Table 2
LCI data for algae biodiesel production/combustion
a
Process/inputs
Value
Unit
Comment
Cultivation: inputs (kg
À1 dry biomass)
Nitrogen fertilizer
0.26
kg
52 g of nitrogen fertilizer is used per kg algae
slurry at 20% solids
Phosphorus fertilizer
0.045
kg
9 g of phosphate fertilizer is used per kg algae
slurry at 20% solids
Freshwater
1.67
m
3
Added to offset evaporation and maintain
salinity
Electricity (paddlewheels)
30
kWh
8 paddles wheels of increasing size (0.5 kW,
0.5 kW, 0.75 kW, 0.75 kW, 1.0 kW, 1.0 kW,
1.5 kW, and 1.5 kW) are used for 12 h/day
Electricity (flue gas
blower)
12
kWh
A 3 kW blower used to bubble the CO 2 into
the ponds for 12 h/day
Electricity (water pump)
3.33
kWh
A 1 kW water pump used 10 h/day
Electricity (algae inoculant
prep)
6.77
kWh
Florescent light (0.846 kW) used 24 h/day
Electricity (algae inoculant
prep)
14.9
kWh
Air conditioner (0.746 kW) used 24 h/day
Flue gas pumped in
À181
kg
Flue gas at 180 m
3 /h for 12 h/day with a
CO 2 concentration of 13–15%. This input is
modeled as an environmental credit
Cultivation: outputs (kg
À1 dry biomass)
CO 2 emitted
179
kg
The ratio of CO 2 absorbed by the algae to dry
biomass assumed to be 2:1
Harvesting and dewatering: inputs (kg
À1 dry biomass)
Electricity
2
kWh
A 0.5 kW harvesting pump is used for 12 h/
day
Electricity
16
kWh
A 4 kW centrifuge is used for 12 h/day for
producing algae slurry
Oil extraction: inputs (kg
À1 algae oil)
Electricity
0.21
kWh
Electricity used per kg oil
Heat (pretreatment and
extraction)
4933
BTU
Energy input for the pretreatment and
extraction of the oil
Heat (solvent recovery)
6278
BTU
Energy input for recovery of hexane
Heat (oil separation)
1805.57
BTU
Energy input for processing of the oil to
separate the oil and other lipids
Electricity (belt filter press)
2.0
kWh
Energy input for belt filter press to dewater
the biomass. Energy needed for this process
is assumed to be comparable to the feed
dryer energy
Heat (feed dryer)
6417
BTU
Energy input for drying the biomass
Hexane
0.33
kg
Solvent extraction method is used to extract
the oil. Hexane is used as the solvent
Chemical A
0.08
kg
Unidentified chemical. It is modeled by using
a generic EcoInvent process for organic
chemicals
(continued)
Life Cycle Analysis
143
LCI data for algae biodiesel production/combustion
a
Process/inputs
Value
Unit
Comment
Cultivation: inputs (kg
À1 dry biomass)
Nitrogen fertilizer
0.26
kg
52 g of nitrogen fertilizer is used per kg algae
slurry at 20% solids
Phosphorus fertilizer
0.045
kg
9 g of phosphate fertilizer is used per kg algae
slurry at 20% solids
Freshwater
1.67
m
3
Added to offset evaporation and maintain
salinity
Electricity (paddlewheels)
30
kWh
8 paddles wheels of increasing size (0.5 kW,
0.5 kW, 0.75 kW, 0.75 kW, 1.0 kW, 1.0 kW,
1.5 kW, and 1.5 kW) are used for 12 h/day
Electricity (flue gas
blower)
12
kWh
A 3 kW blower used to bubble the CO 2 into
the ponds for 12 h/day
Electricity (water pump)
3.33
kWh
A 1 kW water pump used 10 h/day
Electricity (algae inoculant
prep)
6.77
kWh
Florescent light (0.846 kW) used 24 h/day
Electricity (algae inoculant
prep)
14.9
kWh
Air conditioner (0.746 kW) used 24 h/day
Flue gas pumped in
À181
kg
Flue gas at 180 m
3 /h for 12 h/day with a
CO 2 concentration of 13–15%. This input is
modeled as an environmental credit
Cultivation: outputs (kg
À1 dry biomass)
CO 2 emitted
179
kg
The ratio of CO 2 absorbed by the algae to dry
biomass assumed to be 2:1
Harvesting and dewatering: inputs (kg
À1 dry biomass)
Electricity
2
kWh
A 0.5 kW harvesting pump is used for 12 h/
day
Electricity
16
kWh
A 4 kW centrifuge is used for 12 h/day for
producing algae slurry
Oil extraction: inputs (kg
À1 algae oil)
Electricity
0.21
kWh
Electricity used per kg oil
Heat (pretreatment and
extraction)
4933
BTU
Energy input for the pretreatment and
extraction of the oil
Heat (solvent recovery)
6278
BTU
Energy input for recovery of hexane
Heat (oil separation)
1805.57
BTU
Energy input for processing of the oil to
separate the oil and other lipids
Electricity (belt filter press)
2.0
kWh
Energy input for belt filter press to dewater
the biomass. Energy needed for this process
is assumed to be comparable to the feed
dryer energy
Heat (feed dryer)
6417
BTU
Energy input for drying the biomass
Hexane
0.33
kg
Solvent extraction method is used to extract
the oil. Hexane is used as the solvent
Chemical A
0.08
kg
Unidentified chemical. It is modeled by using
a generic EcoInvent process for organic
chemicals
(continued)
Life Cycle Analysis
143