Secondary Use Energy Storage System Design Considerations Michael Starke*, Madhu Chinthavali*, Bert Taube**, Dirk Spiers***, and Bryan Schultz*** *Oak Ridge National Laboratory, Oak Ridge, TN **Southern Research, Birmingham, AL, United States ***Spiers New Technologies, Oklahoma City, OK | 1 Acknowledgement This work has been funded by the Department of Energy, Office of Electricity, Energy Storage Program 2 Presentation Overview 1. Introduction into the idea of Secondary Use – Introduce Electric Vehicle Market – Some generics – Establish the potential. – Challenges 2. Background on Grid Connected Battery System Components 3. System Design Considerations 4. Second use batteries considerations 5. Example prototypes 3 Electric Vehicles in the US Market US Electric Vehicle Sales and Market Share (2008-2019) * 450000 3.00% 400000 Electric Vehicle Models in 2008-2013 2.50% 350000 300000 2.00% 250000 1.50% Chevy Volt (2008) 200000 https://www.chevrolet.com/electric/ 150000 1.00% volt-plug-in-hybrid 100000 % Market Share Number of Vehicles of Number 0.50% 50000 Nissan Leaf (2010) 0 0.00% https://cars.usnews.com/cars- trucks/nissan/leaf US EV Sales EVs as % of Total US Sales Tesla (2012) US Top Selling EV Models 2011-2017** https://www.autoblog.com 35000 /tesla/model+s/ 30000 25000 Fiat 500e (2013) https://www.fiatusa.com/500e. 20000 html 15000 10000 BMW i3 (2011) Sold Vehicles of Number 5000 https://www.bmwusa.com 0 Chevy Volt Tesla Model Nissan LEAF Toyota Prius Ford Fusion Ford C-MAX Tesla Model BMW i3 Fiat 500e Chevy Bolt BMW X5 S PHV Energi Energi X xDrive40e 2011 2012 2013 2014 2015 2016 2017 *Based on data from: GoodCarBadCar.net, Inside EVs, Auto Manufacturers Alliance, IHS Markit, and Automotive News; Chart based on article by Loren McDonald on EVAdoption.com **[L. McDonald, “New Models Drive Majority Of US Plug-In Vehicle Sales Growth, Analysis Shows,” CleanTechnica, 31-Jul-2018. [Online]. Available: https://cleantechnica.com/2018/07/31/new-models-drive-majority-of-us-plug-in- 4 vehicle-sales-growth-analysis-shows/. [Accessed: 12-Jun-2019] Where do battery packs go after end-of-life in electric vehicles? • Send batteries for • But wait! Batteries still have recycling? significant remaining capacity/life following electric vehicle application. Example survey of approximately 80 packs remaining life. 5 EV-BESS potential • General opinion: 2nd use of EV batteries offers a significant cost opportunity – driven by double use [1] • The most promising applications [1] for 2nd use are to: – replace grid-connected combustion turbine peaker plants – provide peak-shaving services • Other promising applications include: – small home batteries (behind the meter) • Tesla has different policy than other vehicles: – markets its Powerwall and Powerpack stationary battery packs – prefers recycling, according to Lux Research, because its NCA cathodes are not suitable for most energy-storage applications. [1] NREL Neubauer, Smith, Wood, Pesaran: Identifying and Overcoming Critical Barriers to Widespread Second Use of PEV Batteries, Technical Report NREL/TP-5400-63332, February 2015 6 Secondary Use – Repurposing of EV- Hybrid Batteries • After vehicle is reached end of life (3 R’s): – Reuse – Repurpose – Recycle • Repurpose: Before recycling can we use the batteries for a different application? M. Smith, M. Starke, A. Herron, D. King, L. Tolbert, Autonomous Battery Identification and Health Parameterization, Power Industry Division Symposium, June 2018. 7 Challenge: Cooling EV batteries • Cooling to keep packs • There are next EV engine between 20-40 C cooling principles [NREL]: – and T difference within the – Phase change – only for peak pack < 5C cooling – Batteries stop working if – Cooling fins – adds 40 weight beyond temperature limit – Air cooling - simple but not • The higher discharging, the so effective higher T & need to cool – Direct liquid cooling – excellent, but in R&D • determining features EV – Indirect liquid cooling – very battery cooling system: good and practical – temperature range and – Direct expansion (kind of liquid uniformity, energy efficiency, c.) –same refrigerant as in the size, weight, and ease of EV’s A/C – applied by BMW – usage (i.e. implementation, good and more practical maintenance). 5/19/2020 8 2nd Use Energy Storage System 9 Secondary Use Design Considerations Considerations Options Design Battery Vendor Based System VS selections will Management Commercially-off-the-Shelf impact system: Systems • Cost Leave as a Electric Vehicle Pack Battery Modules VS Grade and Configure • Complexity Centralized Design VS • Life Systems Integration Decentralized Design 10 Battery Management Systems Original Equipment Manufacturer Commercial off the Shelf (OEM) BMS (COTS) BMS Specifically calibrated to the battery Vendor support for interfacing with open technology communications protocols. Often proprietary datasets and BMS characteristic data must be entered. communications Usually already available from the EV Adds cost to the system. Potentially only available on non- graded systems or new systems Safety mechanisms may be vehicle integrated and not grid ready or follow grid standard product codes 11 Design Consideration: Battery Modules Level of Grading Advantage Challenge Battery available capacity is limited Simple implementation. No Grading Battery system lifetime can be reduced more quickly with further operations. No hardware accessibility to interior of pack Lower repurposing cost Requires decryption of BMS data from CAN bus Pack- Level Battery available capacity is limited (no replacement of aged Automated pack-level Grading hardware, software inside grading to improve battery pack) lifetime above ‘no grading’ Requires development of online scenario battery pack monitor and pack- level grading algorithm Maximized pack life and Requires man-hours and Module Grading capacity resources increasing cost. 12 Design Consideration: Battery Modules 72.00% 37 SOH Capacity 36 70.00% 35 68.00% 34 66.00% 33 64.00% 32 31 62.00% 30 Capacity Remaining 60.00% Remaining State State of Remaining Health 29 58.00% 28 56.00% 27 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 Module Number from Single Pack Since many of battery modules and cells are placed in series, the lowest capacity battery within the system will create a bottleneck and limit the full capacity of the cells within the system. In the above case, this is approximately a 9% immediate loss in capacity of the system. 13 System Integration: Challenges and Advantages Advantage vs. Centralized De-centralized Challenge Provides a quick Single host of all mechanism to the decision Advantage interconnect different making vendor products Tightly coupled and More sophisticated and Challenge changes are can require more initial difficult. development cost. 14 Sample 2nd Use Prototypes • 25 kW, 50 kWh – Near-new batteries – system utilized the GM developed BMS and was tightly coupled with the system in terms of communications and controls • 10 kW, 16 kWh – Nissan Leaf batteries, partners Spiers and ORNL – batteries collected, graded, sorted from a number of EVs – The system utilizes an COTS-based BMS that self-protects the system – An agent based architecture was developed • 80 kW, 160 kWh – Nissan LEAF batteries, not graded, using an updated BMS 15 Conclusions • EV batteries retain significant capacity after the end of their life in a vehicle • Repurposing used EV batteries offers an economic alternative to recycling • A number of considerations impact the cost, complexity and lifetime of 2nd use systems including: – What Battery Management Systems are used? – Are Battery Modules are graded? – How are Battery Systems integrated? • Several systems have been developed to provide proof of concept for 2nd Use EV battery storage systems 16 17.