Enabling Renewables with Energy Storage

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1 Enabling Renewables with Energy Storage EPRI Renewable Energy Council Mark Stoering VP, Portfolio Strategy & Business Development April 5, 2011 Energy Storage at Xcel Energy Storage is a means to provide more system control Generation Shaping wind output to minimize impact of renewables variability; potentially reduce peaking cost; reduce wear and tear on conventional generators Transmission Ancillary services Distribution Voltage regulation and peak shaving Individual customers Power quality & peak shaving Strategic to Xcel Energy because of the high wind and solar PV penetrations expected on our operating systems 1

2 Renewables Integration Value Load Leveling Load (MW) Ramping Frequency Regulation 0 Time (Hr) 24 Str. Chrg Time: ~ 0.5 Day CAES Pumped Hydro Batteries Str. Chrg Time ~ Hrs CAES Pumped Hydro Batteries Str. Chrg Time ~ Min s CAES Batteries Super Capacitors Flywheel Note: Source EPRI Other Other Sources of of Value:: Value:: Reduced standby generation contingency Avoided plant plant maintenance due due to to cycling Luverne Distributed Energy Storage System Sodium Sulfur Battery 1 MW NaS Battery System - can deliver 1 MW for 7.2 hrs Power Conditioning Equipment (PCS) Wind farm/grid interconnection Local and remote data and communication equipment Located in Luverne, MN; connected to Minwind Energy LLC wind facility (11.5 MW) 2

3 Primary Research Focus Areas Understand how storage could improve wind farm economies Understand how storage could improve utility integration of wind resources Modes of Operation Tested Mode of Operation Basic Generation Storage Economic Dispatch Frequency Regulation Wind Smoothing Description The battery discharges during defined on-peak periods and charges during defined off-peak periods at a rate that is proportional and coincident with the power output from the wind farm. (Time Shifting) The battery follows a signal based on market prices to capture arbitrage benefits in forward and spot energy markets. The battery follows a frequency regulation signal both as a load and a generator. The battery is used to reduce the variability of wind power by charging and discharging accordingly to limit the ramping rate of a wind farm. (Ramp Rate Control) * Dynamic voltage regulation is available from all modes of operation 3

4 High-Level Findings Overall, the battery met expectations by performing successfully in all modes tested Overall efficiency of battery With auxiliary energy requirements: 68-79% Without auxiliary energy: 85-92% The demonstration also indicates ability to manage the variability and uncertainty of solar PV Partnership A Key To Success Entity NGK Insulators S&C Electric Minwind Energy University of Minnesota NREL Great Plains Institute GridPoint EPRI Role Battery technology, wind integration expertise, test plan development, and data interpretation Overall system design and construction, supplier of power conversion system Grid interconnection; Wind Farm optimizer Design participation, data collection and interpretation, report preparation Design participation, data collection and interpretation, report preparation Analysis of energy storage regulatory policy implications, independent perspective Battery System communications and remote controls Functional specification development and design participation 4

5 Next Steps Monitor battery performance in the MISO Ancillary Service Market with role providing regulation service Complete University of Minnesota portion of the project scope (chemistry / economy) Continue assessing cost effectiveness of storage technologies Final report expected Summer 2011 (Xcel Energy) SolarTAC Battery Project XP Dynamic Power Resource Advanced lead-acid (dry cell) 1.5 MW / 1 MWh Standard Module Turn-key - Storage, PCS, Controls, Enclosures, and Interconnection Primary Applications for Xcel Energy Solar PV Integration Distribution Grid Reliability Solar Peak Time Shift Ancillary Services Partnerships Xtreme Power EPRI Possibly NREL & Amonix Recent Installation at SolarTAC 5

6 SolarTAC Battery Demonstration Objectives Demonstrate battery s capability mitigate the effects of high penetrations of solar PV, including: Solar smoothing Solar leveling Solar peak extension Voltage/VAR control Frequency response Cycle-life performance Evaluate scale required for given PV penetrations and feeder performance requirements Solar2Battery Demonstration - Schedule June 2010: Executive direction to pursue SolarTAC battery demonstration project, evaluation of battery options July 2010: Decision on Technology, Funding Approval, Initial discussions w/epri August/September 2010: Site selection, system design and project planning October/November 2010: Contracts issuance and site preparation December 2011: Battery delivery (Dec 9), system interconnection and Initial Commissioning Phase 1 January March 2011: Finalized EPRI Agreement, testing plan development, Commissioning Phase 2 April 2011 February 2014: Joint testing, potential direct 480V connection to SolarTAC PV system 6

7 A world-class facility where solar technology moves from research lab to test site. Other Energy Storage Activities Wind-To Hydrogen Project (2006 Present) Two electrolyzers powered by wind and solar energy at NREL to produce and store hydrogen during off-peak hours for use in operating a 50 kw hydrogen internal combustion engine (HICE) generator set during on-peak hours System has been expanded to include a hydrogen fueling station (for hydrogen powered vehicles at NREL) and a 5 kw stationary fuel cell to operate in parallel with the HICE generator set. Location: Golden, Colorado NREL s National Wind Technology Center Partners: NREL, DOE, EPC, Proton Energy, Teledyne Compressed-Air Energy Storage Study ( ): Contracted with EPRI to examine the economics and technical issues of siting a CAES plant in Colorado 7

8 Storage Expensive Now But There s Promise Commercially available storage technologies have a higher capital cost today than alternatives CAES and Pumped Hydro may be first to be cost effective and new battery technologies are promising Storage has the potential to provide other services Functions as a load and a generation source providing operational flexibility Quick response value is system dependent Smaller, distributed systems can serve multiple functions (case specific) Distribution voltage support & congestion relief Solar PV variability mitigation Aggregation to serve bulk storage functions, including time shift and wind energy curtailment avoidance Other Initiatives at Xcel Energy To Further Integration of Renewables Ongoing analysis of economic benefits of energy storage (technology agnostic) Improving accuracy of wind forecasting Improving accuracy of solar output forecasting Improving ramp response rates and turn-down capabilities of existing fossil fleet 8

9 Mark Stoering VP, Portfolio Strategy & Business Development 9