Monthly Archives: March 2013

Short-Term Wind Forecasting: Can We Do Better?

Increasing Amount of Variable/ “Intermittent” Power Generation

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Dominic Geraghty


Let’s first discuss how much renewables’ production capacity we can expect.

Wind and solar power generation facilities are being deployed at a steady rate across the nation. Their cost of fuel is zero, and the source of their power is virtually perpetual. And power production from wind and solar resources creates no pollution.

Most states have instituted Renewable Portfolio Standards (RPS) – targets for the percentage of power generation (kWhs) that must come from renewable sources by certain future dates.  The RPS target percentages range from 10% to 40% (Hawaii) and the target dates from 2015 through 2025.

cropped-DSC_0288_2.jpgWind and solar differ from traditional power generation plants in that their output is less certain and not controllable --  there is (1) a diurnal variation – wind is stronger at night on average, and solar is available only during daylight hours, and (2) a short-term variation (intermittency) due to rapidly changing wind strength and cloud cover. In addition, wind strength can exhibit steep, unexpected “ramps” -- both up-ramps (increases in strength) and down-ramps -- which can persist for hours. These ramps occur between 50 and 1,000 times per year.

For this dialog, I am going to focus on wind intermittency.

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Distributed Energy Storage (I): What Benefits Constitute the “Benefits Stack”?



Dom Geraghty


Distributed Energy Storage (DES) (I): Aren’t We Missing Some of the Benefits in the “Benefits Stack”?

Energy storage, while providing unique and valuable benefits, is relatively expensive.  Based on studies and demonstrations to date of the usual set of bulk and distributed applications, it appears that there is an approximately $250/kW to $500/kW “gap” by which the costs exceed the benefits (see below). But have all the benefits been counted?

Simulation models used for these evaluations to date have not been capable of faithfully simulating the operation of storage facilities within the power system as a whole, calculating all of the potential benefits, and certainly not of co-optimizing these benefits.  It’s a complicated problem.

That leads us to ask: Would a more holistic simulation and a more complete benefits’ “stack” help us close the cost/benefit “gap”? Continue reading

Is The Smart Grid Gridlocked?

Smart Grid Doldrums - Re-Calibrating Smart Grid 1.0



Dom Geraghty



  • Rate case filings have demonstrated transparently that the benefits of AMI investments are less than the costs – AMI does not pay for itself
  • The justification for AMI investments is based on value-added applications beyond AMI (“the Smart Grid”) – if they are not implemented, electricity bills will increase, by definition
  • One must question using the same discount rate for benefits and costs, because they represent different levels of risk
  • AMI business cases are flawed and might be challenged under the “used and useful” principle of rate-making
  • Policy and regulatory changes necessary to realize the Smart Grid benefits of AMI infrastructure (Smart Grid 1.0) have lagged deployments; realizing key benefits of Smart Grid 2.0 investments is strongly dependent on the oft-discussed changes being implemented
  • Value-added applications deployment have lagged vendors’ promises
  • Investors have soured on AMI Smart Grid opportunities
  • We have learned a lot from AMI deployment and operating experience to date
  • We have only just begun – we need to plan for the second wave of investments in the Smart Grid: AMI 2.0 and Smart Grid 2.0, and we need to do a better job on the business cases
  • Some aspects of the market won’t change no matter how much we complain about them – we need to recognize that in our business cases
  • Regulatory policies will change, but very slowly, increasing our ability to realize the benefits of Smart Grid infrastructure

Prequel: The Story So Far Continue reading

Costs of a Cyber-Security Attack on a Regional Power System

Cyber-Security – Part I: Simulation Results for the Costs of a Coordinated Attack on a Regional Power System



Dom Geraghty



  • Cyber-security comes in three forms: physical, IT-based, and industrial control systems-based
  • There is mounting concern about the vulnerability of the electric power system to cyber-attacks
  • Protection can take the form of investments in cyber-security or by increasing the level of contingencies planned for
  • A cyber-attack is a high-impact, low-frequency event, i.e., it has a low probability of happening but its consequences can be costly
  • The cost of successful cyber-attacks can be calculated using sophisticated power system simulation models that are integrated with ISO market protocols
  • Four scenarios of a coordinated cyber-attack on the PJM system has been simulated and the costs estimated
  • The costs are substantial and can include substantial amounts of costs associated with unserved energy; for example, a 31-bus, 1-week outage increased costs by $436 million, of which $285 million was related to unserved energy
  • How much should we be willing to pay to increase the resiliency of power systems to cyber-attacks?

Business Case Challenges Continue reading