Key term
CCEA A-Level Environmental Technology 3930
Fossil Fuels
Global Action on Energy Conservation and Climate Change
Macrogeneration
Microgeneration
Energy From Wind
Topic overviewHorizontal and vertical axis wind turbinesKinetic energy, wind power and the Betz limitPower curves, rated output and energy lossesSwept area, blade length and turbine massAir density, hub height and turbine sitingPower control, yawing and survival speedChoosing a location for a commercial wind farm
Energy From the Sun
Topic overviewSolar radiation, tracking and concentrating solar powerFlat plate and evacuated tube collectorsSizing a domestic solar thermal systemPhotovoltaic cells and semiconductor wafersTypes of photovoltaic module comparedPlanning regulations and solar incentivesPassive solar design in new and existing buildings
Energy From Biomass
Energy Storage
Plastics for the Future
Topic overviewCrude oil as a fuel and a feedstockRefinery gases and the making of polymersPersistent plastic waste and the Great Pacific Garbage PatchToxic gases from incinerating plasticsBiodegradable, photodegradable and compostable plasticsTesting photodegradable plastic against polytheneBio-derived polyethylene and a sustainable plastics future
Renewable Energy Investigations
Sustainable Development
Waste Management
Waste to Energy Technologies
Land Contamination and Remediation
Topic overviewContaminated land, risk and traditional remediationBioremediation principles and bioreactor systemsMicro-organisms that degrade named pollutantsBioremediation benefits and genetically engineered microbesPhytoremediation of metals and other elementsPhytoextraction with Indian mustard and alpine pennycressBiohydrometallurgy and phytomining of ores
Hydrogen Fuel Cells
Transport System Challenges
Energy Performance of Buildings
Emerging Technologies
Sustainable Urban and Rural Communities
The Code for Sustainable Homes
Topic overviewPurpose, levels and assessment of the CodeEnergy, carbon dioxide and water categoriesMaterials, surface water run-off and waste categoriesPollution, health and wellbeing, management and ecology categoriesMeasuring the performance of an existing buildingPerformance profiles, improvements and evaluation
Energy From Wind
Swept area, blade length and turbine mass
- 3 things to know
- AS 1
Overview
Swept area and its calculation, how power grows with blade length, why doubling blade length multiplies mass by about eight, glass and carbon fibre blades, stiffness and fatigue, and siting limits on blade size.
What you need to know
Answer each one before you reveal it.
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Key term
How does power output depend on swept area?
Numbers
Calculate the swept area of a rotor 100 m in diameter.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is the swept area of a wind turbine rotor?
Model answer
The swept area is the circular area traced out by the blade tips as the rotor turns. Swept area is calculated as A = πr², where r is the rotor radius.
- 2
How does power output depend on swept area?
Model answer
Power output is directly proportional to swept area, because a larger area intercepts more moving air each second. A rotor with twice the swept area captures twice the power.
- 3
Calculate the swept area of a rotor 100 m in diameter.
Model answer
The swept area is about 7,850 m². The working is π × 50² = 7,854 m².
- 4
Calculate the swept area of a small turbine with a rotor diameter of 3 m.
Model answer
The swept area is about 7.1 m². The radius is 1.5 m, and π × 1.5² = 7.07 m².
- 5
Calculate the power available to a 3 m diameter rotor in an 8 m/s wind, taking air density as 1.2 kg/m³.
Model answer
About 2.2 kW of power is available in the wind. The working is ½ × 1.2 × 7.07 × 8³ = 2,170 W.
- 6
Demonstrate the effect of blade diameter on power output by comparing rotors of 2 m and 4 m diameter in the same wind.
Model answer
The 4 m rotor sweeps 12.6 m², four times the 3.14 m² of the 2 m rotor. The larger rotor therefore captures about four times the power.
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