Reading Passage 9

Biofuels backlash

A Biodiesel and bio-ethanol are cleaner, sustainable alternatives to petroleum-based fuels, which continue to deplete. Biofuels can be grown repeatedly from crops making them 100% renewable. Bio-ethanol is made in a similar way to ‘moonshine’ by fer­ menting cereals like corn and maize and then distilling the brew to evaporate the ethanol. Biodiesel is manufactured from the vegetable oils found in sunflower seeds, rapeseed and the oil palm. Gasoline (petrol) engines can be tuned to run on 90% ethanol blended with 10% petroleum and biodiesel is a direct replacement for exist­ ing road diesel.

B Carbon-dioxide is the principal man-made greenhouse gas. It traps heat in the atmosphere and increases global warming, causing polar ice to recede and sealevels to rise. Energy crops offer one solution to the deleterious effects of carbondioxide emitted from vehicle exhausts. Biofuels are 100% carbon-neutral, which means that there is no net gain or loss of carbon to the environment when the fuels are burnt. The carbon-dioxide does not add to the total amount in the atmosphere because the crops absorb the equivalent amount of carbon-dioxide by photosynthesis as they grow. Consequently, the ‘carbon footprint’ of gasolineand diesel-powered vehicles can be reduced by switching to bio-ethanol or biodiesel. The latter burns more efficiently than petroleum diesel leaving less unburned hydrocarbons, carbonmonoxide and particulates, which means less atmospheric pollution as well as less global warming. Biofuels are less toxic than fossil fuels and biodegrade if spilt on the ground.

C Not everybody believes that biofuels are the ideal alternative to fossil fuels. The status of biofuels as environmentally friendly can be challenged on several counts. Firstly, to provide space for energy-crop plantations, trees are felled and burnt which creates a surplus of carbon-dioxide. Secondly, in tropical rainforests the loss of trees threatens biodiversity by destroying habitat. Thirdly, deforestation increases the evaporation of water from the ground, which can lead to extensive droughts. These deficits can be discounted if the energy crops are planted on existing agricultural land, but if this is done it reduces the supply of food crops, creating a surge in food prices. Furthermore, in developing countries people have barely sufficient food to eat and switching to fuel crops could threaten their meagre food supplies.

70 How to Master the IELTS

D To judge whether or not biofuels are genuinely a greener alternative to fossil fuels it is necessary to scrutinize the manufacturing steps. Whilst in theory, the carbon released by biofuels is equivalent to that removed from the atmosphere by the growing plants this does not reflect the true energy picture. Substantial amounts of nitrogen-based fertilizers are added to the soil to increase crop production. The process of manufacturing fertilizers consumes large amounts of energy in a process that burns natural gas and releases carbon-dioxide. What’s more, when fertilizers are added to the land the soil releases nitrogen oxides into the atmosphere. As an agent of global warming, nitrous oxide is about 300 times more potent than carbondioxide, and surplus nitrates can leach into nearby rivers and streams where they kill the fish. The ethanol industry generates additional carbon-dioxide because many of its manufacturing plants use coal-fired boilers, and fossil fuels are also consumed by the vehicles that transport materials to and from manufacturing sites. Whilst the transportation of petroleum-based fuels also burns fossil fuels, biofuels are supposed to offer a greener alternative to the fuels they intend to replace.

E Biofuels may not be a panacea for global warning but they can play a part in a sustainable energy programme. To reinforce their green credentials, energy crops should not be planted on land that was being used to produce food. New technologies can produce ethanol from the inedible parts of plants, or from grasses grown on wasteland that is unsuitable for food. Genetically modified plants may be the answer to increasing biofuel crop yields without the need for further land grab. Plant strains can be developed that require little in the way of fertilizers or irrigation. Biodiesel consumption may, in the future, extend beyond transportation to include heating oils for domestic boilers. Developing countries that grow biofuels should be allowed to benefit from the premium prices that fuel crops command, enabling farmers and their communities to reap economic and social benefits. Whatever the advantages and disadvantages of fuel crops it is clear that fossil fuels are a limited resource and cannot remain the mainstay of our economies indefinitely.

Questions 227 to 231

Reading Passage 9 has five sections, A to E.

Choose the correct heading for the sections A, B, C, D and E from the list of headings below.

List of headings

i)Biofuels

ii)Fossil fuel replacements

iii)Advantages

iv)The way forward

v)Man made

vi)Environmentally friendly

vii)Too much carbon

viii)Adverse effects

ix)Unsustainable

x)Thorough examination

227Section A

228Section B

229Section C

230Section D

231Section E

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Questions 232 to 236

Do the following statements agree with the information given in Reading Passage 9? Write:

TRUE if the statement agrees with the information

FALSE if the statement contradicts the information

NOT GIVEN if there is no information on this.

232Bio-ethanol is a non-renewable fuel source.

233Burning biodiesel instead of petroleum diesel generates less pollution.

234Food prices fall when fuel crops are planted on land used to grow food.

235Fuel crops outnumber food crops in developing countries.

236The eco-friendly nature of biofuels cannot be disputed.

Questions 237 to 240

Complete each sentence with the correct ending, A to J, below.

237Excess fertilizer can be deadly to fish

238The green status of energy crops is strengthened

239It may not be necessary to acquire more land

240Farmers in poorer countries will benefit from fuel crops

Aif it is released from the soil into the atmosphere.

Bwhen they play a part in a sustainable energy programme.

Cif they are not planted on agricultural land.

Dif they are planted on land used to produce food.

Eif nitrogen-based fertilizers are added to the soil.

Fwhen new technologies are employed.

Gif it drains into the surrounding watercourses.

Hif they can keep the profits they make.

Iwhen fossil fuels eventually run out.

Jif yields are improved with genetically modified crops.