Arkansas Electric re-visits shelved plans for three hydroelectric projects

Arkansas Electric Cooperative Corp. (AECC) filed March 3 applications at the Federal Energy Regulatory Commission for preliminary permits on three hydroelectric projects to be located on the Arkansas River.

One permit would be for the proposed Joe Hardin Lock and Dam No. 5 Hydropower Project on the Arkansas River in Lincoln and Jefferson counties, Arkansas. The project will utilize the existing U.S. Army Corps of Engineers lock and dam structure located on the Arkansas River at navigation mile 87.

If this application is granted, AECC will update the initial evaluation of the project that was performed in the period 1982-1983 when AECC filed an application for and received a FERC License for the project. In 1983, AECC received seven FERC Licenses for projects on the Arkansas River. Three of those projects, at Dam No. 2, Lock and Dam No. 9, and Lock and Dam No. 13, were constructed by AECC from 1988 to 2000. These three construction projects represented an investment by AECC of approximately $349 million.

The prior licenses for the remaining four projects, at Lock and Dam Nos. 3-6, were surrendered by AECC because further analysis showed them to be economically marginal or uneconomic to develop at the time. AECC also was in the position of needing capacity to meet system load requirements for its electric cooperative members and the remaining four projects were energy-oriented. After a ten-year period of adding capacity, AECC said it is now studying its options for new generation resources, including a program of renewable energy development for the next 20 to 25 years, making the projects worth pursuing at this time.

The proposed project will interconnect by use of a new 115-kV transmission line to the existing White Bluff power plant switchyard located approximately four miles west of the project site. The White Bluff power plant is jointly owned by AECC, Entergy Arkansas Inc. (EAI), and three Arkansas municipal utilities.

Preliminary estimates of the potential generating capacity and energy production at the project have been made utilizing the average flow data from the U.S. Geological Survey and Corps flow release records, and the Corps tailwater rating curve data. The total estimated average annual energy production is approximately 140 GWH annually based on an installed capacity of 36 MW. In the original feasibility study, four horizontal-shaft Kaplan, bulb-type turbines with a combined capacity of 36 MW were proposed to be installed with the associated electrical, mechanical, and control equipment. Alternative concepts for transferring the available water from the reservoir area to the powerhouse would be evaluated during this preliminary permit period to reduce the capital construction costs of modifying the existing Corps structures. Based on the results of the evaluation of these alternative concepts, the exact size and number of units may be adjusted at the conclusion of these studies, taking into account other existing beneficial uses of the water resource. The turbine-generator units are planned to operate as run-of-river units. 

The other two March 3 applications, which are projects that also had past lives, cover:

Lock & Dam No. 6 Hydropower Project

This project is located at the Col. Charles D. Maynard Lock and Dam on the Arkansas River in Jefferson County, Arkansas. The project will utilize the existing U.S. Army Corps of Engineers lock and dam structure located on the Arkansas River at navigation mile 108. It will interconnect via a new 115-kV transmission line to an existing Entergy Arkansas substation located approximately four miles northwest of the project site. Preliminary estimates of the potential generating capacity and energy production at the project have been made utilizing the average flow data from the U.S. Geological Survey and Corps flow release records, and the Corps tailwater rating curve data. The total estimated average annual energy production is approximately 140 GWH annually based on an installed capacity of 39.6 MW. In the original feasibility study, four horizontal-shaft Kaplan, bulb-type turbines with a combined capacity of 39.6 MW were proposed to be installed with the associated electrical, mechanical, and control equipment.

Alternative concepts for transferring the available water from the reservoir area to the powerhouse would be evaluated during this preliminary permit period to reduce the capital construction costs of modifying the existing Corps structures. Based on the results of the evaluation of these alternative concepts, the exact size and number of units may be adjusted at the conclusion of these studies, taking into account other existing beneficial uses of the water resource. The turbine-generator units are planned to operate as run-of-river units.

Joe Hardin Lock and Dam No. 3 Hydropower Project

This is located on the Arkansas River in Lincoln and Jefferson counties, Arkansas. The project will utilize the existing U.S. Army Corps of Engineers lock and dam structure located on the Arkansas River at navigation mile 50.

Joe Hardin Lock and Dam No. 3 has a proposed future highway bridge crossing over the dam. AECC said it will coordinate with the Corps and the Arkansas State Highway Department during detailed design of the project to ensure the powerhouse structure will accommodate a highway bridge. 

The project will interconnect by use of a new 115-kV transmission line to an existing Entergy Arkansas transmission line located approximately five miles southwest of the project site. Preliminary estimates of the potential generating capacity and energy production at the project have been made utilizing the average flow data from the U.S. Geological Survey and Corps flow release records, and the Corps tailwater rating curve data. The total estimated average annual energy production is approximately 155 GWH annually based on an installed capacity of 48 MW. In the original feasibility study, four horizontal-shaft Kaplan, bulb-type turbines with a combined capacity of 48 MW were proposed to be installed with the associated electrical, mechanical, and control equipment.

Alternative concepts for transferring the available water from the reservoir area to the powerhouse would be evaluated during this preliminary permit period to reduce the capital construction costs of modifying the existing Corps structures. Based on the results of the evaluation of these alternative concepts, the exact size and number of units may be adjusted at the conclusion of these studies, taking into account other existing beneficial uses of the water resource. The turbine-generator units are planned to operate as run-of-river units.

An Arkansas Electric contact is: Curtis Q. Warner, Director–Compliance and Support, 501-570-2462, Curtis.Warner@aecc.com. 

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.