integration of csp and ccgt: how it works and pros and...
TRANSCRIPT
Integration of CSP and CCGT: How it
works and pros and consManuel Millan
World Bank July 2017
Content
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• Objective
• General concept
• Types of integration
• Most common concept
• Engineering considerations
• Economic considerations
• Comparatives
• Greenfield vs Brownfield
• Future of integration
• Conclusions
Objective
3
• Explain the types of integration between CSP and
conventional CCGT
• Describe the most common configuration for integration
• Analyze engineering and economic implications
• Describe pros and cons of integration vs stand alone
CSP or stand alone CCGT
• Show some personal experiences and views
General concept of integration
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Conventional Combined Cycle
CSP Field
Technologies combination:
Combined Cycle (CC) GT + HRSG + ST
Concentrated Solar Power (CSP), solar field. Either PT, CRS or LF
Steam generation from solar incorporated in the standard process
Integration may happen in different stages of the process
Types of integration (I): Hybridization and additions
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• Hybridization: Internally within the process
• Addition: Externally to the process
Integration types classification
• Inside the process
• Requires deep interactions inside the process
• Possible in brownfield projects? DependsHybridization
• “Outside” the process
• Has minimum interferences
• Can it be always technically feasible?Addition
• Increase energy efficiency/decrease HR
• Increase power output
• Decrease fuel consumption
One objective
Two ways
Types of integration (II)
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Fuel
Fuel
GAS
TURBINE
STEAM
TURBINE
BOILER
RANKINE CYCLE
BRAYTON CYCLE
Hybridization
Addition
Preheating air to reduce gas
consumption (SOLUGAS – CRS)Injection of saturated solar
steam generation (ISCC – PT)
Injection of solar heat in the
exhaust GT gases (HYSOL –
Any technology)
Injection of superheated solar steam
generation (at ST conditions)
Solar heat for in the ST
extraction
Solar heat for preheating
(Mejillones CFP in Chile)
Types of integration (III)
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1500
1000
500
SS (kJ/kg K)
T (
K)
Fuel
Fuel
• Integration is conditioned
by thermal level in the
process.
• CSP technologies are
standardized in terms of
thermal levels.
• Higher the thermal level,
higher the efficiency
achieved.
HYSOL© Concept
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Source: HYSOL© consortium
CAPTure concept
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Source: CAPTure consortium
Integrated Solar Combined Cycle (ISCC): most common
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Most common concept (I): ISCC
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Solar Field
HRSGGas Turbine
Gas Turbine
Natural gas
Natural gas (post combustion)
HRSG
Aircooled condenser
Natural gas
Steam turbine
Natural gas (post combustion)
• After preheater in HRSG
water is sent to the solar
system (200-250 C)
• Water is transformed into
saturated steam in the
solar system (400 C)
• Saturated steam is
injected just before the
superheater
• All steam together
continues to
superheating and ST
(560 C)
Most common concept (II): Existing experiences
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Title Current StatusSolar Capacity
(MW)
Fossil
Capacity
(MW)
Technology Type of integration
Martin Next
Generation Solar
Energy Center
Operative 75 3700* Parabolic Trough Saturated solar steam
Hassi-R´mel Operative 25 150** Parabolic Trough Saturated solar steam
Kuraymat Operative 22 104** Parabolic Trough Saturated solar steam
Ain Beni Mathar Operative 20 450* Parabolic Trough Saturated solar steam
Agua Prieta Under Construction 14 464* Parabolic Trough Saturated solar steam
Solar Dawn Cancelled 250 Linear Fresnel
*Plant Total Capacity,
**Block Capacity
Technical considerations (I): Why is this the most
common concept?
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1. Generalization of PT technology as first
commercially feasible at large scale
2. PT technologies works in a thermal
range between 293 C and 393 C
3. Rankine cycle in CCGT has those
temperature points perfectly defined
4. Allow the steam to be homogenously
superheated before sent to the ST
5. Does that mean this is the optimum
integration concept? No
- Higher points of injection will allow
better performances
- Concepts avoiding interactions
inside boilers would be much
easier and reliable
PT
op
era
tion
Technical considerations (II): How it works?
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HRSG
SSG
Fa
Fgv
s
Fgv
s
Fa -
FgvsFa
1. Out of daylight the CCGT works normally
(flow Fa in the HRSG)
2. When solar system is in operation a fraction
of Fa (Fgvs) is sent to the solar system.
This fractions comes back as saturated
steam
3. Issues
- If solar fraction is too high, the fraction
Fgvs is so, and during daylight the flow
through the boiler decreases
- At some point the boiler materials are
too stressed and cannot be cooled
down enough by the flow. That is the
integration limit.
- Solutions for increased integrations (for
example):
- Use of special alloys (very
expensive)
- Duct firing in the boiler (decreased
efficiency)
Economic considerations (I): Cost breakdown
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Combined Cycle77%
Solar field materials15%
SF assembly2%
Solar BOP4%
Electric system
1%
I&C0%
Assembly building
1%
O&M material0%
Solar system23%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
5 10 15 20 25 30 35 40
Solar share in annual production (%)
CCGT
Solar Block
For a 5% solar share
Economic considerations (II): Fuel saving results
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Ave
rage H
eat
Rate
(kJ/k
Wh
)
Am
bie
nt
tem
pera
ture
(C
)
Time
Economic considerations (III): Brief analysis for a typical ISCC with PT
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Solar field cost ($250/m2 including solar BoP)
• Own calculations based on energy balances
• Solar field cost includes correspondent solar
BoP
• Break even point is at $150/m2 far from
current prices ($250-200/m2)
• Assumes gas at $10/mmBTU and 80%
Capacity factor for the CCGT+solar
Solar field cost ($200/m2 including solar BoP)
Solar field cost ($150/m2 including solar BoP)
50%
60%
70%
80%
90%
100%
110%
120%
130%
140%
150%
0 10 20 30 40
LCO
E
% electricity from solar
with solar
without solar
50%
60%
70%
80%
90%
100%
110%
120%
130%
140%
150%
0 10 20 30 40
LCO
E
% electricity from solar
with solar
without solar
50%
60%
70%
80%
90%
100%
110%
120%
130%
140%
150%
0 10 20 30 40
LCO
E
% electricity from solar
with solar
without solar
Economic considerations (IV):…
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Nom Power 50MW
DNI 2,500 kWh/m2 y
CF 24%
Annua solar generation 105,120 MWh/y
Eff Solar to Power 16%
Energy to be collected 657,000 MWh (rad)
Surface 262,800 m2
Announced cost 1,600,000 $/MW
Solar cost 80,000,000 $
Ratio (including BoP) 304$/m2
Current ratio (including BoP) Approx. 250$/m2
19 July, 2017
Comparatives (I): Integration vs Stand-alone solar plants
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AdvantagesReduced investment (power block is shared)
Optimized maintenance (shared)
Dispatchability without need for storage
Flexibility of configurations
Better performance for equipments in long term
Avoiding continuous stops and start ups
More competitive LCOE than stand alone
Drawbacks Fossil fuel required (Not 100% renewable)
Location is predetermined in case of additions
Solar block must be adapted
Power from solar limited for technical reasons (Normally low solar fractions)
No standardization
Higher CO2 emissions
Comparatives (II): Integration vs Stand-alone CCGT
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Advantages Increased efficiency (lower HR)
Allow introduction of CSP
Partially hedge the generation cost against fluctuation of fuel cost
Lower CO2 emissions
Drawbacks Huge land required for solar field
Special design of some equipment (mainly HRSG)
More complex to operate than standard CCGT
Higher cost of generation if fuel is at reasonable price
Solar part not dispatchable at least there is storage
Increased maintenance activities
No standardization
Greenfield vs Brownfield
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Greenfield Design from scratch
Appropriate location and land allocation
Optimized radiation and water availability
Design is optimized
Higher solar shares
Brownfield Complicated design difficult to optimize
Probably solar fraction would be very limited
Will require interactions and modifications in the existing process
Will probably require existing plant shut downs
Will change BAU in O&M
Land availability, radiation and water availability might be issues
Future of integration
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?
The actual prices and features (dispatchable) of stand alone CSP plants make difficult for the integration to make economic sense
New developments with higher solar shares configurations are required: using storage, towers, higher thermal levels, etc.
Need for standardization
Reduction in solar components in the last years may also help and make integration a way of reducing cost of electricity from conventional ISCC
It might be a niche for retrofitting existing CCGT, which may have has serious technical challenges
Conclusions
Solar integration (Hybridization/addition) is an interesting option for solar thermal technology development, however the evolution of stand-alone solar plant makes hard to justify this option.
It is not always techno-economically feasible in the process.
Competitive cost Shared equipment with conventional plant
Better performance of equipments
Dispatchability without storage
But is not cheaper than ISCC stand alone (as now)
As purely commercial option, it would be difficult to make the case, considering the current price of stand-alone CSP.
However, depending on the circumstances, it might be an option to develop solar
Lack of investment capability for a stand alone CSP
Desire to “experiment” the technology before engaging more
“Easy” CO2 emissions reduction (INDC)
