S4FESUSTAINABLE FOSSIL FUELS FOR FUTURE ENERGY

ROMA, July 6-10, 2009

CO2 Capture and Storage in the Greek Electricity Generation Sector

A. Doukelis1, E. Kakaras1, D. Giannakopoulos2, N. Koukouzas2

1National Technical University of AthensLaboratory of Steam Boilers and Thermal Plants

2Centre of Research and Technology HellasInstitute of Solid Fuel Technology and Applications

2

Contents

! Lignite in the Greek electricity generation sector

! CO2 Capture and Storage

! Green-field Oxyfuel Greek Power Plant

! Retrofit Greek Power Plant with CCS

! Retrofit and new plant costs for Greek Power sector

! Conclusions

3

Lignite in the Greek electricity generation sector 1/2

" Lignite plays an important role in Greece’s energy sector as it currently satisfies ca. 60% of the country’s needs in electric power. The annual production of lignite is around 65 million tons and almost the entire production is consumed for electricity generation in the Greek coal-fired power plants, which are about 4800 MW and use conventional technology.

" It is estimated that in 2010, approximately 37.5 % of the existing lignite-fired power plants, which produce 49.2 % of electricity in Greece, will reach 30 years of their operational life.

" There is enough Greek low rank lignite to meet the demand of the electricity sector in terms of production and reserves. Certain -but very limited-amounts of local lignite (xylitic type with high heating value between 12-16 MJ/kg) and imported coal, are used as additional fuels.

" Therefore, taking into consideration the forecasts for increase in the electricity demand over the coming years, the old and low-efficiency units should be either renovated or replaced by new units.

4

Lignite in the Greek electricity generation sector 2/2

Share of Electricity production sources in Greece

-

10

20

30

40

50

60

70

2005 2006 2007 2008 2009

Year

(%)

LigniteOilNatural GasHydroWind + RESImports

The Electricity Production balance in Greece was 53.4 TWh in 2005

reaching 56.9 TWh in 2008 for the interconnected system

RES in HV grid

5

EC Directive proposals

European Commission and European Council proposals for post-Kyoto period

" Revision of Directive 2003/87/EC for the improvement and expansion of the Emission Trading System of Green House Gases (23.1.2008 COM(2008) 16 final 2008/0013 (COD))

" Regarding the CO2 storage in geological formations (23.1.2008, COM(2008) 18 final/ 2008/0015 (COD))

" Revision of Directive 2001/80/EC for CO2 capture ready units (> 300 MW)

6

CO2 Capture and Storage

! The development of novel electricity generation technologies aims at (near) zero CO2 emissions, through Carbon Capture and Storage (CCS).

! The current study has focused on a Greenfield application of Oxyfuel firing with advanced drying process and retrofit applications of both Oxyfuel and Amine Scrubbing technologies for typical power plants.

7

0

10

20

30

40

50

60

70

80

90

Hard coal Lignite Natural Gas

EUR

/MW

h

No capturePre-combustionPost-combustionOxyfuel

Note:Power generation cost without CO2 transport and storage cost

CO2 Capture and Storage in the European market 1/2

Estimated electricity generation cost from large coal, lignite and NG units in 2020, without

and with CO2 capture

European Technology Platform, Zero Emission Fossil Fuel Power Plants (ZEP), Working Group 1, Power Plant and Carbon Dioxide Capture

0

20

40

60

80

100

Hard coal Lignite Natural Gas

EUR

/t C

O2

Pre-combustionPost-combustionOxyfuel

Note:CO2 Avoidance cost without transport and storage cost

Power plant andCCS technologyimprovementpotential

Estimated CO2 capture cost from large electricity generation units in 2020 (coal, lignite and NG)

8

CO2 Capture and Storage in the European market 2/2

Pilot Projects CCS(Zero Emission Fossil Fuel Power Plants - ΖΕP)

6 of 43 projects on lignite All technological options are involved Most selected solution is post combustion

9

European Strategic framework for Energy

Carbon Capture and Storage (CCS) Projects

Proposal of Presidency to European Council (20/3/2009) related to European Economic Recovery Plan and call for proposals of

May 2009

Member State Station Capacity (ΜW) TechnologySaline

AquifersOil / Gas

fieldsEnvisaged EC

contribution Μ€Huerth 450 IGCC √

Jaenschwalde 500 OxyFuel √Eemshaven 1200 IGCC √Rotterdam 1080 PC √Rotterdam 800 PC √

Poland Belchatow 858 PC √ 180Spain Compostilla (Leon) 500 OxyFuel √ 180

Kingsnorth 800 PC √Longannet 3390 PC √

Tilbury 1600 PC √Hatfield (Yorkshire) 900 IGCC √

Italy Porto Tolle 660 PC √ 100

France Florange 50Application for transport of

CO2 from steel industry √ 50

Total 1050

United Kingdom

The Netherlands

Germany 180

180

180

Coa

l

105

Green-field Oxyfuel Greek Power Plant 1/6

" The reference power plant used for the assessment of the efficiency of a Greenfield oxyfuel power plant is a 360 MWel lignite-fired power plant with reheat and 7 water preheaters with steam extraction from the ST

" Since the raw lignite has high moisture content, a fuel pre-drying system has been integrated to both the reference and oxyfuel plant, in order to increase the plant efficiency. According to this pre-drying concept, the heat content of the moisture removed in the form of steam from the raw lignite, is used for the drying (WTA drying system).

Raw Lignite ultimate analysis C w% 18.5 H w% 1.5 S w% 0.4 O w% 8.7 N w% 0.6 Ash w% 15.0 H2O w% 55.3 LHV (kJ/kg) 5.418

Dried Lignite ultimate analysis C w% 36.5 H w% 2.9 S w% 0.8 O w% 17.2 N w% 1.1 Ash w% 29.5 H2O w% 12.0 LHV (kJ/kg) 13.025

116

Green-field Oxyfuel Greek Power Plant 2/6

360 MWel lignite-fired PP

S20

G3

G4

G5

G6

G7

G8

G9

G10

S3

S4

S5

S1

S7

S10S9

S6

S11S12

S17

S19

S21

S16

S29S30 S31

S32

S33 S34

S35 S36

S37S38

S40S39

ESP

LUVO

EVAP

SH1

SH2

SH3

RH1

RH2

ECO

HP

IP LP

S24

F1

F3

F21

D1D2

D3

D4 D5

D6

D7D8

D9

D10

D11

G1 G2

S2

S8

S13

S148 S15

S18

S23

S25

S22

S26

S27

S28

G11

127

Green-field Oxyfuel Greek Power Plant 3/6

! Combustion is achieved with high-purity O2 from an ASU. The oxygen purity is 95 % vol (the remaining 5 % vol is mainly Ar and N2).

! The main energy requirements for the O2/CO2 recycle combustion are:" ASU power consumption" Compression of final product for transportation/sequestration (110 bar)" Fans consumption for flue gas re-circulation" CW pumps consumption for flue gas cooling/air inter-cooling at the ASU

! When applying O2/CO2 recycle combustion, the air preheaters are not used, resulting in an increase of the flue gas exit temperature to ca. 310 ºC.

! The molecular sieves (removal of water vapour, CO2 and impurities from air before entering the distillation column) are regenerated utilising dry N2 from the ASU, heated by flue gas to 150ºC.

! The furnace stoichiometry applied is 1.05. ! Air infiltration rate in the boiler and ESP: 0.01 kg/ kg of flue gas (each)! CO2 compression occurs in 5 stages with intermediate cooling to 21 ºC.! Air compression for the ASU occurs in 2 stages with intermediate cooling

down to 21 ºC.

138

Green-field Oxyfuel Greek Power Plant 4/6

! Several process integration options were identified and an optimized scenario has been investigated, integrating these options.

! A hot ESP is used for particle removal at the boiler exit. The flue gas recycle is extracted downstream the hot ESP and mixed with the O2 stream from the ASU. The absence of an air preheater leads to the necessity of a second hot ESP, which increases air inleakage resulting into lower separation efficiency compared to a cold one. The O2 stream is heated from the remaining flue gas, which consequently follows a further particle removal process in a cold ESP.

! The flue gas that exits the boiler, before entering the flue gas treatment process line, is used to partly replace LPH4 water heater.

! Heat from the FGC is integrated in the water steam cycle by partly replacing low-pressure feedwater heaters 1 and 2.

! O2 is heated from the 1st CO2 compression step up to 110 ºC. Heat from the 2nd and 3rd compression steps is used for water preheating at the LPH1, LPH2 and LPH3 water heaters.

149

Green-field Oxyfuel Greek Power Plant 5/6

Feed

wat

er h

eatin

g LP

H1

to L

PH3

Feed

wat

er h

eatin

g LP

H1

to L

PH3

I1 I2

G7

G10

G11

G3

A7

G4

A8

A2

Air leakage

Ash

Air leakage

A5

A6

A9A10

I1 I3I2 I4

I5

G5

G6

G8G9

G1

G2

Lignite Dryer Waste water Dried lignite

F3

DC

AC

ASU

Wet ESP FGC Separation of non-

condensables

TEG

N2 t

o m

olec

ular

sh

ieve

s

ESP

A1 A3 A4

A11 A1

2

F1 F2

F3

Raw lignite

F3

D1

D2

D3

D4 D5 D6 D7 D8 D9 D10

D11

D12

D13

D14

D15

G12G13

G14

G15

G16

G17

G18

G19

S1

S2

S3

S4S5

S6

S7

S8S9

S10S11

S13

S12

S14

S15

S20

S16 S17

S21

S22

S18

S19

S23

S24

S25

I6 I7

I8

Oxygen Flow

I3 I4

G20 G21

G22

G23

1510

Green-field Oxyfuel Greek Power Plant 6/6

Ref. PP Greenfield oxyfuel PP

FW pump MWel 9.17 9.54

FD fan MWel 1.43 -

ID and gas fans MWel 2.77 3.55

Dryer MWel 25.21 25.21

Lignite mills MWel 9.05 9.05

ESP’s MWel 0.50 0.50

Fly ash transport MWel 0.85 0.85 Lignite feeding and handling system MWel 0.78 0.78

Condensate pumps MWel 0.54 0.56 Circulating and cooling water pumps MWel 3.74 3.93

Others MWel 1.14 1.20

ASU MWel - 52.39

CO2 compression MWel - 46.35

Raw Fuel flow kg/s 136.34 136.34

Gross power output MWel 356.78 392.45

Gross el. efficiency % 48.30 53.13

Net power output MWel 301.61 238.53

Net el. efficiency % 40.83 32.29

! In both reference and oxyfuel power plant, the fuel consumption remains the same.

! Despite the increase in gross power output by 10%, the high auxiliary power demand for CO2capture results in a significant penalty in power plant performance.

! The greenfield oxyfuel PP with waste heat integration has an efficiency penalty of ca. 8.5 percentage points.

16

Retrofit Greek Power Plant with CCS 1/5

Retrofit of brown coal Power Plant with CO2 sequestration

! The simulations of the power plant and the CO2 sequestration retrofit options were performed with the thermodynamic cycle calculation software ENBIPRO.

! The 330 Mwel (gross) power plant under examination has a supercritical boiler, a HP-MP-LP steam turbine and 8 preheating stages and represents a typical modern Greek low-quality coal fired power plant with flue gas desulphurisation.

! In the examined retrofit test cases, the following general assumptions have been made:- The fuel consumption remains the same- The water/steam cycle remains as much as possible unchanged- The final CO2-rich stream is compressed to 110 bar, in order to facilitate

transportation and sequestration- The final CO2 stream purity is 98%

17

Retrofit Greek Power Plant with CCS 2/5

" Combustion is achieved with high-purity O2 produced by a cryogenic air separation unit. The oxygen purity is 95%, the majority of the rest being Ar.

" When applying the oxyfuel concept in a coal-fired PP, air preheaters are not used, resulting in an increase of the flue gas exit temperature to ca. 310 ºC.

" Before air enters the distillation column, water vapour, CO2 and any other impurities are removed, utilising adsorption with molecular sieves, which are regenerated by dry N2 from the ASU at about 180ºC. The flue gases exiting the boiler provide the heat required for nitrogen heating.

" For 95% oxygen purity and 3% boiler air infiltration, the O2/CO2 recycle combustion process can capture 79% of the CO2 from coal combustion. In a greenfield application (improved sealing/lower air infiltration rate) the CO2recovery rate can be comparable to the amine scrubbing process.

" Excess oxygen is 1.5%, whereas the flue gas recirculation is chosen so as to maintain the flue gas flow and temperature inside the boiler at the same level as in the conventional power plant.

" The main energy requirements for the O2/CO2 recycle combustion are:# Air compression for the ASU (5.5 bar)# Flue gas compression for transportation and sequestration (110 bar)# CW pumps consumption for flue gas cooling and ASU air inter-cooling

18

Retrofit Greek Power Plant with CCS 3/5

ASU

FGTEG

H2O N2, NOx, O2, Ar Inert gases

N2

N2, to molecular sieves

O

Water

Water

ESP

Ash Coal

Slag Fly Ash

Flue gas from rezi-fans

HPST

IPST LPST

Unit 1200 & 1300

Unit 500

Uni

t 200

Unit 100

Unit 1100

Unit 700

Flue gas cooling/cleaning

Dehydration/ Flue gas compression

Air Separation Unit

Fuel Input/

Slag removal

Water/steam circuit

Retrofit : OxyFuel

Heat integration not implemented

19

Retrofit Greek Power Plant with CCS 4/5

Retrofit : Amine Scrubbing

" In the amine gas processing operation, CO2 is absorbed from flue gas by the liquid solvent in an absorption tower, where gas stream and liquid solvent are contacted in counter-current flow. In the stripper (regeneration) the charged amine solution is heated with steam, in order to strip off the CO2.

" Flue gases at the outlet of the boiler are cooled down to 40ºC to condense the water vapour and then compressed up to about 1.3 bar.

" CO2 recovery from the flue gases is assumed to be 90%. " The energy requirements of MEA scrubbing are:

# Heat consumption for regeneration of the reach solution, in the form of LP steam extraction at ~ 5 bars, which provides its latent heat and the condensate is compressed and returned to the feed-water tank. The thermal consumption (state of the art commercially available solutions) is ca. 3.25 MJ/kg of CO2 removed (or ca. 1.4 kg steam/kg CO2).

# Electricity consumption: the most energy-consuming process is the flue gas blower used to overcome the system pressure drop (~100-200mbar). This category also includes the energy required for the pumping of the amine solution and the pumping of the absorber wash water.

# Compression of the final product to 110 bar for transportation and sequestration.

20

Retrofit Greek Power Plant with CCS 5/5

ConventionalPower Plant

Oxyfuel Amine Scrubbing

Net Power Output MW 293.7 211.0 200.5

Net efficiency % 35.4 25.4 24.2 Power output decrease MW - 82.7 93.2

Efficiency decrease % - 10.0 11.2

Specific emissions

kg CO2/kWh

1.075 0.31 0.17

21

Retrofit and new plant costs for Greek Power sector 1/3

General assumptions

# Rate of return: 8%# Inflation rate: 3%# Lignite cost: 1.8 Euros/GJ# Natural gas cost: 5.5 Euros /GJ# Payback period for solid fuel-fired power plants: 25 years# Payback period for combined cycle power plants: 15 years# Operating and maintenance cost: 3% of the investment cost annually plus

0.01 Euros/kWh for lignite fired power plant or 0.005 Euros/kWh for NGCC# Operating hours per year: 7500h# The CO2 transportation and storage cost has not been included

22

Retrofit and new plant costs for Greek Power sector 2/3

0.760.370.8650.310.171.075kg/ kWh

CO2 specific emissions

13706001150157019001100€/kW

Investment cost

43.056.544.025.424.235.4%Net efficiency

766380300211200293.7MWel

Net power output

IGCCNGCCClean coalOxyfuelAmine scrubbing

Convent.lignite fired power plant

Specific assumptionsSpecific assumptionsSpecific assumptionsSpecific assumptions

23

Retrofit and new plant costs for Greek Power sector 3/3

Cost of Electricity generation

Conventional Clean Coal Technology

Natural Gas Combined

Cycle

Fixed Cost

Variable cost

Risk due to NG price

Risk due to CO2 (as of CCGT)

Fixed Cost

Variable cost

Risk due to NG price

Risk due to CO2 (as of amine -oxyfuel)

Cost of Electricity generation

Clean Coal Technology

NGCC IGCCOxyfuelAmine

Total cost of electricity for different technological options

24

Thessaloniki BasinMesohellenic Trough

Source: GESTCO Project, 2003, European Potential for the Geological Storage of CO2

CCS potential in Greece 1/2

25

CCS potential in Greece 2/2

34onshoreAlexandria

2345Total

360onshoreMesohellenic basin

145onshoreW. Thessalonikisandstone

459onshoreW. Thessaloniki1343offshorePrinos

Storage Capacity (Mt CO2)

LocationAquifer

Source: GESTCO PROJECT

26

Conclusions

! Greek interconnected power system has a strong dependence on domestic fuel (lignite) for electricity generation

! CCS technologies reduce the efficiency of the power plants by 8.5 – 11% percentage points and capacity by 80 – 90 MW for a 300 MW unit, while the CO2 emissions are improved by up to 90%.

! Heat integration can reduce the efficiency penalty, especially in the Oxyfuel technological option by up to 1.5 – 2% percentage points.

! CCS plants can be economically viable compared to other low CO2emissions technological options for power generation