Tri-State Generation and Transmission Association on June 13 issued a request for proposals for renewable energy, the sixth renewables-based RFP issued by the Colorado-based organization, which is seeking proposals for projects capable of generating 10 MW to 200 MW and delivering 30,000 MWh/year with terms of 15 to 25 years.

The RFP gives preference for projects “within the service territories of its member systems,” in the states of Colorado, New Mexico, Wyoming, and Nebraska. Westminster, CO-based Tri-State’s 43 member electric

Under the terms outlined in the RFP, eligible resources meet the renewable energy standard definition of the states of Colorado and/or New Mexico. In addition to solar or wind, this could also include small hydro, geothermal, biomass and, potentially, recycled energy or coal mine methane that meets Colorado’s standard as a renewable source.

Previous Tri-State RFPs added 656 MW of wind and solar resources to the cooperative power supplier’s portfolio. Tri-State said the weighted average cost of all its wind and solar power purchase agreements is now less than half of what it was in 2009.

“Tri-State has a demonstrated record of successfully adding cost-effective and high-performing renewable resources,” Brad Nebergall, Tri-State’s senior vice president, energy management, said in a press release. “In our not-for-profit business model, we get the best pricing and value for our members when we work directly with numerous project developers to build and operate projects.”

In addition to purchase power agreements, it is seeking build-transfer proposals for solar projects where Tri-State would own and operate the project “after investment tax credits have been captured.”

Earlier this year, Tri-State announced it secured PPAs from a 2018 RFP. The addition of the Crossing Trails Wind project in Colorado, a 104 MW project due to start operation in 2020 and Spanish Peaks Solar, also in Colorado, a 100 MW project scheduled to begin commercial operation in 2023, are projected to increase Tri-State’s wind and solar portfolio by 45 percent.

Tri-State said adding these renewables coupled with low-cost market electricity have enabled it to reduce its coal usage. “With competitive electricity markets and our renewable energy contracts, Tri-State is dispatching coal resources less, has closed one coal unit and will retire two other coal units,” Nebergall said.

In addition to its wind and solar resources, Tri-State currently has PPAs for 27 megawatts of small hydropower resources. In 2018, its PPAs for wind, solar and small hydropower combined “exceeded the association’s purchases of renewable hydropower from the Western Area Power Administration,” it said.

Proposals are due by July 25. Finalists should be announced by Oct. 3. Tri-State expects to make decisions on any new projects by the end of 2019.