S T A T E OF M I C H I G A N BEFORE THE MICHIGAN PUBLIC SERVICE COMMISSION * * * *

Transcription

1 S T A T E OF M I C H I G A N BEFORE THE MICHIGAN PUBLIC SERVICE COMMISSION * * * * In the matter of the application of ) CONSUMERS ENERGY COMPANY ) for the Reconciliation of Power Supply ) Case No. U--R Cost Recovery (PSCR) Costs and Revenues ) for the Calendar Year 0 ) ) QUALIFICATIONS AND REVISED DIRECT TESTIMONY OF THERESA L. MCMILLAN-SEPKOSKI MICHIGAN PUBLIC SERVICE COMMISSION November, 0

2 QUALIFICATIONS OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART I Q. Please state your name and business address. A. My name is Theresa McMillan-Sepkoski. My business address is 09 West Saginaw Hwy, Lansing MI, 89. Q. By whom are you employed and in what capacity? A. I am employed by the Michigan Public Service Commission as an auditor in the Act 0 Reconciliation Section of the Financial Analysis & Audit Division. Q. What is your educational background? A. I graduated in 98 from Mott Community College with an A.A.S. degree in Accounting with a minor in Business Management. In June 00 I graduated from Baker College of Owosso with a B.B.A. degree with emphasis in Accounting. Since becoming employed here at the Commission, I have participated in numerous MPSC training sessions and attended the NARUC Advanced Regulatory Studies Program. Q. Please describe your professional background. A. Prior to my employment at the MPSC, I worked in accounting in the private sector for sixteen years after receiving my Associate degree. I began my employment at the Shiawassee County Health Department as an Accounts Processor. I gained further accounting experience by working for Federal Forge Inc., also known as Bharat Forge Ltd., from an entry level position in Accounts Payable to the level of Controller. Subsequently, I worked for CSI Inc. as an Assistant Controller/Human Resource Administrator. I began employment with the Michigan Public Service Commission in December, 00. Q. Briefly discuss your experience with the MPSC.

3 QUALIFICATIONS OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART I A. I have served as the lead auditor, case coordinator, or performed audit work in numerous cases for the MPSC, most recently: U-09-R Wisconsin Electric Power Co. 0 PSCR Reconciliation U-099-R Midwest Electric Cooperative 0 PSCR/TIER Reconciliation U-0-R Michigan Gas Utilities Corp. / / GCR Reconciliation U--R Consumers Energy Co. / / GCR Reconciliation U-88 Consumers Energy Co. Self-Implementation Refund Current Cases are: U--R Consumers Energy Company 0 PSCR Reconciliation U--R Michigan Gas Utilities Corp. / / GCR Reconciliation U--R Consumers Energy Co. / / GCR Reconciliation U--R Presque Isle Electric & Gas / / GCR Reconciliation U-88 Presque Isle Electric & Gas 0 TIER Ratemaking Mechanism Review Q. Have you previously filed testimony before the MPSC? A. Yes, I have filed testimony in the following cases: U-90 Consumers Energy Company Gas Rate Case U- Detroit Edison Company Electric Rate Case U- Consumers Energy Electric Rate Case U-0 Consumers Energy Gas Rate Case U-0-R Wisconsin Electric Power Co. 00 PSCR Reconciliation U-9-R Consumers Energy /0 / GCR Reconciliation U--R Wisconsin Electric Power Co. 0 PSCR Reconciliation

4 QUALIFICATIONS OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART I U-09-R Consumers Energy 0 PSCR Reconciliation U-0-R Michigan Gas Utilities Corporation / - / GCR Reconciliation U--R Consumers Energy / / GCR Reconciliation

5 REVISED DIRECT TESTIMONY OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART II Q. What is the purpose of your testimony? A. The purpose of my testimony is to support Staff s adjustments to Consumers Energy Company s (CECo or the Company) 0 PSCR Reconciliation overrecovery in the amount of $,,0, which is inclusive of interest. Q. Are you sponsoring any exhibits in this proceeding? A. Yes, I am sponsoring the following exhibits: Exhibit Title 8 S-(TMS-) Revised Staff s Over/(Under) Recovery Calculation for S-(TMS-) 0 Biomass Merchant Plant Capped Actual Fuel & Variable O&M Costs Pursuant to PA 8 of 008, MCL 0.a(), (8), (9) Q. Was this exhibit prepared by you or under your direction? A. Yes. Q. What is Staff s audited over-recovery amount for the 0 PSCR reconciliation, and how does this differ from the Company s filed over-recovery amount? A. In Exhibit S- (TMS-) Revised, Staff determined that the over-recovery amount for the 0 PSCR reconciliation period is $,,, inclusive of interest. The Company s over-recovery amount filed with their application and testimony is $,,0, inclusive of interest, for a difference of $,,09. These amounts differ due to the following adjustments: ) a $,08,0 increase to Purchased, Interchange, & Renewable Power for the increase to the actual Biomass Merchant Plant s (BMPs) capped costs recoverable per PA 8 MCL 0.a(), (8), and (9);, ) the effect on the monthly interest calculated on the over / (under)

6 REVISED DIRECT TESTIMONY OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART II recovery amount; and, ) the revised recovery beginning balance change due to the re-calculation of the BMP actual costs for the previous two PSCR reconciliation cases: U-890-R and U-09-R. Q. Please explain what the terms capped and uncapped mean in relation to the costs that have been presented for recovery in this case by the BMPs. A. MCL 0.a(8) discusses the costs that are recoverable by the BMPs. Capped costs consist of actual fuel and variable O&M costs subject to a $,000,000 monthly limit, which may be adjusted by the Commission. The annual amount of the adjustment shall not exceed a rate equal to the United States consumer price index for all urban consumers (CPI-U). Uncapped costs consist of actual fuel and variable O&M costs not subject to the $,000,000 monthly limit. These costs result from changes in federal or state environmental laws or regulations implemented after October, 008 (the effective date of PA 8 of 008). Q. Does Staff agree with the capped 0 actual fuel and variable O&M costs for recovery identified on Exhibit BMP- in the amount of $,9,09? A. Yes, Staff agrees with the 0 actual fuel and variable O&M costs for recovery calculated on Exhibit BMP-. The Michigan Court of Appeals recently determined that the annual adjustments to the $,000,000 capped costs shall be calculated by using the cumulative consumer price index (CPI) rate from 009 forward. Cadillac Renewable Energy LLC, et al v MPSC, Court of Appeals Docket No. 88 (MPSC Docket No. -R). Staff used the cumulative CPI rate in the calculation of the capped costs as seen in Column J of Staff s Exhibit S- (TMS-).

7 REVISED DIRECT TESTIMONY OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART II Q. Does Staff agree with the BMP s request for recovery of uncapped 0 actual fuel and variable O&M costs for recovery of NOx and SO allowances totaling $9,8 found on Exhibit BMP- (RJT-), line? A. No. These costs were incurred by the BMPs due to the Federal Clean Air Interstate Rule (CAIR) requirements implemented by the State of Michigan prior to October, 008. The Commission has addressed this issue frequently in prior PSCR reconciliation cases. Recently, the Michigan State Court of Appeals affirmed the Commission on this issue in TES Filer City Station Ltd Partnership v Mich Pub Ser Comm, Mich App, ; NWd (0) (Docket No. issued May 8, 0). TES Filer filed an application for leave to appeal the Court of Appeals decision to the Michigan Supreme Court, but the Court has not yet ruled on the Application. Q. Please explain Staff s Exhibit S- (TMS-) Revised. A. Staff s Exhibit S- (TMS-) Revised is the calculation of the Company s over / (under) recovery of PSCR revenues and costs, inclusive of interest, for the 0 reconciliation period. Q. Please explain Staff s first adjustment on Exhibit S- (TMS-) Revised. A. Staff s first adjustment on Exhibit S- (TMS-) Revised to the over / (under) recovery calculation is on Line, during the month of December, to the Purchased, Interchange, & Renewable Power. The adjustment is an increase to PSCR costs in the amount of $,08,0. This amount is the result of the CPI calculation of the total amount owed to the BMPs in the capped costs, above what the Company reported as owed to the BMPs in its Exhibit A- (MTD-) line.

8 REVISED DIRECT TESTIMONY OF THERESA MCMILLAN-SEPKOSKI CASE NUMBER U--R PART II Since this is a true-up of the yearly costs associated with the BMPs, it is an accepted accounting practice to make this adjustment in the month of December. Q. Please explain Staff s second adjustment on Exhibit S- (TMS-) Revised. A. Because of the effects of the previously mentioned adjustment on the monthly over/(under) recovery amount, this in turn effects the calculation of the monthly interest totals. Staff s total net cumulative over-recovery amounts to $,8,9 compared to the Company s total net cumulative over-recovery of $,,. Staff s total of the monthly interest for the PSCR period amounts to $0,808. The Company had calculated a total amount of interest for the PSCR period of $,. Staff s calculation of the over-recovery amount (with interest) of $,, results in a decrease to the Company s proposed over-recovery of $,,09. Q. Please explain Staff s revised adjustment to the Company s filed recovery beginning balance. A. Persuant to the Court of Appeals decision, Staff recalculated the two previous year s (0 & 0) PSCR over/(under) recovery ending balances. The ending over/(under) recovery balance for those years rolled forward as beginning balances for the following years, thus causing the beginning balance for the 0 to change from what Staff had previously filed testimony. Exhibit S- (TMS-) Revised reflects the updated beginning balance after recalculation and inclusion of the results of the BMP actual recoverable costs. Q. Does this conclude your testimony? A. Yes it does.

9 S T A T E OF M I C H I G A N BEFORE THE MICHIGAN PUBLIC SERVICE COMMISSION * * * * In the matter of the application of ) CONSUMERS ENERGY COMPANY ) for the Reconciliation of Power Supply ) Case No. U--R Cost Recovery (PSCR) Costs and Revenues ) for the Calendar Year 0 ) ) REVISED EXHIBITS OF THERESA L. MCMILLAN-SEPKOSKI MICHIGAN PUBLIC SERVICE COMMISSION

10 Consumers Energy Company U--R Case No. U--R 0 Power Supply Cost Recovery Reconciliation Exhibit S- (TMS-) Revised Staff Over/(Under) Recovery Calculation Date November, 0 Page of Ln Description January February March April May June July August September October November December Total kwh Sales Cycle Billed PSCR Sales,00,,8,90,,9,,,8,8,9,0,9,9,,,,,8,9,90,8,0,,9,08,,,80,8,0,,,,,8,8,,8 Unbilled PSCR Sales - Current Month,8,,,,,0,,80,09,,88,,,,80,8,0,9,80,,,0,0,088,0,9,,8,00,9,90,9,,09,,99,8,0,8 Unbilled PSCR Sales-Prior Month (,8,0,0) (,8,,) (,,,0) (,,80,09) (,,88,) (,,,80) (,8,0,9) (,80,,) (,0,0,088) (,0,9,) (,8,00,9) (,90,9,) (,9,,09) Total Calendar PSCR Sales,989,8,009,8,008,00,8,0,00,80,,0,0,9,90,8,9,,8,80,8,0,,,0,0,8,9,08,0,,9,,8,,,,98, Total Calendar Sales,0,,,9,8,8,88,990,0,,98,9,9,,,9,9,8,90,9,09,0,0,,,90,80,,9,,,990,,8,,8,,0, 8 Less Interruptible Wholesale and GSG- Sales,,,,0,9,8,88,,,,88,,8,9,,8 0,0,8,8,0 0,,8 8,89,,88,9 9 Total Sales w/o Interruptible Wholesale and GSG-,0,8,08,,9,,8,9,,08,0,8,,0,,90,0,,889,,,08,8,88,,00,,9,,08,,,,8,8,,89,, 0 Percentage PSCR Sales to Net of Incremental Total 99.0% 98.90% 99.% 98.8% 99.00% 99.0% 99.0% 98.9% 99.00% 99.0% 98.9% 99.0% Base and Fuel Factors, $/kwh Base Recovery Factor Billed PSCR Factor (0.00) (0.00) (0.0000) (0.0000) (0.0000) (0.0000) Current Month Unbilled PSCR Factor (0.00) (0.0000) (0.0000) (0.0000) (0.0000) (0.00) Prior Month Unbilled PSCR Factor (0.00) (0.00) (0.0000) (0.0000) (0.0000) (0.0000) PSCR Revenue, $ 9 Billed PSCR,,0,98,8,,8,8,,, 0,80,0 8,8,8 8,8,00 90,88,8,,09 9,8, 9,9,0,0,9,89 0 Current Month Unbilled PSCR 0,8, 99,8,8 0,, 9,9,9 98,9, 0,0,9,,98,, 0,90,,9,8 0,,8,9,98,,88, Prior Month Unbilled PSCR (0,,8) (0,8,) (99,8,8) (0,,) (9,9,9) (98,9,) (0,0,9) (,,98) (,,) (0,90,) (,9,8) (0,,8) (,8,0,0) Total PSCR Revenue,0,8 0,90,8,,9 9,09, 8,08, 8,99,8 8,9, 9,8, 9,,9 8,,9,09,0,8,,0,88,00 Power Supply Cost, $ Fuel for Generation,0,,,9,0,8 8,,98,0, 0,99,,98,0 0,9, 0,9, 8,,9,,8 8,00,0,,00 Purchased,Interchange, & Renewable Power,9,9 8,,,0,09 0,9,,,0 0,9,90 8,8, 9,88,0 0,9,,09,00,0,,8, [],,, Urea Expense,0,00,9, 8,90, 0,8 89,,09,8 0,909,,0,0 8 Nox/SO Costs () (88,09) 0 (89,0) 9 Aqueous Ammonia, 0,0 99,8,8,0,,,98 09,08 00, 8,88 8,,0,0 Lime ,8 0,8 0 Total Costs 9,9,0,98,90,89,0,9,0,,,0,8 8,00, 80,99,0,99,9,0,8,9,8 0,,,09,08,80 Less Costs of Interruptible Wholesale/GSG- Sales 9,,8 0,88 8, 0,,,,,,9,0,0,0, Total Costs w/o Interruptible Wholesale/GSG- Costs 9,0,0,,,,,8,8,,9,, 8,8, 80,,0,8,9 0,,,9,8 9,90,,088,8,9 Jurisdictional Percentage 99.0% 98.90% 99.% 98.8% 99.00% 99.0% 99.0% 98.9% 99.00% 99.0% 98.9% 99.0% Total Cost Allocated to PSCR 9,08,08 9,89, 09,8,8,,,09,8 9,98, 8,9, 8,,0 9,8,90 9,08,,88, 8,0,8,08,09,8 Over/(Under) Recovery,9,9 Monthly 8 PSCR Revenue,0,8 0,90,8,,9 9,09, 8,08, 8,99,8 8,9, 9,8, 9,,9 8,,9,09,0,8,,0,88,00 9 LESS: PSCR Cost 9,08,08 9,89, 09,8,8,,,09,8 9,98, 8,9, 8,,0 9,8,90 9,08,,88, 8,0,8,08,09,8 0 Over /(Under) Recovery (,00,8) (9,0,08) (8,,8),88,89,9,9,00,9,0,9,,8 9,9,80 9,8,0 9,808,8,88,0 (,,8) Cumulative Over (Under) Recovery Recovery Beginning Balance 9,00, (,9,) (,,8) (0,80,) (9,98,) (9,00,) (9,98,) (,9,) (,0,) (,,9) (,8,9) (8,08,98) ADD: Monthly O/(U) Recovery (,00,8) (9,0,08) (8,,8),88,89,9,9,00,9,0,9,,8 9,9,80 9,8,0 9,808,8,88,0 Recovery Ending Balance (,9,) (,,8) (0,80,) (9,98,) (9,00,) (9,98,) (,9,) (,0,) (,,9) (,8,9) (8,08,98),8,9,8,9 Interest Recovery Average Balance,9,8 (,,9) (8,9,0) (00,9,) (9,9,) (8,99,) (,,9) (,0,9) (,,) (,,) (,9,8) (,8,) Monthly Interest Rate (Annual Rate divided by months) Monthly Interest,8 (,09) (8,00) (,) (9,80) (,9) (,9) (,00) (,0) (,9) (,8) () (0,808) 9 0 Cumulative O/(U) Recovery w/ Interest (,98,08) (,,0) (0,8,) (9,00,8) (9,0,) (80,00,) (,0,) (,,99) (,,0) (,9,00) (8,9,9),,,, [] Purchased Power Costs adjusted to reflect actual BMP costs recoverable under PA 9 MCL 0.a (), (8) and (9) of

11 Case No. U--R Exhibit S- (TMS-) September, 0: Page of 0 BIOMASS MERCHANT PLANT CAPPED ACTUAL FUEL & VARIABLE O&M COSTS PERSUANT TO a OF 008 PA 8, MCL 0.a (), (8) & (9) A B C D E F G H I J K L M N O 0 Line No. January February March April May June July August September October November December Total Gross Cost Recovery Amounts This is the SHORTFALL between the costs which the BMPs incurred and the payments they received from CECo Cadillac Renewable Energy, LLC $, $9,0 $9, $9, $9,80 $,8 $8, $0,80 $9,0 $, $, $,8 $,9,08 Genesee Power Station LP $9,8 $, $9,8 $,0 $, $8, $8,0 $0,0 $,00 $9,0 $,9 $8, $,00, Grayling Generating Station LP $0 $,9 $0, $8, $9,90 $9, $9,0 $,9 $,8 $,9 $0, $8,9 $,,9 Hillman Power Company, LLC $, $, $, $8,9 $, $,8 $0,9 $,9 $,089 $, $, $, $9, TES Filer City LP $,, $,8 $8,88 $80,0 $0,8 $,89 $0,8 $,09 $, $8,80 $8, $9,08 $,8, Viking Energy of Lincoln, LLC $,9 $,9 $0, $,8 $,00 $8,0 $9,9 $,00 $8,8 $,80 $, $, $88, Viking Energy of McBain, LLC $, $9,99 $,8 $,9 $0,098 $0 $0,0 $, $,88 $,9 $,9 $8,9 $,0,8 8 Total $,8,0 $,, $,,9 $,,80 $,88,8 $9, $,,8 $9,8 $9, $,0,8 $,0,8 $,9,9 $,9,09 9 Monthly Cap, Unadjusted $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 0 Recoverable Percentage.8% 8.%.0%.%.0% 00.00% 8.% 00.00% 00.00%.% 90.% 0.% Capped Payments This is the shortfall capped at $,000,000 per month Cadillac Renewable Energy, LLC $8,0 $8,8 $, $0,8 $,8 $,8 $,00 $0,80 $9,0 $8, $,8 $8,0 $,,99 Genesee Power Station LP $9,980 $00,80 $, $,8 $,99 $8, $,8 $0,0 $,00 $,9 $0, $0, $,, Grayling Generating Station LP $0 $,0 $,08 $,9 $8,9 $9, $,08 $,9 $,8 $0,8 $,80 $9,0 $8,8 Hillman Power Company, LLC $,0 $,8 $,9 $,8 $,0 $,8 $8, $,9 $,089 $,8 $,8 $,90 $0,9 TES Filer City LP $,009 $,9 $8,8 $, $0, $,89 $,99 $,09 $, $9, $9,88 $9,8 $,,0 Viking Energy of Lincoln, LLC $, $0,9 $0,0 $,89 $9,0 $8,0 $0,0 $,00 $8,8 $09,0 $0,0 $8,99 $,0 Viking Energy of McBain, LLC $8,00 $0, $, $, $,8 $0 $, $, $,88 $, $,0 $, $,9 8 Total $,000,000 $,000,000 $,000,000 $,000,000 $,000,000 $9, $,000,000 $9,8 $9, $,000,00 $999,999 $,000,000 $,8,8 A B C D E F G H I J K L M N O SUMMARY DATA FOR CAPPED FUEL AND VARIABLE OPERATION AND MAINTENANCE COSTS RECOVERABLE UNDER SECTION a OF 008 PA 8, MCL 0.a (), (8) & (9) WITH CPI INFLATIONARY ADJUSTMENT = 0.09 Summary Data January February March April May June July August September October November December Total Gross Cost Recovery Amounts This is the SHORTFALL between the costs which the BMPs incurred and the payments they received from CECo 9 Cadillac Renewable Energy, LLC $, $9,0 $9, $9, $9,80 $,8 $8, $0,80 $9,0 $, $, $,8 $,9,08 0 Genesee Power Station LP $9,8 $, $9,8 $,0 $, $8, $8,0 $0,0 $,00 $9,0 $,9 $8, $,00, Grayling Generating Station LP $0 $,9 $0, $8, $9,90 $9, $9,0 $,9 $,8 $,9 $0, $8,9 $,,9 Hillman Power Company, LLC $, $, $, $8,9 $, $,8 $0,9 $,9 $,089 $, $, $, $9, TES Filer City LP $,, $,8 $8,88 $80,0 $0,8 $,89 $0,8 $,09 $, $8,80 $8, $9,08 $,8, Viking Energy of Lincoln, LLC $,9 $,9 $0, $,8 $,00 $8,0 $9,9 $,00 $8,8 $,80 $, $, $88, Viking Energy of McBain, LLC $, $9,99 $,8 $,9 $0,098 $0 $0,0 $, $,88 $,9 $,9 $8,9 $,0,8 Total $,8,0 $,, $,,9 $,,80 $,88,8 $9, $,,8 $9,8 $9, $,0,8 $,0,8 $,9,9 $,9,09 Monthly Cap $,0, $,0, $,0, $,0, $,0, $,0, $,0, $,0, $,0, $,0, $,0, $,0, 8 Recoverable Percentage 9.% 9.%.%.% 8.% 00.00% 89.99% 00.00% 00.00% 8.0% 99.9%.% Capped Payments This is the shortfall capped at $,000,000 per month with an 0.09% CPI Adjustment 9 Cadillac Renewable Energy, LLC $0,8 $8,0 $, $,8 $, $,8 $,99 $0,80 $9,0 $9,0 $, $9,08 $,98,09 0 Genesee Power Station LP $, $, $,8 $8, $80,9 $8, $, $0,0 $,00 $,009 $,8 $,8 $,8,80 Grayling Generating Station LP $0 $,8 $8,09 $,9 $,80 $9, $8,0 $,9 $,8 $,8 $0,8 $, $880,8 Hillman Power Company, LLC $8,9 $,0 $,9 $,8 $,9 $,8 $9, $,9 $,089 $9, $,9 $8, $,98 TES Filer City LP $8,89 $9, $0,88 $9, $,0 $,89 $,9 $,09 $, $8,909 $8,08 $, $,,8 Viking Energy of Lincoln, LLC $,8 $, $,9 $9, $00,0 $8,0 $, $,00 $8,8 $0,9 $,8 $90,0 $8,0 Viking Energy of McBain, LLC $, $,90 $,9 $8,0 $9,9 $0 $8, $, $,88 $0, $,8 $,89 $8, Total $,0, $,0, $,0, $,0, $,0, $9, $,0, $9,8 $9, $,0, $,0, $,0, $,9,09 Consumers Energy Exh. A- (MTD-) line total for Biomass Merchant Plant $,0,8 Total amount owed to BMP's per CPI adjustment $,08,0

12 STATE OF MICHIGAN BEFORE THE MICHIGAN PUBLIC SERVICE COMMISSION * * * * * In the matter of the Application of ) CONSUMERS ENERGY COMPANY ) for the Reconciliation of Power Supply Cost ) Case No. U--R Recovery (PSCR) Costs and Revenues ) (e-file paperless) for the Calendar Year 0. ) PROOF OF SERVICE Jennifer Brooks, being duly sworn, deposes and says that on November, 0, A.D., she ed a copy of the attached MPSC Revised Testimony and Exhibits to the persons as shown on the attached list. Jennifer Brooks Subscribed and sworn to before me this th day of November, 0. Lisa Felice Notary Public, Eaton County, MI My commission expires 0//00

13 Service List for U--R Consumers Energy Company: Robert W. Beach Anne M. Uitvlugt MCV: David R. Whitefield Ford J. Turrell Charles E. Dunn MPSC Staff: Lauren D. Donofrio Bryan A. Brandenburg Assistant Attorneys General Cadillac Renewable Energy: Thomas J. Waters David E.S. Marvin Attorney General: John A. Janiszewski Wendy Cadwell Sebastian Coppola Administrative Law Judge: Hon. Mark D. Eyster