The reaction to make ethanol is:
Glucose→ Ethanol + Carbon Dioxide+ Heat
The reaction is carried out at about 250-300C. Normally we need to process the crops before obtaining the glucose in order to increase efficiency, using a process called hydrolysis.
Transesterification, to make biodiesel, is a reaction in which oil is converted into an alkyl ester with the help on an alcohol. A typical reaction would be:
Usually vegetable oils, or recycled oils, are used to produce biodiesel through transesterification, but we should take into account the additional processes that the recycled oil needs and the energy needed to produce the vegetable oil specifically for the production of biodiesel. Other types of bio fuels include hydrogen, bio oil, methanol, bio methane and a wide range of fuels [5]. Processes to make these bio fuels are digestion, pyrolysis, and gasification respectively [6].
Biomass Energy in the UK
The UK has 16 dedicated biomass plants and a further 10 in planning (As of October 2010). These 16 plant combined have a capacity of 2,096.6 MW (Figure 3), during 2010 these plants produced 11,915GWh of energy (Figure 4). By comparing the potential energy and actual produced a figure can be calculated which shows the ratio of these two figures, or how much is being produced in relation to how much could potentially be produced this is known as the load factor. The statistics for the UK show that the load factor for biomass energy production is on average 55%, meaning nearly half of the installed capacity is not being used (Figure 5)[7].
Figure 3: Shows the total installed capacity for renewable resources in the UK.
Figure 5: Shows the load factors for renewable energy in the UK.
Since the introduction of the Renewable Transport Fuels Obligation (RFTO) in 2008 it has been mandatory for all fuels intended for road use to contain a certain percentage of bio fuels, this percentage, which started at 2.5, has increased each year with the government looking to double it by 2014 [8].
The introduction of this obligation has been the main determining factor in the increased use of bio fuels in the UK, with the rail; shipping and aviation industry’s contributing very little to the overall figure. It was estimated that the UK produced 177 million litres of bio diesel in 2010; this is one third of the amount produced in 2007 at 485 million litres. Despite the reduced volume of production the UK consumption was roughly 1,045 million litres meaning that over 80% of the biodiesel used is imported. The UK’s estimated capacity of bio diesel for 2010 was estimated to be 575 million litres; the small amount that was produced compared to the potential is thought to be because of adverse market conditions and firms choosing to reduce biodiesel output below capacity [9].
In line with these targets of increased bio fuel usage the UK has joined the Renewable Energy Directive, this sets the UK a target of sourcing 15% of its total energy from renewable sources by 2020. Included in this directive is a specific target for transport, which for the UK is to supply 10% of the energy used by all forms of transport from renewable resources. It also states that bio fuels derived from waste materials and ligno-cellulosic material count as double towards the 10% target [10].
Current UK figures suggest a trend that will not reach this target. The figures show in volume total bio fuels for transport down 12.7% as of the 2nd quarter of 2011, and overall total bio fuels in road fuels is down 0.5% on last year’s figure at 3.1%. Although the figures show an increase in bio fuel consumption from the introduction of the RFTO in 2008 the growth has stopped during 2011 (Figure 6), this could be due to the reduction in use of cars during the economics conditions or reduction in fuel sales due to higher prices.
Figure 6: Shows bio fuels consumption quarterly since 2005
The UK government has set out guidelines for the increased uses of renewable energy up to 2020 [11]. It predicts that 48 TWh of transport energy will come from renewable resources and will theoretically account for 10% of total transport energy (Figure 7). However, the fact that bio fuels count for double and electric cars have a weighted factor of 2.5 means that in reality a proportion smaller than 10% will be provided in 2020. Another possible problem with this future outlook is the prediction of total energy use in 2020; the calculations are based on data now and extrapolated meaning unforeseen events could happen that would change our energy needs for the future.
Energy consumption and production of bio-fuels, worldwide
Both figures 8 and 9 show almost the same trend, a severely sharp increase in the production of both bio-ethanol and bio-diesel. The graphs follow almost exactly the same shape with this sharp increase arising around 2005. Interestingly, the graphs show that world ethanol production is substantially greater throughout production history. This demonstrates the worlds increasing demand for renewable energy sources. With the world population increasing year on year it makes sense that the demand for energy increases. Figure 10 shows us that around 90 percent of the global bio fuel production in 2007 comes from the US, Europe and Brazil. With Brazil and the US leading production by a 15% margin. Surprisingly China only contributes to 3% of bio fuel production, however their CO2 emissions increased by 2% that year [12]. This shows that despite China being one of the largest global exporters, they barely contribute to renewable energy systems especially that of bio fuels. In addition to this, 75% of the world’s bio fuels production comes from the US and Brazil. Due to a lack of production elsewhere, this means that the world is reliant on these countries in terms of imports for bio fuels. This brings about the issue of transportation of bio fuels.
The importation of bio fuels may be pointless as the carbon neutral process is no longer carbon neutral due to how far it has travelled on the use of burning fossil fuels. It can be argued however that if we weren’t transporting bio fuels it would be fossil fuels which contribute nothing towards conservation. Bio diesel and bio ethanol are not a realistic sustainable alternative to diesel and petrol due to the large number of motor vehicles which are not compatible with these bio fuels. These cars would therefore need to be taken of the road or modifications required which would increase the carbon footprint of the operation. As we have seen bio fuels is widely only used for transport; in the transport bracket, the majority of that is used in road going vehicles. Due to the chemistry of bio-diesel and bio-ethanol, this can only be used for modern cars as they both corrode natural rubber meaning that a high percentage of bio diesel mixed with conventional diesel and a high percentage of bio ethanol in petrol vehicles would mean only modern cars with synthetic rubber would be able to handle these bio fuels without major engine failures. Unless the UK government or worldwide politicians took away old cars or paid for these components to be replaced, it is unlikely bio fuels would be substantial enough to sufficiently reduce the rate we are currently burning fossil fuels. This would have other environmental impacts for example the making of synthetic rubber and transporting it could outweigh the benefits of implementing such a system. Another solution to conserve more fossil fuels would be to do research into what else bio fuels could be used for, whether they could replace fossil fuels for smaller tasks. Other possible applications of bio fuels could be: producing hydrogen for hydrogen fuel cells, cleaning up oil spills, generating electricity, heating homes, cleaning grease or removing paint and adhesives [13].
Figure 11: Shows the current potential for bio fuels to grow until 2019.
Over the 10 year gap shown, 35% of the global production of bio fuels will come from sugar cane (Figure 11). The graph also shows an almost 5% increase across the board in the production of bio fuels. If this increase is not spread between currently low producing bio fuel countries then the problem with transport will still be apparent. Bio fuels should be in the interest of the countries sustainability plans, i.e. growing their own crops to use for bio fuels so that the importation of bio fuels is clearly reduced and thus reducing their carbon footprint.
Economics of Bio-Fuels
As bio fuels are being increasingly promoted in the UK it will have an impact on the economy. This will most probably result in increased job opportunities. The UK’s dependency on imported bio fuels is very likely to increase [17] as bio fuels are used more and more.
The price of bio-mass varies widely as there are many different sources of biomass. Wood chips and pellets are relatively cheap but costs greatly vary with geographical region, order quantities, overall contract size and duration other factors that affect the price biomass are, time of year, delivery distance and time [18].
The global production of bio fuels is rising annually and production is currently estimated to be at 300,000 barrels per day, this is one third of the growing demand of oil which is currently at 900,000 barrels per day. Bio fuel plays a major and critical part in the current world economy. Commodity strategist, Francisco Blanch of Merrill Lynch, says that if bio fuel producers were not increasing their output, oil prices could be as much as 15% higher. That would put the price of oil at more than £74 per barrel, instead of the current price of about £65.
In terms of satisfying world demand, chief economist of the Paris-based International Energy Agency Faith Birol says “it would be much more difficult to balance global oil markets”[14].
Figure 10 shows us that the US is the largest producer of bio-fuels. Bio fuels are not only benefiting the environment of the US but it is also improving their economic position. An analysis was conducted by bio-era (Bio Economic Research Associates) to estimate the economic implications of bio fuel production in the U.S in terms of economic output and job creation from 2009 to 2022.
The analysis concludes that [15]:
- Job creation would reach 94,000 by 2016, rising to 190,000 by 2022.
- Investments in advanced bio fuels processing plants would reach £5.4 billion in 2016, rising to £7.8 billion by 2022.
- Total economic output from advanced bio fuels production would be £72.3 billion by 2030.
- Biomass feedstock’s could be provided by a mix of agriculture, forest wastes and energy crops, providing a total 470 million dry tons of biomass by 2030.
This scenario would see the U.S bio fuels production grow to 60 billion gallons by 2030.
Environmental impacts of bio fuels
Bio fuels are more effective than fossil fuels in many aspects. However, if not used or processed correctly it can have a greater environmental impact than the other renewable energy sources. There are many types of bio fuels and all of them have different impacts but in general well-formed bio fuels have the potential to create around 98% less emissions compared to coal.
Currently gases like carbon dioxide are increasing in the earth’s atmosphere with the combustion of coal, oil, natural gas and fuels produced from biomass as well. One negative impact of bio mass is the storage of it. This is because bio mass releases a lot of methane gas. Methane gas is 30 times more affective at storing heat than a carbon dioxide molecule. Greenhouse gases allow solar energy to pass into the earth’s atmosphere but stops it escaping and thus results in global warming. Therefore to prevent global warming carbon dioxide and greenhouse gases emissions must be cut. In this case fuels produced from biomass are preferred, due to their carbon neutrality; also plants use carbon dioxide as their feedstock. This means that plants recycle some carbon dioxide produced during the combustion.
By using bio diesel and bio ethanol instead of fossil fuels, this significantly reduces some types of pollution from automobiles. Both these bio fuels evaporate more slowly than gasoline, thus helping evaporative emissions of volatile organic compounds to be reduced; otherwise changing chemically with heat and sunlight to generate a component of smog. According to the estimates of the Environmental Protection Agency, in pure bio diesel or bio ethanol powered vehicles, VOC emissions could be reduced 85 to 95% from the exhaust, while carbon monoxide emissions could be reduced by between 30 to 90%. However, emissions of nitrogen oxides would not change much compared to gasoline-powered vehicles [3].
One of the possible implications for producing large amount of bio fuels is the land intensive nature of bio mass. The consequence of huge fields for biomass crops has an impact on the agricultural landscape. In some countries there is conflict in using land as one wants the land for energy biomass and the other wants it for food biomass. Also it creates possible biological diversity as the reduction and the potential increase in intensive farming with high inputs of fertilisers and pesticides. For instance fertilisers may have nitrogen or phosphorous to improve plants growth but these elements are toxic when they reach water bodies.
Water demand is increasing over time as populations are increasing and changing dietary trends. Global warming has effects on evaporation; causing temperatures to increase thus evaporation of water increases too. The expansions of biomass projects are another factor that affects water availability. Some biomass projects required high amount of energy input in the form of fertilizers, harvesting and processing. However, energy input and output must be taken into account to avoid the wasting of useful energy [16].
References
[1] Efficient home energy saving, , Accessed 11th November 2011
[2] ehow, , Accessed 16th November 2011
[3] Renewable energy, Power for a sustainable future, Goodfrey Boyle, 2nded, Oxford University Press 2004
[4]Green world Investor,, Accessed 15th November 2011
[5]Imperial college London, Bio Ethanol Seminar, Accessed 14th November 2011
[6]Power generation technologies, Paul Breeze, Elsevier, 2005
[7]UK Department for Energy, , Accessed 10th November 2011
[8] UK Department for Energy, , Accessed 10th November 2011
[9] UK Department for Energy,, Accessed 17th 2011
[10]UK Department for Energy, , Accessed 17th November 2011
[11]UK Department for Energy,, Accessed 8th November 2011
[12]Netherlands Environmental Agency, , Accessed 18th November 2011
[13]Gas 2,, Accessed 12th November 2011
[14] Renewable Energy Information, , Accessed 21st November 2011
[15] Bio Technology, , Accessed 20th November 2011
[16]European Bio fuels, , Accessed 22ND November 2011
[17]UK Biomass Strategy 2007 Online Publication, , Accessed 24th November 2011
[18] Fuel costs per kWh http://www.biomassenergycentre.org.uk/portal/page?_pageid=75,59188&_dad=portal&_schema=PORTAL, Accessed 24th November 2011
Figures
[1]Energy Future Coalition, , Accessed 21st November 2011
[2] Esru Energy,, Accessed 19th November 2011
[3-7] UK Department for Energy, , Accessed 8th November 2011
[8&9] Imperial College London, Bio fuels Seminar,, Accessed 14th November 2011
[10]United States Department for Agriculture, Amber waves, , Accessed 22nd November 2011
[11] Organisation for Economic Co-operation and Development, , Accessed 14th November 2011
