Potential Contributions of Biomass Toward Sustainable Energy

Larry BaxterBrigham Young University

Provo, UT 84602

GCEP Conference Beijing, China

August 22-23, 2005

Global and Detailed Overivew

• Energy Industry (10 km)• Biomass Resource Characteristics (3 km)• Overview of Technical Issues (1 m)• Fuel Conversion Issues (1 mm)• Desirable process characteristics (3 km)• Conclusions (40 Mm)

US Energy Flow Diagram - 2001

Combustion fraction of total energy (85%)Source: Energy Information Administration, Annual Energy Review 2001

Units in Quads

International Energy Supplies

0.75

0.8

0.85

0.9

0.95

1

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001Year

Com

bust

ion

Frac

tion

of E

nerg

y C

onsu

mpt

ion

OECD Non OECD OPEC

EU IEA World Total

Energy and Economy

90

80

70

60

50

40Ene

rgy

Con

sum

ptio

n (Q

uadr

illio

n B

TU)

200019901980197019601950

Year

8000

6000

4000

2000

GD

P (B

illion

199

6 D

olla

rs)

Energy GDP

(linear correlation coefficient = 0.95)

Environmental Impacts

Impacts Quantified

Resource Depletion Climate change Health Impactsden Uil et al., 2002

Impacts Quantified

Smog, Haze, VOCs, etc.

Acid Rain, etc. Water Pollution, etc.

den Uil et al., 2002

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%

Biomass Availability• Wood waste: logging residues,

sawdust, nonrecyclable paper

• Crop residues: wheat/rice straw,bagasse, almond shells

• Energy crops: poplar,switchgrass, willow

18.7 Quads of Coal

WoodResidues

~ 10%Paper~ 4%

AgriculturalResidues

~ 14%

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

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

Fuel Prices

$0.00$0.50$1.00$1.50$2.00$2.50$3.00$3.50$4.00$4.50

Biodeisel BGFT Corn Ethanol Petroleum

$/ga

l gas

equ

ival

ent Retail Prices

Production Prices

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

Transporation Fuel Impact

2-4% of US oil supply could be offset from forest process industry residues.

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

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:

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

No Unusual NOx Synergies

0

200

400

600

800

1000

0 200 400 600 800 1000

15% SW G33% SW G66% SW G58% W C 20% W C

Mea

sure

d N

O X (p

pmv,

dry

)

P red icted N OX (ppm v, dry)

Alfalfa Generates NH3

0 .4

0 .3

0 .2

0 .1

0 .0

Sign

al (a

rbitr

ary)

1 1 2 51 1 2 01 1 1 51 1 1 01 1 0 51 1 0 0

W ave num b e r (cm -1)

C alib ratio n @ 1 0 0 0 p p m NH3 A lfalfa C alib ratio n @ 2 5 0 p p m NH3 Natural G as

NOx Behavior Complex (No Surprises)

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

Stoichiometry and Temperature Impacts

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.9 1.0 1.1 1.2

Nominal Reburn Zone Equivalence Ratio

Nor

mal

ized

NO

x (bo

th d

ry a

t 3%

O2)

900 C, 250 ppm

1200 C, 500 ppm

900 C, 500 ppm

1200 C, 250 ppm

Alfalfa

Cofiring Deposition

Deposition Rates Vary Widely• Cofiring biomass can

lead to either decrease or increase in deposition rates.

• Cofiring decreases deposition relative to neat fuels.

0.01

0.1

1

10

100

Dep

ositi

on R

ate

(gm

dep

osit/

kg fu

el)

Woo

d

Sw

itchg

rass

Str

aw

Whe

at S

traw

Pitt

sbu

rgh

#8

Eas

tern

Ken

tuck

y

Commercial Stoker

Slag Screen

SecondarySuperheater

PrimarySuperheater

BoilerGenerator Bank

Stokers

Overfire Air

Grate

Stoker

Fuel Bin

1

2 3

4

5

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

Oxygen Isosurfaces

Striations in T-fired Units

Vapor deposition

Vapor deposition flux [g/m2/h]

Strength

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

1 3 7 28 56 91 365

Day

Com

pres

sion

(MPa

)

Cement

Class C

Class F

SW1

SW2

Wood

Wood C

Wood F

Compression test

RGB Camera Performance

0

5

10

15

20

25

30

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Wavelength (micron)

Spec

tral

Res

pons

ivity

[(D

N)/(

nJ/c

m^2

)]

Red

Green (R)

Green (B)

Blue

Optical Signal Validation

800

900

1000

1100

1200

1300

1400

1500

1600

800 900 1000 1100 1200 1300 1400 1500

T exp, K

T ca

lcul

ated

, K

Optical Signal Validation

800

900

1000

1100

1200

1300

1400

1500

800 900 1000 1100 1200 1300 1400 1500

Blackbody Temperature, K

Cal

cula

ted

Tem

pera

ture

, K

CalculatedtemperatureBlackbodytemperature

Surface Temperature & Emissivity

Devolatilization

Char burning (0.26 s later)

Measurable range (1000-1800 K), -40 ~ 80 K uncertainty

Combustion History: Switchgrass

0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Vol

ume

(mm

3 )

Time (s)

Char Oxidation

Devolatilization

Heat &Dry

Initial nominal diameter = 3 mm

Typical Mass/Temperature Data

0 10 20 30 40200

400

600

800

1000

1200

1400

0.0

0.2

0.4

0.6

0.8

1.0

Mas

s Lo

ss

T Center T SurfaceTe

mpe

ratu

re, K

Time, s

Mass Loss

Isothermal Approximation

0 2 4 6 8 10 12200

400

600

800

1000

1200

1400

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Tem

pera

ture

, 'K

Time, s

E F

0 10 20 30 40 50200

400

600

800

1000

1200

1400

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

3/8" poplar in N2

Mas

s Lo

ss

Tem

pera

ture

, 'K

Time, s

Shape Impacts

0 5 10 15 20 25 30 35 40-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0M

ass

Loss

, 1-m

/m0

Residence Time, s

in N2

d = 11 mm. Plate (exp.) Plate (model) Cylinder (model) Cylinder (exp.) Near-sphere (exp.) Near-sphere (model)

Impacts on Conversion Time

-2 0 2 4 6 8 10 12 14 16 18

1.0

1.2

1.4

1.6

1.8

2.0

2.2 Near-sphere/Plate, exp Cylinder/Plate, exp Plate/Plate Near-sphere/Plate, model Cylinder/Plate, model

Con

vers

ion

Tim

e R

atio

Equivalent Diameter, mm

AR=5.0, in N2

Impacts on Conversion Time

0 2 4 6 8 10 12 14 16 18 200.5

1.0

1.5

2.0

2.5

3.0

Con

vers

ion

Tim

e R

atio

Equivalent Diamter, mm

near-spherical/plate - exp. cylinder/plate - exp. plate/plate near-spherical/plate - model cylinder/plate-model plate/plate

AR=8, in N2

Impacts on Temperature

-5 0 5 10 15 20 25 30 35 40 45 50 55200

300

400

500

600

700

800

9001000

1100

1200

1300

1400

Tem

pera

ture

, K

Time, s

Center (TC) Surface (TC) Surface (Camera 1) Surface (Camera 2) Surface (Camera 3) Center (model) Surface (model)

d=11mm in N2

Tw=1373 KTg=1050 K

In Situ Experimental Data

Chlorine Controls Aerosol Amount

Chenevert

0.001

0.01

0.1

1

10

0.1 1 10aerodynamic diameter, µm

d(M

/Mo)

/dln

(d)

0.12% Cl, 0.17% Alkali 0.16% Cl, 0.25% Alkali0.01% Cl, 0.09% Alkali 0.01% Cl, 0.48 % Alkali

High-chlorine Aerosol Composition

Si 13% Al

4%Ca5%

Na17%

K14%

Cl45%

S 2%

Chenevert

Low-chlorine Aerosol Composition

Si45%

Al12%

Mg3%

Ca20%

Na6%

K9%

S 5%

Chenevert

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.

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

20

18

16

14

12

10

8

6K

, cm

3 /g*s

590580570560550540530520Temp, K

Light sulfatedA = 27045 +/- 7580Ea = 34556 +/- 1270

FreshA = 17736 +/- 21500Ea = 34640 +/- 5720

24-hour sulfatedA = 28527 +/- 18400Ea = 34737 +/- 2920

24-hour sulfated fit 24-hour sulfated CI_24HSK Lightly sulfated fit lightly sulfated CI lightly sulfated Fresh fit fresh CI_KF

Ultimate Best Practices Attributes

• Use of residues• Integration in existing industry• Production of fungible product• Broad opportunity• Focus on objective (climate change,

sustainable energy, energy security, etc.)

Bottom-line Conclusions

• Any solution to the global climate change problem involves all of the following:• All practical renewable energy options• Storage and capture• Substantial increase in nuclear power• Substantial change in lifestyle in

developed world

Australia is the Key

Acknowledgements

• 12 Graduate Students and 163 Undergraduate students at BYU

• DOE, EPRI, Eltra, and many industrial collaborators

• Faculty and staff collegues