Agricultural/Bioengineering Renewable Energy 2 — Questions and Answers
Question 1: Which anaerobic digestion product can be used directly as a vehicle fuel after upgrading to remove CO2?
- Biogas (biomethane) (Correct answer)
- Syngas
- Producer gas
- Hydrogen
Correct answer: Biogas (biomethane)
Biogas upgraded to remove CO2 and H2S becomes biomethane, which meets natural gas vehicle fuel standards.
Question 2: In a wind energy system for an agricultural operation, what is the purpose of a charge controller?
- Prevents battery overcharging by regulating current flow (Correct answer)
- Converts AC to DC power
- Increases turbine rotational speed
- Measures wind velocity at hub height
Correct answer: Prevents battery overcharging by regulating current flow
A charge controller regulates the voltage and current from the wind turbine to prevent battery damage from overcharging.
Question 3: A farm uses a micro-hydropower turbine. If flow rate doubles but head remains constant, how does power output change?
- Power doubles (Correct answer)
- Power quadruples
- Power increases by 50%
- Power remains the same
Correct answer: Power doubles
Hydropower is P = ρgQH, so doubling flow rate Q directly doubles power when head H is constant.
Question 4: Which feedstock produces the highest methane yield per unit of volatile solids in anaerobic digestion?
- Fats and oils (Correct answer)
- Carbohydrates
- Proteins
- Lignocellulosic biomass
Correct answer: Fats and oils
Fats and oils yield approximately 1,000 L CH4/kg VS, the highest among common organic substrates.
Question 5: What does the term 'net metering' allow agricultural solar installations to do?
- Sell excess electricity back to the grid and receive credit on utility bills (Correct answer)
- Measure net solar radiation reaching panels
- Operate independently from the utility grid
- Monitor real-time energy consumption
Correct answer: Sell excess electricity back to the grid and receive credit on utility bills
Net metering allows farms to export surplus solar generation to the grid and offset future electricity costs.
Question 6: In bioengineering, which enzyme complex is responsible for breaking down cellulose into fermentable sugars?
- Cellulase (Correct answer)
- Amylase
- Lipase
- Protease
Correct answer: Cellulase
Cellulase is the enzyme complex (including endoglucanase, exoglucanase, and β-glucosidase) that hydrolyzes cellulose into glucose.
Question 7: A solar thermal collector on a grain dryer has an efficiency of 60% and receives 800 W/m² insolation. What is the useful heat output per square meter?
- 480 W/m² (Correct answer)
- 320 W/m²
- 600 W/m²
- 800 W/m²
Correct answer: 480 W/m²
Useful output = efficiency × insolation = 0.60 × 800 = 480 W/m².
Agricultural/Bioengineering Renewable Energy 2
Which anaerobic digestion product can be used directly as a vehicle fuel after upgrading to remove CO2?