LCAs

Question 1

4 stages in life cycle assessments

Answer 1

1. extracting and processing raw materials
2. manufacturing and packaging
3. use and operation during its lifetime
4. disposal at the end of its useful life, including transport and distribution at each stage

Question 2

problems of LCAs

Answer 2

-effects of pollutants are difficult to quantify, meaning we have to use value judgements, so not purely objective
-selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes

Question 3

explain step 1

Answer 3

-extracting raw materials can damage local environment
-also result in pollution due to amount of energy required
-processing often requires large amounts of energy

Question 4

explain step 2

Answer 4

-manufacturing products and their packaging can use a lot of energy resources
-also cause a lot of pollution
-can produce waste products which can be turned into other chemicals, reducing pollution or disposed of unethically

Question 5

explain step 3

Answer 5

-use can damage the environment
-e.g burning fuels releases greenhouse gases
-e.g fertilisers can leach into streams damaging ecosystems
-products that need lots of energy to produce but last longer may mean less waste in long run

Question 6

explain step 4

Answer 6

-often disposed in landfill sites
-takes up space
-pollutes land and water
-energy use to transport waste, releasing pollutants
-products may be incinerated, which releases air pollution

Question 7

plastic bag LCA

Answer 7

1. made from hydrocarbons obtained from crude oil (cheap, plentiful) by fractional distillation, followed by cracking then polymerisation. little waste as the other fractions of crude oil have other uses
2. processed into long roll of film, cut into shape, requires energy, packaged in cardboard boxes
3. constantly reusable, (strength) can be used as other things such as bin liners, no environmental impact
4. recyclable but not biodegradable so take up space in landfill and pollute land
5. transported from oilrig to processing plant, to manufacturer to shops to landfill, does release pollution

Question 8

paper bag LCA

Answer 8

1. made from timber (renewable) but obtained via deforestation. a lot of wood required, pulping and processing so lots of energy required, unusable waste
2. rolled into long sheets, cut into shape, machinery requires energy, packaged in cardboard boxes
3. unable to reuse if wet, relatively weak so only one use therefore more needed to make
4. recyclable but requires energy, are biodegradable and non-toxic so break down without causing pollution
5. timber transported from forest to processing plant to manufacturer to shops, releases pollution

Question 9

paper v plastic

Answer 9

-plastic is better
-despite being non-biodegradable they take less energy to make and have a longer lifespan