alternative to produce these fuels.
Fischer-Tropsch process (FT) (2nd generation)
The Fischer-Tropsch process converts carbon monoxide and hydrogen, called synthesis gas or syngas, into liquid hydrocarbon fuels like synthetic diesel and jet fuel. Prior to the FT process, the biomass is gasified to produce this syngas using intense heat and pressure, turning these feedstocks into hydrogen and carbon monoxide. Synthetic fuels burn cleanly so they offer improved environmental performance along with addressing energy diversity. Bio to liquid technology (BTL) would mean a less carbon-intensive alternative that could not only use agricultural feedstocks but also waste biomass materials (Siuru 2008).
One of the most exciting possibilities for aviation (and transport) is the research into algae as an alternative fuel. The pentagon are looking at algae to fuel military jets at the same cost as fossil fuels. Reported by Goldenburg (2010) algal farms do not threaten food supplies like corn-based ethanol. Algae feed on carbon dioxide and when the derived fuel is used the same amount of CO2 is released, making algae carbon neutral, although processing and transporting the fuel requires energy (Goldenburg 2010). McQuiston a special assistant for energy at Darpa said “Give the military the capability of creating jet fuel in the field. In Afghanistan, if you could be able to create jet fuel from indigenous sources and rely on that, you’d not only be able to source energy for the military, but you’d also be able to leave an infrastructure that would be more sustainable.”
The potential impact of these new fuels
iv. Greenhouse gas emissions (GHG)
There is worldwide scientific evidence that the burning of fossil fuels is causing global climate change (Allen et al 2009). The use of biofuels is considered to be better for the environment compared to fossil fuels. Yet the growing and burning of many biofuels may actually raise greenhouse gas emissions, says a study led by Nobel prize-winning chemists Crutzen et al (2007). The US Department of Energy disputes this as being a myth (DOE 2007).
Figure 8: U.S. department of energy
Much of the debate surrounds indirect land usage in calculations of the extent of GHG, the utilisation of by products and which generation of biofuel technology is employed. Recommendation 6.1 from The Gallagher Review states, “Significant increases in the use of land for bioenergy, and biofuels specifically should only be contemplated once effective controls are implemented at a global level. This is to avoid indirect land-use change causing significant GHG‑emissions or destruction of high value conservation areas” (Gallagher 2008). The report is also critical of limited reduction of GHG emissions achieved from biofuels based on feedstocks used in Europe and North America, finding that the current biofuel support policies would reduce greenhouse gas emissions from transport fuel by no more than 0.8% by 2015, while Brazilian ethanol from sugar cane reduces greenhouse gas emissions by at least 80% compared to fossil fuels.
v. Food production
There are several reasons why biofuels have impacts on food production. Government subsidies and tax breaks encourage farmers to change from growing food crops to producing biofuel crops (OECD/FAO 2007). Also the amount of land required to grow these crops puts pressure on food and water prices. OECD/FAO (2007) report food prices are expected to rise between 20% and 50% by 2016. The biofuel industry especially 1st generation feedstock is thought to be one of the main causes. Finally a report by the UN (2007) says “It is estimated that to fill one car tank with biofuel (about 50 litres) would require about 200kg of maize – enough to feed one person for one year”.
vi. The global environment
The UK and USA introduced Renewable Transport Fuels Obligation (RTFO) to help reduce the carbon emissions for transport but according to Kinver (2010) “Currently under the RTFO, only the volume target is mandatory; the carbon savings and environmental standards goals were voluntary”. This certainly doesn’t seem like a particularly well thought out policy to help save the environment.
Also multiple studies have concerns about the negative environmental impact of the unintended consequences of biofuel production, particularly the indirect land use change (ILUC) impact of releasing more carbon emissions as forests and pristine lands are converted to cropland due to biofuel expansion (Al-Riffai et al 2010).
vii. The political implications
The importance of the role of government efforts on second generation biofuels is emphasised in the paper Biofuel Production Technologies (UNCTAD 2008). This could be “facilitated” it says by financial incentives or biofuel subsidies with clear “sunset” provisions and / or subsidy caps. It also agrees that policies should be supportive of international joint ventures.
Inevitably government national and international policies will encourage or repress the use of biofuels. The Nuffield Study, due to report its recommendations in spring 2011, says these policies include greenhouse gas emissions and bioenergy targets, incentives, subsidies and regulatory policies, research funding and trade agreements (NCOB 2009). Clearly there are significant implications for governments and international organisations in political decision-making in the future use of biofuels.
viii. Economic implications
There are many detailed studies which have sought to predict the likely economic impacts of the growth of the biofuel industry. They look at the consequences of economic factors such as job creation, economic output, commodity prices and world trade. Most negative impacts involve first generation biofuels. Increased prices for foods in competition according to Gallagher (2008) with biofuel production will have effects such as reducing gross national product, in particular for developing countries. The Rapporteur report UN (2007) is concerned that biofuels will bring “hunger in their wake” and that there are “serious risks of creating a battle between food and fuel”. They recommend that “All states should ensure their international politics and economic policies do not have a negative impact on the right to food in other countries”, whilst a study commissioned by OFID (2009) concluded that first generation biofuels will increase food insecurity in the world’s poorest countries. This concern was highlighted when in Mexico in January 2007 the price of corn tortillas rose by 400% prompting riots (UN 2007). In some cases, as with corn prices in the US, prices for feedstocks have increased dramatically and are expected to increase to unprecedented levels (UNCTAD 2008).
The development of advanced biofuels however shows possible economic benefits. Bio-era (2009) conducted an analysis of nearly two dozen studies of the economic impacts of biofuels production. Its analysis concluded that advanced biofuel production in the U.S. would increase direct job creation, investment in processing plants and direct economic output. Other studies by Hodur and Leistritz (2009) back up these positive economic advantages. “An emerging biofuels industry could offer new jobs that would help to support rural communities and farm households and provide the kind of economic stimulus many agriculturally dependent areas have been seeking”
The strengths and weaknesses in the role of biofuels in transport
Cheaper than fossil fuels to purchase at the petrol station (Subsidies).
Biofuels are low in sulphur.
Biodiesels are more lubricating than fossil fuel alternatives.
Drivers of ‘green cars’ pay less road tax due to less carbon emissions.
Reduce dependence on foreign imports of fossil fuels (energy security).
Biofuel ‘overall’ produces less carbon emissions than fossil fuels.
Without government subsidies biodiesel could be more expensive than fossil fuels.
Limited options to purchase biofuel from petrol stations.
Current technologies especially 1st generation require large areas of land to grow the crops and natural habitats and rain forest have been destroyed.
Many vehicles especially older transport vehicles need converting to be able to run biofuels.
Biodiesel are known to have problems in colder weather due to viscosity.
ix. Own justified view as to what their future role might be in both the short-term and the long-term.
Short term there is increasingly important steps for world politicians to make, especially in first world countries. It is imperative that much more legislation and investment is put in place to concentrate energies into 2nd & 3rd generation technologies and to abandon subsidies for 1st generation food crops. The long-term outlook for biofuels looks very promising especially will the possibility of carbon neutral algae biofuels. If more focus was placed on developing public transport systems less people would require cars and this could only be a good thing.
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