Tri-State Generation and Transmission Association — which supplies electricity to Garland Light & Power — has issued its sixth request for proposals (RFP) for renewable energy resources.

“Steady investment in renewables from Tri-State and our members means one of every three electrons consumed in our association comes from emissions-free renewable resources,” said Duane Highley, chief executive officer of Tri-State. “This RFP advances our drive to be a 21st century power supplier for our members that is increasingly flexible and clean.”

As renewable energy prices have decreased, Tri-State said it’s accelerated the pace of its renewable additions. The association’s weighted average cost of all 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,” said Brad Nebergall, senior vice president, energy management.

Tri-State’s addition of renewable resources, as well as the availability of low-cost market power, has reduced the association’s use of coal. Nebergall noted that the coop closed one coal-fired plant and plans to retire two others.

The coop and its members currently have enough renewable resources to power the equivalent needs of more than 570,000 rural homes.

With the new RFP, Tri-State said it’s seeking low-cost solar and wind projects that will receive federal tax benefits. They’re seeking proposals of 10 to 200 megawats with terms of 15 to 25 years, with a preference for projects within the service territories of its member systems. Tri-State expects to make decisions on any new projects by the end of 2019.