MISO on May 15 said it plans to move ahead after all with Entergy Louisiana’s original version of a $260 million reliability project proposed for the southeast part of the state. 

The RTO announced about eight months ago it would delay recommending Entergy’s project to study alternatives. But this week it revealed it was unable to choose a suitable substitution, as the project’s higher-voltage alternative configurations were not cost effective. 

The project initially was introduced for MISO’s 2023 Transmission Expansion Plan (MTEP 23) as the third phase of Entergy Louisiana’s three-part, nearly $2 billion Amite South reliability project to satisfy the utility’s local reliability criteria. The RTO ultimately advanced a substitution for the first phase of the project last year. (See MTEP 23 Catapults to $9.4B; MISO Replaces South Reliability Projects.) 

This time, however, MISO said Entergy’s original proposal to construct a 40-mile, 230-kV line between its Adams Creek and Robert substations and upgrade the substations is more appropriate for the area than the 500-kV possibilities it analyzed. Entergy said in addition to the line solving potential overloads, the project would help it meet load growth in the Amite South load pocket and address upcoming generation retirements, which could be exacerbated by EPA’s new power plant emissions rules. Entergy also reasoned the line would provide an “additional hardened path” into Amite South, which can be useful during restorations following hurricanes or other extreme events. 

MISO studied two alternatives to Entergy’s proposal, including a $1.1 billion option involving construction of two 500-kV substations and more than 50 miles of 500-kV line. However, the RTO said construction costs would be too high and the project itself would be impractical to build. 

A second alternative — resulting in a new 500/230-kV station, an 11-mile 500-kV line to operate at 230 kV and a 26-mile 230-kV line — was found to cost about $100 million more than Entergy’s original proposal without solving any other reliability issues, MISO said. 

MISO plans to recommend Entergy’s project proceed as a late addition to MTEP 23. It will run its recommendation past the Planning Advisory Committee before seeking approval from the Board of Directors’ System Planning Committee and, later this year, from the board itself.