Client: Sierra Club
Authors: Tyler Comings, Joshua R. Castigliego, and Jordan Burt
January 2025
Principal Economist Tyler Comings, Senior Researcher Joshua Castigliego, and Researcher Jordan Burt co-wrote comments on the Duke Energy Kentucky 2024 Integrated Resource Plan (IRP). The comments focused on the utility's decision to co-fire a coal unit (East Bend Unit 2) with natural gas. We found that full conversion of the unit to gas was more cost-effective and reduced regulatory risk.
Authors: Tyler Comings and Joshua Castigliego
October 2024
Principal Economist Tyler Comings and Senior Researcher Joshua Castigliego co-wrote comments on Evergy's Integrated Resource Plan (IRP) that were filed with the commissions in Kansas and Missouri. AEC's comments showed that Evergy did not fully address greenhouse gas compliance costs at its coal and gas generators. AEC also showed that Evergy overstated the costs of clean energy replacement options, and unfairly favored gas replacement.
Author: Tyler Comings
April 2024
Principal Economist Tyler Comings prepared an advisory filing for the State Review Board (SRB) of the Massachusetts Division of Insurance. Mr. Comings estimated the cost of capital and asset rate of return for the industry for use in regulated rates of workers' compensation insurance.
Author: Tyler Comings
August 2024
Principal Economist Tyler Comings contributed to both comments (with Clean Energy Organizations) as well as an expert report (with Chelsea Hotaling at Energy Futures Group) that addressed the Xcel MN resource plan. Mr. Comings contributions focused on the cost of new resources and he helped develop an alternative portfolio.
Author: Tyler Comings
May 2024
Principal Economist Tyler Comings filed testimony before the Colorado Public Utilities Commission on Tri-State Generation and Transmission’s resource plan. Mr. Comings discussed how Tri-State failed to justify its planned gas plant investment, including by ignoring key costs and risks of carbon capture storage (CCS) at the plant. He also discussed how Tri-States proposed requests for proposals (RFPs) for its upcoming new resource procurement were too limited; and as a result provided recommended changes to expand the resource types that could bid.
Author: Tyler Comings
July 2024
Principal Economist Tyler Comings filed testimony on the cost of Duke Energy Indiana’s coal fleet before the Indiana Utility Regulatory Commission. Mr. Comings showed that the Edwardsport plant, which runs on gasified-coal and natural gas, is exorbitantly costly and that ceasing coal at the plant is likely the best option for ratepayers. He also recommended disallowances for some of the costs of running the plant and proposed a sub-docket for the Commission to further review capital costs at Duke’s coal fleet.
Client: Southern Environmental Law Center (SELC)
Author: Chirag T. Lala, Joshua R. Castigliego, Tyler Comings, Elisabeth Seliga
March 2024
On behalf of the Southern Environmental Law Center, Researchers Chirag T. Lala and Joshua R. Castigliego, Senior Economist Tyler Comings, and Assistant Researcher Elisabeth Seliga prepared a report that models the costs to consumers of alternatives for the soon-to-be retired Kingston Fossil Plant—a coal-fired power plant in Harriman, Tennessee that is owned and operated by the Tennessee Valley Authority (TVA). TVA’s Alternative A plan replaces Kingston with a gas-heavy portfolio that constructs gas combined cycle (CC) and combustion turbine (CT) plants, while Alternative B focuses on replacing Kingston with a clean energy portfolio that relies on solar and battery storage resources.
Among its four modeled alternatives, AEC finds the net present value costs of Alternative B—renewable and storage replacements that are self-built or procured through power purchase agreements—to be the lower cost option. This contradicts TVA’s claim that Alternative A is the lower cost option. In addition, it is not clear why TVA selected the amounts of solar and storage capacity in Alternative B. The storage capacity is exorbitant compared to the size of the Kingston plant and the solar capacity is made additional to a large amount of capacity TVA is already scheduled to build.
These irregularities are partly attributable to TVA’s failure to synchronize site specific resources assessments with an integrated planning process that provides a full range of plausible alternatives. AEC provides the following recommendations for TVA’s 2024 IRP:
Conduct an all-resource RFP that assesses the range of resources that could reasonably be constructed.
Consider the full set of resources that could facilitate decarbonization of TVA’s grid, including transmission and distribution, distributed energy resources, energy efficiency, demand response, and others.
Conduct optimization modelling on all potential resources instead of on pre-selected portfolios.
Ensure site-specific planning does not contradict TVA’s most recent IRP.
Ensure the IRP provides plausible schedules for the installation and decommissioning of capacity.
Use transparent assumptions and modeling inputs
Client: Ameren 2023 Integrated Resource Plan
Author: Tyler Comings, Joshua R. Castigliego
March 2024
Senior Economist Tyler Comings and Researcher Joshua Castigliego co-wrote comments with Sierra Club on Ameren Missouri's 2023 Integrated Resource Plan (IRP) filed at the Missouri Public Service Commission. The comments focused on flaws in the IRP including the lack of a thorough evaluation of the coal units' futures, the understatement of new gas replacement costs and overstatement of clean energy costs.
Client: Mountain Association, Appalachian Citizens’ Law Center, Kentuckians for the Commonwealth, and Kentucky Solar Energy Society
Author: Tyler Comings
December 2023
AEC Senior Researcher Tyler Comings filed testimony before the Kentucky PSC on behalf of Joint Intervenors (Mountain Association, Appalachian Citizens’ Law Center, Kentuckians for the Commonwealth, and Kentucky Solar Energy Society). Mr. Comings recommended that the utility's return on equity (ROE) should not be increased because of several flaws in its estimate of the ROE; and that the utility had exaggerated its level of financial distress.
Client: Sierra Club
Author: Tyler Comings
December 2023
Senior Researcher Tyler Comings (along with Telos Energy and Strategen Consulting) assisted Sierra Club and NRDC in comments on Xcel Colorado's Electric Resource Plan. The comments argued for rejecting a proposed biomass project and instead adding more solar and battery resources than what Xcel included in its preferred plan. The comments also discussed the risks of Xcel's planned new gas procurement: in particular the utility's assumption that new gas units could become carbon-free, but not incorporating all of the costs required to achieve that status.
Client: Michigan Environmental Council (MEC), Natural Resources Defense Council (NRDC), Sierra Club (SC), and Citizens Utility Board of Michigan
Author: Tyler Comings
December 2023
AEC Senior Researcher Tyler Comings filed testimony before the Michigan PSC on the DTE Electric Company (DTE) 2023 rate case on behalf of Michigan Environmental Council (MEC), Natural Resources Defense Council (NRDC), Sierra Club (SC), and Citizens Utility Board of Michigan. Mr. Comings recommended disallowance of capital investments that could be avoided if DTE followed through on its recent plan to retire Monroe units 3 and 4 in 2028.
Client: Sierra Club
Author: Tyler Comings, Joshua Castigliego
October 2023
Senior Researcher Tyler Comings and Researcher Joshua Castigliego co-wrote comments on Evergy's Integrated Resource Plan (IRP) that were filed with the commissions in Kansas and Missouri. AEC's comments focused on Evergy's bias towards choosing new gas replacement, including its assumption that new gas would become carbon-free at no cost. AEC also noted assumptions that were overly optimistic for Evergy's coal units and that the company's consideration of early retirement for some units was too limited.
Clients: Michigan Environmental Council (MEC), Natural Resources Defense Council (NRDC), Sierra Club (SC) and Citizens Utility Board of Michigan
Author: Tyler Comings
April 2023
Senior Researcher Tyler Comings filed testimony before the Michigan Commission on DTE Electric Company's Integrated Resource Plan (IRP). Mr. Comings argued that two of the Monroe coal should be retired in 2032, as opposed to 2035 in DTE's plan. He helped develop an alternative plan that included earlier retirement of the coal units with clean replacement resources which was cheaper than DTE's plan.
Photo Credit: Missouri Department of Natural Resources
Client: Sierra Club
Author: Tyler Comings
April 2023
Senior Researcher Tyler Comings filed testimony before the Missouri Commission on Ameren Missouri's rate case. Mr. Comings argued that Ameren should be considering earlier retirement of its coal units, especially given pending environmental regulations and lower-cost clean replacement options. He also recommended that Ameren be asked to identify capital costs that could be avoided should they be retired earlier than currently planned.
Client: Sierra Club
Author: Senior Researcher Tyler Comings
Senior Researcher Tyler Comings filed testimony before the Michigan Commission on the Indiana Michigan Power (I&M) Integrated Resource Plan (IRP). Mr. Comings found several major flaws with I&M's calculations which unfairly biased the results in favor of keeping its contracted power from some of the oldest coal units in the U.S. He also argued that this contract should be re-evaluated and that, in the event of its termination, related costs should not be passed on to ratepayers.
Client: Sierra Club
Authors: Senior Researcher Tyler Comings and Researcher Joshua Castigliego
Senior Researcher Tyler Comings and Researcher Joshua Castigliego assisted the Sierra Club in comments on the Evergy Kansas Integrated Resource Plan (IRP). AEC had several criticisms of the Evergy plan, including that the company 1) failed to choose one of its alternative plans that was lower-cost and had accelerated coal unit retirements; 2) failed to conduct true optimization of coal unit retirements; 3) inflated the costs of new renewable resources; and 4) failed to consider any battery storage.
Client: The Sierra Club
Authors: Senior Researcher Tyler Comings and Researcher Joshua Castigliego
Senior Researcher Tyler Comings and Researcher Joshua Castigliego assisted the Sierra Club in comments on the Evergy Missouri Integrated Resource Plan (IRP). AEC had several criticisms of the Evergy plan, including that the company 1) failed to choose one of its alternative plans that was lower-cost and had accelerated coal unit retirements; 2) failed to conduct true optimization of coal unit retirements; 3) inflated the costs of new renewable resources; and 4) failed to consider any battery storage.
Clients: Michigan Environmental Council (MEC), Natural Resources Defense Council (NRDC), Sierra Club (SC) and Citizens Utility Board of Michigan.
Authors: Senior Researcher Tyler Comings
AEC Senior Researcher Tyler Comings filed testimony before the Michigan PSC on the DTE Electric Company (DTE) rate case on behalf of Michigan Environmental Council (MEC), Natural Resources Defense Council (NRDC), Sierra Club (SC), and Citizens Utility Board of Michigan. Mr. Comings recommended disallowance of capital investments that could be avoided if DTE's coal units retired earlier than currently planned--as well as disallowance of other capital projects that were not justified.
Author: Tyler Comings
July 2022
AEC Senior Researcher Tyler Comings co-authored comments (along with Sierra Club) on Entergy Louisiana's Integrated Resource Plan (IRP). The comments ask Entergy to include more reasonable costs for renewable and storage resources, to model more early retirement options for its coal units, and fully capture the costs of using hydrogen fuel.
Author: Tyler Comings
July 2022
AEC Senior Researcher Tyler Comings filed direct and rebuttal testimony on Consumers Energy's Integrated Resource Plan (IRP) before the Michigan Public Service Commission. Mr. Comings argued with the economics of the company's proposal to acquire three affiliate gas plants, and also supported the company's plan to retire its Campbell coal units by 2025.