IMPA's Power Supply System

Learn about IMPA's Power Supply System for Indiana Municipal Power Agency Investor Relations, including Solar Parks, Gibson Unit 5, and IMPA Combustion Turbines.

Solar Parks

IMPA has developed and takes power from 21 solar parks in IMPA Member communities with a total capacity of approximately 53 MW (the “IMPA Solar Parks”).   Ranging in size from .25 MW to 8 MW, these environmentally-responsible resources mark the addition of solar as a renewable energy resource in IMPA's power supply portfolio.  IMPA developed solar parks in the communities of Advance (.24 MW), Anderson (5 MW and 8 MW), Argos (.7 MW), Bainbridge (.3 MW), Crawfordsville (3 MW), Flora (0.81 MW), Frankton (1 MW), Greenfield (2.84 MW), Huntingburg (2MW), Pendleton (2 MW), Peru (3 MW), Rensselaer (1 MW and 3.8 MW), Richmond (1 MW and 7.4 MW), Spiceland (.53 MW), Tell City (1 MW), Tipton (5.2 MW), Washington (4 MW) and Waynetown (.25MW). Several of the parks feature single axis tracking systems, allowing the panels to move and track the sun throughout the day, while other parks rely on fixed tilt panels. 

IMPA’s current target is to build a total of 200 MW of solar generation.  In addition to the 53 MW currently in operation, IMPA plans to construct an additional 16 solar parks with an expected additional capacity of 83 MW during 2019, 2020 and 2021, with the remaining 64 MW of solar generation to be constructed thereafter.  

Data for each of the solar parks is available at Solar Parks.

Gibson Unit 5

Gibson Unit 5 is a 625 MW coal-fired baseload generating facility located in southwestern Indiana.  The unit was placed in service in 1982 and relies on high sulfur coal supplies predominantly from southern Indiana.   Coal for Gibson Unit 5 is delivered to the plant by rail and truck and is purchased from several suppliers under contracts with varying terms.

Gibson Unit 5 is equipped with sulfur dioxide (“SO2”) and nitrogen oxide (“NOX”) removal facilities and burns high sulfur coal that is predominantly from southern Indiana. Gibson Unit 5 installed a selective catalytic reduction system (“SCR”) for NOX control, upgraded its flue gas desulfurization system (the “FGD” system) to increase SO2 removal efficiency.  Gibson Unit 5 upgraded the unit’s electrostatic precipitator, added calcium bromide injection equipment, made certain duct modifications and added additional monitoring equipment in order to comply with the Mercury and Air Toxics Standards. with particulate, sulfur dioxide (SO2) and nitrogen oxide (NOX) removal facilities.  Installation of a Selective Catalytic Reduction (SCR) system for NOXcontrol was completed in 2004, and in 2008, Gibson Unit 5 upgraded its flue gas desulfurization system to increase SO2 removal efficiency.

IMPA has a 24.95% ownership interest, or approximately 156 MW, in Gibson Unit 5, which it jointly owns with Duke Energy and the Wabash Valley Power Association.

IMPA Combustion Turbines

IMPA has seven wholly-owned combustion turbines and associated facilities aggregating 419 MW.  The Combustion Turbines include two 41 MW units, placed in service in 1992 and one 85 MW unit placed in service in 2004 located in Anderson, Indiana; two 41 MW units, placed in service in 1992 located near Richmond, Indiana; and two 85 MW units, acquired by IMPA in 2004, located in Indianapolis, Indiana.  IMPA employees operate and maintain the combustion turbines located in Anderson and Richmond.  The Georgetown Plant is currently operated and maintained by Indianapolis Power & Light Company. 

The Anderson and Richmond Combustion Turbines operate primarily on natural gas, which is delivered under an interruptible transportation contract with Vectren.  This contract gives IMPA the option to obtain its own gas supplies with local distribution supplied by Vectren.  The Anderson and Richmond Combustion Turbines also maintain an inventory of No. 2 fuel oil as an alternative fuel in the event of interruptions in natural gas supply, or as an economic option.  The Georgetown Plant operates solely on natural gas, which is delivered pursuant to a capacity reservation and gas transportation agreement with Citizens Gas.  Natural gas used to operate the Combustion Turbines is purchased at market prices.

Prairie State Energy Campus 

The Prairie State Energy Campus includes a pulverized coal-fired generating station and associated mine, rail, water, coal combustion waste storage and ancillary support that is located in Washington and Randolph Counties in southwest Illinois. The generating station consists of two supercritical units with a nominal net output capacity of 815 MW each. IMPA’s 12.64% undivided ownership interest in Prairie State is approximately 206 MW.  

The Prairie State Energy Campus is situated adjacent to underground coal reserves owned by the Prairie State Participants.   The coal mine is expected to supply all the fuel for Prairie State for approximately 30 years.  Prairie State is among the cleanest coal burning plants in the United States. The plant utilizes state-of-the-art control technologies including low NOx burner controls, SCR for NOx removal, dry electrostatic precipitators, wet flue gas desulfurization and wet electrostatic precipitators.


IMPA, Duke Energy Indiana, Duke Energy Ohio, and the Wabash Valley Power Association are all joint owners of the Joint Transmission Sytem (JTS), which provides transmission access to approximately two-thirds of the State of Indiana.

The JTS includes approximately 1,274 miles of 345-kilovolt (kV) transmission line, 777 miles of 230 kV line, 2,185 miles of 138 kV line, and 3,259 miles of 69 kV line.  The JTS also includes 108 transmission substations and 450 distribution substations, which are classified as local facilities.  The JTS arrangements include all rights to the use, output and capacity of these transmission and local facilities. 

The JTS Owners are transmission-owning members of the Midcontinent Independent System Operator, Inc. (MISO).  The JTS Owners retain ownership of the JTS, but MISO schedules, manages and oversees the use of the JTS.

In addition to its ownership of transmission facilities, IMPA receives transmission service provided by MISO and the PJM Interconnection, LLC (PJM) under their open access transmission tariffs and under bilateral contracts with other utilities. The JTS, together with these open access transmission tariffs and bilateral contracts, provide IMPA sufficient access to transmission facilities to deliver power and energy under the Power Sales Contracts, to purchase and sell economic wholesale energy, to allow power exchanges with other utilities and to participate in the MISO and PJM energy markets.

Trimble County

Trimble County Unit 1 is a 491 MW coal-fired electric generating unit located in Kentucky on the Ohio River approximately 20 miles southwest of Madison, Indiana.  Trimble County Unit 1 was placed in service in 1990.  IMPA has a 12.88% undivided ownership interest in Trimble County Unit 1, which is jointly owned by Louisville Gas & Electric Company (LG&E) and the Illinois Municipal Electric Agency (IMEA).  Trimble County Unit 1 is equipped with particulate, SO2 and NOX removal facilities and utilizes high sulfur coal.  Installation of a SCR for NOX control was completed in 2003.  The SO2 removal facilities were upgraded in 2005 to increase removal efficiency.

Trimble County Unit 2 is a nominal 740 MW, supercritical steam unit constructed at the same site as Trimble County Unit 1.  Trimble County Unit 2 was placed in service in 2011.  IMPA has a 12.88% ownership interest in Trimble County Unit 2, which is approximately 100 MW.  LG&E, Kentucky Utilities, and IMEA also hold ownership interests in the unit.  Trimble County Unit 2 includes state-of-the-art emissions control, including a SCR, a dry electrostatic precipitator, a bag house; wet flue gas desulfurization; and a wet electrostatic precipitator.  The plant is designed to comply with all current emissions regulations and permit conditions and is well prepared to comply with upcoming federal regulations.  Trimble County Unit 2 also allows for fuel flexibility enabling the use of lower-cost or low sulfur fuels in the unit’s operation.

Whitewater Valley Station

IMPA assumed operational control of the Whitewater Valley Station (WWVS) located in Richmond, Indiana in 2014.  Since then, the station has been utilized by IMPA during peak load periods during the hot summer months and cold winter months.  WWVS is composed of two sub-critical pulverized coal fired generation units.  The aggregate capacity of WWVS’s generating facilities is 91 MW.