Salt River Project will spend $220,000 buying renewable-energy credits from the Navajo Nation to help meet the metro-Phoenix utility's sustainability goals.

A renewable-energy credit, or REC, is a paper marker representing the environmental benefits of alternative energy. The credits can be bought and traded separately from the actual electricity generated from solar arrays, wind farms and other renewable-energy projects.

The Navajo Tribal Utility Authority will use the money from SRP to buy solar- and wind-power systems that it leases to customers living off the grid in the remote reservation in northeast Arizona, northwest New Mexico and a sliver of Utah.

The authority provides electricity to about 39,000 customers but estimates that 16,000 families live beyond its power lines.

The RECs that SRP is buying will come from alternative energy generated on the reservation.

The authority has a few large solar arrays at the tribal facilities and provides portable solar and wind systems to about 263 customers who live too far from power lines to get line extensions built to their homes. The program was established in 1998.

Families who participate in the program with the tribal utility appreciate the ability to power their homes.

The Johnson family in northeast New Mexico got one of the systems installed more than a year ago. When visited by The Republic in November, the family's two young daughters, Erika and Maria, spoke excitedly about being able to watch movies, make popcorn and keep milk in the refrigerator without having to haul ice to their home.

Terry Battiest, a renewable-energy engineer for the tribal utility, said the utility will buy 25 solar and wind systems for off-grid families with the proceeds of the SRP deal.

"They are in high demand," he said. "It was a great opportunity for (the tribal authority)."

The latest generation of systems the utility is providing families can generate 1.7 kilowatts of electricity from solar panels; they also have small wind turbines, batteries to store the power and include an efficient refrigerator.

"With this partnership, SRP is helping us help families who otherwise might not be able to have any access to electrical power," said Walter Haase, general manager of the tribal utility. "This program will provide that basic access."

SRP officials voted last year to meet 20 percent of the utility's power demand with renewable energy and conservation. As much as one-quarter of that goal can be met with RECs.

Some industry experts criticized that policy, saying that purchasing RECs would send ratepayer money out of the utility territory that could be better spent stimulating the local economy.

SRP officials said the option to buy RECs instead of buying renewable energy was important in case they could not find enough suitable energy projects in their utility territory.

SRP will purchase as many as 4,583 RECs through the deal. The utility also has another deal to purchase as many as 50,000 RECs a year, but even that much larger deal doesn't bring the company near its authorized limit of REC purchases, officials said.

"We are really trying to develop a balanced portfolio with some solar, wind, biomass and some RECs," said Mark Russell, a senior planning analyst for SRP.

The deal is one of many between SRP and the tribe. SRP and Tucson Electric Power also help provide alternative energy to Navajo organizations and other tribes through a $5 million fund that was set up as part of an agreement to allow the expansion of the Springerville Generating Station, a coal-fired power plant.

That fund announced several recipients earlier this week.

The Navajo utility entered a partnership with another coal-fired plant, the Navajo Generating Station, which is run and 21 percent owned by SRP. That February deal will extend power lines to more than 62 families in the LeChee region of the reservation and cost the power-plant owners $2 million.

The Navajo Nation also is developing a wind farm on a parcel of land it owns separate from the reservation, about 80 miles west of Flagstaff, and has an arrangement to sell that power to SRP.