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Economic, CO2 and Security performance of power system operation with carbon capture plant

and renewable generation

(Theme A5 - UK Real Time Energy Supply and CCS Plant)

Anser Shakoor, Cheeyong Chen, Goran Strbac (Imperial College London)

(UKCCSC meeting – Nottingham- 18 April 2007)

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Presentation Outline

Objectives Modelling CC technologies Case studies Results

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Project Objectives:

Development and implementation of a simulation (system operation) platform to evaluate the cost, CO2 and security performance of UK power generation system, with carbon capture applied to conventional (fossil fuelled) generation.

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• How the introduction of carbon capture technologies impact on the technical, economic and environmental performance of UK generation system?

• How the combination of carbon capture process and high penetration of intermittent renewable (wind) generation influence the UK power system operation?

Key Questions:

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Modelling CC Technologies -1a - Post Combustion Capture

• Approx. 85% CO2 is removed through amine scrubbing of flue gases. • Does not alter the combustion process and provides flexibility• Solvent regeneration & CO2 compression is required that needs large amount of energy (~ 10% of plant capacity effected)• Option-1: store solvent thus reclaiming plant capacity during high demand periods, with later regeneration during low demand periods. • Option-2: stop carbon capture during high demand periods (associated with high CO2 release to atmosphere).

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Summary of different modes of operation in post combustion CCMode of Operation / Generator Characteristics

Minimum Stable Generation (MSG) MW

Generator Registered Capacity

(GRC) MW

CO2 Release

(%)

Without Capture (simple venting) 250 500 100

With Capture (Regeneration) 225 450 10

With Capture (Solvent Storage with No Regeneration)

250 500 10

With Capture (Regeneration + stored solvent regeneration)

200 400 10

Modelling CC Technologies -2

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b – Pre Combustion Capture

• Uses fuel conversion before combustion/conversion• Operating characteristics of pre combustion plant (less flexible) is very different from post combustion plant • Can not be operated like solvent storage in post combustion as continuous removal of CO2 is required (also high pressure vessel req.).• Limited gain of simple venting as most of the CC related energy is consumed before removal of carbon. • Plants with pre combustion carbon capture are modelled as inflexible with 10% reduction in their output

Modelling CC Technologies -3

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System Description -1Demand:

Pk. Demand = 57 GW, Min. Demand = 18GW • Annual hourly demand profile considering 6

characteristic days, three seasons (winter, summer and spring/autumn) and two types of days (business and non business day).

• Demand is assumed to be fully predictable (i.e., impact of demand forecasting error is not included).

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System Description -2

THERMAL SYSTEMS

Parameters Inflexible Generation

Moderate flexibility

Generation

Flexible Generation

Low Flexibility (LF)

MSG 100% 77% 50%

Capacity installed

9.5GW 26GW >25.6GW

Medium Flexibility

(MF)

MSG 100% 62% 50%

Capacity installed

9.5GW 26GW >25.6GW

Generation System

• WIND GENERATION: Annual hourly generic UK wind generation profile is used to represent 26 GW (20%) of wind generation capacity installed

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Reserve Requirement & Provision

• Two cases of reserve provision:i. Entire reserve provided by synchronised plantii. Part of reserve provided by conventional

synchronised plant and rest by standing reserve form; a) OCGTs, b) Carbon capture plant

• Amount of reserve req. derived from the standard deviation of wind variations (4-hr time horizon)

No. of Standard Deviation in wind

variation

Wind output

forecast error (MW)

Operating Reserve

Requirement (MW)

Maximum Spinning Reserve

(MW)

Maximum Standing Reserve

(MW)

Standing Reserve

from OCGT (MW)

Standing Reserve

from CCS (MW)

3.5 2415 8451 8451 0 0 0

2.5 2415 6036 6036 2500 1550 950

2.3 2415 5554 5554 3000 2050 950

2 2415 4829 4829 3500 2550 950

1.7 2415 4105 4105 4500 3550 950

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Model OutputSimulation of system operation (hour by hour, year round) with 26 GW of wind capacity, taking into consideration daily and seasonal demand changes and variations in wind output provides the following key output per annum.

- energy produced by conventional plant - CO2 emissions - generation cost including cost associated with carrying spinning reserve - energy not supplied (due to insufficient reserves and constraints on ramp rates)- wind generation curtailed (due to minimum stable generation constraints and constraints on ramp rates) - energy produced by OCGTs (when OCGT plant is used)

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Preliminary Results

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Total Standing Reserve Capacity

(MW)

OCGT Capacity

(MW)

CCS Capacity

(MW)

Low Flexibility System (£m/pa)

Medium Flexibility System (£m/pa)

2500 1550 950 196 189

3000 2050 950 243 232

3500 2550 950 316 298

4500 3550 950 395 366

Reduction in fuel cost

• 10% (950MW) of the total CC plant capacity is available for provision of standing reserve• Assumption: cost of OCGT is 50£/MWh (in contrast to marginal cost of synchronised plant of 20£/MWh)

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Reduction in CO2 Emissions Total Standing

Reserve Capacity (MW)

OCGT Capacity

(MW)

CCS Capacity

(MW)

Low Flexibility System (tonnes/p

a)

Medium Flexibility System

(tonnes/pa)

2500 1360 950 3,926,361 3,792,819

3000 1860 950 4,872,426 4,663,161

3500 2360 950 6,379,451 6,013,640

4500 3360 950 8,008,434 7,427,662

• Assuming that standing reserve plant emit 0.6 tonne/MWh compared to 0.4 tonne/MWh by synchronised plant.

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Reduction in thermal energy / Increase in Utilization of Wind energy

Total Standing Reserve Capacity

(MW)

OCGT Capacity

(MW)

CCS Capacity

(MW)

Low Flexibility System (MWh/pa)

Medium Flexibility System

(MWh/pa)

2500 1360 950 5,117,497 2,191,325

3000 1860 950 6,103,847 2,555,790

3500 2360 950 7,476,273 3,042,481

4500 3360 950 8,722,823 3,464,049

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Further Work

Model enhancement including: Effect of demand forecast errors Reserve req. assessment based on temporal

wind & demand level Oxy fuels Start-up costs….

Further studies involving real systems, levels of system security, fuel prices, ……

Documentation of developed model and results (report)

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Economic, CO2 and Security performance of power system operation with carbon capture plant

and renewable generation

(Theme A5 - UK Real Time Energy Supply and CCS Plant)

Anser Shakoor, Cheeyong Chen, Goran Strbac(Imperial College London)

(UKCCSC meeting – Nottingham- 18 April 2007)