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Biomass 2nd Renewable in California
California Gross System Power for 2006 (GWh)
Fuel Type In-State NW Imports SW Imports GSP GSP PercentageCoal 17,573 5,467 23,195 46,235 15.70%Large Hydro 43,088 10,608 2,343 56,039 19.00%Natural Gas 106,968 2,051 13,207 122,226 41.50%Nuclear 31,959 556 5,635 38,150 12.90%Renewables 30,514 1,122 579 32,215 10.90%
Biomass 5,735 430 120 6,285 2.10%Geothermal 13,448 0 260 13,708 4.70%Small Hydro 5,788 448 0 6,236 2.10%
Solar 616 616 0.20%Wind 4,927 244 199 5,370 1.80%
TOTAL 230,102 19,804 44,959 294,865 100.00%
Source: CEC http://www.energy.ca.gov/electricity/gross_system_power.html
Bio-fuels: Clean and Renewable Energy?
Biomass stores energy and carbon
Source: Boyle, Renewable Energy, 2nd edition, 2004
Conversion efficiency
Typical solar energy in the Central Valley : 6 kWh/m2/day
6 KWh/ m2/ day
2,190 KWh/ m2/ year
Reaching the leaves 10% 219 KWh/ m2/ yearPart of spectrum contributing to Photosynthesis
50% 110 KWh/ m2/ year
Absorption coefficient of leaves 85% 93 KWh/ m2/ year
Converted to store energy 20% 19 KWh/ m2/ year
Non directly consumed 60% 11 KWh/ m2/ year0.5% 11 KWh/ m2/ year
402 GJ /ha/year154 MMBTU/acre/year
Average daily Solar Energy
Stored Energy
Annual Solar Energy
Biomass conversion and storage rate: 0.5%
Effective radiation on photosynthesis
So
lar
Sp
ectr
al I
rrad
ian
ce (
103 W
.m-2.μ
m)
No conversionConversion
min.. hh
λ (m)
Carbon Balance
Theoretically:
Biomass is carbon neutral
Actually: Additional CO2 emissions for:
Planting, Maintaining and Harvesting Water management Fertilizer Biofuel manufacturing
Avoided decomposition GHG emissions for residues
Life cycle analysis depending on the bio-fuel and technologies
CombustionEmittedExcessStoredspirationDesorbedesisPhotosynthAbsorbed
COOCCOCO 22Re
22
Global Warming Potential
GWP: Normalized index provided by the Intergovernmental Panel on Climate Change (IPCC)
IPCC was established in 1988 by two United Nations organizations: the World Meteorological Organization (WMO), the United Nations Environment Program
(UNEP),
to evaluate the risk of climate change caused by human activity.
IPCC shared the 2007 Nobel Peace Prize with former Vice President Al Gore.
GWP
By definition:
Time Horizon is very important because of the complex decay of the chemical components in the atmosphere
timetheduringxofionconcentrattheofVariationtx
xtodueabsorptionraredAdditionala
yearsHorizonTimeTH
componentchemicalx
dttCOa
dttxaxGWP
x
TH
CO
TH
x
:)(
inf:
)(:
:
).(.
).(.)(
0 2
0
2
GWP
Values provided by IPCC in 2001
20 years 100 years 500 years
Methane CH4 3.7x10-4 12 62 23 7
Nitrous oxide N2O 3.1x10-3 114 275 296 156
CFC-12 CCl2F2 0.32 100 10,200 10,600 5,200
HCFC-22 CHClF2 0.2 12 4,800 1,700 540
HFC-134a CH2FCF3 0.15 14 3,300 1,300 400
Time horizonGas
Chlorofluorocarbons
Hydrochlorofluorocarbons
Hydrofluorocarbons
Radiative efficiency
(Wm-2 ppb-1)
Lifetime (years)
Global Warming Potential
Source: IPCC Climate Change 2001 The Scientific Basishttp://www.grida.no/climate/ipcc_tar/wg1/index.htm
Net life cycle emissions from Electricity Generation
CO2 SO2 NOx
10 2.42 3.913 0.88 1.5529 0.11 1.95
364 2.54 3.3
4 1.13 2.0131 1.12 2.3849 0.34 2.6
14 0.06 0.4324 0.06 0.57
446 0 0.5955 11.8 4.3
Natural gas, CCGTCoal, best practice
Fossil fuels
Poultry litterStrawForestry residuesMunicipal Solid Waste (MSW)
Sewage gasAnimal slurryLandfill gas
Energy cropsForestry residues
Emissions in kg/ MWh
Combustion, steam turbine
Anaerobic digestion, gas engine
Gasification, BIGCC
Source: Boyle, Renewable Energy, 2nd edition, 2004
Net Life Cycle Greenhouse Gas Emissions
Taking the avoided decomposition methane emission into account forest residue direct combustion may have a negative GWP
Source: Margaret K. Mann and Pamela L. Spath LIFE CYCLE ASSESSMENT COMPARISONS OF ELECTRICITY FROM BIOMASS, COAL, AND NATURAL GAS, 2002 Annual Meeting of the American Institute of Chemical Engineers November 2002
Biofuels
Biofuels cover a broad range of technologies and applications:
Thermochemical Conversion
Direct Combustion
Direct Combustion
Gasification
Gasification
PyrolysisLiquefaction
PyrolysisLiquefaction
Biochemical Conversion
Anaerobic Digestion
Anaerobic Digestion
Fermentation
Fermentation
Extraction
Extraction
Heat Electricity Transportation
Steam Gas Oil Charcoal Bio-dieselBiogas Ethanol
Source: From Boyle, Renewable Energy, 2nd edition, 2004
Biomass for Power Generation in California (2005)
Wood
40%
Agricultural
waste
11%
Landfill gas
12%
Digesters
5%
Others
32%
Direct Combustion
Wood and straw residues are dominant About 600 MWe in California
Location of wood power plants in California
Number ofPlants
California 29 588Maine 7 184
Michigan 7 165Florida 5 151
Washington 3 83Virginia 2 80Vermont 2 70
New Hampshire 4 51Pennsylvania 3 50North Carolina 3 56TOTAL USA 65 1,478
Plants Operating in 2003State Sales
generation, MW
Wood combustion Wood has an energy content of 6 to 18
MJ/kg depending on its moisture Wood macro-molecules (cellulose polymers)
break-down starts at about 300oC (575oF) It generates inflammable gas (CnHm) which
burn with the air oxygen (Gaseous combustion releases about 85% of the energy content of dry wood)
The combustion requires about 5.5 kg of air per kg of dry wood
Remaining charcoal is directly oxidized at high temperature (600oC)
Steam Cycle
0 1 2 3 4 5 6 7 8 90
500
1000
1500
2000
2500
3000
3500
40004000
s [kJ/kg-K]
h [
kJ
/kg
] 90 bar
30 bar
0.055 bar
SteamNBS
turbineW
CondensorQ
Cycle conversion rate: η=35%
GeneratorSteamQ
pumpW
Honey Lake Power Plant
Wood Honey Lake Power Plant: 36MW Wood processing: 1,300 tpd Condensate water pre-heating with
geothermal source
Gasification To obtain a better efficiency and a better control
of the combustion and pollution, pyrolysis, charcoal gasification and combustion are controlled separately.
Integrated Gas Combined Cycle
IGCC is the association of a gasifier, a gas turbine and a steam cycle
Biomass
Gas turbine generates electricity by direct combustion of syngas
Heat of the exhaust gas is recovered to run a steam cycle
Gas Turbine
CompressorTurbine
Combustion
5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.07.00
200
400
600
800
1000
1200
s [kJ/kg-K]
h [
kJ
/kg
]
1 bar
17 bar
Air
Conversion rate: 36%Brayton Cycle
IGCC
Steam Cycle
0 1 2 3 4 5 6 7 8 90
500
1000
1500
2000
2500
3000
3500
40004000
s [kJ/kg-K]
h [
kJ
/kg
]
90 bar
30 bar
0.055 bar
SteamNBS
Conversion rate: 29%
IGCC
Conversion rate
Example:ηIGCC= 55%
TurbineGasCycleSteamTurbineGasIGCC 1.
Fluidized Bed Gasifier in Gussing Burgenland Austria operated on wood chips
Wood bio-mass potential in California
Forest biomass represents about 50% of the wood residue resource
The potential for the forestry residue is 27 MM BDT/year
Biomass wood source (2005)
Urban Wood
31%
Forest
46%
Agricultural
16%
Food
Processing
7%
Source: CEC An Assessment of Biomass Resources in California, 2006
(BDT = Bone Dry Ton)
Calculation of the Electricity Generation potential
Energy content: Ec=18 MJ/kg Conversion rate: η=25% Capacity factor: CF=85%
GW
CF
EPower
yTWhETontonBDTE
year
Cyearyear
1.48760.
/30...
This potential represents about 10% of the electricity consumption in California and about 15 times what is currently in operation