10.2 Life cycle assessment and recycling

10.2.1 Life cycle assessment

- Life cycle assessments are carried out to assess the environmental impact of a product over its entire life cycle.
- The stages of a product's life cycle include:

- Use of water, resources, energy sources and production of some wastes can be fairly easily quantified by simply measuring.
- Allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process.
- Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, e.g. in support of claims for advertising purposes.

Paper or plastic?

Paper bag Plastic bag
Raw materials and extraction Paper from trees - could cause deforestation if trees not replanted, but most paper (in the UK) comes from managed woodlands (which have less biodiversity). Trees are a renewable resource.
Water - from (most likely) rain, non-renewable (or slowly refilling but not fast enough) aquifers, or potentially desalination plants.
Sodium Hydroxide - extracted from seawater.		 Plastic from crude oil - finite. These can cause habitat destruction in order to reach the oil.
Lots of energy for distillation, cracking, and polymerisation.
Manufacture Pulp made from wood and water, if making white paper we add bleach (NaOH). Lots of energy required (4x as much as plastic). Lots of energy required.
Use Once or twice. Used once or many times before it breaks.
Disposal Easily recyclable, but a limited number of times. Can be composted (biodegradable) or incinerated (reclaims heat energy but releases toxic compounds). Not very recyclable - often ends up in landfill (producing methane emissions) or in incineration plants. Recycling is technically possible through cracking and breaking down into monomers, and this is infinitely possible, but this does not happen very often. Non-biodegradable.

I think that paper bags are better for the environment due to being made from renewable resources and being biodegradable, despite the higher energy costs (which, if from renewable sources, are less harmful).


Stages of an LCA (example 6 marker response using information from question)

Coated Paper Cups Polystyrene Cups
Raw materials and extraction
  • Wood is renewable
  • Cutting down trees causes habitat destruction and increases CO2 in atmosphere
  • Crude oil is finite
  • Oil must be distilled and then cracked with uses lots of energy
Manufacture and transportation
  • Takes 550 kJ of energy to provide 1 cup which is more than the plastic cup which is more than the plastic cup
  • Only 200 kJ to produce 1 cup.
  • Plastic cups are ligher (1.9 g per cup) so more cups can be transported for less fuel so less CO2 emitted
Use
  • Mostly single use
  • Mostly single use but more durable so more likely to be reused
Disposal
  • Biodegradable so they can be composted
  • Cannot be recycled due to potential plastic coating
  • Incineration produces 166 kJ per cup which can be used to generate electricity
  • They are carbon-neutral
  • Can be recycled although this is rare
  • Might end up in landfill
  • Not carbon-neutral but conserves fuel resources

I think paper cups are better for the environment overall despite the higher energy costs in manufacture because they are made from renewable resources, are biodegradable, and are carbon-neutral. The plastic cups are made from finite resources and are not biodegradable, although they do use less energy in manufacture and transportation.


10.2.2 Ways of reducing the use of resources

- The reduction in use, resuse, and recycling, of materials by end users reduces the use of limited resources, use of energy sources, waste, and environmental impact.
- Metals, glass, building materials, clay ceramics and most plastics are produced from limited raw materials.
- Much of the energy used in manufacturing also comes from limited resources - fossil fuels.
- Obtaining the raw materials has an environmental impact - habitat destruction, pollution from mining and quarrying, and CO2 emissions from machinery.


Glass

- Some products, such as glass bottles, can be reused without any further processing.
- Glass can be recycled by melting and remoulding it to make new glass products.
- Recycling glass saves energy and raw materials.
- Glass (and metals) can be recycled an infinite number of times.
- Other products cannot be reused directly but can be recycled, e.g. aluminium cans.


Metals

- Metals are often recycled by melting and recasting them to make new products.
- They have to be separated - the amount of separation required depends on the use of the recycled metal.
- Magnets can be used to separate ferrous metals (which contain iron) from non-ferrous metals.
- Metals can be separated by density using a centrifuge.
- Some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore.


Aluminium Table

Environmental, Economic, and Social

Reduce Reuse Recycle
Environmental
  • Advantages: Less virgin bauxite mining, lower energy and carbon emissions, reduced transport impacts, and less habitat destruction/deforestation/pollution.
  • Disadvantages: Changing materials or behaviour may lead to trade-offs if alternatives have their own impacts.
  • Advantages: Saves resources and energy, eliminates the production footprint of new aluminium, and high-quality reusable products reduce demand.
  • Disadvantages: Limited reuse cycles before recycling is needed, which still requires resource-intensive logistics.
  • Advantages: Aluminium can be melted and remade indefinitely, saving up to 95% of the energy compared to primary production and keeping material out of landfill.
  • Disadvantages: Collection, sorting, and cleaning increase emissions if not optimised and rely on proper consumer behaviour.
Economic
  • Advantages: Reduces cost by avoiding expensive primary aluminium production and can be cheaper to repair than replace.
  • Disadvantages: Redesigning products or supply chains to prioritise reduction can incur upfront costs.
  • Advantages: Extends product life, reducing the need for constant manufacturing and associated costs.
  • Disadvantages: Requires investment in cleaning, collection, and redistribution systems.
  • Advantages: Collection schemes can earn money or fund recycling programmes, supports the circular economy, and less reliance on imported bauxite.
  • Disadvantages: Sorting logistics add cost, contamination lowers quality, and more labour may be required.
Social
  • Advantages: Encourages behaviour change that values sustainable products, which can build community awareness.
  • Disadvantages: Some consumers may resist change if familiar materials are replaced.
  • Advantages: Higher-quality reusable goods (e.g., aluminium water bottles) strengthen consumer trust in longevity.
  • Disadvantages: Not all groups have easy access to the infrastructure needed for reuse schemes.
  • Advantages: Jobs are created through collection, sorting, and recycling initiatives, and community programmes can be supported.
  • Disadvantages: Effective recycling relies on people sorting correctly, which isn’t always the case.

Paper

- Paper can be recycled by pulping it and then re-forming sheets of paper from the pulp.
- Recycling paper saves trees, energy, water, and landfill space.
- Paper can only be recycled a limited number of times because the fibres get shorter and weaker as they are cut.


Plastics

- Some plastics can be recycled by melting and remoulding them to make new products.
- Different types of plastic have to be separated before recycling.
- Some plastics can be recycled chemically by breaking them down into their monomers which can then be used to make new polymers.
- Not all plastics can be recycled - some are thermosetting plastics which cannot be melted and remoulded.