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 KoritarovCenter for Energy, Environmental, and Economic Systems AnalysisEnergy Systems DivisionARGONNE NATIONAL LABORATORY9700 South Cass AvenueArgonne, IL 60439Tel: 630-252-6711Email: koritarov@anl.gov

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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

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

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PSH Installations in the U.S. by Plant Size

Source: DOE – 2014 Hydropower Market Report

Lake Hodgesin 2012 (40 MW)

Existing PSH Plants in the U.S.

Source: Argonne National Laboratory

…and Now – Growth of Variable Energy Resources (VERs)

Source: AWEA 2014Wind 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

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U.S. Annual PV Installations

Ancillary Services, such as Operating Reserves are Needed to Balance Wind

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Almost 2,000MW range in a single day

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

Advanced Forecasting Helps Reduce Uncertainty, Energy Storage Helps Manage Variability

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Current wind forecasts tools do reasonably well Forecasting ramps is still an issue

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.)

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PSH Has a Key Role in the Integration of Variable Generation ResourcesPSH 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

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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 capacityEnergy imbalance reduction

–Balance the variability of wind and solar power and correct the control area intertie exchanges 10

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

efficiencyActive and reactive power can be controlled electronically and separately The units are able to operate in partial load pumping mode

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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 modeDecoupled 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

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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

13Source: Koritarov et al., HydroVision 2015

Operating Mode Transition Times

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Source: Fisher et al. (HydroVision 2012)

Ternary PSH Technology with Hydraulic Bypass Provides for Extraordinary FlexibilityKops 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

15Source: Illwerke VKW Group, 2009

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

Advanced PSH Project Overview

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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

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 StatesDynamic simulation models for adjustable

speed PSHDynamic simulation models for ternary PSH

units

Model Development

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Comparison of system frequency with the FS and AS PSH units in response to generation outage in a test case

FS PSH

AS PSH

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

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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.

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Production Cost and Revenue Simulations

First, the Project Team developed a matrix of various PSH contributions and services provided to the power systemA suite of computer models

(PLEXOS, FESTIV, and CHEERS) was utilized to simulate system operation and analyze various operational issues occurring at different timescalesProduction cost and revenue

simulations were performed to analyze the operation of PSH and the value of their services and contributions to the power system

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 scheduleof thermal units and annual-levelPSH economics

– Runs at hourly and 5-min time stepsfor 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

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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&ASPSH

Annu

al S

yste

m

Prod

uctio

n C

ost

Savi

ngs

(%) Western Interconnection

Base RE Scenario High Wind Scenario

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2

4

6

8

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No PSH With FS PSH With FS&ASPSH

Annu

al S

yste

m

Prod

uctio

n C

ost

Savi

ngs

(%) California

Base RE Scenario High Wind Scenario

Production Cost Savings due to PSH Capacity in 2022

PSH Provisions of System Reserves in 2022 (As % of Total System Requirements)Western

Interconnect

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California:

Western Interconnection: Impact of PSH on VER Curtailments in 2022 Baseline RE scenario:

High Wind RE scenario:

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VER curtailments reduced 50%

Annual generation of about 5,000 MW of wind capacity

PSH Impacts on Power System Emissions

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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

Reductions in Thermal Generator Ramping in 2022 due to PSH Capacity

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California: Thermal Generator Cycling in 2022

Baseline RE scenario:

High Wind RE scenario:

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FS & AS PSH plants reduce cycling cost of thermal units by one third

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

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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

PSH Projects with Preliminary FERC Permits

30April 1, 2015

January 1, 2013

April 1, 2016

October 1, 2014

Decline in Proposed PSH Projects – Why?

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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

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Contact: Vladimir KORITAROVARGONNE NATIONAL LABORATORY9700 South Cass AvenueArgonne, IL 60439Tel: 630-252-6711Koritarov@ANL.gov