Energy and the Environment
Core concepts
This domain examines how energy is produced, transformed, and used. Candidates must understand energy forms (kinetic, potential, thermal, chemical, electrical, nuclear), conservation of energy, and efficiency as useful output divided by total input. Know renewable sources (solar, wind, hydro, geothermal, biomass) versus non-renewable (coal, oil, natural gas, nuclear fuel). Understand fossil fuel combustion and its emissions, greenhouse gas contributions, and the enhanced greenhouse effect. Understand energy transformations in power plants (chemical → thermal → mechanical → electrical) and the losses at each stage. Know alternative energy trade-offs: intermittency of solar and wind, habitat impacts of hydro, and waste issues for nuclear. Understand energy density, cost, and life-cycle emissions as comparison criteria, and recognise energy conservation strategies and carbon footprint calculations.
Traps to watch
- Claiming energy is "used up"; energy is transformed, not destroyed.
- Using efficiency greater than 100% by mixing input and output units.
- Assuming renewable means zero environmental impact.
- Confusing power (watts, energy per second) with energy (joules).
- Forgetting that nuclear power has low operational emissions but produces radioactive waste.
Worked example
A power plant takes 500 MJ of chemical energy and delivers 150 MJ of electrical energy. Efficiency = 150 ÷ 500 × 100% = 30%. Rule of thumb: always express input and output in the same unit before dividing, and remember the remaining 70% is mostly lost as waste heat.