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Technical Analysis of Pumped Storage and Integration with Wind Power in the Pacific Northwest Final Report prepared for: U.S. Army Corps of Engineers Northwest Division Hydroelectric Design Center prepared by: August 2009 Pumped Storage and Wind Power Final Report Integration in the Pacific Northwest DISCLAIMER The findings, interpretations of data, recommendations, specifications or professional opinions presented in this report are based upon available information at the time the report was prepared. Studies described in this report were conducted in accordance with generally accepted professional engineering and geological practice, and in accordance with the requirements of the Client. There is no other warranty, either expressed or implied. The findings of this report are based on the readily available data and information obtained from public and private sources. Additional studies (at greater cost) may or may not disclose information that may significantly modify the findings of this report. MWH accepts no liability for completeness or accuracy of the information presented and/or provided to us, or for any conclusions and decisions that may be made by the Client or others regarding the subject site or project. This report was prepared solely for the benefit of the Client. No other entity or person shall use or rely upon this report or any of MWH's work products unless expressly authorized by MWH. Any use of or reliance upon MWH's work product by any party, other than the Client, shall be solely at the risk of such party. i August 2009 August 20, 2009 MWH-HDC-T12 U.S. Army Corps of Engineers Hydroelectric Design Center PO Box 2946 Portland, OR 97208-2946 Attn: Mr. Dan Davis Subject: Report on Technical Analysis of Pumped Storage and Integration with Wind Power in the Pacific Northwest Ref: Solicitation No. W9127N-07-R-0018, MWH Americas, Inc. - Task 12 Dear Dan, Enclosed is our final report discussing various aspects of pumped storage hydro development and integration with wind energy in the Pacific Northwest. This work was performed under Task 12 of our IDIQ contract for Hydroelectric Power and Pumping Plant Engineering and Design Services. We enjoyed working with the Corps on this interesting assignment and hope this document provides useful background information to support your ongoing discussions with BPA and DOE regarding policy development and potential future pumped storage research activities. Although preparing this report presented several challenges to us including the very short amount (approximately 4 weeks) of time available for us to complete the work, the need for multiple authors working in parallel, and the collaborative nature of the final editing process, we believe the report fully addresses all of the important topics included in the work scope. Primary authors of the report include Peter Donalek, Patrick Hartel, Bruno Trouille, Kathleen King, Manoj Bhattarai, Ron Krohn, Kirby Gilbert, Howard Lee, and John Haapala. We enjoyed our collaboration with the USACE and BPA on this study and look forward to additional opportunities to be of service. Stanley J. Hayes Project Manager MWH Americas, Inc. encl: Final Report 2353 130 Ave NE Tel: 425.896.6900 Suite 200 Fax: 425.602.4020 Bellevue, Washington 98005 This page left blank intentionally Pumped Storage and Wind Power Final Report Integration in the Pacific Northwest EXECUTIVE SUMMARY The difficulties of wind integration lie in the variability of wind, making wind energy a difficult resource to dispatch. The challenge is to find a way to make energy created by wind resources available on demand. BPA has already experienced large ramping events of several hundred megawatts of unscheduled changes in wind output occurring within an hour. As the percentage of wind penetration grows, the risk of having a major system failure event from an unpredicted change of the wind energy level increases. Pumped storage offers the ability to store energy produced from wind or other renewable resources when it is difficult to utilize these resources on the power grid or integrate them into the power system, and to release the energy at a time when it is needed, most often during peak electrical demand, at a higher value. The burden of integrating wind power into the Pacific Northwest power grid has been imposed on existing hydroelectric facilities that were not designed for that purpose and already have many operating constraints (maintenance of flow rates, temperature controls, limits in dissolved gas concentration, etc.). This burden is likely to increase maintenance costs and failure rates of the equipment. The wind integration service needs from the existing hydroelectric system will soon exceed system limits due to the combined operational restrictions on the hydroelectric facilities. Properly designed pumped storage (PS) facility (or facilities), if integrated into the Pacific Northwest (PNW), can assist with integration of intermittent wind energy resources into regional dispatch. A projected 6,000 MW wind generating capacity by the year 2013, representing 60% of BPA’s present peak load in the BPA control area, is under consideration. By comparison, a portfolio of 15% to 20% of wind resources within the grid has been anticipated as the practical limit by a number of recent technical papers on the subject. It is therefore evident that new transmission interconnections and energy storage facilities will be required. PS sites require two water reservoirs with different elevations so that energy can be stored in the upper reservoir and released when needed to generate electricity. When the elevation difference between the reservoirs is large, more energy can be stored using smaller reservoirs, smaller water conveyance conduits, and smaller physical equipment sizes, usually resulting in lower investment costs. A dedicated off-stream PS project will not have operational restrictions imposed such as those that occur on the Columbia River and hence can freely start, stop, reverse, and fluctuate as needed by the power system. By investing in the newest technology available, adjustable speed or ternary units, the PS project can not only supply load following, but can become one of the fastest response stations on the power system. It can offer frequency regulation whether pumping or generating, and can allow pumping at less than full load, thereby increasing the flexibility to integrate the PS project specifically with wind energy resources. The big improvement with the new technology is that frequency regulation and load following are also possible in pumping mode. A iii August 2009 Pumped Storage and Wind Power Final Report Integration in the Pacific Northwest conventional PS project cannot provide frequency regulation or load following in pumping mode. This is a quantum change in favor of the new technology. The present transmission congestion and overload could be reduced by having a PS project located near the wind energy source. Storing wind energy, even a portion during critical times, could allow that same power to flow at a time when the congestion is reduced and/or the power is needed on other parts of the system. Studies for capacity and storage sizing and location of PS projects should determine what percentage of the wind energy needs to be reinforced by PS. To maintain overall dynamic performance and stability of the transmission system, BPA has used Special Protection Schemes (SPS) to deal with system disturbance events. These include shedding of large industrial loads. A PS project could reduce the frequency of these events that can have significant financial consequences to the owner/operator of the industrial loads. The operation of a PS project requires understanding that the near continuous cycle duty on the equipment at varying loads will shorten the life of the equipment. More frequent maintenance outages for major rehabilitations are required than for base loaded equipment. Some of this is caused by thermal cycling, and some of this is caused by operation under less than ideal conditions with resulting increased fatigue loading. The use of adjustable speed generation can eliminate some of the fatigue in turbine components and some of the stress imposed by starting and stopping, because of reduced vibrations and smoother operation. Otherwise, operation and maintenance practices are similar to those in conventional hydroelectric projects. Use of PS provides a cycle efficiency of 70% to 80% that must be overcome by rate structures if dispatch of a PS project is to be financially viable. At some point in time, it will be necessary to consider the financial viability as well as the funding mechanisms, since no entity will be interested in operating a facility that does not earn enough revenues. To make this work, especially in the environment of wind energy where rates are already high, additional revenues from ancillary benefits for the facility will be needed, besides the arbitrage gains between rates when buying and selling power. While pumped storage may or may not be the optimum solution, it is certainly one solution that offers maximum flexibility to resolve the problem of wind integration. If a decision is made to move forward with a PS project, the usual choice would be to bundle as many features as possible into the resource so as to be able to collect revenues for as many features as possible. Valuation of design features is a necessary prelude to selecting the features to be provided in a new facility. There are a number of potential PS sites that were identified in the Pacific Northwest during the past 30 years. Some are now in the FERC licensing process. It is recommended that these previous studies be reviewed and updated to prioritize and rank the best projects. Unfortunately, permitting, designing, procuring equipment and constructing a PS project is a long term process iv August 2009 Pumped Storage and Wind Power Final Report Integration in the Pacific Northwest requiring at least 6 to 7 years and 10 to 12 years to completing construction is more likely.

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