What is biomass? - 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 - 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 - ANSWER-Conversion efficiency: <8% of radiation
reaching plant <1% of total radiation
-photosynthesis: 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 the reverse of combustion
Photosynthesis Efficiency - 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? - 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 - ANSWER--Switchgrass- 0.26%
-Corn- 0.79%
-Sugarcane- 2.24%
-Willow/poplar- 0.41%
-green algae- 4.90%
Basic requirements for crop production - ANSWER--solar insolation, precipitation,
temperature, nutrients/soil fertility, CO2
Nutrients required for plants - 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 - ANSWER--highly digestible contents: proteins, sugars &
starches, fats (foods)
-structural contents: cellulose, hemicellulose, and lignin
Plant constituents - 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 - 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 - ANSWER-Ash has no energy value, so the lower the ash
the higher the heating value
C3 Plants - 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
C4 plants - ANSWER--different photosynthesis pathways
-need plentiful sunlight but less water than C3 plants
-high starch, and simple sugar content
-higher lignin content than C3 plants
-dry matter yields greater than C3 plants
, -corn, sugar cane, switchgrass, sorghum
Typical yield comparision - ANSWER-Switchgrass- 14,000 kg DM/ha
Corn stover- 8,400 & grain- 8,400
Alfalfa- 12,500
How many bales of corn stover would it take to power your house for a year?
Assume: house needs 25,000 kWh a year (electricity + heat + hot water)
-energy content for corn stover = 15 GJ/tonne
-assume a round rale ( 1x1x1m)= 500 kg= 0.5 tonne
-conversion efficiency= 0.50 (heat and power)
How much land was harvested for that one house? Assume harvest 1 tonne/acre -
ANSWER-25,000 kWh x 0.0036 GJ/1 kWh x 1/0.5 (energy conversion) x 1 tonne/15 GJ
= 12 tonnes x 1 bale/0.5 tonnes= 24 bales
-12 tonnes =12 acres
Biomass storage - ANSWER--annual crops (switch grass, corn stover, other crop
residuals) are only harvested once a year, so they will need to be stored for 12 months
or more at a processing plant.
-storage comes at a cost especially for these low density materials, which can spoil if
stored too long, is too wet, or is too warm
-woody biomass can be harvested year round, sometimes called storage on the stump
-allows wood processing plants that make pellets or other biofuels to have much less
storage of only 1-2 months
-But, woody biomass has more difficult harvesting and conversion into fuels
Corn ethanol production steps - ANSWER-plant (+fertilize), tillage (pre-planting and/or
mechanical weed control), chemical application (fertilizer/weed control), harvest,
transport field-farm gate, transport farm gate to drying/storage facility, transport
drying/storage- ethanol plant
Corn stover ethanol logistics - ANSWER-chopping (drying/particle size), raking (to
facilitate baling), bailing (to facilitate transport), transport to farm gate- ethanol plant
Feedstock logistics systems challenges include: - ANSWER--agricultural and forest
resources have low mass and energy density: makes them cost-prohibitive to transport,
handle, and store
-moisture content at the time of harvest or collection leads to degradation: can cause
aerobic instability during storage
-equipment is inefficient: insufficient capacity
-quality characteristics are variable and inconsistent: vary with feedstock source and
season, biorefineries require feedstocks of consistent quality, particle size, and moisture
content
-transportation is costly and can strain transportation networks: truck traffic is costly,
often damaging to roadways, and can be socially undesirable
Harvest- dealing with plant moisture - ANSWER--allow plants to dry in the field- field
conditioning
-equipment is very expensive (combine or SPFH >$300,000)
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 - 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 - ANSWER-Conversion efficiency: <8% of radiation
reaching plant <1% of total radiation
-photosynthesis: 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 the reverse of combustion
Photosynthesis Efficiency - 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? - 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 - ANSWER--Switchgrass- 0.26%
-Corn- 0.79%
-Sugarcane- 2.24%
-Willow/poplar- 0.41%
-green algae- 4.90%
Basic requirements for crop production - ANSWER--solar insolation, precipitation,
temperature, nutrients/soil fertility, CO2
Nutrients required for plants - 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 - ANSWER--highly digestible contents: proteins, sugars &
starches, fats (foods)
-structural contents: cellulose, hemicellulose, and lignin
Plant constituents - 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 - 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 - ANSWER-Ash has no energy value, so the lower the ash
the higher the heating value
C3 Plants - 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
C4 plants - ANSWER--different photosynthesis pathways
-need plentiful sunlight but less water than C3 plants
-high starch, and simple sugar content
-higher lignin content than C3 plants
-dry matter yields greater than C3 plants
, -corn, sugar cane, switchgrass, sorghum
Typical yield comparision - ANSWER-Switchgrass- 14,000 kg DM/ha
Corn stover- 8,400 & grain- 8,400
Alfalfa- 12,500
How many bales of corn stover would it take to power your house for a year?
Assume: house needs 25,000 kWh a year (electricity + heat + hot water)
-energy content for corn stover = 15 GJ/tonne
-assume a round rale ( 1x1x1m)= 500 kg= 0.5 tonne
-conversion efficiency= 0.50 (heat and power)
How much land was harvested for that one house? Assume harvest 1 tonne/acre -
ANSWER-25,000 kWh x 0.0036 GJ/1 kWh x 1/0.5 (energy conversion) x 1 tonne/15 GJ
= 12 tonnes x 1 bale/0.5 tonnes= 24 bales
-12 tonnes =12 acres
Biomass storage - ANSWER--annual crops (switch grass, corn stover, other crop
residuals) are only harvested once a year, so they will need to be stored for 12 months
or more at a processing plant.
-storage comes at a cost especially for these low density materials, which can spoil if
stored too long, is too wet, or is too warm
-woody biomass can be harvested year round, sometimes called storage on the stump
-allows wood processing plants that make pellets or other biofuels to have much less
storage of only 1-2 months
-But, woody biomass has more difficult harvesting and conversion into fuels
Corn ethanol production steps - ANSWER-plant (+fertilize), tillage (pre-planting and/or
mechanical weed control), chemical application (fertilizer/weed control), harvest,
transport field-farm gate, transport farm gate to drying/storage facility, transport
drying/storage- ethanol plant
Corn stover ethanol logistics - ANSWER-chopping (drying/particle size), raking (to
facilitate baling), bailing (to facilitate transport), transport to farm gate- ethanol plant
Feedstock logistics systems challenges include: - ANSWER--agricultural and forest
resources have low mass and energy density: makes them cost-prohibitive to transport,
handle, and store
-moisture content at the time of harvest or collection leads to degradation: can cause
aerobic instability during storage
-equipment is inefficient: insufficient capacity
-quality characteristics are variable and inconsistent: vary with feedstock source and
season, biorefineries require feedstocks of consistent quality, particle size, and moisture
content
-transportation is costly and can strain transportation networks: truck traffic is costly,
often damaging to roadways, and can be socially undesirable
Harvest- dealing with plant moisture - ANSWER--allow plants to dry in the field- field
conditioning
-equipment is very expensive (combine or SPFH >$300,000)
