MAINTAININGTHE POWER OUTPUTWITHTHE ADDITIONOF CO2 …

3rd POST COMBUSTION CAPTURE

CONFERENCE: PCC3

MAINTAINING THE POWER OUTPUT WITH THE ADDITION OF CO2

CAPTURE: A TECHNO-ECONOMIC ASSESSMENT OF INTEGRATED

RETROFITS WITH SEQUENTIAL COMBUSTION OF GAS TURBINE FLUE GAS

María Sánchez del Río*, Mathieu Lucquiaud, Hannah Chalmers,

Jon Gibbins

School of Engineering, The University of Edinburgh, United Kingdom

*contact e-mail: [email protected] / [email protected]

08 – 11 September 2015 • Regina, Canada

PRESENTATION OUTLINE

1.- Carbon capture retrofit options

2.- Estimation of carbon capture retrofit performance

3.- Technical analysis

4.- Economic analysis

5.- Sensitivity analysis

6.- Conclusion


CONFERENCE: PCC3







6.- Conclusion


CONFERENCE: PCC3

POST-COMBUSTION CARBON CAPTURE RETROFIT OPTIONS

STANDARD INTEGRATED RETROFIT

All electricity and heat required to operate the capture equipment is supplied from the existing

steam cycle. The thermal energy of solvent regeneration is provided by steam extraction from

the main power turbine and the electricity output of the site is typically reduced.


HEAT MATCHED RETROFIT

A CHP plant supplies the electrical power and all the heat required for the capture process,

matching the thermal energy requirement for solvent regeneration. This option provides

additional power increasing the net power output of the site (IEAGHG 2011).

IEAGHG, 2011. “Retrofitting CO2 Capture to Existing Power Plants,” Report Number 2011/02, May, 2011.


POWER MATCHED RETROFIT

A combined heat and power (CHP) plant provides the electrical power required for the capture

process and covers any loss in power output to restore the net power output of the plant. The

remainder of the heat is provided by extraction from the existing steam cycle (IEAGHG 2011).

IEAGHG, 2011. “Retrofitting CO2 Capture to Existing Power Plants,” Report Number 2011/02, May, 2011.



Rules followed to achieve optimum PCC plant thermodynamic and

economic performance (Gibbins & Crane, 2004).

“produce as much electricity as possible from any additional fuel

used” �� CHP Plant considered in this work is a Gas Turbine (GT)

Gibbins, J. and Crane, R. 2004. Principles and performance limits for integrating amine scrubbing with coal and gas fired power plants", in Report on 6th

IEA GHG Workshop, International Test Network for CO2 Capture, 8-9 March 2004, Trondheim, Norway. IEA GHG, Cheltenham (www.ieagreen.org.uk).



Abated GTCC Option

90% capture from the

coal plant and no

capture from the GT

flue gases.

This approach has been

selected by CCS project

development in recent

years (e.g. Longannet,

NRG Parish)

An important concern in the context of decarbonisation of fossil fuel

use is whether carbon emissions from both the additional fuel source

and the retrofitted coal plant are captured, or from the latter only.

An important concern in the context of decarbonisation of fossil fuel

use is whether carbon emissions from both the additional fuel source

and the retrofitted coal plant are captured, or from the latter only.



EPS GTCC Option:

In the UK Emissions

Performance Standard

(EPS) limits CO2

emissions from new

fossil fuel power

station to 450 g/kWh

and in Canada to 420

g/kWh.

http://www.ec.gc.ca/lcpe-cepa/eng/regulations/detailReg.cfm?intReg=209

http://www.iea.org/policiesandmeasures/pams/switzerland/name



High levels of CO2 capture in coal plant retrofits with a GT can be achieved by :

a.) Adding two PCC units downstream of the coal plant and downstream of the GT

b.) Mixing the flue gas from both fuel sources and treating them in the same PCC Plant

Air & Coal

Secondary Air

THERMAL

ENERGY &

ELECTRICAL

POWER



High levels of CO2 capture in coal plant retrofits with a GT can be achieved by :

a.) Adding two PCC units downstream of the coal plant and downstream of the GT

b.) Mixing the flue gas from both fuel sources and treating them in the same PCC Plant

Air & Coal

Secondary Air

THERMAL

ENERGY &

ELECTRICAL

POWER

Mixing large volumes of gas could result in:

• Stratification issues �� critical issue as it controls the degree of

pollutant dispersion.

• Decrease in CO2 concentration of flue gas entering capture

plant: transfer rates in the absorber are relatively slower at lower

CO2 partial .

• Increase in O2 concentration of flue gas entering capture plant:

intensifies MEA degradation.

Air & Coal

THERMAL

ENERGY &

ELECTRICAL

POWER


GAS TURBINE FLUE GAS WINDBOX RETROFIT

Since mixing flue gas streams from two fuel sources can prove to be challenging, a viable

method is a sequential combustion of gas turbine exhaust gas in the existing coal boiler

Air & Coal

THERMAL

ENERGY &

ELECTRICAL

POWER



It reduces the O2 concentration and the total volume of the flue gas

entering the PCC plant and achieves similar CO2 concentration to

that of the coal power plant.

Air & Coal

THERMAL

ENERGY &

ELECTRICAL

POWER



It reduces the O2 concentration and the total volume of the flue gas

entering the PCC plant and achieves similar CO2 concentration to

that of the coal power plant.

Technical results of this work can be found at:

Sanchez del Rio, M.; Lucquiaud, M.; Chalmers, H.; Gibbins, J.

2015, ‘Gas turbine repowering options for carbon capture

retrofit’, 8th Annual Conference on Trondheim CO2 Capture

Transport and Storage, Trondheim, Norway.



Based on the principles used for hot-windbox repowering (Stenzel, W., Sopocy, D., Pace 1997).

Process:

- GT flue gas passes first through a heat recovery steam generator (HRSG), then through the

secondary air heater and finally is fed to the windbox of the coal boiler.

- The HRSG is designed to supply steam to the coal boiler in order to maintain the steam

production and reach the steam temperatures. Steam is supplied to both the superheater

and reheater outlet. The HRSG also produces LP saturated steam for solvent regeneration.

- The existing steam turbines are operated as the combined cycle of the CCGT.









6.- Conclusion


CONFERENCE: PCC3

ESTIMATION OF CARBON CAPTURE RETROFIT PERFORMANCE

2.- Calibration Mode of the coal power plant

3.- Operational Mode of the coal power plant

4.- Carbon Capture Plant Design

1.- Design Basis of the coal power plant

5.- Gas Turbine Combined Cycle Design

6.- Economic Analysis

7.- Sensitivity Analysis















































































































6.- Conclusion


CONFERENCE: PCC3





3.1.- Technical metrics

3.2.- Technical performance results of the retrofits with high levels of CO2 capture

3.3.- Technical performance results of the retrofits with intermedium levels of CO2 capture


CONFERENCE: PCC3

ELECTRICITY OUTPUT PENALTY ~ Overall energy requirement for CO2 capture

a.) Standard Integrated Retrofit

b.) With an additional fuel input to the site

b1.) Power / Heat Matched Retrofit

b2.) GT flue gas Windbox Retrofit

EOP = Power_LossST + PowerComp + PowerAncmCO 2

�� = �� !"# − �� #"& ��'��2

�� = �� /� #"& �� + ��)��*"� − �� #"& ��'��2

�� = �� /� #"& �� +�#�+ #�"* �" � + ��)��*"� − �� #"& ��'��2

NATURAL GAS MARGINAL EFFICIENCY ~ Effectiveness of the additional gas

consumption

Definition:

Maximum possible useful work for power regeneration recovered from the

combustion of the additional fuel source, before heat is supplied to the PCC process

b1.) Power / Heat Matched Retrofit

b2.) GT flue gas Windbox Retrofit

,"�-_�!! = �� #"& �� − ��. �"'/� ��!0 1�&� 2" 3"4

,"�-_�!! = 5�� #"& �� + ��)/.3 _6�0*�� 7 − ��. �"'/� ��!0 1�&� 2" 3"4




3.- Technical analysis:

3.1.- Technical metrics

3.2.- Technical performance results of the retrofits with high levels of CO2 capture

3.3.- Technical performance results of the retrofits with intermedium levels of CO2 capture


CONFERENCE: PCC3

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

capture(90% capture) (90% capture)

CASE A1 CASE D1 CASE B1 CASE C1Retrofitted PC Power Plant

Coal thermal input MWth 1517.9 1517.9 1348.6 1517.9 1517.9

Gas thermal input MWth - - 358.4 269.6 265.3

Net Power output MWe 600.3 473.9 600.3 600.3 600.3

Carbon intensity of electricity g CO2 / kWh 765.3 96.9 79.5 84.7 84.6

Thermal efficiency % LHV 39.5 31.2 35.2 33.6 33.7

Carbon Capture Plant

Overall carbon capture rate of two

fuel sources combinedw/w - 0.9 0.9 0.9 0.9

Gas flow rate to PCC Plant kg/s - 632.8 697.9 632.8 847.5

Gas flow rate to Gas PCC Plant kg/s - - - 218.2 -

Electricity output penalty kWh / tnCO2 - 305.8 291.5 315.8 311.3

Marginal efficiency of additional

gas combustion% LHV - - 53.9 46.9 47.7


Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGTThermal efficiency drops by 8 % points . The

best possible scenario for thermodynamic

integration is considered in this work, with

two back pressure turbines added to the

existing steam cycle

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

Thermal efficiency drops by 8 % points . The

best possible scenario for thermodynamic

integration is considered in this work, with

two back pressure turbines added to the

existing steam cycle

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT

The GT windbox retrofit reaches the

lowest EOP and the highest marginal

efficiency due to:

• The CO2 concentration reaches 12.6%

v/v, in comparison to 4.0% v/v at the

exhaust gas of the turbine and 13.6%

v/v for the coal plant with air-firing ��

lower reboiler duty

• The lower flow rate entering the

capture plant �� lower power

consumption of the flue gas blowers.

• The heat addition from the gas

turbine flue gas for steam generation is

more reversible than in a standard

HRSG, since the dedicated HRSG has no

IP evaporator.

Standard

Integrated

Retrofit

GT Windbox

Retrofit with

















Existing

coal plant

w/o

capture

90% capture

from CCGT.

(mixing flue

gas streams)

90% capture

from CCGT







6.- Conclusion


CONFERENCE: PCC3





4.- Economic analysis:

4.1.- Total revenue requirement

4.2.- Economic performance results of retrofits with high levels of CO2 capture

4.3.- Economic performance results of retrofits with intermedium levels of CO2 capture


CONFERENCE: PCC3

TOTAL REVENUE REQUIREMENT

The economic model is based on a spreadsheet where the total revenue

requirement, defined as the revenue that makes the project break-even, is

calculated by annualizing the total capital cost and levelising the total operating

and maintenance costs and variable costs. This allows separate assessment of

levelised cost of electricity and other revenues, e.g. those generated by the sales

of CO2 for EOR.

8 �& = 9 ∙ ;1 − 9 �& =;1 − 9= ∙ �/> 9 = 1 + �0

1 + �

8 �? = 1 �?

∙ @ ;1 + �=A −0.5

;1 + 0=A −0.5

�?

A =1

>�> = ��* = ��&E ∙ �/>

F// + ��/ ∙ >��2�"& �40 �

∙ 8 �& = F�� ∙ >�> ∙ 8 �? + >�, ∙ 8 �&8> ∗ 365 ∗ 24 ∙ �40 �

+ KL�, + >� ∙ ))L�40 �

+ ��2F. ∙ >��2�"& �40 �

M ∙ 8 �&

Fossil Fuel Costs

UK US

Coal $/MWh th 12.24 8.09

Natural

Gas$/MWh th 34.18 16.5

As the results of any economic analysis very much depend on fossil fuel prices two

scenarios have been evaluated: a European scenario considering UK fossil fuel prices

and the North American one considering US fossil fuel prices.

Fuel costs are based on average cost of fuel delivered for electricity generation in

2014 (Government 2015; EIA 2015a).

TOTAL REVENUE REQUIREMENT

Government, 2015. Quarterly Energy Prices. Available at: https://www.gov.uk/government/collections/quarterly-energy-prices.

EIA, 2015a. Average costs for fossil fuel for electricity generation. Available at: http://www.eia.gov/electricity/data.cfm#avgcost.





4.- Economic analysis:

4.1.- Total revenue requirement

4.2.- Economic performance results of retrofits with high levels of CO2 capture

4.3.- Economic performance results of retrofits with intermedium levels of CO2 capture


CONFERENCE: PCC3

ECONOMIC PERFORMANCE RESULTS OF RETROFITS WITH

HIGH LEVEL OF CO2 CAPTURE

Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT



Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

The GT windbox retrofit

has a good potential in

North America due to its

low TRR.



Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

The cost of CO2 avoided

is equivalent to the

value of the carbon tax

at which the TRR of the

existing plant equals

that of the plant with

CCS.

Carbon tax could be

largely reduced if CO2 is

used for EOR.



Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

The cost of CO2 avoided

is equivalent to the

value of the carbon tax

at which the TRR of the

existing plant equals

that of the plant with

CCS.

Carbon tax could be

largely reduced if CO2 is

used for EOR.



Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

Standard integrated

retrofits seems to

achieve a lower

TRR than other

opitions

BUT

actually it incurs

additional costs

related to the new

capacity needed to

re-store the power

output of the site



Existing

Coal Plant

Standard

Integ. Ret.

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

Standard integrated

retrofits seems to

achieve a lower

TRR than other

opitions

BUT

actually it incurs

additional costs

related to the new

capacity needed to

re-store the power

output of the site

ECONOMIC PERFORMANCE RESULTS OF RETROFITS WITH HIGH LEVEL OF CO2 CAPTURE

New CCGT

+ Standard

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

New CCGT

+ Standard

GT Windbox

Ret.

Ret. with

CCGT-mixing

Ret. with

CCGT

When the additional investment and the associated running costs of the new capacity

are considered the GT Windbox retrofit reaches the lowest TRR.



Additionally, the GT flue gas windbox retrofit seems to be a promising alternative for

repowering standard integrated capture retrofits.

Boundary Dam 3 unit (0 to ~90% capture) - Operate at 90% capture

- Restore power output of the site

- Use the asset of the existing PCC plant











6.- Conclusion


CONFERENCE: PCC3

CONCLUSION

• GT windbox retrofit could have a good potential in North America due to its low total

revenue requirement compared to other options. A similar outcome is achieved in Europe

although with a lower potential as natural gas is more expensive in the UK than in the USA.

• GT windbox retrofit seems to be a promising alternative for repowering standard

integrated capture retrofits without additional emissions by using the existing capture

plant without major modifications. This could be the case, for example of Boundary Dam 3

unit, where a standard integrated retrofit is designed for operation with zero to ~90%

capture. The addition of a GT flue gas windbox retrofit would allow full CO2 capture using

the original capture plant and restoring the power output of the site.

• The combination of a CO2 emission trading system with an EOR market would increase

the speed of CCS deployment for a fast-track emission mitigation strategy


CONFERENCE: PCC3

THANKS FOR YOUR ATTENTION ☺☺☺☺

Technical and economic analysis are discussed in detail in:

Sanchez del Rio M. (2015), Gas turbine power cycles for retrofitting and repowering coal plants

with post-combustion carbon dioxide capture, Ph.D. Thesis, School of Engineering, University of

Edinburgh, United Kingdom of Great Britain and Northern Ireland (UK).

*contact e-mail: [email protected] / [email protected]

08 – 11 September 2015 • Regina, Canada

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MAINTAININGTHE POWER OUTPUTWITHTHE ADDITIONOF CO2 …