Coal Gasification (for Power Generation_comparision Technology)

Coal Gasification 101

Dr. Jeff Phillips EPRI [email protected]

Outline • What is coal? • What is coal gasification? • What can you do with it? • Gasification-based power plants compared to other fossil fuel power generation options • A few words on CO2 capture

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U.S. Forecasts Largest Coal Generation Capacity Installation in 40 Years

Capacity Added (GWs)

U.S. Coal Capacity Additions, 1940 – 2025 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Capacity Addition Levels Not Seen in 40 Years

Industry Growth Trend Not Seen in 50 Years

20 Year Market Trough

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 Source: U.S. Department of Energy NETL & Annual Energy Outlook 2005.

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Carbon Ash (rock) Sulfur Nitrogen Hydrogen Mercury Water

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U.S. Coal Basins

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Typical U.S. Coal Analysis (Coal Properties Differ Markedly)

Pittsburgh #8 Illinois #6 Ultimate Analysis Moisture Carbon Hydrogen Nitrogen Chlorine Sulfur Oxygen Ash Higher Heating Value-as Received (Btu/lb)

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5.2 73.8 4.9 1.4 0.07 2.13 5.4 7.1

12.2 61.0 4.25 1.25 0.07 3.28 11.0 6.95

13,260

10,982

Wyoming

ND Lignite

30.24 48.18 3.31 0.70 0.01 0.37 11.87 5.32

26.80 45.82 3.11 0.70 N/A 0.69 14.68 8.20

8,340

7,810

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What happens when coal burns?

• Carbon => CO2 (carbon dioxide) • Ash => flyash • Sulfur => SO2, SO3 (SOx) • Nitrogen => N2 and NOx • Hydrogen => H2O • Mercury => Hg, HgCl2 • Water => water vapor (H2O)

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What is gasification? • Similar to combustion (burning) but with less than half the amount of oxygen needed to fully burn the coal • Combustion: excess air • Gasification: excess fuel (by a lot!!)

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Combustion & Gasification Products

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Combustion vs Gasification • SO2 & SO3 is scrubbed out of stack gas – reacted with lime to form gypsum

• H2S & COS are easily removed from syngas and converted to solid sulfur or sulfuric acid

• NOx controlled with low NOx burners and catalytic conversion (SCR)

• NH3 washes out of gas with water, thermal NOx controlled by diluent injection in GT

• Large volume of flyash & sludge

• Ash is converted to glassy slag which is inert and usable

• Hg can be removed by contacting flue gas with activated carbon

• >90% of Hg removed by passing high pressure syngas thru activated carbon bed

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Dakota Gasification Gasifier • The dry ash (non-slagging) Lurgi gasifier is used in Dakota Gasification’s lignite-to-natural gas plant • The Lurgi process was developed in the 1930s, and was the only “mature” gasification process available when the Dakota project was initiated (circa 1980) • The Lurgi process operates at relatively low temperature and has some undesirable characteristics – Cannot handle coal fines, produces tars & phenols as well as syngas, bottom ash instead of slag • Since 1980 several “second generation” gasification processes have been developed which avoid some of the Lurgi process’ undesirable characteristics © 2005 Electric Power Research Institute, Inc. All rights reserved.

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The 3 Major Types of Gasification Processes 1. Moving-Bed Gasifier (e.g., Lurgi)

2. Fluidized-Bed Gasifier (e.g., KBR/Southern)

3. Entrained-Flow Gasifier (e.g., GE Energy, ConocoPhillips, Shell, Siemens) © 2005 Electric Power Research Institute, Inc. All rights reserved.

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What can you do with coal gasification? • Produce Electricity – In a Gas Turbine-based Combined Cycle power plant – Emissions approaching that of a natural gas fired power plant • Make Fuels – Sasol has been making gasoline from coal since the 1950s in Republic of South Africa – Dakota Gasification has been making “synthetic’ natural gas from lignite since the 1980s • Make Chemicals – Eastman Chemicals has been doing this since 1980s • Make Fertilizer – Coffeyville Resources in Kansas makes ammonia-based fertilizer from petroleum coke © 2005 Electric Power Research Institute, Inc. All rights reserved.

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Steam Cycles vs “Combined” Cycles

• Steam Cycles have – a boiler – a steam turbine • Referred to as “Rankine” cycle, fossil boiler, “fossil steam” plant, “conventional coal” plant

• Combined Cycles (the “CC” in IGCC) have – a Gas Turbine – a “heat recovery steam generator” (HRSG) – a steam turbine

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Conventional Coal Plant

41 % Efficiency

14 MW

(LHV basis)

86 MW 41 MW

100 MW

45 MW

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Gas Turbine

Photo source: Siemens

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Gas Turbine “simple cycle”

100 MW 62 MW

38 MW

38% Efficiency (LHV basis) © 2005 Electric Power Research Institute, Inc. All rights reserved.

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Combined Cycle 22 MW

100 MW Fuel

40 MW 62 MW 38 MW

19 MW

21 MW to condenser © 2005 Electric Power Research Institute, Inc. All rights reserved.

19 + 38 = 57 MW 57% Efficiency! (LHV basis) 24

100MW

Net Coal to Power: 30 + 21 – 9 = 42% (LHV basis)

17MW 9MW 79MW

15MW 49MW 21MW

30MW

47MW 26 MW © 2005 Electric Power Research Institute, Inc. All rights reserved.

IGCC schematic from US DOE 25

Comparison to other fossil fuel power generation options • Emissions • Greenhouse gases • Cost of Electricity

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Emissions Comparison – State-of-the-Art Coal Combustion, IGCC, and NGCC Values represent technology capability, not permit levels Bituminous

0.8 0.7

lb/MW-hr

0.6 0.5

PRB

0.4 0.3

NOx SO2 PM

0.2 0.1

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R SC

PC

+S C

R SC

PC +S C

C C IG

C R C +S IG C

N G

C C

+S C

R

0.0

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Emissions Comparison with Older Coal Plants and Federal Standards 18 16 14

lb/MW-hr

12 10

NOx SO2 PM

8 6 4 2

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ld -o PC

N SP S 20 06

SC

PC +S

C

R

R

C C IG

PC +S C SC

C C IG

N

G

C C

+S C

+S C R

R

0

250 US plants exceeded these levels in 2004 28

Solid Waste Comparison (Based on nominal 500 MW plant size) 450

Pittsburgh #8

Wyoming PRB

Illinois #6

TX Lignite

400

Sulfur

Spent Sorbent

350

Solid Waste, lb/MWh

Ash/Slag 300 250 200 150 100 50 0 PCSub

PCUSC

CFB IGCC

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PCSub

PCUSC

CFB IGCC

PCSub

PCUSC

CFB IGCC

PCSub

PCUSC

CFB IGCC

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Makeup Water Comparison 10 9

Makeup Water, gpm/MW

8 7 6 5 4 3 2 1 0 PC © 2005 Electric Power Research Institute, Inc. All rights reserved.

CFB

IGCC 30

Atmospheric CO2 Trends

Source: CSIRO Atmospheric Research, www.cmar.csiro.au

Peak of last Ice Age - 20,000 yrs ago

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CO2 Emissions without CO2 Capture 1,200

CO2 Emissions (kg/MW-hr)

1,000

800

600

400

200

0 PC-Sub © 2005 Electric Power Research Institute, Inc. All rights reserved.

PC-Super

PC-Ultra

NGCC

IGCC

PC-old 33

IGCC with CO2 Removal and Optional Hydrogen Co-Production Sulfur

Coal Prep

Gasification C + H2O = CO + H2 O2

Gas Cooling

Shift CO+ H2O = CO2 + H2

CO2 to use or sequestration

Sulfur and CO2 Removal Hydrogen

N2

Air Separation Unit

Gas Turbine

Air

BFW Air

Steam

HRSG

BFW

Steam Turbine © 2005 Electric Power Research Institute, Inc. All rights reserved.

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FutureGen Project • A 275 MW (nominal) IGCC with CO2 capture and H2 export – Coal gasification followed by water-gas shift reaction – 90% of CO2 will be removed from syngas, compressed to circa 2000 psia and injected into deep geologic formations for sequestration – Remaining syngas will be primarily H2 • Small slipstream will upgraded to high purity H2 and sold “over the fence” • Balance will be fired in an advanced combined cycle

• Site selection RFP issued in March 2006 • Operation targeted to begin in 2012

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Pulverized Coal (PC) with CO2 Removal CO2 to use or Sequestration

Fresh Water

Coal Air

PC Boiler

SCR

Steam Turbine

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ESP

Fly Ash

FGD

CO2 Removal MEA

Flue Gas to Stack

Gypsum/Waste

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CO2 Capture Comparison Exhaust or Syngas Pressure

CO2 Volumetric Concentration

CO2 Partial Pressure

Natural Gas Combined Cycle Exhaust

14.7 psia

4%

0.6 psia

Supercritical Coal Boiler Exhaust

14.7 psia

13%

1.9 psia

IGCC Syngas

825 psia

40%

330 psia

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Impact of CO2 Capture Results from recent IEA & US DOE studies on bituminous coal adjusted to standard EPRI economic inputs, $2/MMBtu coal, 85% capacity factor, 2005 USD 80

30-year Levelized Cost of Electricity, $/MWhr

70 Range of Uncertainty

60

16.3 21.3

11.6

19.0

Range of Uncertainty

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Delta for Capture Without Capture

40

30 49.6

52.0 45.7

46.1

SCPC-IEA

SCPC-DOE

20

10

(Excludes cost of emission allowances and CO2 pipeline to sequestration site)

0 GE IGCC © 2005 Electric Power Research Institute, Inc. All rights reserved.

Shell IGCC

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The End