Grid-Connected EVs: The New Age of EVs as Distributed Energy Resources – DERs
Charles Botsford, P.E., Monrovia, California
It’s nice when things come together. Recently, a perfect storm of enabling rules, orders, and standards arrived that pave the path for grid-connected electric vehicles (EVs) to serve as distributed energy resources (DERs): California Rule 21, FERC Order 222, and SAE J3072. Why is this important?
The grid is evolving to one powered by DERs. Rather than large centralized power plants fueled by coal, nuclear, and natural gas, the grid is increasingly powered by wind, solar, and other renewables. As this happens, the spinning mass and momentum buffer capacity that traditional power plants provide must be replaced. This buffer capacity protects system components and balances the grid supply and system demand.
The general consensus is that energy storage is the necessary mechanism to replace the capacity buffer that provides stability and resiliency. At the same time, EV adoption is increasing dramatically. Rather than becoming a growing problem, EVs and their batteries could act in concert with the grid to provide the much needed energy storage. Many regulatory, technical, and other obstacles have made that almost impossible. Until Now.
Breaking News: California Rule 21 Change Enables V2G
On September 24, 2020, the California Public Utility Commission (CPUC) issued changes to Rule 21 Interconnection [1] that enables distributed energy resources, including energy storage projects significantly easier access to the grid [2]. One of the driving forces for this rule change was to enable integration of renewable generation via energy storage. Of note, energy storage includes three types of vehicle-grid-integration from EVs:
- Managed unidirectional EV charging, sometimes called grid-to-vehicle, G2V, or V1G.
- Bi-directional Direct Current (DC) vehicle-to-grid, or DC V2G, and
- Bi-directional Alternating Current (AC) vehicle-to-grid, or AC V2G.
The Rule 21 revision allows bi-directional EV power flow to the grid with permission from the local utility. The summary of the proposed decision states:
“Our primary objective in adopting the modifications is to streamline the interconnection process by incorporating the Integration Capacity Analysis results from Rulemaking 14-08-013, the Distribution Resources Plans proceeding. Other objectives include improving efficiency, transparency, certainty, and clarity. The adopted changes emanate from recommendations contained in three reports: Working Group Two Report, Working Group Three Report, and Vehicle-to-Grid Alternating Current Subgroup. Utilities are directed to implement these changes as described in the Ordering Paragraphs of this decision.”
This is a groundbreaking change to California’s interconnection rule. However, this impacts much more than California. It arguably impacts all of the US and Canada. Rule 21 also embraces two standards from International Electrical and Electronics Engineers (IEEE). For distributed energy resources (DERs), putting power onto the grid requires compliance with the IEEE 1547-2018 and tested according to the procedures laid out in IEEE 1547.1-2020. IEEE 1547 is the standard for “Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power System Interfaces.”
As state utility commissions adopt the latest versions of IEEE 1547 and 1547.1, they will also likely review and evaluate the latest action of CPUC on Rule 21.
source: Abbot, COVID Lockdown Graphics Dept.
Figure 1. SoCal Windfarm with EVs and Second Use Batteries as DERs
Breaking News: FERC Order 2222 Enables DER Trading
On September 17, 2020 the Federal Energy Regulatory Commission issued draft Order 2222, which becomes a final rule 60 days after publication in the Federal Register [3]. The summary paragraph from the final rule states:
“The Federal Energy Regulatory Commission (Commission) is amending its regulations to remove barriers to the participation of distributed energy resource aggregations in the capacity, energy, and ancillary service markets operated by Regional Transmission Organizations and Independent System Operators (RTO/ISO).”
This is a significant order, which will enable distributed energy resources to participate in RTO/ISO wholesale markets to provide ancillary grid services for: reliability, resiliency, and system balancing [4].
Significantly, the FERC technical presentation [5] says:
“The draft final rule finds that existing RTO/ISO market rules are unjust and unreasonable in light of barriers that they present to the participation of DER aggregations in the RTO/ISO markets.”
Removing barriers to participate in such resource aggregations in the RTO/ISO markets means that Order 2222 will enhance competition in the RTO/ISO markets. This will have a major impact for energy storage, including grid-connected EVs as energy storage.
Breaking News: SAE J3072 Sets the Standard for AC V2G
IEEE 1547 is the standard for DER interconnection to the grid. The interconnection process is well established for stationary DERs, including utility-scale batteries and even EVs that connect to the grid using stationary bi-directional direct current (DC) chargers. Connecting mobile sources to the grid via alternating current (AC), however, is another matter.
EVs in the U.S. that wish to use their on-board charger to provide alternating current AC V2G services must comply with Society of Automotive Engineers (SAE) J3072. Earlier versions of SAE J3072 have been around since 2015. The latest version of SAE J3072 references IEEE 1547-2018 and 1547.1-2020. This is important because it reconciles with California Rule 21, which also references IEEE 1547-2018 and 1547.1-2020. This version of SAE J3072 just entered the ballot process and is projected to publish January 2021.
Grid-Connected EVs
The impact of a single EV as a load on the grid is insignificant. However, California alone is approaching 750K EVs, and the US is over 1.6M. By 2030, the population of EVs in the U.S. is projected to be in the range of 15-25M. To convert these EVs from grid loads to grid resources will require managed EV charging (unidirectional), DC V2G, and AC V2G.
With the future capacity of EV sedan packs in the 50-100kWh range and much larger packs for medium- and heavy-duty EVs, this translates to over 1,000 GWh and 150 GW of usable EV battery storage and power, after discounting for limited pack state-of-charge availability, EV owner opt-out, and EV time availability for charging. This should be enough energy storage and power to significantly offset potential renewables curtailment [6].
The bulk of grid-connected EV energy storage will come in the form of managed unidirectional charging, which is a very low cost resource to the grid. DC and AC V2G will provide higher value and costs to the grid, but may only be needed for niche applications. One example of DC V2G would be a medium-duty delivery fleet that charges and discharges while in the depot.
The services of managed EV charging, DC V2G, and AC V2G are numerous in addition to enabling greater renewables penetration, and include [7, 8]:
- Peak shifting
- Peak shaving
- Supply capacity and firming
- Frequency regulation
- Spinning, non-spinning, and supplemental reserves
- Reactive supply and voltage control
- Transmission upgrade deferral
- Congestion relief
- Distribution upgrade deferral
- Power quality
- Power reliability
- Demand charge management
- Demand response
- Time-of-use management
Retired EV Batteries
The economic cost of grid-connected EVs to provide energy storage and grid ancillary services is much lower than that of stationary energy storage. However, EVs may not provide enough energy storage and power capacity in the short-term.
Whatever shortfalls grid-connected EVs might encounter for these services, could be made up via second use of EV packs, also called EV pack retirement [9, 10, 11]. Used EV packs still have many years of life for utility-scale energy storage and other applications if properly conditioned and balanced. EV pack cells are of the highest quality, the packs have world-class battery management systems, and they are greatly over-engineered for stationary use (e.g., cooling and other issues). The other significant benefit of second use packs is their much lower cost, which is almost as low as grid-connected EVs. EV battery second use would go a long way to address what to do with retired EV packs.
source: Abbot, COVID Lockdown Graphics Dept.
Figure 2. Clean Vehicle with Organic Energy Storage
Conclusion
The Triumvirate of Rule 21, FERC 2222, and SAE J3072
For any one of these rules, orders, or standards to gain approval would be a big deal for energy storage, and in particular grid-connected EVs. For all three to make it through their long tortuous route to the light of day in September and October 2020 is something of a miracle in timing.
The path forward is clearer but by no means an easy one. Ahead lies a multitude of utility demonstration programs, negotiations between utilities and aggregators, decisions and development by vehicle manufacturers regarding bi-directional inverters and the implications on their vehicle’s batteries, and most importantly, how to make this an economic win-win for everybody, including the person who owns the EV.
The pot of gold will be a resilient grid of the future with 100% renewables generation served by grid-connected EVs and retired EV packs.
Acknowledgement
Thanks go to Mr. Matt Zerega for a spirited discussion on the topic and his very helpful comments on the draft.
References
1. California Public Utilities Commission, Agenda ID # 18718, Rulemaking 17-07-007, Order Instituting Rulemaking to Consider Streamlining Interconnection of Distributed Energy Resources and Improvements to Rule 21. August 20, 2020.
2. Misbrener, K., CPUC Updates California’s Interconnection Rules to Better Accommodate Renewables Onto the Grid. Solar Power World, September 25, 2020.
3. Federal Energy Regulatory Commission, Docket: RM 18-9-000, September 17, 2020.
4. Brooks, Richard, My Review of FERC Order 2222, Energy Central, September 20, 2020.
5. Federal Energy Regulatory Commission, Staff Presentation Item E-1. Docket: RM 18-9-000, September 17, 2020.
6. Sheppard, C, J. Szinai, N. Abhyankar, A. Gopal, Grid Impacts of Electric Vehicles and Managed Charging in California, Energy Analysis and Environmental Impacts Division, Lawrence Berkeley National Laboratory, November 2019.
7. Chhaya, S., etal, “Distribution System Constrained Vehicle-to-Grid Services for Improved Grid Stability and Reliability”, Final Project Report, California Energy Commission, Publication Number: CEC-500-2019-027, March 2019.
8. Vehicle-Grid Integration Working Group, Final Report to the California Joint Agencies, CPUC DRIVE OIR Rulemaking R.18-12-006, June 30, 2020.
9. California Energy Commission, Validating Capability of Second-life Batteries to Cost-Effectively Integrate Solar Power for Small/Medium-sized Commercial Building Applications, GFO-19-310 Solicitation, http://www.energy.ca.gov/contracts/index.html, February 2020.
10. Engel, H., P. Hertzke, and G. Siccardo, McKinsey & Company, Second-Life EV Batteries: The Newest Value Pool in Energy Storage, April 2019.
11. Anderson, M., Used EV Batteries Could Power Tomorrow’s Solar Farms, IEEE Spectrum, June 10, 2020.
Author
Charles Botsford, PE is a professional chemical engineer in the State of California with 30 years’ experience in engineering process design, distributed generation, EV charging infrastructure, and environmental management. He participated in California’s Vehicle Grid Integration (VGI) Working Group and participates in the Society of Automotive Engineers (SAE) J3072 AC Vehicle-to-Grid standards committee. Mr. Botsford holds a bachelor’s degree in chemical engineering from the University of New Mexico, and a master’s degree in chemical engineering from the University of Arizona.