Agricultural/Bioengineering Renewable Energy 5

Question 1

Which process converts biomass into a combustible gas mixture (CO, H2, CH4, CO2) through partial oxidation at high temperatures?

Accepted Answer

Gasification

Answer

Gasification reacts biomass with a controlled amount of oxygen or steam at 700–1000°C to produce syngas (producer gas).

Question 2

A biochar soil amendment is a co-product of which biomass energy process?

Accepted Answer

Pyrolysis

Answer

Slow pyrolysis of biomass in the absence of oxygen produces biochar as the solid co-product alongside bio-oil and pyrolysis gas.

Question 3

What is the primary advantage of using a biogas combined heat and power (CHP) unit on a farm?

Accepted Answer

Simultaneously generates electricity and recovers waste heat for use in farm operations

Answer

CHP (cogeneration) captures both electrical output and thermal energy from combustion, raising overall system efficiency to 80–90%.

Question 4

In agrivoltaic systems, crops are grown beneath solar panels. What is the main observed benefit for the crops in hot, arid climates?

Accepted Answer

Reduced water evapotranspiration due to panel shading

Answer

Agrivoltaic shading lowers crop canopy temperature and reduces soil evaporation, cutting irrigation water needs by 20–50% in arid conditions.

Question 5

Which microbial group is responsible for the final step of methanogenesis in anaerobic digestion, converting acetate and H2/CO2 to methane?

Accepted Answer

Methanogens (Archaea)

Answer

Methanogenic archaea (e.g., Methanosaeta, Methanobacterium) perform the terminal step converting acetic acid and hydrogen gas into CH4 and CO2.

Agricultural/Bioengineering Practice Test