Utah has the potential to develop solar, wind and geothermal energy resources on over 13,000 square miles throughout the state, according to a draft report prepared for a state task force.

Transmission of energy from some of those areas will be the tricky part.

"We realize that to be able to bring those resources on line, we need to be able to tie them into the grid," said Dianne Nielson, energy adviser to Gov. Jon Huntsman Jr.

Nielson said additional lines will need to be built, and some alternative-energy sources are already close to the grid.

The Utah Renewable Energy Zone Task Force met Thursday to finalize the report called a "Renewable Resource Assessment." With its maps that pinpoint where the best sources are, the report is seen by Nielson as a guide — and encouragement — for industry, as companies consider development projects in Utah's renewable energy zones.

According to the report, "While Utah's technical potential for renewable energy generation is apparently great, development of these resources is constrained, due to a multitude of factors that are unknown at this time."

The task force, which met for the first time last July, is made up of 20 members chosen by Huntsman, whose goal is to see the state fulfill 20 percent of its electricity needs from renewable-energy sources by 2025. Utility-company leaders; energy developers; federal, state and local government officials and environmental groups make up the task force.

The report identified 6,371 sites for solar energy on as many square miles, 51 sites for wind power on 1,838 square miles and four major geothermal zones on 5,053 square miles. Southern Utah has "higher quality" solar resources, the report said. All but five of Utah's 29 counties have a potential wind-power site, with the greatest concentration of wind-power potential, at 2,500 megawatts, near Milford in Beaver County.

For solar-generated electricity alone, the state appears to have the potential to produce 826 gigawatts of utility-scale capacity, according to the report. One gigawatt is equal to 1 billion watts, or enough electricity to power 500,000 homes.

The task force's goal is to identify areas in Utah with the greatest potential to yield utility-scale energy. So far, the group hasn't researched land-use and environmental issues related to developing renewable energy sources. Nielson said the task force's next phase will also require industry to develop cost estimates for projects and look further into the economics of developing the resources.

Geothermal resources are considered "significant" enough in Utah to provide 750 megawatts of electric generation over the next 10 years, and twice that amount long-term. Geothermal companies are "aggressively" leasing properties with geothermal potential, the report noted.

Last month, Interior Secretary Dirk Kempthorne announced that 118 million acres overseen by the Bureau of Land Management and 79 million acres of National Forest Service land in the West were being made available for geothermal development. Almost 9.5 million acres of BLM land and more than 2.7 million acres of Forest Service land in Utah are potential sites for geothermal drilling.