On January 19, 2021 the New York State Department of Public Service (DPS) submitted the Initial Report on the Power Grid Study (“Power Grid Study”) prepared pursuant to the Accelerated Renewable Energy Growth and Community Benefit Act (AREGCBA). The AREGCBA legislation is intended to ensure that Climate Leadership and Community Protection Act (CLCPA) renewable generation is sited in a timely and cost-effective manner. The primary purpose of the Power Grid Study is to “inform planning for the bulk transmission and local transmission and distribution (T&D) investments that will be necessary to achieve the clean energy mandates established under the CLCPA”. In order to achieve those mandates and maintain the same level of reliability as the existing system, somebody, somewhere has to provide transmission grid ancillary services. Because none of those reports addressed the requirement for those services, I submitted comments to the DPS. This post documents those comments for future reference.
I have written extensively on implementation of the CLCPA closely because its implementation affects my future as a New Yorker. I have described the law in general, evaluated its feasibility, estimated costs, described supporting regulations, listed the scoping plan strategies, summarized some of the meetings and complained that its advocates constantly confuse weather and climate. The opinions expressed in this post do not reflect the position of any of my previous employers or any other company I have been associated with, these comments are mine alone.
I do not understand why the transmission grid ancillary services described here have not been addressed. A reliable electric power system is very complex and must operate within narrow parameters while balancing loads and resources and supporting synchronism. New York’s conventional rotating machinery such as oil, nuclear, and gas plants as well as hydro generation provide a lot of synchronous support to the system. This includes reactive power (vars), inertia, regulation of the system frequency and the capability to ramping up and down as the load varies. Wind and solar resources are asynchronous and cannot provide the necessary grid ancillary support.
Some, but not all of the disadvantages of solar and wind energy in this regard can be mitigated through electronic and mechanical means. When these renewable resources only make up a small percentage of the generation on the system, it is not a big deal. The system is strong enough that letting a small percentage of the resources that don’t provide those services to lean on the system. But as the penetration of solar and wind energy increases the system robustness will degrade and reliability will be compromised without costly improvements. A renewable system could be coupled with extensive batteries and other storage devices, large mechanical flywheels and condensers (basically an unpowered motor/generator that can spit out or consume reactive power). These devices could approximate the behaviors of our conventional power system.
My particular concern is that so far, the CLCPA process has only considered the energy storage ancillary services needed to keep the system operating when intermittent wind and solar resources are not available. Unfortunately, the reports in the Power Grid Study primarily considered bulk transmission and T&D investments related to capacity needs. As important as those investments are, the other grid support requirements needed so the electric grid can transmit the power from where it is produced to where it is needed are not adequately discussed in the Power Grid Study that is supposed to inform the CLCPA implementation process.
The comments were based on my review of four reports in the Power Grid Study to see if the ancillary transmission grid services necessary to keep the grid operating were considered:
- Initial Report on the New York Power Grid Study;
- Appendix C: Utility Transmission & Distribution Investment Working Group Study;
- Appendix D: Offshore Wind Integration Study; and
- Appendix E: Zero-Emissions Electric Grid in New York by 2040 Study.
I checked these reports in two ways. First, I reviewed the approaches and then I searched the documents for specific references to these services.
I extracted the study approaches for the Initial Report and Appendices C, D, and E. In my opinion, there is no indication that any of the approaches included this problem as part of their charge. It also appears that the guidelines established by the PSC in its May 2020 Order that do not include a charge to look at these services.
The other screening methodology I used was a term search of the documents. I searched documents for terms that I believe should be associated with the ancillary services requirement. I used the following search terms: “Synchro”, “Ancillary”, “Frequency”, “Inertia”, “Reactive” and “Vars”.
In the Initial Report I found several cursory references to the ancillary services challenge. Static synchronous series compensators were mentioned because they offer the operating flexibility to avoid congestion in meshed networks and provide an effective solution to congestion that may arise from variable renewable energy. There were two references to the fact that Smart Inverters can provide ride-through capability for frequency and voltage fluctuations that would typically trip the inverters and can regulate the use of ancillary services that may be provided by solar or storage devices. However, the full extent of this challenge was not addressed.
The Utility Transmission & Distribution Investment Working Group Study was the only report that included a section of the report that actually addressed the problem. in a section on potential technology solutions that included “Energy storage for T&D services”. It addressed ancillary services beyond energy storage:
“Energy storage is increasingly being considered for many transmission and distribution (T&D) grid applications to potentially enhance system reliability, support grid flexibility, defer capital projects, and ease the integration of variable renewable generation. Central to the State’s policies and mandates is the need to enhance power system flexibility to effectively manage renewable energy deployment and the associated increase in variability. As power systems begin to integrate higher penetrations of variable, renewable, inverter-based generation in place of conventional fossil-fuel fired synchronous generation, grid-scale energy storage could become an increasingly important device that can help maintain the load-generation balance of the system and provide the flexibility needed on the T&D system. Pumped hydro storage (PHS) and compressed air energy storage (CAES) are long-established bulk energy storage technologies.”
Utility-scale lithium-ion battery storage has expanded dramatically, as decreasing lithium-ion battery costs make this an increasingly cost-effective solution to meet T&D non-wire, reliability, and ancillary service needs. Redox flow batteries, sodium sulfur batteries, thermal energy storage (both latent and sensible heat), and adiabatic compressed air energy storage are all in various stages of demonstration. This information provides a concise overview of a wide variety of existing and emerging energy storage technologies being considered for T&D systems. It describes the main technical characteristics, application considerations, readiness of the technology, and vendor landscape. It also discusses implementation and performance of different energy storage technologies. In this Report, energy storage systems greater than 10 MW and four or more hours of duration, are considered as bulk and transmission and sub- transmission-connected energy storage.
Two of the eight utilities participating in the report included specific projects related to these ancillary services. However, the study did not quantify the risks of adverse inverter-based resource behavior or voltage instability in general and only LIPA included specific projects to address that problem. Clearly, someone has to quantify these risks.
The Offshore Wind Integration Study was primarily focused on the narrow scope of getting offshore wind into the New York grid. Most of the references to these terms were in the context of transmission capacity not transmission support. In connection to the costs, it was mentioned that the cost of each offshore wind project could be impacted by certain specific cost drivers such as required ancillary services.
I reviewed Zero Emissions Study the same way. According to the findings of the report:
“Based on the analysis carried out in the study, New York State should be able to achieve its 70 x 30 and zero-emission generation by 2040 goals under both the Initial Scenario and the High Demand Scenario using a mix of distributed energy, energy efficiency measures, energy storage, planned transmission projects, utility-scale renewables, and zero-emission resources. The most significant difference in these scenarios was the amount of renewable generation added and the scope (transmission capacity increases) of the transmission projects required to manage congestion and reduce costs.”
Note that this summary described transmission capacity increases but did not mention the ancillary support services requirements. I found no references that addressed reactive power (vars), inertia, or regulation of the system frequency, but they did mention the ramping adequacy ancillary service. Given that achieving the CLCPA goals will require these ancillary services and the report did not address the problem the conclusion that New York should be able to achieve the goals is unsupportable.
My particular concern is that other venues of the CLCPA process have also only considered the energy storage ancillary services needed to keep the system operating when intermittent wind and solar resources are not available. The Power Grid Study was concerned about the related issue of transmission capacity and availability to support the renewable energy resources projected. Unfortunately, the other grid support requirements needed so the electric grid can transmit the power from where it is produced to where it is needed are not discussed in sufficient detail to acknowledge the problem in three of the reports included in the Power Grid Study that is supposed to inform the CLCPA implementation process. Instead, all but Appendix C: Utility Transmission & Distribution Investment Working Group Study ignore or dismiss these services.
The future CLCPA electric system that will be dependent upon wind and solar resources has to be coupled with other devices that can approximate the behaviors of our conventional power system in order to get the power where it is needed. This is a significant shortcoming in the CLCPA process that must be addressed. The conclusion from these reports that New York State should be able to achieve the 2040 CLCPA targets is not based on adequate analysis. The transmission grid ancillary services needed for a wind and solar powered electric system issue must be addressed to determine feasibility.