Tri-State's $186 million transmission plan

by Allen Best

Tri-State Generation and Transmission has filed an application with Colorado regulators to build two new transmission lines that would cover a combined 130 miles in the state’s eastern plains.

The two transmission lines, both with capacity of 230-kV, would complement a new transmission line already under construction and an existing line being upgraded.

Tri-State, Colorado’s second largest electricity provider, says that it expects these two new lines and the two other lines with work underway all to be completed by late 2028. Work on the four lines will cost a cumulative $185.6 million.

“By strategically and cost-effectively interconnecting three new transmission lines into our existing network and improving an existing transmission line, we will ensure power reliability, eliminate bottlenecks in our system, and support significant clean energy additions as part of our transformative Responsible Energy Plan,” said Duane Highley, chief executive of Tri-State.

In addition to the 17 member electrical cooperatives in Colorado, Tri-State delivers electricity to 25 other cooperatives in Nebraska, Wyoming, and New Mexico.

Highley noted that Tri-State’s electric resource plan now before the Colorado Public Utilities Commission calls for an additional 2,000 megawatts of renewable capacity.

“These transmission upgrades will help us achieve our aggressive greenhouse gas emission reductions goals,” he added.

Will Tri-State need this new transmission if United Power and other members leave? Tri-State responded to this question saying that if departure of any member is firm, then planning for that future can begin—but not until then.

“With a firm, unconditional notice to withdraw from membership in Tri-State, we would begin our planning on all issues related to a member’s departure,” said a statement from the company in response to a question from Big Pivots. “We cannot and will not plan any changes to our business with non-firm, conditional notices of withdrawal.”

Tri-State plans to close the three coal units it operates in Colorado, all at Craig, the last by 2030. It is targeting an 80% reduction in emissions of carbon dioxide associated with its electricity sales in Colorado by 2030.

Xcel Energy, more than double the size of Tri-State, aims higher, an 86% reduction by 2030 as compared to 2005. It has transmission plans that dwarf those of Tri-State. Those plans, called Colorado’s Power Pathway, could cost nearly $2 billion. They include 560 miles of 345-kV transmission in eastern Colorado with a possible 90-mile extension.

See: On the brink of yes in Colorado

The PUC commissioners concluded that Xcel has proven the need for the permit, which is formally called a certificate of public convenience and necessity. The commissioners are being asked to make a similar determination about Tri-State’s plans.

Tri-State’s studies have found Xcel’s and Tri-State’s proposed transmission systems will not interfere with each other. Instead, they will together help achieve Colorado’s renewable energy and greenhouse gas emissions reduction goals.

In creating the transmission plan, Tri-State assembled 60 stakeholders representing 24 entities to help evaluate alternatives during six months of 2021. This was in conjunction with the Colorado Coordinated Planning Group, a consortium created in 1991 to help ensure a high degree of reliability in the planning, development, and operation of the high-voltage transmission system in the Rocky Mountain region.

The proposed projects emerged as those among the 15 alternatives studied best able to meet Tri-State’s needs at the lowest cost. Stakeholders who took part in the analysis were from regional utility services providers, Colorado state government, the environmental community, the legal community, renewable energy developers, and related energy business and consulting communities.

Of the new power lines, one is a 30-mile segment east of Pueblo, and the second is an 80-mile line from near Limon to a switching station south of Fort Morgan.

Tri-State is also constructing a previously approved transmission line between substations near Burlington and Lamar. Another existing line, Big Sandy-Burlington, is being modified.

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