INTERVIEW: US Midcontinent ISO to measure more benefits in next grid portfolio

The Midcontinent Independent System Operator plans to consider a bigger pool of benefit as it develops its second tranche of long-range transmission plan grid projects, which could cost two to three times more than the first batch of projects, according to top transmission executive at MISO.

"Tranche 2 is going to be an order of magnitude bigger than what we've done in Tranche 1," Aubrey Johnson, vice president of system planning and competitive transmission at MISO, said in a recent interview with S&P Global Commodity Insights.

One new metric MISO plans to use in Tranche 2 is an analysis of the benefits of using higher voltage lines instead of lower voltage lines, Johnson said.

Compared to a 345 kV line, a 765 kV line will require less land per MW and have less line losses. "There are some quantifiable benefits that we think we can monetize," Johnson said.

MISO did not consider this benefit in the first tranche because the projects were predominantly 345 kV, Johnson said. Using a lower voltage line would not accomplish the regional impact that MISO was looking for, he said.

High-voltage direct current lines will also be considered in Tranche 2, but the picture might look different due to the injection and withdrawal points of HVDC lines, Johnson said. "I don't know, quite frankly, if some of the same things are going to map themselves out," he said.

Transfer capability

Transfer capability is also a consideration in MISO's benefits analysis. For instance, Tranche 1 considered the benefits of imports into Michigan, Johnson said.

In addition, the Federal Energy Regulatory Commission is weighing whether to impose a minimum level of interregional transmission capacity as the agency considers ways to safeguard the nation's power grid.

MISO has urged FERC to focus on assigning a value to that transfer capability, Johnson said. If those benefits are better defined and standardized, it would help MISO stack the benefits of transmission projects, he said.

For instance, one project could provide benefits for transfer capability, resilience and congestion. "And what otherwise might not have been a project in the past now becomes a viable project because I have enough benefits there," Johnson said.

Lessons learned

Other regions have reached out to MISO for information about the LRTP process, and the number one question is how to develop futures, Johnson said.

MISO develops a range of futures that underpin transmission planning. The futures consider different scenarios for changes in the resource mix, electrification and decarbonization.

MISO staff gets asked what tools they used to develop the futures, how they came up with scenarios and how they worked through the stakeholder process, Johnson said.

MISO has been very open, sharing information with anybody who asked, and helping them stand up any processes that they would like to have, Johnson said.

MISO has learned some lessons itself from the first tranche of projects. A key takeaway is the importance of setting expectations about how difficult the modeling is and how long the process will take. "We've kind of recognized that when we talk schedule, we talk big timeframes," he said.

In Tranche 2, MISO can also use its existing processes and analyses, and have time to focus on additional benefit metrics that might be pursued, Johnson said.

Tranche 2 costs

MISO plans to develop four tranches of LRTP projects. MISO's LRTP Tranche 1 included 18 transmission projects in MISO Midwest at a cost of $10.3 billion. Tranche 2 will also focus on projects in MISO Midwest, Tranche 3 will look at projects in MISO South, and Tranche 4 will consider projects that link MISO Midwest and MISO South.

MISO has said that Tranche 2 could cost $20 billion to $30 billion, and the grid operator has estimated the total cost of the four tranches could hit $100 billion.

The costs of Tranche 2 are driven by the scale of utility and state climate goals, Johnson said. When you consider how many renewables will be added to the system, MISO will need a significant amount of transmission to support that, he said.

"We have to also remember that the resources being planned don't carry the same capacity factors as the resources that are being retired," Johnson said. "Think about the amount of arteries that you need to deliver to some of the same points," he said.

While Tranche 1 was the biggest grid investment in US history and Tranche 2 will be even bigger, some stakeholders continue to urge MISO to be as aggressive as possible.

MISO's goal is to optimize both transmission and generation at the best value, Johnson said. "I think we'll let the chips fall where they may," he said. "History will tell us whether or not we were aggressive enough."