Passage III (7 marks)
Biofuels
P1 Many companies are developing various types of biofuels. We reveal the pros and cons of the top three: Ethanol, Biodiesel, and Biobutanol.
P2 Ethanol is essentially pure alcohol and is perhaps the most commonly used of the alternative biofuels. It can be made from various sources, but the most common are corn and sugarcane. Ethanol is cleaner burning than gasoline, releasing approximately 15 percent less greenhouse gas emissions. Moreover, domestic production of ethanol reduces dependence on foreign fossil fuels and improves rural farming economies. However, one disadvantage of ethanol is that since it comes from corn, beets, and sugarcane, it competes directly with food supply and increases the cost of other foods and grain-fed meats. In addition, farmed ethanol crops are likely to erode soil and use toxic industrial agrochemicals that can contaminate water supplies.
P3 Biodiesel is like petroleum-based diesel fuel. It is produced from vegetable or animal oils. In fact, many biodiesel companies simply collect used restaurant cooking oil and convert it into biodiesel. Biodiesel is renewable. Sufficient plant, algae or bacteria crops can yield abundant biodiesel fuel. It also reduces tailpipe emissions compared to petroleum-based diesel. Since it contains no sulfur, it eliminates sulfur dioxide emissions. One of the cons is it is currently more expensive to produce than petroleum diesel. It is likely to be affected by cold weather and can gel when the temperature drops. This will cause fuel injection problems.
P4 Biobutanol is less well known of the three biofuels and it has great potential as an alternative source of energy. Biobutanol is simply isobutanol obtained from bacteria or algae, much like biodiesel. There are three types of butanol: 1-butanol (commonly known as N-butanol), 2-methyl-1-propanol (commonly known as isobutanol), and 2-butanol. The beauty of biobutanol is that it can be directly used in standard gasoline engines with no modification. It has a high octane level, so there’s little loss in fuel mileage. One of the cons of biobutanol is its relatively high production costs. However, since the industry is still in its early stage, the cost will come down as it grows.
1. Fill the diagram of a classification of biofuels. (1 point)
Biofuels
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1-butanol 2-methyl-1-propanol _________________
2. Write TWO sentences to explain a classification of biofuels based on the above diagram. (2 marks)
2.1 Use passive form for classification from general to specific.
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2.2. Use either passive OR active form for classification from specific to general.
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3. List TWO disadvantages of ethanol (1 mark)
3.1 ___________________________________________________________________
3.2 ___________________________________________________________________
4. Where do companies get material for biodiesel production? (1 mark)
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5. Which type of biofuels can replace gasoline without changing the engine? (1 mark)
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6. Would you consider using biofuels for your cars? Why or Why not? (1 mark)
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