- Title Pages
- 1 Energy and Society
- 2 Buildings
- 3 Electrical Power Generation: Fossil Fuels
- 4 Nuclear Power Generation
- 5 Electrical Power Distribution
- 6 Electrical Power Generation: Renewables—Solar and Wind
- 7 Electrical Power Generation: Hydroelectricity, Tides and Pumped Storage
- 8 Transportation: Fuel Energies
- 9 Ground Transportation: Road and Rail
- 10 Air Transportation
- 11 Ground Transportation: Ships
- 12 Materials That Come from the Earth
- 13 Agriculture—Things That Are Grown
- 14 Embodied Energy and Energy Return on Investment
- 15 Summary—What Should Be Done?
- Appendix A Energy Used by Different Countries, from the <i>BP Statistical Review</i>
- Appendix B Thermodynamic Relations
- Appendix C Ground Source Heat Pumps
- Appendix D1 Work Done By Stirling Engine
- Appendix D2 Ultimate Efficiency of Photovoltaic Cell
- Appendix D3 Maximum Power of Photovoltaic Cell
- Appendix E Betz’s Law
- Appendix F Optimal Airspeeds
- Appendix G Units
- General Bibliography
- (p.152) 10 Air Transportation
- The Simple Physics of Energy Use
- Oxford University Press
When an airplane is full, the energy used to travel a given distance compares very favourably with driving an economical car. Primary energy use is less since airplane turbofan engines are more efficient than car engines. Even airplanes with propellers driven by petrol engines are more efficient than cars as the engines are operating at near-peak rpm and producing a higher proportion of the rated power. Air travel uses a lot of energy because it makes travelling long distances easy, even if not very comfortable. The airplane is limited by the weight it can carry, which puts a limit on how tightly the passengers can be squeezed together. Given that drag will always be a factor in high-speed transportation, even for ground transportation, energy use can be minimised by reducing the cross-sectional area and squeezing more people into even smaller spaces, such as in the hyperloop.
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