1. Energy Storage Definitions/Definitions ETWG 18 Feb 2013

2. Compare Terms From FERC CAISO CPUC NYISO MISO ISO-NE PJM SPP

3. Terms Include Non Generator Resource Stored Energy Resources Energy Storage Resource Non Traditional Suppliers Limited Energy Storage Resources Energy Storage System Net Energy for Load Energy Storage Device

4. FERC Non Generator Resource – "The Commission directed the RTOs and ISOs, in their compliance filings, to set forth a proposal to adopt reasonable standards necessary for system operators to call on non-generator resources for ancillary services, and mechanisms to measure, verify, and ensure compliance with any standards for the provision of ancillary services". Wholesale Competition in Regions with Organized Electric Markets, Order No. 719, FERC Stats. & Regs. 127 FERC ¶ 61,135. at P 61.

5. PJM Energy Storage Resource – “Energy Storage Resource” shall mean flywheel or battery storage facility solely used for short term storage and injection of energy at a later time to participate in the PJM energy and/or Ancillary Services markets as a Market Seller. – Energy used to charge the storage device is settled at wholesale rates. – Energy used for station power is consumed and not resold. PJM II ORDER, 94 FERC ¶61, 251 (March 14, 2001).

6. CAISO / CPUC Energy Storage Resource – “Energy storage system” means commercially available technology that is capable of absorbing energy, storing it for a period of time, and thereafter dispatching the energy". – See Appendix for remainder of AB 2514, Section 2835.

7. CAISO / CPUC Non-Generator Resource – ʺ Non-generator resources may include battery storage, flywheels, and dispatchable demand-side processes“ Limited Energy Storage Resource – "Regulation energy management implemented additional market functionality which enabled limited energy storage resources, such as flywheels and batteries, the ability to participate in the day-ahead and real-time regulation market based upon their ability to inject and withdraw energy from the grid. The market functionality observes the resource’s state of charge so that the resource can continuously provide regulation although its storage capacity is less than one hour. In addition, the ISO implemented a new resource model which recognizes that storage devices can seamlessly move between charging and discharging. These changes were approved by FERC in November 2011 and implemented by the ISO in Fall 2012. The ISO has made similar market design enhancements to accurately model resource operating limits for other technologies."

8. NYISO Limited Energy Storage Resource – A Generator authorized to offer Regulation Service only and characterized by limited Energy storage, that is, the inability to sustain continuous operation at maximum Energy withdrawal or maximum Energy injection for a minimum period of one hour. LESRs must bid as ISO-Committed Flexible Resources. – Energy used by LESRs for recharging will not be treated as Station Power and thus will be exempt from the special settlement rules applicable to generators under the NYISO station power program

9. NYISO (Cont.) Non-Traditional Suppliers – These technologies act as a load when withdrawing energy or charging and as a generator when injecting energy or discharging. NYISO states that these devices can continuously switch between charging and discharging and can respond to a NYISO signal to charge or discharge very rapidly.

10. SPP Net Energy for Load – The electrical energy requirements of an electric system are defined as system net generation plus energy received from others, less energy delivered to others through interchange. It includes system losses but excludes energy required for the storage at energy storage facilities.

11. ISO-NE Limited Energy Resource – Resources that, due to design considerations, environment restrictions on operations, cyclical requirements, such as the need to recharge or refill, or other non-economic reasons, are unable to operate continuously on a daily basis. Asset Related Demand – A physical load that has been discretely modeled within the ISO’s dispatch and settlement systems, settles at a Node and, except for pumped storage load, is made up of one or more individual end-use metered customers receiving service from the same point or points of electrical supply, with an aggregate average hourly load of 1 MW or greater during the 12 months preceding its registration.

12. MISO Stored Energy Resources Note: "Charging and discharging are treated separately by MISO. This means that when the plant offers generation and load into the day ahead energy market, the Locational Marginal Price (LMP) for electricity purchases to charge the storage is not linked to the generation price.“ – MISO Energy Storage Study, EPRI

13. Appendix

14. California Assembly Bill 2514 Chapter 7.7. Energy Storage Systems 2835. For purposes of this chapter, the following terms have the following meanings: (a) (1) “Energy storage system” means commercially available technology that is capable of absorbing energy, storing it for a period of time, and thereafter dispatching the energy. An “energy storage system” may have any of the characteristics in paragraph (2), shall accomplish one of the purposes in paragraph (3), and shall meet at least one of the characteristics in paragraph (4).

15. California Assembly Bill 2514 (2) An “energy storage system” may have any of the following characteristics: (A) Be either centralized or distributed. (B) Be either owned by a load-serving entity or local publicly owned electric utility, a customer of a load- serving entity or local publicly owned electric utility, or a third party, or is jointly owned by two or more of the above.

16. California Assembly Bill 2514 (3) An “energy storage system” shall be cost effective and either reduce emissions of greenhouse gases, reduce demand for peak electrical generation, defer or substitute for an investment in generation, transmission, or distribution assets, or improve the reliable operation of the electrical transmission or distribution grid.

17. California Assembly Bill 2514 (4) An “energy storage system” shall do one or more of the following: (A) Use mechanical, chemical, or thermal processes to store energy that was generated at one time for use at a later time. (B) Store thermal energy for direct use for heating or cooling at a later time in a manner that avoids the need to use electricity at that later time. (C) Use mechanical, chemical, or thermal processes to store energy generated from renewable resources for use at a later time. (D) Use mechanical, chemical, or thermal processes to store energy generated from mechanical processes that would otherwise be wasted for delivery at a later time.

18. California Assembly Bill 2514 (b) “Load-serving entity” has the same meaning as defined in Section 380. (c) “New” means, in reference to an energy storage system, a system that is installed and first becomes operational after January 1, 2010. (d) “Offpeak” means, in reference to electrical demand, a period that is not within a peak demand period. (e) “Peak demand period” means a period of high daily, weekly, or seasonal demand for electricity. For purposes of this chapter, the peak demand period for a load-serving entity shall be determined, or approved, by the commission and shall be determined, or approved, for a local publicly owned electric utility, by its governing body.

19. California Assembly Bill 2514 (f) “Procure” and “procurement” means, in reference to the procurement of an energy storage system, to acquire by ownership or by a contractual right to use the energy from, or the capacity of, including ancillary services, an energy storage system owned by a load-serving entity, local publicly owned electric utility, customer, or third party. Nothing in this chapter, and no action by the commission, shall discourage or disadvantage development and ownership of an energy storage system by an electrical corporation.