Duke Energy Florida, LLC v. Gary F. Clark, etc.

Supreme Court of Florida·Decided July 7, 2022·No. SC20-1601·Published

Opinion

Supreme Court of Florida

No. SC20-1601

DUKE ENERGY FLORIDA, LLC, Appellant,

vs.

GARY F. CLARK, etc., et al., Appellees.

July 7, 2022

LAWSON, J.

Duke Energy Florida, LLC (DEF), appeals a final order of the Florida Public Service Commission (Commission) denying DEF’s request to recover approximately $16 million from its customers for costs DEF incurred to meet its customers’ demand for electricity when a 420-megawatt (MW) steam-powered generating unit went offline at its Bartow plant in 2017 and was placed back in service at a derated capacity of 380 MW. We have jurisdiction, see art. V, § 3(b)(2), Fla. Const.; § 350.128(1), Fla. Stat. (2020), and for the

reasons explained below reverse the Commission’s order and remand for entry of an order awarding the costs.

I. Background

A. Summary of Dispute Below To prevail below and recover the $16 million in costs, DEF had to prove by a preponderance of the evidence that its actions and decisions leading up to and in restoring the steam unit to service were “prudent.” See § 366.06(1), Fla. Stat. (2021) (requiring that costs be “prudently invested by the public utility company”); see also Sierra Club v. Brown, 243 So. 3d 903, 908 (Fla. 2018) (“It is from [section 366.06(1)] that the Commission derives its prudence standard, which it applies to ensure that the recovered costs result from prudent investments.”). The “standard for determining prudence is . . . ‘what a reasonable utility manager would have done, in light of the conditions and circumstances that were known, or should [have] been known, at the time the decision was made.’ ” S. All. for Clean Energy v. Graham, 113 So. 3d 742, 750 (Fla. 2013) (quoting In re Nuclear Cost Recovery Clause, Docket No. 110009-EI, Order No. PSC-11-0547-FOF-EI, 2011 WL 5904236, at 26 (Fla. Pub. Serv. Comm’n, 2011)).

The Commission referred critical factual issues to the Division of Administrative Hearings for a closed hearing before an administrative law judge (ALJ) after concluding that trying these issues would reveal confidential information that could not be disclosed and discussed in the Commission’s open hearing. After the closed hearing, the ALJ entered a recommended order denying cost recovery, which the Commission adopted in the final order on appeal.

i. The plant and its operational history The Bartow plant consists of four natural-gas-fueled combustion turbines (CT) and a much larger steam turbine. Each of the four CTs compress ambient air, mix it with natural gas, and ignite the mixture to produce a hot gas. The heated air-fuel mixture expands through the CT blades, causing each CT to rotate its shaft. The spinning shaft of each CT independently drives its own generator that produces electricity. Then, hot waste gas that exhausts from each CT is used to create steam that similarly rotates the larger steam turbine, thereby powering the larger fifth electrical generator.

When constructing the plant, DEF purchased an “after-

market” steam turbine that Mitsubishi had originally designed for another plant, where it was intended to run on steam created from the exhaust of three CTs with a steam supply capable of generating 420 MW, which Mitsubishi had also listed as the nameplate capacity of the steam turbine at the time of manufacture.

When the plant was placed online in 2009, however, DEF operated the steam unit using steam produced from the waste heat from all four CTs, producing electricity from the attached generator well above the steam turbine’s nameplate capacity. Because the steam-powered generator produced electricity using waste heat, operating this portion of the plant in this manner would have been cost-effective.

However, during a routine inspection in March 2012, DEF discovered unusual wear or damage to the steam turbine’s blades, which required DEF to replace them. The parties refer to this initial period of operation, from June 2009 to March 2012, as Period 1. Although the steam turbine was not routinely operated above 420 MW after Period 1, the replacement blades suffered similar damage and had to be replaced again in 2014, twice in 2016, and again in

2017 during the forced outage at issue in this case. The parties mark the operational time between each blade replacement as a separate period: Period 2 starts in April 2012 and ends in August 2014; Period 3 starts in December 2014 and ends in April 2016; Period 4 starts in May 2016 and ends in October 2016; and, finally, Period 5 starts in December 2016 and ends in February 2017.

In 2017, at the end of Period 5, DEF decided against reinstalling any of the previous blade types—as they all experienced damage—and installed a pressure plate which derated the steam unit from 420 MW to 380 MW. This caused DEF to incur the replacement power costs that it now seeks to recover. The pressure plate remained in the steam turbine until Mitsubishi installed redesigned turbine blades in December 2019. The blades installed in 2019 have apparently been performing normally, without unusual wear or damage.

ii. Factual issues tried before the ALJ The evidence presented to the ALJ primarily focused on whether the steam turbine’s 420 MW nameplate capacity constituted an operational limit of the unit, such that DEF acted imprudently in Period 1 (from June 2009 to March 2012) by

regularly operating the steam turbine above its nameplate capacity without first consulting with Mitsubishi.

DEF offered testimony from its Vice President of Generation, Jeffrey Swartz, who testified that the nameplate capacity is an estimate of ultimate generator output and not an operational limitation on the steam turbine. He explained that the operational parameters for the steam turbine were supplied by Mitsubishi and were expressed in permissible pressure and temperature combinations, or limitations, which DEF did not exceed. 1 Mr. Swartz further testified that Mitsubishi should have designed all components of the steam turbine to operate without undue wear or damage so long as the unit was being operated within the heat and pressure parameters Mitsubishi provided to DEF when the steam unit was being placed into service. If this were true, it would have been prudent for DEF to operate its Bartow plant to regularly

1. DEF’s expert explained that the utility measures the heat and pressure of the steam entering the turbine, with these factors determining the mass flow of steam entering the turbine. Increased heat and pressure mean an increased steam flow into the turbine and a higher energy output to the generator, resulting in a higher electrical output from the generator.

produce extra low-cost electricity from the generator despite the steam turbine’s 420-MW nameplate capacity.2 By contrast, the Office of Public Counsel (OPC) offered testimony from a retained expert, Richard Polich, who testified that 420 MW represented the design limit of the steam turbine such that DEF acted imprudently by operating the steam turbine using enough heat and pressure to produce electricity above that limit without first consulting with Mitsubishi, which would likely have conducted tests to determine whether the steam turbine could safely operate regularly above its 420-MW operational limit. Indeed, the DEF-Mitsubishi contract identified 420 MW as the steam turbine’s maximum electrical output. 3 OPC’s expert also testified that DEF damaged the blades by consistently operating the steam turbine beyond its nameplate

2. Consistent with DEF’s theory, its expert explained that Mitsubishi accomplished the “derating” by reducing the heat and pressure operating parameters from those originally provided in the contract documents. Mitsubishi’s lowering of the heat and pressure parameters resulted in a lower electrical output from the attached generator.

3. The 420.07 MW “MPS Net Steam Turbine Maximum Electrical Output” is listed under the heading “Liquidated Damage Performance Guarantees.”

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Duke Energy Florida, LLC v. Gary F. Clark, etc., (Fla. 2022).

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