MISO began running the nation’s biggest Regional Transmission Organization by geography with the integration last week of Entergy’s transmission system and those of six smaller transmission owners.

The addition of territory in Arkansas, Mississippi, Louisiana and southeastern Texas gives the RTO control of transmission in 15 states from Canada to the Gulf of Mexico. MISO’s transmission system grew by nearly one-third (to  65,787 miles), while it added more than 30,000 MW of generation capacity, to almost 197,000 MW. MISO’s 900,000 square miles makes it the nation’s largest RTO by area.

In addition to Entergy’s six operating companies, the new MISO South region includes Cleco Corp.; Lafayette Utilities System; Louisiana Energy and Power Authority; NRG Energy’s Louisiana Generating; South Mississippi Electric Power Association and East Texas Electric Cooperative.

Generation, Load Diversity

The MISO South “cutover,” which was completed Dec. 18, provides more diversity for MISO, with summer peaking regions in the south offsetting winter peaking areas in the north.

It also provides the Midwest easier access to natural gas and nuclear generation in the south, reducing the RTO’s dependence on coal, from 51% of capacity to 46%. A recent survey of MISO market participants projects a capacity shortage of 7,500 to 8,500 MW in 2016. (See MISO to PJM: We Need Capacity)

In theory, the transition also will make it easier for Midwest wind generators to move power to the south. But the lack of renewable portfolio standards in the region means wind power will have to compete on price alone.

Savings for Entergy

Entergy said the access to MISO’s market and the RTO’s economies of scale and transmission cost allocation will save its consumers $1.4 billion in the first decade. It also is expected to help Entergy escape a U.S. Justice Department inquiry into complaints by independent power companies, who have complained about what they called Entergy’s anti-competitive behavior for more than a decade.

ITC Merger Cancelled

Although the MISO integration was completed as expected, Entergy was forced to cancel its plan to sell its transmission system to ITC Holdings Corp. The $1.78 billion deal, announced two years ago, was scotched after the Mississippi Public Service Commission ruled Dec. 10 that the transaction was not in the public interest. The regulators said they feared state ratepayers’ costs would increase by $300 million over 30 years.

Entergy shareholders would have controlled about 51% of ITC after the transaction.

Power Trading

With the completion of the integration, MISO started reporting prices for trading hubs in Arkansas, Louisiana and Texas.