MISO approves 2000 miles of new transmission

The Tranche 1 Long Range Transmission Planning portfolio includes new transmission projects that were recently approved by MISO.

The MISO Board of Directors unanimously approved the Tranche 1 Long Range Transmission Planning Portfolio (LRTP) of new transmission projects. This is a significant step toward a future powered entirely by clean energy.

The $10.3 billion investment includes 18 transmission projects in MISO’s Midwest Subregion. The grid operator determined that the benefit-to-cost ratio was at least 2.6. This means that benefits far outweigh costs.

The portfolio of what MISO calls “least-regrets” projects will mean more than 2,000 miles of additional transmission lines will be built. The portfolio is the most complex transmission study efforts in the organization’s history, the grid operator said. The new transmission will connect to the transmission grid for up to 53 GW.

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MISO approved projects of this size for the last time in 2011. It took four years to do so. MISO said that the new project portfolio, which was larger in terms cost and mileage, took half the time.

The top photo shows the transmission lines approved. The table below gives more details.

The MISO portfolio of least-regrets project will result in more than 2,000 miles of additional transmission line construction.

MISO examined a number of benefits when approving transmission projects. It stated that system reliability was the most important factor, but also mentioned congestion and fuel savings, avoided transmission investment, resource sufficiency savings, and avoided risk of loadshedding and decarbonization.  

Over a 20-year period, the calculated benefit/cost ratio was 2.6. The 40-year b/c was 4. (An executive summary of the figure is below.

Six benefits were analyzed by MISO when the transmission projects were approved.

MISO also stated that the approved lines are meant to address specific transmission issues within its footprint.

  • Line 1 (as shown in the table), addresses voltage and thermal issues for Western Minnesota, and Eastern Dakotas.
  • Line 3 is a second low-impedance path that unloads and alleviates 115 kV, 230 kV issues and provides voltage stability.
  • Line 6 relieves constraints within the Minneapolis/St. Line 6 relieves constraints in the Minneapolis/St. Paul metro area because of high renewable flow towards and past the Twin Cities load centre; reinforces the outlet towards load centers in Wisconsin for congestion relief; and, eases thermal loading & transfer voltage stability.
  • Line 7 connects the high-renewable region of Iowa with the Quad Cities load centre and 354kV outlets to the rest of MISO. It provides an additional 345kV path southwest across Iowa.
  • Line 9 reduces the load on transmission elements in Iowa Missouri and Illinois.
  • Lines 16, 17 and 18 are expected reduce severe thermal issues in Michigan and Illinois, Missouri, Iowa, and Illinois.

MISO is currently studying three more portfolios (tranches). These portfolios would increase interconnectivity and further enhance the reliability of the system.

“Collectively, the multiple tranches of the LRTP comprise one of the four key elements of MISO’s Reliability Imperative, which outlines a shared responsibility to evolve MISO’s planning, markets, operations, and systems in an orderly fashion that preserves system reliability in the face of rapid changes in the MISO region,” said MISO in its executive summary.

#EnergyTwitter quickly reacted to the announcement with heartfelt praises and appreciation.

“While Tranche 1 represents an important start, further work is needed to ensure reliability,” said Aubrey Johnson, MISO’s vice president of system planning in a statement. “Tranche 2 will focus on the MISO Midwest Subregion, Tranche 3 in MISO South, and Tranche 4 will address the limitations on power exchange between the MISO Midwest and South Subregions.”

In a June letter, state regulators advised MISO that it was time for market signals to be reviewed and reliability requirements to be updated. They also suggested that MISO, the states and other entities responsible in resource adequacy should work together more. The letter, dated June 9, came a day before MISO released a joint report that said the region was projected to have a capacity deficit of 2.6 GW below the 2023 planning reserve margin requirement (PRMR). Similar to 2022 the capacity deficit for 2023 would be limited to MISO North/Central. This would be partially offset by exports to the South.

Addressing market signal deficits, the regulators said, “Put simply, MISO must ensure it has the markets and planning processes in place that can deliver the reliability and economic efficiencies its members expect.”

In May, MISO said in a summer readiness workshop that it would likely need to import more non-firm energy and/or need additional energy resources to meet the 2022 summer peak demand. At that time, temperatures were expected to rise above normal across the MISO footprint.