Pumped Storage

Pumped storage is experiencing a revival in the hydropower industry and DTA is at the forefront of this movement.  The storage of potential energy is critical to the integration of intermittent energy sources, such as wind and hydro kinetic, to an electric power grid.  Pumped storage is the only proven, large scale technology with the ability to efficiently store energy which  can provide a means of firming these other clean and renewable energy sources, making them more practical and valuable.   Pumped storage units also provide many stabilizing features to the grid in the form of ancillary services, which are becoming a market in the deregulated energy environment.

A concurrent resurgence in nuclear power, which was a driver in the original development of pumped storage, anticipates the need for new pumped storage facilities to balance the load of these large capacity units.

Owners of existing pumped storage facilities are reevaluating their assets and, in many cases, rehabilitating and upgrading them.  Advances in technology are providing significant opportunities to make pumped storage units even more flexible in their operating ranges, which again results in higher value to owners of these facilities. 

DTA remains a leader in the pumped storage market. 

Project Examples

Jocassee

Duke Energy’s Jocassee Pumped Storage Plant is a four unit, 612 MW station built in the early 1970s.  In the mid 1990’s, Devine Tarbell & Associates, Inc. (DTA) assisted Duke in implementing generator-motor capacity upgrades to a new unit rating of 215 MVA. During the same outages, DTA provided pump-turbine design improvements to eliminate chronic maintenance problems. The focus then turned to upgrade of the pump-turbines to utilize the increased rating of the generator-motors. The first two-unit outage concluded at the end of May, 2007.

The second set of runners is scheduled for installation in the 2010-2011 timeframe.

 Red Mountain Bar

DTA was retained by Turlock Irrigation District (TID) in 2005 to perform a reconnaissance-level site identification and screening study to evaluate potential opportunities for constructing a new, yet to be sized, pumped storage project that would use the existing Don Pedro Reservoir as the lower pool.  Specific objectives of the study included the identification of potential upper reservoir resources that appeared suitable for pumped storage, the formulation of representative conceptual development schemes, the execution of high level desktop geological/seismological and environmental/regulatory screening studies, and the determination of rough order-of-magnitude cost estimates for the resources identified.   As a result of this recon study, TID secured DTA to perform a pre-feasibility study for two of the seven sites identified. 

DTA performed a pre-feasibility study to evaluate two prospective pumped storage project sites located adjacent to the existing Don Pedro Reservoir.  With approval from TID to continue with the evaluation of this project, DTA is currently performing a detailed feasibility study of the selected site.

Lake Elsinore Advanced Pumped Storage Project (LEAPS)

DTA has been retained by The Nevada Hydro Company to provide the next stage of technical and cost evaluations for developing this 500 MW pumped storage project.  The study involves the evaluation various dam types and locations, tunnel alignments, intake structure locations and configurations, and geotechnical and seismic conditions to develop cost estimates and further assess the technical feasibility of the project.  In addition, the study will address the following:

• Subsurface conditions at dam location(s), along conceptual tunnel alignments, in the vicinity of the powerhouse, and at the intake/outlet structure locations.

• Availability and suitability of materials to be used for dam construction and/or reservoir lining, including on-site borrow areas.

• Potential impacts of geotechnical conditions on the location of the dam, alignment of the water conveyance structures, location of the powerhouse, and on project constructability and risk.

Cockwell (Bear Swamp)

The Cockwell (formerly Bear Swamp) Pumped Storage Plant was recently purchased by Brookfield Power - New England Hydro (BPNE).  BPNE has been evaluating the upgrade potential of the two existing, 300 MW reversible units and is now proceeding with an implementation plan that includes at a minimum the replacement of the pump-turbine runners and rewinding of the two generator-motors.  BPNE is now in the final engineering and tendering phase of the program and realized the need for an experienced project manager to lead the effort on their behalf.  DTA was recently retained by BPNE for this role to oversee all aspects and deliverables of the project,.DTA is currently serving as BPNE’s regulatory and environmental consultant in support of obtaining a non-capacity amendment to their current FERC operating license, reflecting the upgrade goals of the project.

 Investor-Owned Utility (confidential)

DTA has been retained by an investor-owned utility client to conduct a confidential, conceptual study to evaluate the potential for constructing a new pumped storage project having an installed capacity of approximately 1050 MW and 20 hours of storage.  The facility under study would utilize an existing reservoir as the lower pool and a newly constructed upper reservoir within a local tributary. 

The primary of objectives of this study are to utilize project information generated to date and develop a conceptual layout of the proposed project, including sizing, performance and operating characteristics, performing quantity take-offs and generating a rough order-of-magnitude cost estimate.

In addition, the client has requested that DTA identify impacts to the existing lower reservoir and powerhouse and provide an estimate of annual operations and CapEx costs in support of economical and financial analysis to be performed by the client.  Lastly DTA is to identify necessary licensing and environmental permitting process requirements, complete with development schedules and costs.

Abandoned Mines

DTA is currently performing conceptual studies for the development of pumped storage utilizing abandoned surface mines for two separate clients.  Each study involves the development of a conceptual layout of the proposed project, including sizing, performance and operating characteristics, performing quantity take-offs and generating a rough order-of-magnitude cost estimate.  Also included is a review of necessary licensing and environmental process requirements. 

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