To classify a green-technology application, ask what problem it solves and group it by that purpose. Energy supply, energy saving, waste handling and water care are four useful groups.
This lesson is part of SPM Science green technology. The next lesson, comparing energy choices using supplied data, uses the same groups.
What purpose groups can I use?
A purpose group is a short label that says what the technology does for the environment. Four groups cover most SPM examples.
- Energy supply: produces energy from sources that are replaced naturally, such as solar, wind and hydro.
- Energy saving: uses less energy for the same job, such as an LED lamp.
- Waste handling: reduces or reuses waste, such as composting and recycling bins.
- Water care: saves or cleans water, such as rainwater harvesting.
Always tie the feature to the purpose in one sentence, because that sentence earns the reasoning mark.
Worked example: sort six applications
Here are six applications. Sort each one and say why.
| Application | Purpose group | Reason |
|---|---|---|
| Rooftop solar panels | Energy supply | Convert sunlight to electricity without burning fuel |
| LED street lamps | Energy saving | Give the same light with less electrical energy |
| Food waste composter | Waste handling | Turns food scraps into soil improver instead of landfill waste |
| Rainwater tank | Water care | Stores rain for washing, so less treated water is used |
| Wind turbine | Energy supply | Uses moving air to turn a generator |
| Sensor taps | Water care | Release water only when hands are present, so less is wasted |
In this table, LED street lamps is the only energy saving entry. Sensor taps save water, not energy, so they belong under water care.
The mistake that costs marks
The usual slip is to classify by appearance: a device that looks natural or has a leaf on it is called green. Two devices can look alike and have very different purposes.
| Device | Wrong reason | Right reason |
|---|---|---|
| Wind turbine | It looks clean | It supplies energy without burning fuel |
| LED lamp | It is modern | It uses less electrical energy for the same light |
| Plastic recycling bin | It is coloured green | It helps waste be reused as material |
The fix is to write the purpose before you write the group. If you cannot state the purpose, the classification is a guess.
Check yourself
Classify each one and give a reason in one sentence: a biogas digester on a farm, an insulated roof that keeps a building cooler.
Answer
Biogas digester: waste handling, since it breaks down animal waste, and it also supplies energy as gas. If one group is required, choose waste handling.
Insulated roof: energy saving, because a cooler building needs less electricity for air conditioning.
What to study next
Move on to comparing energy choices using supplied data. Then test the cluster with the green technology practice set.
Use the mistake log and paper-error review to track wrong purposes. If you want a teacher to question your reasons for each placement, see online one-to-one Science tuition.