2 Objectives Students should learn: that biofuels can be made from natural products by anaerobic fermentationthat there are advantages and disadvantages in using ethanol-based biofuels.
3 Outcomes Most students should be able to: describe how yeast can produce ethanol for fueldescribe the advantages and disadvantages of using ethanol-based fuelsdescribe how second-generation biofuels are being developed.Some students should also be able to:interpret economic and environmental data relating to the production of fuels by fermentation and their uses.
4 SpecificationBiofuels can be made from natural products by anaerobic fermentation. Deforestation has occurred so that: ■ crops can be grown from which biofuels, based on ethanol, can be produced
6 Biology B3 4.6BiofuelsAnswers to in-text questionsa They are fast-growing and contain a lot of sugar that can be fermented.b There is no overall increase in the levels of carbon dioxide in the air as a result of the industry in question.Summary answers12 a i 725 million gallons.ii 730 million gallons.iii 4850 million gallons.b Use of ethanol as a fuel grew steadily through the 1980s and 1990s but has increased dramatically in the first 7 years of the 21st century. Any other points givingsuggested reasons can be credited.
12 Boardworks GCSE Separate Sciences 2009 Other Uses for Micro-organisms What are biofuels?Biofuels are fuels made using living organisms or the waste that they produce. These include:Biogas – produced from the breakdown of organic material.Ethanol – produced by the fermentation of sugar from plant material.Unlike fossil fuels, biofuels provide a renewable source of energy. Biofuels are also thought to have less of an impact on the environment than fossil fuels.
16 Boardworks GCSE Separate Sciences 2009 Other Uses for Micro-organisms Carbon neutral?Teacher notesThis voting activity enables the individual opinions of the class to be represented graphically. It could be used as a precursor to a debate on the use of biofuels. The class could vote again after the debate to see if their opinions have changed.This may be a good opportunity to discuss what is meant by the term carbon neutral.
17 What are the disadvantages of biofuels? Boardworks GCSE Separate Sciences 2009Other Uses for Micro-organismsWhat are the disadvantages of biofuels?Biofuels are not completely carbon neutral because energy is used in the production and transportation of the biofuel. This energy is often provided by fossil fuels.There are also concerns that the production of biofuels could affect food production. As biofuel production increases, more land is being used for growing crops for fuels such as gasohol. This could mean that less land is being used for food production, causing a shortage of food.Land previously unused is being harnessed for biofuel crops, this could contribute to a loss in biodiversity.Teacher notesThe term carbon neutral is used to mean an substance or an act that absorbs the same amount of carbon dioxide as it produces. Some biofuels themselves are said to be carbon neutral, however more carbon may be released during the manufacturing and transport process.Gasohol includes petrol, using this fuel therefore involves burning petrol – a fossil fuel.Currently there are few UK producers of biofuels, and only small quantities of fuel are made. Biofuels therefore need to be imported, mainly from Brazil and South-East Asia, therefore it needs to be transported causing more fuel to be used.
18 Boardworks GCSE Separate Sciences 2009 Other Uses for Micro-organisms Which biofuel?
19 Using ethanol as biofuel for cars AdvantagesCo2 neutralLittle pollutionEfficientCan mix with petrol so current cars can be converted to itDisadvantagesExpensive to produce/right conditions neededUse lots of land/need large amount of plant materialStill pollution if mixed with petrolLots of cellulose waste – can we develop this in future?
20 Which biofuel would you use to: Generate electricity?Heat your home?Which biofuel would you use to:Cook your food?Power a vehicle?
21 Yak faeces Energy output: 2 Poor Ease of use: 3 OK, need to dry out before useEase of production: 4Simple - if you keep yaks!Uses: 1Mainly for cooking in special stovesFACT FILEEquipment needed: 3Modified stovesFumes produced: 1Very smoky!
22 Willow Energy output: 3 Ease of use: 3 Ease of production: 3 Uses: 2 GoodEase of use: 3GoodEase of production: 3Two years to produce cropUses: 2Mainly in modified power stationsFACT FILEEquipment needed: 3Modified burnersSmoke can be produced if burningis not controlled carefullyFumes produced: 3
23 Gasohol Energy output: 4 Excellent Same as ordinary petrol Ease of use: 4Requires a fermentation plant toproduce the alcohol which is thenadded to petrol.Ease of production: 2Uses: 2Mixed with petrol in standard carsFACT FILESome cars need to be modified(particularly if alcohol:petrol mix usesmore than 10% alcohol)Equipment needed: 4Fumes produced: 4Cleaner than petrol alone
24 Biodiesel Energy output: 4 Excellent Ease of use: 4 Same as standard dieselEase of production: 2Requires a chemical plant toextract the oil from crops and thenmodify it to make diesel.Uses: 2In diesel-engined road vehiclesFACT FILEEquipment needed: 5Standard diesel engineFumes produced: 4Cleaner than standard diesel
25 Biogas Energy output: 4 Excellent Ease of use: 4 Same as standard gas Ease of production: 2Requires a digester which canconvert old organic wastes tomethaneUses: 4Heating, cooking and power stationsFACT FILEEquipment needed: 5Standard gas applianceFumes produced: 4Very clean