Unit 8, exercise 29c Unit 11, exercise 4 Read the proposal and answer the questions. 1 In what ways are the ‘trees’ like real trees? In what ways are they different? 2 How do they absorb CO2? 3 What happens to the CO2 after it has been extracted? Professor Klaus Lackner has invented an ingenious way of counteracting CO2 emissions, which he believes could solve global warming. His invention is an artificial tree. It’s made of metal but works in the same way as a real tree by extracting CO2 from the air as it flows over its ‘leaves’. Large quantities of CO2 could be removed from the atmosphere and could be stored deep beneath the Earth’s surface in a solid form, which would be stable and safe. Just like a real tree, an artificial tree would have a structure to support it – a steel pillar (like a trunk) and two steel ‘branches’ which would hold the ‘leaves’. The synthetic tree would stand more than 100 metres tall and 60 metres wide and would look like a huge upright tuning fork with slats between its uprights. Unlike in a real tree, where the leaves are spread out as much as possible because they need to catch sunlight, the leaves on an artificial tree could be packed much more closely together and be parallel with each other, like a venetian blind. So an artificial tree could extract far more CO2 than a natural tree; and of course, unlike a real tree, they could be ‘planted’ anywhere, even at the North Pole or in the Sahara Desert. The apparatus would work by using a series of simple chemical reactions. The slats would be coated in liquid sodium hydroxide, so as the air passed over them, the CO2 would be extracted and converted into sodium carbonate. A series of further chemical reactions would extract the carbon from the sodium carbonate and turn it into a concentrated, solid form of CO2 that could be buried deep underground. It would be quite feasible to produce thousands of artificial trees and put them in any available space. Each tree would collect 90,000 tonnes of CO2 a year from the atmosphere – as much as is produced by 20,000 cars. 214 A Activities Nur zu Prüfzwecken – Eigentum des Verlags öbv
RkJQdWJsaXNoZXIy ODE3MDE=