Hillary Clinton laid out ambitious plans Monday to invest in solar and other renewable energy if elected US president, drawing a contrast with her fossil fuel-loving Republican rivals.

"We will make America the world's clean energy superpower," she declared at a campaign event in Des Moines, Iowa, unveiling highlights of a concept she said could ultimately impact every American household.

But she declined to weigh in on the controversial Keystone XL pipeline that would send Canadian crude oil to US refineries, a project criticized by environmentalists and many Democratic lawmakers that is awaiting a final State Department review.

"I refuse to turn my back on what is one of the greatest threats and greatest opportunities America faces," the Democratic 2016 frontrunner said about greenhouse gas emissions and their climate impact.

"I refuse to let those who are deniers, who disagree with what we need to do, to rip away all the progress we've made and leave our country exposed to the most severe consequences of climate change," she added.

"America needs to lead this fight, not go MIA."

Clinton laid out a two-pronged renewables agenda.

"We need to have more than half a billion solar panels installed across the country by the end of my first term," she said.

"Second, we'll set a 10-year goal of generating enough renewable energy to power every single home in America."

According to her campaign, those goals translate into an installed solar energy capacity of 140 gigawatts by 2020, or a 700 percent increase over the number of solar panels installed today.

Her plan calls for using renewable energy to generate a third of all electric power in 2020, along with investments that her campaign says will put America's economy on the road toward "deep decarbonization by 2050."

Climate change is a hyper-partisan issue in the United States, with many Republicans, including some 2016 presidential candidates, questioning whether human activity contributes to global warming.

In Congress, the Republican majority has fought anti-pollution standards established by President Barack Obama, notably for coal-fueled power plants.

Clinton signaled the need for a compassionate approach to Americans in the coal industry.

"We cannot close our eyes to the challenges facing hard-working families in Coal Country, who kept our lights on and our factories running for more than a century," she said.

In 2014, about 67 percent of US electricity came from fossil fuels, principally coal, according to the Energy Information Administration.

About 13 percent comes from renewables, including just 0.4 percent from solar. The rest, almost 20 percent, is generated by nuclear power plants.

Keystone is a quandary for Clinton, whose silence on the matter -- she was the top US diplomat when the State Department began its pipeline review -- has earned her rebukes from liberals seeking the Democratic nomination.

"I will refrain from commenting because I had a leading role in getting that process started and we have to let it run its course," she said.

Clinton proposes giving states and localities financial incentives to fight climate change, either by placing tighter emissions curbs than the law requires or through stepped-up investments in renewables.