Evaluating energy sources
Big idea: No energy source is perfect. Choosing an energy mix requires balancing multiple factors: environmental impact, reliability, cost, scalability, and social acceptance.
Evaluation criteria
- GHG emissions: Lifecycle carbon footprint (extraction → use → disposal)
- Air pollution: SO₂, NOₓ, particulates, mercury
- Water use: Cooling, extraction, processing
- Land use: Footprint per unit energy produced
- Reliability: Baseload capability, intermittency, capacity factor
- Cost: Levelized cost of electricity (LCOE)
- Scalability: Can it meet large-scale demand?
- Energy return on investment (EROI): Energy output ÷ energy input
Comparing sources
- Fossil fuels: Reliable, cheap, scalable — but high emissions, pollution, finite
- Nuclear: Low carbon, reliable, high density — but waste, safety, cost concerns
- Solar/wind: Low emissions, decreasing cost — but intermittent, need storage
- Hydro: Reliable, controllable — but site-limited, ecosystem impacts
- Geothermal: Reliable baseload — but geographically limited
Exam tip: The energy essay is highly predictable. Prepare a table comparing at least 4 sources across 5+ criteria. Practice writing balanced evaluations with clear conclusions.
Energy transitions and EVSs
Big idea: Different environmental value systems (EVSs) lead to different energy preferences — from technocentric faith in nuclear and CCS to ecocentric emphasis on efficiency and demand reduction.
EVS perspectives on energy
Technocentric approaches
- Nuclear power as climate solution
- Carbon capture and storage (CCS)
- Large-scale renewable projects
- Continued economic growth possible
- Technology will solve problems
Ecocentric approaches
- Demand reduction and efficiency
- Small-scale, distributed renewables
- Opposition to nuclear (waste/risk)
- Question growth model
- Lifestyle and system change needed
The energy transition
- Current status: Fossil fuels still ~80% of global energy; renewables growing rapidly
- Challenges: Intermittency, storage, grid infrastructure, stranded assets, political resistance
- Opportunities: Falling renewable costs, climate urgency, air quality co-benefits, energy independence
- Policy tools: Carbon pricing, renewable targets, fossil fuel subsidy reform, R&D investment
The energy transition is not just technical — its also economic, political, and social. Vested interests, infrastructure lock-in, and lifestyle expectations all create barriers.
Exam tip: Link energy choices to EVSs explicitly. E.g., A cornucopian would support nuclear expansion, believing technology can manage waste safely.
Stop wasting time on topics you know
Our AI identifies your weak areas and focuses your study time where it matters. No more overstudying easy topics.
IB-style question — Energy choices and sustainability [1]
Marava's annual electricity demand is 4000 GWh. Hydro supplies 360 GWh and solar 120 GWh. Calculate the percentage of demand met by renewables. [1]
How to answer it, step by step
- Add the renewable totals
• 360 + 120 = 480 GWh
• This is the renewable supply - Express as a percentage
• 480 / 4000 x 100
• = 12%
Final answer
Examiner tip: combine BOTH renewables before dividing — a common slip is using only one source.
IB-style question — Energy choices and sustainability [6]
Marava plans to cut coal to 10% by 2040 using wind, solar and one nuclear plant. Evaluate the sustainability of this energy strategy, reaching a reasoned judgement. [6]
How to answer it, step by step
- Build a balanced two-sided case
• For: cuts CO2, diversifies supply, less import reliance, nuclear gives steady base-load
• Against: high build cost, wind/solar intermittent, nuclear waste/risk, slow rollout - Reach a reasoned judgement
• Weigh evidence both ways
• End with a clear verdict (e.g. more sustainable long-term IF storage and waste are managed)
Final answer
Examiner tip: the 6th mark is the conclusion — finish with an explicit, justified judgement, not just a list.