CEA Renewable Energy Technologies 5 — Questions and Answers
Question 1: What is 'agrivoltaics'?
- Using agricultural waste to generate biogas for electricity
- Co-locating solar panels and agricultural crops on the same land (Correct answer)
- Applying fertilizers to improve soil conductivity near ground-mounted arrays
- Growing algae in water beneath floating solar panels only
Correct answer: Co-locating solar panels and agricultural crops on the same land
Agrivoltaics combines solar energy generation with crop production or grazing on the same land, optimizing dual use of agricultural land.
Question 2: Which wind turbine configuration places the rotor downwind of the tower?
- Upwind turbine
- Downwind turbine (Correct answer)
- Vertical-axis turbine
- Savonius rotor
Correct answer: Downwind turbine
Downwind turbines have their rotor positioned on the leeward side of the tower, allowing passive yaw alignment with wind direction.
Question 3: What is 'levelized cost of storage' (LCOS) used to evaluate?
- The cost per kilowatt-hour of installing new transmission lines
- The all-in cost of storing and dispatching one kilowatt-hour of electricity over a storage system's life (Correct answer)
- The insurance premium for battery storage installations
- The cost of recycling end-of-life solar panels
Correct answer: The all-in cost of storing and dispatching one kilowatt-hour of electricity over a storage system's life
LCOS expresses the total lifecycle cost of a storage system—capital, O&M, charging energy—divided by total energy discharged, enabling comparison across technologies.
Question 4: In solar resource assessment, what does 'direct normal irradiance' (DNI) specifically measure?
- Total solar radiation on a horizontal surface
- Solar radiation on a surface tilted at the latitude angle
- Solar radiation received per unit area on a surface perpendicular to the sun's rays (Correct answer)
- Diffuse radiation scattered by clouds and atmosphere
Correct answer: Solar radiation received per unit area on a surface perpendicular to the sun's rays
DNI measures the intensity of solar radiation arriving on a surface held perpendicular to the direct beam from the sun, excluding diffuse radiation.
Question 5: What is the primary environmental concern associated with large-scale lithium mining for battery storage used in renewable energy systems?
- Radioactive contamination of nearby groundwater
- High water consumption and habitat disruption in arid mining regions (Correct answer)
- Release of sulfur dioxide during smelting operations
- Mercury contamination from lithium refining processes
Correct answer: High water consumption and habitat disruption in arid mining regions
Lithium brine extraction in arid regions like the Atacama Desert consumes large amounts of water and can disrupt local ecosystems and indigenous water rights.
Question 6: What is a 'renewable energy certificate' (REC) and what does it represent?
- A government license required to operate a renewable energy facility
- A tradable instrument representing the environmental attributes of one megawatt-hour of renewable electricity (Correct answer)
- A tax form filed when claiming the Investment Tax Credit
- A utility interconnection approval document for renewable generators
Correct answer: A tradable instrument representing the environmental attributes of one megawatt-hour of renewable electricity
A REC (or SREC for solar) represents proof that one MWh of electricity was generated from a renewable source and carries the associated environmental attributes.
Question 7: Which characteristic makes hydrogen produced via electrolysis using renewable electricity considered 'green hydrogen'?
- It is produced at temperatures below 50°C
- It emits no carbon dioxide during production because renewable power drives the electrolyzer (Correct answer)
- It is stored in green-colored pressurized cylinders
- It is derived from biomass rather than natural gas
Correct answer: It emits no carbon dioxide during production because renewable power drives the electrolyzer
Green hydrogen is produced by splitting water via electrolysis powered entirely by renewable electricity, resulting in zero CO2 emissions during production.
