The politics of renewable energy headed the agenda in battleground Nevada, where Democratic Senate Majority Leader Harry Reid and Interior Secretary Ken Salazar opened a fifth annual green energy conference touting the start of a 12-square-mile wind energy farm in rural White Pine County.

San Francisco-based Pattern Energy's Spring Valley project is the first wind major wind farm in Nevada and is designed to produce to up to 150 megawatts of electricity, or enough to power 45,000 homes. Salazar called it an example of an Obama administration strategy toward freeing the use of federal lands for energy production.

In Washington, the administration announced Tuesday that seven solar and wind energy projects in Arizona, California, Nevada and Wyoming would be fast-tracked. Officials said they together could produce nearly 5,000 megawatts, or enough to power 1.5 million homes.

"We've come too far to allow the clock of progress to be turned back," Salazar said at the conference focusing on wind, solar and geothermal energy.

President Barack Obama and Republican candidate Mitt Romney have differing approaches to domestic energy production.

Obama touts renewable energy, while Romney wants to reduce obstacles to coal, natural gas and nuclear energy development. Romney also supports opening the Atlantic and Pacific outer continental shelves to drilling, as well as Western lands, the Arctic National Wildlife Refuge and offshore Alaska. He says green power has yet to become viable and the causes of climate change are unknown.

Reid declined to comment Tuesday about Arctic drilling, saying he wanted to keep the focus of his conference on renewable energy projects. But in his opening comments to the conference, called the National Clean Energy Summit 5.0, Reid derided those who deny that the burning of fossil fuels has contributed to global climate change.

"Those people aren't just on the other side of the debate," he said, "they're on the other side of reality."

A Romney aide said Tuesday that Congress should let a tax break for wind energy producers expire at the end of the year. But Salazar said the Senate Finance Committee agreed last week on a bipartisan proposal to extend the production tax credit for wind energy.

"That shows it ought not to be a Republican or Democratic issue, it ought to be an American issue," Salazar told nearly 700 people during his morning speech at the Bellagio resort. "Our national security, our economic security, our environmental security, those are American issues and everyone should stand behind them."

Reid told reporters he'd like the measure to pass before the November election, but he was confident it would pass by the end of the year.

Salazar told the conference that a planned 3,000-megawatt wind power complex in Wyoming would provide electricity to homes as far away as Nevada and California. He also touted administration efforts to spur the first Atlantic Ocean wind energy projects. The U.S. currently has no operating offshore wind farms, but Salazar said the Cape Wind project off Massachusetts has received permits to become the first.

The conference was expected to feature an afternoon address by Bill Clinton, a "fireside chat" involving the former president and his former White House chief-of-staff, John Podesta, and a closing speech by Reid.

Clinton and Podesta have appeared at earlier Reid energy summits. Podesta co-chaired Barack Obama's presidential transition and now heads a liberal think tank in Washington.

Republicans have blamed Obama for granting more than $500 million in federal stimulus loan guarantees to the Solyndra Inc. solar power project in California. The venture declared bankruptcy in September. Other companies with smaller loan guarantees have also folded.

The Obama administration said losses were expected when Congress set aside $10 billion for high-risk program loan guarantees to projects that would have trouble obtaining private financing. It points to a former Treasury Department official's report saying more rigorous financial oversight and stricter performance standards could reduce the risk of future defaults.

In Nevada, a North Las Vegas green energy plant closed last month, a little more than a year after it began producing concentrated photovoltaic solar power systems. Seal Beach, Calif.-based Amonix Inc. had received a $15.6 million federal Energy Department grant in 2007 under the Bush administration.

But Nevada is home to the Hoover Dam hydroelectric power plant on the Colorado River and is third in the nation for utility-scale solar projects. It has served several times as a stage for Obama and Reid to highlight renewable energy projects.

In March, the president visited the largest photovoltaic solar power plant in the nation, about 20 miles east of Las Vegas. He praised its ability to produce 48 megawatts of power, or about enough for 14,000 homes. A Copper Mountain Solar 1 official said $50 million in federal tax credits represented about 30 percent the cost of building the project. The plant sells its output to a California utility.

Pattern Energy Group LP's $225 million wind farm, some 200 miles north of Las Vegas, will plug into the Silver State power grid under a 20-year agreement with NV Energy Inc.

The state's dominant electric utility faces a state requirement to draw up to 20 percent of its power from renewable sources and conservation by 2015 and 25 percent by 2025. Critics complain NV Energy relies too heavily on coal.

The project went ahead after settlement of a lawsuit alleging the federal government unfairly fast-tracked approval. Environmentalists argued the 66 giant turbines standing about 30 stories tall will be too near caves that biologists call a key roosting point for migrating Mexican free-tailed bats.

Pattern Energy CEO Mike Garland said cave entrance sensors and a wind farm radar system are designed to provide time to shut turbines down when the flying creatures are active.