This document summarizes a presentation given by Vladimir Koritarov from Argonne National Laboratory on the state of pumped storage hydropower and research efforts. Some key points: - There is about 130 GW of pumped storage hydropower globally, with 40 GW in Europe and 22 GW in the US. New projects are being built. - Historically, pumped storage was used for load shifting and providing backup capacity. Now it helps integrate variable renewable resources like wind and solar by providing flexibility, energy storage, and ancillary services. - Adjustable speed and ternary pumped storage technologies provide even more flexibility to support the grid compared to traditional fixed speed designs. - The US Department of Energy funded

1. Public Workshop: Challenges and Opportunities
for Pumped Storage Hydropower in the U.S.
April 27, 2016
State of the Industry and
Research Efforts in PSH
Vladimir Koritarov
Center for Energy, Environmental, and Economic Systems Analysis
Energy Systems Division
ARGONNE NATIONAL LABORATORY
9700 South Cass Avenue
Argonne, IL 60439
Tel: 630-252-6711
Email: koritarov@anl.gov

2. 2
Pumped Storage Hydropower (PSH)
 About 130 GW of PSH in the world, of which:
–40 GW in the European Union
–22 GW in the United States
 Many utilities are building new PSH capacity
–1,200 MW Alto Tamega in Portugal,
–760 MW Venda Nova 3 in Portugal,
–852 MW La Muela 2 in Spain, etc.
Seneca PSH in Pennsylvania

3. Drivers for the Development of PSH – Then …
 Historically, key drivers for the development of PSH capacity were to perform load
shifting (load levelling) and provide backup capacity for large nuclear and coal units
3
PSH Installations in the U.S. by Plant Size
Source: DOE – 2014 Hydropower Market Report
Lake Hodges
in 2012 (40 MW)
Existing PSH Plants in the U.S.
Source: Argonne National Laboratory

4. …and Now – Growth of Variable Energy Resources (VERs)
Source: AWEA 2014
Wind capacity is now over 65 GW Solar capacity is now over 17.5 GW
Source: SEIA 2015
Key challenges for larger
integration of VERs are their:
• Variability
• Uncertainty
4
U.S. Annual PV Installations

5. Ancillary Services, such as Operating Reserves are
Needed to Balance Wind
5
Almost 2,000MW
range in a single day

6. Power Systems will Need Flexible Capacity to
Support Variable Generation
Source: http://www.caiso.com/Documents/Presentation-Mark_Rothleder_CaliforniaISO.pdf
About 13,000 MW
ramping in 3 hours

7. Advanced Forecasting Helps Reduce Uncertainty,
Energy Storage Helps Manage Variability
7
 Current wind forecasts tools do reasonably well
 Forecasting ramps is still an issue

8. Value of PSH in Utility Systems
Three main components:
1. Energy/price arbitrage
2. Ancillary services
3. System-wide effects (lower system operating costs,
better integration of VER, reduced cycling of thermal
units, increased system reliability, etc.)
8

9. PSH Has a Key Role in the Integration of Variable
Generation Resources
 PSH plants are well-suited to provide a number of ancillary and other grid
services
 Characterized by fast, flexible, and reliable operation with quick starts and
excellent ramping capabilities
 Proven technologies, commercially widely available
 New PSH technology designs are focusing on providing even more flexibility
 In the pumping mode, PSH plants create system load which can be used to
store excess generation of VER and reduce their curtailments
 PSH plants can provide ancillary services at lower cost than thermal
generating units
9

10. PSH Provides FLEXIBILITY to the Grid!
Load shifting from peak to off-peak periods
–Increase efficiency of system operation by:
• Increasing the generation of base load units
• Reduces the operation of expensive peaking units
Contingency reserve (spinning and non-spinning)
–Provide large amount of fast contingency reserve (e.g., for the
outages of large nuclear and coal units)
Regulation reserve
– Help maintain system frequency at a narrow band around nominal
system frequency by balancing supply and demand
Flexibility reserves and load following
– Provide quick-ramping capacity
Energy imbalance reduction
–Balance the variability of wind and solar power and correct the
control area intertie exchanges 10

11. Vt
PS+jQS
Pr+jQr
Stator
Rotor
Power
Converter
Ptotal+jQtotal
Adjustable Speed PSH Provide Even More Flexibility
 One type of adjustable speed unit is doubly-fed induction machine (DFIM)
 The rotors of DFIM units are equipped with three-phase windings and fed via
frequency converter
 The actual mechanical speed is the result of superposition of both rotor and
stator rotating magnetic fields and is controlled by frequency converter
 The units can vary the speed (typically up to 10% around the synchronous
speed)
 It is possible to adjust the speed to actual water head, which increases turbine
efficiency
 Active and reactive power can be controlled electronically and separately
 The units are able to operate in partial load pumping mode
11

12. Additional Benefits of Adjustable Speed PSH
(Compared to Fixed Speed PSH)
 More flexible and efficient operation in generation mode
–Minimum unit power output as low as 20%
–Increased efficiency and lifetime of the turbine at partial loads by operating at
optimal speed
 Frequency regulation capabilities also available in the pumping mode
 Decoupled control of active and reactive power (electronically)
–Provides more flexible voltage support
 Improved dynamic behavior and stability of power system
–Improved transient stability in case of grid faults (e.g., short circuit faults in the
transmission system)
–Reduced frequency drops in case of generator outages
 Increased capabilities to balance variable renewables
–More flexible and quicker response in generating (turbine) mode
–Variable power in pumping mode to counterbalance variability of VERs
–Excellent source of frequency regulation during off-peak hours
12

13. Fixed and Adjustable Speed PSH Technologies
 Adjustable speed PSH use doubly-fed induction machines (DFIM) or
converter-fed synchronous machines (CFSM)
 Adjustable speed PSH can operate in partial load pump mode, which allows
them to provide regulation service also during pumping
13
Source: Koritarov et al., HydroVision 2015

14. Operating Mode Transition Times
14
Source: Fisher et al. (HydroVision 2012)

15. Ternary PSH Technology with Hydraulic Bypass
Provides for Extraordinary Flexibility
 Kops 2 (3x150 MW) PSH plant in Austria has implemented ternary pump-
turbine arrangement with hydraulic bypass
 Turbine and pump are connected with a mechanical clutch (pump can be
separated during the generation mode to increase efficiency)
 During the pumping, the power taken from the grid can be supplemented by
the power produced by the hydro turbine (“hydraulic short circuit”)
 This provides for flexibility in regulating the pumping power needs from the
grid
15
Source: Illwerke VKW Group, 2009

16. DOE Funded a Study on the Modeling and Analysis of Value
of Advanced PSH in the U.S.
 Clean energy goals require reliance on large amount of VER, which makes electric
grid difficult to manage
 PSH enables high penetration of VER:
– Provides large quantities of energy storage and full range of ancillary services necessary for
grid operation
– Provides large amount of flexible dispatchable capacity with no greenhouse gas emissions
– Has none of the limitations of other flexible technologies like gas turbines and demand
response
– Can mitigate over-generation of VER through storing and time-shifting excess generation
– Improves dynamic behavior and stability of power system
16Source: C. Barnhart, Stanford University, 2014
Energy Stored
on Energy
Invested (ESOI)
U.S. Energy Storage Capacity Mix
Source: Grid Energy Storage, DOE 2013

17. Advanced PSH Project Overview
17
 Argonne-led study funded by the DOE Water Power Program
Project website: http://ceeesa.es.anl.gov/projects/psh/psh.html
Project Team
Main Objectives:
 Improve modeling representation of
advanced PSH plants
 Quantify their capabilities to provide
various grid services
 Analyze the value of these services
under different market conditions and
levels of variable renewable generation
 Provide information on full range of
benefits and value of PSH

18. Advanced Technology Modeling – Model Development
 Developed vendor-neutral dynamic
models for advanced PSH technologies
(adjustable speed and ternary units)
Review of existing CH and PSH models in
use in the United States
Dynamic simulation models for adjustable
speed PSH
Dynamic simulation models for ternary PSH
units
Model Development
18
Comparison of system
frequency with the FS
and AS PSH units in
response to generation
outage in a test case
FS PSH
AS PSH

19. Advanced Technology Modeling – Integration and Testing of
Dynamic Models
 Dynamic models for adjustable speed PSH
and ternary units were coded and integrated
into the PSS®E model
 Testing of these models for both generating
and pumping mode of operation was
performed using PSS®E test cases and
dynamic cases for Western Interconnection
(WI)
 Additional AGC studies have been
performed for SMUD balancing authority
 Published a report on frequency regulation
capabilities of advanced PSH technologies
Model Integration and Testing
19

20. Study Addressed Wide Range of Operational Issues & Timeframes
 Analysis aimed to capture PSH dynamic responses and operational characteristics
across different timescales, from a fraction of a second to days/weeks.
20

21. Production Cost and Revenue Simulations
 First, the Project Team developed
a matrix of various PSH
contributions and services
provided to the power system
 A suite of computer models
(PLEXOS, FESTIV, and CHEERS)
was utilized to simulate system
operation and analyze various
operational issues occurring at
different timescales
 Production cost and revenue
simulations were performed to
analyze the operation of PSH and
the value of their services and
contributions to the power system

22. PLEXOS Model with Detailed Representation of PSH
was Used for Production Cost Simulations
 Several levels of geographical scope, including the entire Western
Interconnection, California, and SMUD
 Simulations were conducted for 2022
– Multiple runs at different time resolutions
– Hourly simulations for the entire year to
determine maintenance schedule
of thermal units and annual-level
PSH economics
– Runs at hourly and 5-min time steps
for typical weeks in each season to
analyze PSH operation under conditions
of variability and uncertainty of
renewable resources
 Simulations were based on detailed WI grid representation (3,700 generators,
17,000 transmission buses) and examined impact of different levels of wind
and solar penetration
22

23. Annual Simulation Results Show that PSH Significantly
Reduces Power System Operating Costs
0
2
4
6
8
10
No PSH With FS PSH With FS&AS
PSH
AnnualSystem
ProductionCost
Savings(%)
Western Interconnection
Base RE Scenario High Wind Scenario
0
2
4
6
8
10
No PSH With FS PSH With FS&AS
PSH
AnnualSystem
ProductionCost
Savings(%)
California
Base RE Scenario High Wind Scenario
Production Cost Savings due to PSH Capacity in 2022

24. PSH Provisions of System Reserves in 2022
(As % of Total System Requirements)
 Western
Interconnect
24
 California:

25. Western Interconnection: Impact of PSH on VER
Curtailments in 2022
 Baseline RE scenario:
 High Wind RE scenario:
25
VER curtailments reduced 50%
Annual generation of about
5,000 MW of wind capacity

26. PSH Impacts on Power System Emissions
26
California: CO2 and
NOx emissions
decrease, SO2
emissions increase
under both scenarios
WI: Emissions
increase under Base
RE scenario, but
decrease under High
Wind RE scenario
SMUD: Emissions
decrease under both
scenarios

27. Reductions in Thermal Generator Ramping in 2022 due
to PSH Capacity
27

28. California: Thermal Generator Cycling in 2022
 Baseline RE scenario:
 High Wind RE scenario:
28
FS & AS PSH plants reduce cycling
cost of thermal units by one third

29. Additional Results, Details, and Information
 A total of 7 reports were published during the project
 Available at: http://ceeesa.es.anl.gov/projects/psh/psh.html
29
 U.S. Congress has also requested a
report on the role a value of PSH in
integrating VERs and on potential
hydropower from conduits
 Detailed benefits of PSH for grid
integration of VERs were documented in
a supporting technical report
Main Project Report

30. PSH Projects with Preliminary FERC Permits
30
April 1, 2015
January 1, 2013
April 1, 2016
October 1, 2014

31. Decline in Proposed PSH Projects – Why?
31
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
45,000
50,000
(MW)
PSH Capacity (MW) with Preliminary FERC Permits

32. 32
Contact:
Vladimir KORITAROV
ARGONNE NATIONAL LABORATORY
9700 South Cass Avenue
Argonne, IL 60439
Tel: 630-252-6711
Koritarov@ANL.gov