Technoeconomic Analysis of Pumped Hydroelectric Storage as a Means to Mitigate the Variability of Renewable Generation

Open Access
Richards, Scott Alan
Graduate Program:
Mechanical Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 09, 2012
Committee Members:
  • Horacio Perez Blanco, Thesis Advisor
  • pumped hydroelectric storage
  • pumped storage hydro
  • renewable energy
  • wind power
  • solar power
  • PJM
  • variable generation
Because its “fuel” is free, it makes economic sense to utilize renewable energy whenever it is available. But due to its inherent variability, efficiently integrating large amounts of renewable generation will require a flexible generation fleet. One way of increasing a generation fleet’s flexibility is through the adoption of pumped hydroelectric storage (PHS). Like traditional hydropower generation, PHS is capable of quickly varying its power output but it is also capable of operating in reverse to store excess energy for later use. This paper addresses many of the financial and operational aspects of complementing variable wind and solar power generation with PHS, which is typically used to store excess energy from traditional generators. The benefits that a PHS facility can offer to renewable power generators are many, but the biggest drawback to doing so is the high capital cost of PHS. In order to study the revenue streams and operational requirements of PHS facilities and the revenue streams of renewable power generators in the PJM interconnection, a computer model with one-minute resolution was programmed in Mathcad 14. Hourly electricity demand, power prices, and wind power production were obtained from PJM’s website for the year 2010. The NREL program PVWatts v.1 was used to generate the simulated hourly solar power production which was combined with the PJM data and used as input to the model. For this thesis, the model scaled the wind and solar power production inputs to match the proposed 38,131 MW wind and 3,721 MW solar power penetrations in PJM as of October 6, 2011. It then analyzed the variability of the wind and solar power production and the ability of a 1000 MW, fixed speed, pump-turbine PHS facility to mitigate the previously mentioned variability. The model also calculated the hourly profits and penalties that resulted from the variable renewable generation being sold in PJM’s day-ahead market and compared them to selling the electricity in PJM’s real-time market. In addition, the model was used to quantify the effects that changes in pumping efficiency, generating efficiency, power capacity, and energy storage capacity have on the annual energy arbitrage profit of a PHS facility in PJM. The output of the model demonstrates that the annual penalties that result from the variability of renewable power production can be significant. It also suggests that large amounts of renewable power production have the potential to suppress high electricity prices that occur during periods of peak electricity demand. In terms of PHS parameters, the model shows that a 14% decrease in round trip efficiency would reduce annual energy arbitrage profits by more than 33%. The analysis presented in Chapter 8 illustrates the need for PHS facilities with increased flexibility and Chapter 9 details a variety of abstract concepts that are not addressed in the previous chapters but are pertinent to this thesis.