Pumped Energy Storage System

Scope

This document includes the Scope of Services.

Project Schedule

Staffing

This document inludes the cost of engineering services

Final Proposal

This document includes the summation of all the work the team has done throughout CENE 476.

Project Location

The Pumped Storage system is located approximately 3 miles south of Kingman, Arizona.

There is already an existing WindFarm that is owned by Brookfield Renewables and operated by Unisource Energy Services

Turbine Information Five Gamesa G90 Wind Turbines, each generating 2 Megawatts with a total site generation of 10 Megawatts

Reservoir Selection

As the project progressed, it became clear that the amount of water required would be massive. While searching for reservoir systems, the team narrowed it down between a Dammed Reservoir System vs. Tanks.

Dammed Reservoir Details: Located 5.6 Miles from Wind Farm. Has 280,289 Cubic Feet of Volume Capacity. Total Cost is $70,000,000.00

Tank Reservoir Details: Located approximately 3 Miles from Wind Farm. Each tank has a capacity of 25,000,000 Gallons, will need 4 tanks total. Total Cost is $131,740,000.

Reservoir Selected: Dammed Reservoir

System Design

Hydraulic Design for Dammed Reservoir:

The pipe network has been designed to connect the lower and upper reservoirs to allow water to flow between each. There are two separate pipes, one to pump water to the upper reservoir and a second to discharge water to the lower reservoir. The system shall pump water from the lower reservoir to the upper reservoir when energy is being produced but not purchased. When energy is in demand, the system shall release water from the upper to the lower reservoir, generating energy through the hydroelectric turbines. Below, Figure 12 provides a plan and preview of the pipe design for the reservoir system. The pipes shall be of Low Coated Carbon Steel and a diameter of 2 ft. The reservoir system faces a max head of 624.2 ft and a minimum head of 303.3 ft. Due to friction losses, there is an expected head loss between 4.49 to 19 feet. The expected charge flowrate with friction losses range from 6,000-12,000 gpm while the expected discharge flowrate ranges from 3000-7000 gpm. It is expected that after pump efficiencies, the flowrate will decrease. The following sections shall detail the pump and turbine chosen for the reservoir system. In addition, the hydraulic design for the tank system can be found in Appendix C which can be found in the Final Report

The pump for the hydraulic system was decided based off flowrate capacity and total dynamic head. A horizontal sing-stage centrifugal pump has been chosen for the system with a flowrate capacity of 14,000 gpm, capable of handling up to 337 ft of dynamic head. Below, Figure 12 depicts the centrifugal pump chosen and Table XX provides the pump technical details. As mentioned, the expected head of the system ranges from 624.2 to 303.3 ft, therefore one pump alone cannot handle the head alone. Therefore, two pumps in series will be needed for the hydraulic design. A total of four pumps will be purchased, assuming two pumps are down for maintenance. With the expected flowrate of 6,000-12,000 gpm and changing head, the system will see an efficiency between 79-81%. The pump curve used to find the efficiency per flowrate can be found below in Figure 13. Due to the efficiency and friction losses, the pump system shall see a power loss between 19-21%. This means that on any given day, the system can only pump a storage capacity between 12.9 to 13 MW, opposed to the ideal 16.4 MWhr supplied to the system for pumping.

Electrical Design: Information Coming Soon

Power generation for the Pump Energy Storage system comes from two main systems; The Wind Farm and the Reservoirs. The wind farm has a generating capacity of 10 MW. Using the equation 2, the voltage generated from the system was determined to be 3450 V. Using the power and voltage variables as well as the second form of the equation below, the max current that can be allowed in the system before losses occur is 2898.55 Amps.

The power generated at the reservoir was determined based on data from the system model. The green line in Figure 19 represents the combined system energy production. Evaluation of the system model determined that the reservoir is able to generate a power capacity of 8.6 MWh. Now that the power variables have been determined for both generating systems, the specifications for the turbines were determined. Based on the information that was determined and given, the total power output from the turbines is 13.8 kV.

Transmission line specifications were determined by total weight, rated strength, total resistance in the wire, and max current. As shown in the table below, two types of transmission lines were selected as an example. Conductor type for the transmission lines are selected to be ACSR.

The reservoir will be not have its own dedicated transmission line and will be utilizing the same transmission line that delivers transmits power from the wind farm to the reservoir. The voltage generated at the windfarm will only be powering essential systems such as the pumps. As mentioned in the hydraulic design, the pumps only need minimal power to operate. However the power generated from the turbines will need to be multiplied at a substation located at the reservoir site in order to efficiently deliver power into the utility grid. Utility grid transmission lines operate at a minimum of 230 kV. With a power output from the turbines of 13.8 kV, the substation at the reservoir will multiply the incoming voltage by a factor of 17. With voltage losses taken into consideration, total voltage delivered after entering substation is 233.28 kV. Supporting a two way transmission system requires a 230 kV double circuit design. A double circuit design is able to handle support transmission lines that sends power in one direction and power in the other direction. The structure chosen is a Tubular Steel tower over a lattice tower. A tubular steel tower was chosen due to capability to withstand heavy loads, with special consideration that the selected transmission lines will have a total weight of 85043.376 lbs. Minimum distance between tubular steel towers is 1300 ft. To cover the complete 5.29 miles of transmission, 22 tubular steel towers will be placed.

For a complete overview of the Hydraulic and Electrical Designs, please view document or click on the "Scribd" logo.

System Model

Displaying all the gathered data together gives an overview of how the whole system of wind turbine facility and pumped storage interact. Figure 18 shows the daily average energy production from the wind turbines over the year as yellow bars. The charge limit, which represents the maximum amount of energy supplied to the power grid, is shown as the red line. The blue line shows the daily fluctuation of the water reservoir’s stored capacity, which is a reaction to the amount of energy produced by the wind turbines. The green line, which was previously referred to as the “discharge limit,” now represents the combined system energy production. In other words, this is the baseline power generating capacity of the whole system and has a consistent value of 8.6 MWh.

Combined Data:Combine wind farm and hydro energy production, reservoir capacity. Gives a wholistic model of how the system would operate throughout the year.

Conclusion

Affect on Electricity Supply: Implementing the pumped storage system would allow the Western Wind facility to generate a constant 8.67 MWh of electricity. Enough to be a baseload generator for an average of 233 AZ homes. A system of this scale could make a small community energy independent.

Is the System Feasible for the Proposed Location? High cost of construction with relatively low baseline generating capacity indicates that the Kingman, AZ area is not feasible for a pumped storage system. Better suited locations would have a large existing supply of surface water. Seaside cliffs, rivers with in steep gorges, or locations with existing reservoirs would be ideal.

Recommendations By implementing a pumped storage system in combination with the Western Wind facility, a consistent base load of 6.8 MWh can be supplied. This is enough to power about 233 average Arizona homes with a reliable supply of renewable energy all year long . Considering the high cost to construct the reservoirs and the low baseline per generated by the system, this location is not well suited. Further research is recommended to find a location that has topography where a much larger elevated reservoir could be built with an abundant supply of readily available water in close proximity. Ideal examples would include seaside cliffs, steep walled canyons with large rivers below, or already existing dams.

For a complete overview of our Final Report, please view document or click on the "Scribd" logo.

Costs

System Cost for Dammed Reservoir: $71,121,990.01

System Cost for Tank Reservoir: $22,000,000.00

System Cost for Hydraulics: $795,000.00

System Cost for Electrical: $27,538,795.00

Total Cost of Construction: $102,498,619.00

Project Project Cost: $53,670.00

Actual Project Cost: $31,283.00

The cost estimate was completed using online sources. Pumps and hydraulic turbines we found based on required specifications to meet the demands of the hydraulic design, and cost $120,000 and $35,000 per unit respectively. Schedule 10 steel pipes of 24-inch diameter will be bought in “double random” sections (approximately 40 ft sections) and is sold by the pound. The unit cost per foot is $95, and an additional cost of $3 per square foot of surface area must be added for corrosion resistant coating. Field welding was estimated at $15 per weld-inch. The cost of the two dams was estimated based on a dam construction project of similar scale. Including labor, equipment, and materials the cost of the dams was $35 million each. The construction of the reservoirs will require an estimated 218,683 cubic yards of cut. About half of this will be wasted on site in the construction of future roads, leaving a net export of about 219,000 tons (rock weights approx. 2 tons per cubic yard) to be hauled away to a dump site at a cost of $15 per ton. Bulk of the capital electrical costs came from transmission lines. Baseline transmission costs for the 230 kB double circuit class begin at $1,536,400. There are cost factors that multiply the cost such as conductor type, supporting structure type, length of line, and the environmental terrain [15]. Substation design accounted for the second highest cost with a capital cost starting at $1,706,250. Other cost factors multiply the base cost such as the transformer types and reactor components. Figure 18 below shows a detailed summary of all items with unit pricing. The total cost of construction came to $102,498,619.

For a complete breakdown for the Cost of the System and the Staffing Costs, please view document or click on the "Scribd" logo.

For more information on Staffing costs, view first document.

For more information on the Cost of the System, view the second document.

Hours Log

Total Hours Worked: 540.75

Philip Neumann: 126.5

Richard Peterson: 116.25

Jacob Sanders: 115.00

Adias Fostino: 104.25

Francis Cruz: 113.00

For a complete overview of the hours log, please view document or click on the "Scribd" logo.

Tasks and Schedule

For a complete overview of the tasks and schedule, please view document or click on the "Scribd" logo.

Final Project Report

Pump Energy Storage System: Kingman Western Wind

Final Project Report

Prepared for CENE 486C

December 12, 2018