Life Cycle Lab

From cradle to grave

Every product has a life, and chemists judge its impact on the planet with a life cycle assessment. This tracks four stages. First the extraction of raw materials, such as digging ore or drilling oil. Then the manufacturing that turns those materials into a product. Then the use of the product, which may need energy or cause pollution. Finally the disposal, when the product is thrown away, reused or recycled. Some stages are easy to measure, but others, such as the harm from waste decades later, are hard to judge fairly. To ease the strain on limited resources we reduce, reuse and recycle, and recycling a metal uses far less energy than extracting fresh metal from ore.

Life cycle words

Learn these before you assess any product, and keep the four stages in your head as you go.

Extract fresh against recycle

One of the clearest results of an assessment is how much better recycling a metal is than making it from scratch.

How to run an assessment

Judge a product across every stage, not just the one in front of you. Step through where the materials come from, how it is built, what it does in use, and what happens once it is finished with. Weigh the energy and waste at each point. Then be honest about trust: figures for digging and building are fairly solid, but guesses about harm far in the future are shaky. A strong answer covers all four points and flags which numbers deserve doubt.

Match the stage to what it covers

Which stage is this?

A worn-out drinks can is thrown into a bin and sent to be melted down. Which stage of the life cycle assessment does this belong to?

• Disposal.
• Extraction of raw materials.
• Manufacturing.
• Use.

Why recycle metals

Select the TWO real reasons recycling a metal is better than extracting it fresh.

• It uses far less energy than extraction
• It saves finite ore that cannot be replaced
• It always uses more energy than extraction
• Metal ore is an unlimited resource

Energy saved by recycling

Extracting one tonne of a metal from its ore uses 45 units of energy. Recycling the same tonne uses only 5 units. Subtract to find the energy saved, in units.

Order the life cycle stages

Put the four stages of a life cycle assessment in order, earliest first.

• Extraction of the raw materials
• Manufacturing the product
• Use of the product
• Disposal at the end of its life

Complete the facts

A study of the impact of a product across all its stages is a life cycle _____. The first stage, digging ore or drilling oil, is the _____ of raw materials. The last stage, when a product is thrown away or recycled, is _____. Making a metal by recycling rather than extraction saves a great deal of _____.

Match the idea to its point

Spot the true life cycle facts

Tap the TWO statements that are true about a life cycle assessment.

• An assessment covers all four stages of a product
• Recycling a metal uses less energy than extraction
• Every stage can be measured with perfect certainty
• Metal ore can never run out

Judge the impact

Read each case and choose the best response, with a reason.

• A company compares making cans from fresh ore against recycling old cans. Which choice lowers both energy use and the drain on finite ore?
• An assessment must estimate the harm a plastic will cause in landfill over the next fifty years. Why should this figure be treated with care?
• A student writes that recycling is simply good for the environment. How could the answer be made stronger?

Assess a product life cycle

A drinks company wants to know the environmental impact of an aluminium can. Explain how a life cycle assessment would judge it.

• Name the four stages an assessment covers
• Explain what happens at the extraction and manufacturing stages
• Explain why the disposal stage can be hard to judge fairly
• Explain how recycling the can saves energy and finite ore
• Finish with a judgement on how the company could lower the impact