coal facilitation of renewable energy alternativescoal facilitation of renewable energy alternatives...
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Coal Facilitation of Renewable Energy Alternatives
Larry BaxterBrigham Young University
Provo, UT 84602
Global Climate and Energy ProgramAdvanced Coal Workshop
March 15-16, 2005
Environmental Impacts
Coal Facilitates Renewable Energy
• Coal-biomass integrated systems (pcc, igcc, etc.) advantages relative to dedicated plants• Increased
• Availability• Efficiency• Reliability
• Decreased • Cost (capital, operating, and power production)• Risk (technical, financial, project)• Implementation time
Cofiring is a Cross Cutting Option
Combustion
Oxyfuel
Gasification
Liquefaction
Fuel CellsC
ofiri
ng
US CO2 Emissions
• Coal Facts and Figures:• 1 Billion Tons of Coal
Consumed
• Coal generates 54% of US Electricity
• ~ 1200 Coal-Fired Power Plants
15% of Coal Emissions
Transportation32%Electric
Other 4%
ElectricCoal 30%
Industrial21%
Other13%
Potential Biomass Contribution
400
450
500
550
600
650
1990 1995 2000 2005 2010
Car
bon
Em
issi
ons
(106 m
etri
c to
ns)
Year
Kyoto Protocol
Cofiring Scenario
Status Quo
Cofiring Reduces Net CO2 Emissions
1
1.5
2
2.5
3
3.5
4
0% 20% 40% 60% 80% 100%
40%
60%
80%
100%
120%
140%
Eff
icie
ncy
Mul
tiplie
r
Effective Reduction in CO2 Emissions
Po
wer
Pla
nt E
ffic
ienc
y
Thermodynamic Limit
FutureTechnology
100% Efficient
Cofiring Effectively Reduces Net CO2Emissions
1
1.04
1.08
1.12
0% 2.5% 5% 7.5% 10% 12.5%
38%
39%
40%
41%
42%
ExistingFacilities
Best Proven Technology
Eff
icie
ncy
Mul
tiplie
r
Effective Reduction in CO2 Emissions
Pow
er P
lant
Eff
icie
ncy
Biomass Energy Economics
Typical biomass Cost
(US$ per ton)
Cost of Electricity compared to feedstock prices,
with various conditions, incentives, or subsidies
Typical Cost of Energy from Conventional Co-firing Combustion
Acknowledgement: Graph provided by Antares Group Inc
PTC – proposed production tax credit
Incentive, e.g., Green Pricing Premium
Biomass Cofiring Best Uses Resource
0.4
0.5
0.6
0.7
0.8
0.9
1
Effic
ienc
y/C
oal E
ffici
ency
Cofired Units(demonstation and optimized)
Dedicated Unit Increasing Size
10 MWe 60 MWe
US Commercial Experience• Over 40 commercial demonstrations (>100 world wide)• Broad combination of fuel (residues, energy crops,
herbaceous, woody), boiler (pc, stoker, cyclone), and amounts (1-20%).
• Good documentation on fuel handling, storage, preparation.
• Modest information on efficiency, emissions, economics.
• Almost no information on fireside behaviors, SCR impacts, etc.
Fuel Properties2.0
1.5
1.0
0.5
0.0
H:C
Mol
ar R
atio
1.00.80.60.40.20.0
O:C Molar Ratio
SemianthraciteBituminous Coal
Subbituminous CoalLignite
Anthracite
Cellulose
Average BiomassWood
Grass
Lignin anthracite semianthracite bituminous coal subbituminous coal lignite peat biomass black liquor
average values
Peat
Black Liquor
Typical Fuel Properties
Coal & Biomass Elemental Compositions Differ
Black Thunder Pittsburgh #8
Imperial Wheat Straw Red Oak Wood Chips
C
H
N
S
Cl
Ash
O (diff)
COAL:
BIOMASS:
Pittsburgh #8
7.8% Ash
Imperial Wheat Straw
15.4% Ash
Red Oak
1.3% Ash
Black Thunder
7.2% Ash
SiO2
Al2O3
TiO2
Fe2O3
CaO
MgO
Na2O
P2O5
K2O
SO3
Cl
COAL:
BIOMASS:
Coal & Biomass Ash Compositions Differ
Commercial Fuel Mix Varies
Woodland Fuel Mix, Spring-Summer 1993
0%
20%
40%
60%
80%
100%
23-A
pr
30-A
pr
7-M
ay
14-M
ay
21-M
ay
28-M
ay
4-Ju
n
11-J
un
18-J
un
25-J
un
2-Ju
l
9-Ju
l
16-J
ul
23-J
ul
30-J
ul
6-A
ug
13-A
ug
20-A
ug
27-A
ug
EucalyptusAlmondCoffeeMich CalPit MixPitsSawdustShellsPruningsPine DustWhite PineWEYCOUWW
Major Technical Cofiring Issues• Fireside Issues
• Pollutant Formation• Carbon Conversion• Ash Management• Corrosion• SCR and other
downstream impacts
• Balance of Process Issues• Fuel Supply and
Storage• Fuel Preparation• Ash Utilization
Lab and field work indicate there are no irresolvable issues, but there are poor
combinations of fuel, boiler, and operation.
NOx Behavior Complex
200
150
100
50
0
Axia
l dist
ance
(cm
)
-20 0 20Radial distance (cm)
500
450
450
450 450
450
400
400
400
400
400 400
400
350 350 350
350
350
350
3
50
350
300
300
250 2
00
200
150
150
100 100
50
50
200
150
100
50
0
Axia
l dist
ance
(cm
)
-20 0 20Radial distance (cm)
450 450
450
400 400
400
400
400
400
400 400 400
400
400
350
350
300 250 250 200 200
150 150 100
100 50 50
200
150
100
50
0
-30 -20 -10 0 10 20 30
600
6
00
600 600
550
550 550
550 500
500
450
450
400
400
400 350
350
350
300
300
250 250
200
150
100 100 100 50 50
Straw (φ = 0.6) Coal (φ = 0.9) 70:30 Straw:Coal (φ = 0.9
NO
NH3
Cofiring Deposition
Deposits Dissimilar to Fuel
SiO2 Al2O3 TiO2 Fe2O3 CaO MgO Na2O K2O P2O5 SO30
10
20
30
40
50
60
Mas
s P
erce
nt [-
]
Fuel
Ceiling/Corner Deposit
Composition Maps Support Corrosion Hypothesis
Cl S Fe
100% Imperial Wheat Straw
85% E. Kentucky 15% Wheat Straw
Fuel Properties Predict Corrosion
Increasing Time
Vapor depositionVapor deposition flux [g/m2/h]
Oxygen Isosurfaces
Basic Compounds Poison CatalystsCatalyst Activity vs. Na Poison Amount
0.000.100.200.300.400.500.600.700.800.901.00
0 0.5 1 1.5 2 2.5 3
Poison Ratio (Na:V)
Act
ivity
(k/k
0)
BYU wetBYU dryChen et al.
20
18
16
14
12
10
8
6
K, c
m
3/g
*s
590580570560550540530520
Temp, K
Light sulfatedA = 27045 +/- 7580Ea = 34556 +/- 1270
FreshA = 17736 +/- 21500Ea = 34640 +/- 5720
24-hour sulfatedA = 28527 +/- 18400Ea = 34737 +/- 2920
24-hour sulfatedLightly sulfatedFreshfit 24-hour sulfatedfit lightly sulfatedfit freshUC_24HSKUC lightly sulfatedUC_KF
1.0
0.9
0.8
0.7
0.6
0.5
0.4
NO
Con
vers
ion
340320300280260240
Temperature (OC)
M1 Catalyst Fresh Fresh Fit Exposed 2063 hr Exposed 2063 hr Fit Exposed 3800 hr Exposed 3800 hr Fit
Conclusions• Major technical issues include fuel handling, storage,
and preparation; NOx formation; deposition; corrosion; carbon conversion; striated flows; effects on ash; impacts on SCR and other downstream processes.
• Importance of these issues depends strongly on fuel, operating conditions, and boiler design.
• Proper choices of fuels (coal and biomass) and operating conditions can minimize or eliminate most impacts for most fuels.
• Ample short-term demonstrations illustrate fuel handling feasibility. Paucity of fireside and long-term data.
• Cofiring residuals is a no-regrets process in almost all implementations.
How does this talk grow corn?
Research Issues• Fundamentals
• Behavior of inorganics• Materials• Impurities/Emissions (N, S, Hg, etc.)
• Process Issues• Pressure• Matrix Effects
• Radical Changes• Processes that have stable, condensed-phase
effluents under conditions accessible on earth.
Acknowledgements• Financial support provided by the DOE/EE, EPRI,
NREL, BYU, a dozen individual companies.• Work performed by research group including four other
faculty members, two post docs, ten graduate students, 30 undergraduate students.