Renewable Energy Systems Exam 3 Newest 2026
Questions and Correct Detailed Answers Already
Graded A+
What is biomass? - CORRECT ANSWER-mass of any organism or living thing. In
the energy space it is meant as organic matter intended for fuel or feedstocks into
a fuel production process
-can be converted into heat and electricity through combustion
-can be directly converted into transportation fuels to replace fossil fuels allowing
it to fill a special niche in renewable energy systems
Biomass Energy - CORRECT ANSWER--stored solar energy as chemical energy
-carbon bonds between carbon, hydrogen, and oxygen broken by digestion,
combustion, or thermal decomposition, the stored solar energy is released
-biomass residues and wastes already provide about 14% of the world's primary
energy supplies
Solar Energy Stored in Biomass - CORRECT ANSWER-Conversion efficiency:
<8% of radiation reaching plant <1% of total radiation
-photosynthesis: 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 the reverse of
combustion
,Photosynthesis Efficiency - CORRECT ANSWER--Actual efficiency of conversion
from total solar radiation to stored energy in plant:
-for corn grain- 0.4%, whole corn plant- 0.8%, C4 plant- theoretical eff. 7%
-why is actual so much less than theoretical? Many conversion processes
-compared biomass solar energy conversion efficiency to PV cell efficiency (>20%)
but plants replicating and low cost
Where do photons go? - CORRECT ANSWER-100% sunlight -> non-bioavailable
photons loss 47%
-53% (light that is compatible) -> incomplete absorption loss 30%
-37% (absorbed into plant) -> wavelength-mismatch degradation to 700 nm
energy loss 24%
-28% (at chlorophyll) -> conversion of ATP and NADPH to D-glucose 24% efficient
-9% (converted to sugar) -> 35-40% of sugar is recycled/consumed by the leaf in
dark and photorespiration, leaving
~5% net leaf efficiency
-only about 1/8 of the light able to reach leaf
~0.7% of light energy converted
,Biomass Productivity and Efficiency - CORRECT ANSWER--Switchgrass- 0.26%
-Corn- 0.79%
-Sugarcane- 2.24%
-Willow/poplar- 0.41%
-green algae- 4.90%
Basic requirements for crop production - CORRECT ANSWER--solar insolation,
precipitation, temperature, nutrients/soil fertility, CO2
Nutrients required for plants - CORRECT ANSWER-N, P2O5, and K2O
-nitrogen, phosphorus, and potassium
-some plants such as legumes can fixate N2 from air
-increase in nutrients as more crops go to intensive cropping
Biomass composition - CORRECT ANSWER--highly digestible contents:
proteins, sugars & starches, fats (foods)
-structural contents: cellulose, hemicellulose, and lignin
, Plant constituents - CORRECT ANSWER--oils, sugars and starches: easily
metabolized, high food value, easily converted to bio-products like soy diesel,
ethanol, etc. Susceptible to degradation during storage
-lignocelluloses: more difficult to convert, needs special enzymes and/or micro-
organisms, ease of conversion cellulose, hemi-cellulose then lignin
Wood composition & grass composition - CORRECT ANSWER-Hardwood- 47%
cellulose, 20% hemicellulose, 33% lignin
Softwood- 41% cellulose, 31% hemicellulose, 29% lignin
Corn- 36% cellulose, 31% hemicellulose, 23% lignin
Switchgrass- 44% cellulose, 34% hemicellulose, 22% lignin
Biomass composition- Ash - CORRECT ANSWER-Ash has no energy value, so
the lower the ash the higher the heating value
C3 Plants - CORRECT ANSWER--about 95% of global plants, high protein and
lipid (oil) content, thrive in cool and wet climates, yield less than C4 plants
-wheat, soybeans, alfalfa, sunflowers and trees
Questions and Correct Detailed Answers Already
Graded A+
What is biomass? - CORRECT ANSWER-mass of any organism or living thing. In
the energy space it is meant as organic matter intended for fuel or feedstocks into
a fuel production process
-can be converted into heat and electricity through combustion
-can be directly converted into transportation fuels to replace fossil fuels allowing
it to fill a special niche in renewable energy systems
Biomass Energy - CORRECT ANSWER--stored solar energy as chemical energy
-carbon bonds between carbon, hydrogen, and oxygen broken by digestion,
combustion, or thermal decomposition, the stored solar energy is released
-biomass residues and wastes already provide about 14% of the world's primary
energy supplies
Solar Energy Stored in Biomass - CORRECT ANSWER-Conversion efficiency:
<8% of radiation reaching plant <1% of total radiation
-photosynthesis: 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 the reverse of
combustion
,Photosynthesis Efficiency - CORRECT ANSWER--Actual efficiency of conversion
from total solar radiation to stored energy in plant:
-for corn grain- 0.4%, whole corn plant- 0.8%, C4 plant- theoretical eff. 7%
-why is actual so much less than theoretical? Many conversion processes
-compared biomass solar energy conversion efficiency to PV cell efficiency (>20%)
but plants replicating and low cost
Where do photons go? - CORRECT ANSWER-100% sunlight -> non-bioavailable
photons loss 47%
-53% (light that is compatible) -> incomplete absorption loss 30%
-37% (absorbed into plant) -> wavelength-mismatch degradation to 700 nm
energy loss 24%
-28% (at chlorophyll) -> conversion of ATP and NADPH to D-glucose 24% efficient
-9% (converted to sugar) -> 35-40% of sugar is recycled/consumed by the leaf in
dark and photorespiration, leaving
~5% net leaf efficiency
-only about 1/8 of the light able to reach leaf
~0.7% of light energy converted
,Biomass Productivity and Efficiency - CORRECT ANSWER--Switchgrass- 0.26%
-Corn- 0.79%
-Sugarcane- 2.24%
-Willow/poplar- 0.41%
-green algae- 4.90%
Basic requirements for crop production - CORRECT ANSWER--solar insolation,
precipitation, temperature, nutrients/soil fertility, CO2
Nutrients required for plants - CORRECT ANSWER-N, P2O5, and K2O
-nitrogen, phosphorus, and potassium
-some plants such as legumes can fixate N2 from air
-increase in nutrients as more crops go to intensive cropping
Biomass composition - CORRECT ANSWER--highly digestible contents:
proteins, sugars & starches, fats (foods)
-structural contents: cellulose, hemicellulose, and lignin
, Plant constituents - CORRECT ANSWER--oils, sugars and starches: easily
metabolized, high food value, easily converted to bio-products like soy diesel,
ethanol, etc. Susceptible to degradation during storage
-lignocelluloses: more difficult to convert, needs special enzymes and/or micro-
organisms, ease of conversion cellulose, hemi-cellulose then lignin
Wood composition & grass composition - CORRECT ANSWER-Hardwood- 47%
cellulose, 20% hemicellulose, 33% lignin
Softwood- 41% cellulose, 31% hemicellulose, 29% lignin
Corn- 36% cellulose, 31% hemicellulose, 23% lignin
Switchgrass- 44% cellulose, 34% hemicellulose, 22% lignin
Biomass composition- Ash - CORRECT ANSWER-Ash has no energy value, so
the lower the ash the higher the heating value
C3 Plants - CORRECT ANSWER--about 95% of global plants, high protein and
lipid (oil) content, thrive in cool and wet climates, yield less than C4 plants
-wheat, soybeans, alfalfa, sunflowers and trees
