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Testing of a new supercritical ORC technology for efficient power generation from geothermal low temperature resources ASME ORC 2013 Conference Nicola Rossi Rotterdam, 6-8 October 2013
Testing of a new supercritical ORC technology for efficient power generation from geothermal low temperature resources ASME ORC 2013 Conference Nicola Rossi
Rotterdam, 6-8 October 2013
USE: Public
ASME ORC Conference, 6-8 October 2013
Presence in: 40 countries
Installed capacity: 97.839 MW
Annual output: 295,7 TWh
EBITDA: 16,7 bln €
Customers: 60,5 million
Employees: 73.702
CAPEX 2013-2017:
€27 billion
Data updated @ 31/12/2012
Enel today An international, integrated energy operator
1st utility in Italy, 2nd largest in Europe by installed capacity Present throughout the entire electricity and natural gas value chain
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USE: Public
ASME ORC Conference, 6-8 October 2013
Enel today An international, integrated energy operator
8.001 MW 25.114 GWh
Installed
capacity
Generated
electricity
Geothermal energy represents 30% of the total renewable energy generated by the ENEL group, excluding big hydro installations
RENEWABLES - ENEL GROUP - YEAR 2012
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USE: Public
ASME ORC Conference, 6-8 October 2013
Enel geothermal experience: a long history of success
Piancastagnaio/Bagnore
(Mt. Amiata – 50 km2)
• Since 1955 – water dominated
• Installed capacity: 69 MW
Larderello/Lago (250 km2)
• Since 1913 – superheated steam
• Installed capacity: 478 MW
Travale-Radicondoli (30 km2)
• Since 1950 – saturated steam
• Installed capacity: 175 MW
34 units, 722 MW gross generating capacity
Pisa FIRENZE
Siena
Grosseto ROMA
Pisa FIRENZE
VITERBO
ROMA
Data updated @ 31/12/2011
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USE: Public
ASME ORC Conference, 6-8 October 2013
Installed Capacity [MW]
2005 2010 Δ%
TOT_GEO 8.912 10.715 20,2%
GEO_LH 685 1.178 72,0%
653
209 137
52 29 21 14 14 0
100
200
300
400
500
600
700
Binary Plant: Installed Capacity [MW]
GEO - Total GEO – Low/medium enthalpy
The big potential of low-medium enthalpy resources
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USE: Public
ASME ORC Conference, 6-8 October 2013
ENEL international projects
• ORC (Organic Rankine Cycles)
• 2 plants in operation (Salt Wells, Stillwater)
• 1 under construction (Cove Fort I)
• Other investments under evaluation (Cove Fort II, Surprise Valley)
• Future developments: coupling with CSP technology
• Participation in LaGeo S.A. (~1/3 of shares)
• 2 fields under exploitation (Ahuachapan, Berlin) – 200MW, 1,4 TWh/yr
• 2 fields under exploration (San Vicente, Chinameca)
• Cerro Pabellon 40 MW Single Flash plant (Apacheta area)
• Construction to be started
• Exploration in the Mediterranean Area (Greece, Turkey) and in
Central America (Nicaragua)
USA
Salvador
Chile
Other
Countries
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USE: Public
ASME ORC Conference, 6-8 October 2013
Stillwater Plant – Pictures & Layout
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USE: Public
ASME ORC Conference, 6-8 October 2013
Innovation in binary cycle technology
ENHANCED
PERFORMANCES &
OPERATIONAL FLEXIBILITY
• To upgrade geothermal
resources exploitation and
reduce risks (electric
generation more profitable)
• To better match the
characteristics of geothermal
reservoirs (more flexibility)
• To avoid performance decline
due to the natural resource
depletion and temperature drop
ORC power production
from low temperature
resources has a low
thermal efficiency
ORC PLANT
CAPITAL COST
1,4 ÷1,6 M€/MW (1)
Low efficiency requires
increased power plant
equipment size that can
become cost prohibitive
ORC
EFFECTIVENESS
7% ÷ 10%
STATE OF THE ART INNOVATION MAINSTAYS
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(1) 5 ÷ 10 MWe units, only supplies excluding extraction/injection wells
USE: Public
ASME ORC Conference, 6-8 October 2013
Subcritical vs. Supercritical Cycles
Subcritical cycle Supercritical cycle
. Supercritical cycles allow a better exploitation of the geothermal
resource (no pinch point limitation), an higher generation efficiency and
simpler plant configuration
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USE: Public
ASME ORC Conference, 6-8 October 2013
Experimental activities
Optimization and demonstration of
performance and control strategy
Tuning of process and CFD models
Validation of design criteria
Evaluation of component reliability
Fluid degradation and new fluids
Basic data for Feasibility &
Costing analysis of a FULL
SCALE power plant, with
respect to conventional
technologies
2012
2009-2011
Cycle conceptual
design and pilot plant
EPC
Advanced ORC technologies – Development program
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USE: Public
ASME ORC Conference, 6-8 October 2013
Project detailed program and partnership
2009 2010 2011 2012
Basic studies and feasibility
Engineering Procurement Construction 500kW pilot
Tests in Livorno
Jan. 2012 Commissioning
Time
schedule
2013
Dec. 2012 Final technology evaluation
On field tests on real fluid
Scale up and cost assessment
MIT Massachssets Institute of Technology
Scientific Partners Technology provider End user
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USE: Public
ASME ORC Conference, 6-8 October 2013
Fluid and cycle selection
0
10
20
30
40
50
60
100 110 120 130 140 150 160 170 180 190 200
Geo-fluid Temperature (°C)
Uti
liza
tio
n E
ffic
ien
cy (
%)
Supercritical Cycles
Subcritical Cycles
H-1
H-2
R-1
R-2
R-3
Temperature range of interest
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Supercritical cycles provide higher utilization efficiency for all geo-fluid
temperature range, resulting in max 23% increase in net power
USE: Public
ASME ORC Conference, 6-8 October 2013
Pilot plant in operation since January 2012
Supercritical ORC cycle
• Working Fluid: refrigerant
(not toxic, not flammable)
• Axial turbine
• N°3 shell & tube heat
exchangers
• N°1 shell & tube regenerator
• Air cooled condenser “spray &
dry“
• Multi-stadium centrifugal
pump
Advanced 500 KWe ORC pilot plant (Livorno)
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USE: Public
ASME ORC Conference, 6-8 October 2013
USE: Public
Boiler
(2,8kg/s, 30bar/a satured steam)
ORC 500kWe Pilot Circuit
Pilot Plant circuit overall scheme
Possibility to operate in flexible and controlled conditions
Closed loop Heat Transfer Section
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USE: Public
ASME ORC Conference, 6-8 October 2013
Experimental program
• PHASE 1 Commissioning and performance tests
• PHASE 2 Component characterization and operational optimal curve determination
• PHASE 3 System control philosophy optimization
• PHASE 4 Operating stability evaluation through long-run tests
Experimantal phases Heat source experimental conditions
T [°C] M [kg/s]
Mmax-Tmax 170 16,6
Mmax-Tnom 152 16,6
Mmax-Tmin 130 16,6
Mnom-Tmax 170 12,3
Mnom-Tnom 152 12,3
Mnom-Tmin 130 12,3
Mmin-Tmax 170 8,6
Mmin-Tnom 152 8,6
Mmin-Tmin 130 8,6
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M = Flow rate, T=Temperature, nom=nominal, max=maximum, min=minimum
USE: Public
ASME ORC Conference, 6-8 October 2013
Performance tests at design conditions
DESIGN MEASURED NORMALIZED @ 25°C AMB. TEMP.
DELTA
KW
Gross power (kW) 462 471 471 + 9
Partial net power 1 (kW) 362 383 383 + 21
Net power2 (kW) 319 364 350 + 31
Ambient temperature (°C) 25 22,5 25
1 Gross power minus circulating pump power consumption
2 Gross power minus circulating pump and ACC power consumption
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USE: Public
ASME ORC Conference, 6-8 October 2013
Thermodynamic cycle - Design vs. experimental
Design
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Theoretical thermodynamic cycle was reproduced with
negligible deviations
74
153
22
34
0
20
40
60
80
100
120
140
160
180
0 1000 2000 3000 4000 5000
Te
mp
era
tura
(°C
)
Potenza (kW)
Actual
152
33
0
20
40
60
80
100
120
140
160
180
0 1000 2000 3000 4000 5000
Te
mp
era
tura
(°C
)
Potenza (kW)
3223
47
132
6550
152
75
35
Power (kW) Power (kW)
Te
mp
era
ture
(°C
)
Te
mp
era
ture
(°C
)
USE: Public
ASME ORC Conference, 6-8 October 2013
55%
60%
65%
70%
75%
4 6 8 10 12
ise
ntr
op
ic E
ffic
ien
cy (
%)
Turbine discharge pressure (bara)
P_in=45 bar, T_in=131°C
Experimental Guaranteed Expected
55%
60%
65%
70%
75%
30 35 40 45 50
Isen
tro
pic
Eff
icie
ncy
(%)
Turbine inlet pressure (bara)
P_dis=9 bar, T_in=131-132°C
Experimental Guaranteed Expected
Iso
en
trop
ic e
ffic
iency (
%)
Performance tests on main componets
Turboexpander
Performances higher than design for all main components (turbine, feed pump, heat exchangers)
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@ Fixed WF discharge P and inlet T @ Fixed WF inlet P and T
USE: Public
ASME ORC Conference, 6-8 October 2013
Cycle optimization tests
Optimized performance curves implemented in DCS
Cycle optimization Optima operating curves
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300
325
350
375
400
425
450
15 20 25 30 35
Po
ten
za N
ett
a P
arzi
ale
(kW
)
"Surriscaldamento" (°C)
p_cond 8 bar p_cond 8,9 bar
p_cond 10 bar Nom @ p_cond 8,9 bar
Design conditions Pa
rtia
l n
et p
ow
er
(1) (k
We)
WF Super-heating (°C) Is
oe
ntr
op
ic e
ffic
iency (
%)
200
250
300
350
400
450
500
550
600
7,0 8,0 9,0 10,0 11,0 12,0P
ote
nza
(k
W)
p_cond (bara)
Gross
Partial net
Net_DRY
Net_SPRAY
100%
30%
75%50%
100% 30%50%75%
Net p
ow
er(
2) (k
We)
Condensing pressure (bar)
1 Gross power minus circulating pump power consumption
2 Gross power minus circulating pump and ACC power consumption
USE: Public
ASME ORC Conference, 6-8 October 2013
Operational limit evaluation
High operational flexibiliy, capability to operate in subcritical and supercritical conditions
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0,04000
0,05000
0,06000
0,07000
0,08000
0,09000
0,1000
0,1100
9
10
11
12
13
14
15
16
4
5
6
7
8
9
10
11
130
1 4 0
1 5 0
1 6 0
1 7 0Eff
icie
nza
Ne
tta
Pa
rzia
le (
%)
Temper
atura G
eofluid
o (°C)
Portata Geofluido (kg/s)
9
10
11
12
13
14
15
16
26
28
30
32
34
36
38
40
42
44
46
130
1 4 0
1 5 0
1 6 0
1 7 0
Pre
ssio
ne
In
gre
sso
Tu
rbin
a (
ba
r)
Temper
atura
Geoflu
ido (°C
)Portata Geofluido (kg/s)
Nominal
conditions
Nominal
conditions
USE: Public
ASME ORC Conference, 6-8 October 2013
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12/nov 12:00 13/nov 00:00 13/nov 12:00 14/nov 00:00 14/nov 12:00 15/nov 00:00 15/nov 12:00 16/nov 00:00 16/nov 12:00
T_amb
p_cond
Pot. Netta
Pot. Lorda
LR-1 LR-2 LR-3 LR-4
Net power
Gross power
Long run tests P
_co
nd (
bar)
/ T
-am
b (
°C)
Ele
ctr
ic p
ow
er
(kW
e)
Experimental configurations
Heat source Cycle conditions
LR-1 Mnom-Tnom Super-critical
LR-2 Mnom-T=162°C Super-critical
LR-3 Mnom-Tmin Sub-critical
LR-4 Mnom-Tmin Sub-critical
No working fluid degradation observed after 1000h of
operation M = Flow rate, T=Temperature, nom=nominal, min=minimum
USE: Public
ASME ORC Conference, 6-8 October 2013
Scale up preliminary evaluation
Supercritical vs. Subcritical with iso-butane
INPUT DATA
• Brine inlet temperature: 152°C
• Brine mass flow: 190 kg/s
• Design net power: 10 MWe
• Design ambient temperature: 10.7 °C
• Summer ambient temperature: 31.1 °C
• Winter ambient temperature: -1.1 °C
Ne
t p
ow
er
(kW
e)
Supercritical Subcritical
Super-critical Sub-critical
Annual net energy
production estimation
~ 15-20% higher for
supercritical ORC with
respect to subcritical
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USE: Public
ASME ORC Conference, 6-8 October 2013
Concluding remarks
• During the experimentation at the pilot scale, supercritical technology showed no criticalities in terms of components and control stability
• Design criteria were confirmed by experimental results and performances of main
components and equipments were in line or higher than those expected • The pilot plant was able to operate in a wide range of brine temperature and flow
rates (± 30% vs. design), highlighting a high operational flexibility and the ability to operate even in subcritical conditions
• During the experimental activities significant degradation phenomena of the working
fluid were not observed which, not being flammable, determines obvious simplifications in the authorization and design phases compared to conventional hydrocarbon fluids
• The extrapolation of results from pilot scale (500kWe) to full scale (10MWe)
confirmed the findings of the feasibility phase: the supercritical technology results in an increase of net annual electricity production in the range of 15-20% compared to one-level pressure subcritical cycles available on the market
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Use: Public
ASME ORC Conference, 6-8 October 2013
Thank you for your attention
