Illinois Power Company v. Illinois Commerce Commission

Appellate Court of Illinois·Decided April 11, 2008·No. 3-06-0879, 3-07-0569 Cons. Rel·Published

Opinion

No. 3-06-0879

consolidated with No. 3-07-0569

Filed April 11, 2008 IN THE

APPELLATE COURT OF ILLINOIS THIRD DISTRICT

A.D., 2008

ILLINOIS POWER COMPANY, ) d/b/a/ AMERENIP, )

) Petition for Review of an Petitioner-Appellant, ) Order of the Illinois ) Commerce Commission in

v. ) Docket No. 03-0699 and ) Docket No. 04-0677.

ILLINOIS COMMERCE COMMISSION ) and DYNEGY, INC., )

)

Respondents-Appellees. )

JUSTICE LYTTON delivered the opinion of the court:

The petitioner, Illinois Power Company, d/b/a AmerenIP (Illinois Power), seek review of two orders issued by the Illinois Commerce Commission (Commission), finding that Illinois Power did not act prudently in remediating deliverability issues at its natural gas storage facility in Hillsboro, Illinois. As a result, the Commission concluded that the costs Illinois Power incurred to obtain natural gas to reinject the field in 2003 and 2004 could not be recovered from its customers. On appeal, Illinois Power argues that (1) the Commission’s findings are not supported by substantial evidence in the record, and (2) the Commission improperly applied the prudence standard. We affirm.

I. Commerce Commission Proceedings This consolidated appeal concerns Illinois Power’s Hillsboro natural gas storage facility. The Hillsboro facility is an

underground reservoir that contains two different storage layers. The top layer of the reservoir contains working gas. Working gas is the volume of gas in the reservoir that is injected for storage during the summer months and then withdrawn to be supplied to customers in the winter months. The bottom layer houses base gas which is the volume of gas required to provide adequate pressure to cycle the working gas. Generally, a utility does not remove the base gas from a reservoir field.

Following an expansion project in 1993, Illinois Power began experiencing reduced inventory and deliverability problems at the Hillsboro plant and inadvertently began removing base gas from the field. After years of investigation, the company determined that the problems were caused by improper metering. In 2003, they began reinjecting the field to restore the depleted natural gas inventory. The reinjection process was not completed until the spring of 2004. Pursuant to the Public Utilities Act (Act) (220 ILCS 5/10-201 et seq. (West 2002)), Illinois Power passed $6,879,109 in 2003 and $2,979,849 in 2004 onto its customers in the form of purchase gas adjustment (PGA) tariffs to recover the costs of the reinjection process.

In November of 2003, the Commission commenced reconciliation hearings in accordance with section 9-220 of the Act and directed Illinois Power to present evidence showing its reconciliation of PGA tariff revenues with the actual cost of gas supplies prudently incurred for the 12 month period ending December 31, 2003 (Docket No. 03-0699). One year later, the Commission initiated a second reconciliation proceeding directing Illinois Power to present

evidence for the 12 month period ending December 31, 2004 (Docket No. 04-0677). The evidence presented at both proceedings was substantially the same.

Illinois Power engineers and expert witnesses testified that the expansion of the Hillsboro field increased the working gas inventory from 3.1 billion cubic feet (Bcf) to 7.6 Bcf and increased the peak day capacity (the amount of gas to be withdrawn per day) from 50,000 million cubic feet (Mcf) to 125,000 Mcf. The company operated Hillsboro at those levels for the 1993-1994 season. In subsequent winters, however, Illinois Power was unable to withdraw the full amount of gas that had been previously injected into the field.

Given the actions taken to expand the storage reservoir, the possibility existed that the reservoir was physically breached during the expansion process, thereby allowing the newly injected gas to escape or migrate into other areas of the reservoir from which the gas could not be accessed. Other potential causes involved gas migration, gas leaks to the surface, or damage to the intake and withdrawing wells, which would have prevented efficient production of gas inventory. Illinois Power conducted numerous tests in an attempt to determine the cause of the problem. The company was concerned about taking corrective action without first properly identifying the cause of the problem.

The company’s experts testified that because of the expansion, it was logical and appropriate to focus initially on a reservoir or structural defect. Thus, Illinois Power decided to pursue an extensive structural investigation beginning in 1997. Illinois

Power had a vertical seismic profile of the reservoir field prepared by outside consultants. This study concluded that a more detailed three dimensional seismic analyses was necessary. The preliminary results of the 3-D seismic study indicated that approximately 3.5 Bcf of gas had migrated to another structure northeast of the field. In November 2000, based on the results of this study, Illinois Power drilled a new well but found no substructure below. In light of these inconsistent findings, Illinois Power asked the consultants to reevaluate the 3-D seismic analysis. After collecting additional information and reprocessing the 3-D seismic data, the firm concluded that the additional structure that had been thought to exist to the northeast of the Hillsboro field did not exist. This conclusion was reached in the fall of 2001.

While investigating the possibility of structural causes or reservoir problems, Illinois Power also retained Peterson Engineering to conduct an audit of the metering instruments at Hillsboro. Peterson was retained in August of 1999 and issued its finding in December of 1999. In its report, Peterson identified two problems with the Hillsboro meters. First, two new turbine injection meters were over-registering gas volumes under certain operating conditions. Specifically, when the nearby plant compressors operated at certain levels, they caused the meters to over-spin, thereby recording a greater amount of gas as having been injected than was actually passing through the meter. The turbine meter over-registration was calculated to be 26% when the compressors were operating at 50% but only 1.7% when the

compressors were operating at 100% loadings. Second, the orifice meter on one of the four withdrawal wells had an opening that was smaller than the size value stamped on the orifice plate. The diameter stamped on the plate was 10% larger than its actual diameter. This meant that less gas was being withdrawn from the field that had been believed. In basic terms, there was less gas going in and less gas coming out than the meters were indicating.

According to Illinois Power, the amount of error on the withdrawal meter could be easily calculated based on the different sized orifice measurements. However, the company maintained that the injection meter over-registration could not be as easily determined. Illinois Power attempted to calculate the loss by estimating when the compressors were operating at certain levels. Using this estimation method, Illinois Power initially determined that the two metering errors offset each other. It was subsequently discovered that the injection metering error was much larger than the withdrawal metering error. Illinois Power made several meter operating corrections to the facility to eliminate both meter measurement error. These changes were implemented in May 2000.

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