Wind, solar and other renewable energy sources now make up just about 10% of the U.S.’ electricity supply, but transitioning to 100% clean energy is both necessary and feasible, according to a new report from Environment America and Frontier Group.

On Wednesday, David Freeman, author of All-Electric America and longtime utility CEO, joined other clean energy advocates and academic experts for an online presentation and discussion of the new white paper.

“My colleagues have exhaustively proven, in infinite detail, that we can put together an electric power supply that’s all renewable,” says Freeman. “Their studies prove that beyond any reasonable debate.”

The report, titled “We Have the Power: 100 Percent Renewable Energy for a Clean, Thriving America,” lays out whys, wherefores and how-to’s for transforming the nation’s energy supply entirely to non-polluting sources. The paper cites the rapidly falling costs of both wind and solar and notes that the growth in solar has outstripped even clean energy advocates’ expectations.

“Renewable energy has strong public support, and clean energy is nearing a tipping point in our economy,” says Rob Sargent, energy program director at Environment America and one of the report’s co-authors. “It’s revitalizing local economies while every day, the imperative of addressing our environmental challenges becomes clearer.”

Citing stats from the National Renewable Energy Laboratory, the report says the U.S. has the technical potential to meet its current electricity needs more than 100-times over with solar energy and more than 10-times over with wind energy. In addition, the report says the U.S. also has massive potential to save energy, citing estimates from the American Council for an Energy-Efficient Economy that the country can reduce its overall energy use by 40% to 60% below current levels by mid-century, even as the economy continues to grow.

The report reviews several detailed studies on clean energy systems conducted by academics, government agencies and nonprofit organizations showing that there are no insurmountable technological or economic barriers to tapping the country’s vast potential to achieve 100% renewable energy.

“It all works. There’s lots of resources; you don’t have the lights go out,” says Dr. Willett Kempton of the University of Delaware, author of one of the studies reviewed in the paper.

The report adds that economists predict the U.S. can build a 100% renewable energy system at costs comparable to or less than what the country would have to spend to continue its reliance on dirty energy. It also says the International Energy Agency estimates that limiting global warming to 2 degrees C would require an additional investment of about 1% of global gross domestic product per year. That investment would yield savings of more than $115 trillion on fuel by 2050 – a net savings of more than $70 trillion.

“There’s very little downside to the transition,” comments Mark Jacobson of Stanford University, author of several studies showing the feasibility of 100% clean energy. “We think this is a winning situation for everyone in the long term.”

The report says dozens of cities around the country are already leading the way to 100% clean energy. Georgetown, Texas, for example, is 90% powered by wind power from Amarillo and will get another 10% from solar power in West Texas by 2017.

“Our decision here was first and foremost a business decision, and the objective was to have cost certainty,” explains Georgetown Mayor Dale Ross. “But we’re also just doing what’s best for our citizens. Don’t we have a moral and ethical obligation to leave the planet in a better condition than we found it?”

In Paris in December 2015, the nations of the world made a historic commitment to protect the climate, pledging efforts “to limit [global] temperature increase to 1.5 degrees C above pre-industrial levels.” Advocates say a transition to 100% clean energy was critical to fulfilling the Paris agreement.

“We’ve been told by the family doctor, the climatologist, that we have to reduce greenhouse gases to near zero in the next 35 years, or we’re going to cook,” says Freeman. “This is no longer something that we ought to do, or should do – it’s something we’ve got to do.”

“We can have healthier and more economically vibrant communities right now and a livable future for our kids,” adds Sargent. “But to get there, we need to transform the way we produce and consume energy. The good news is that 100 percent renewable is 100 percent possible.”

The report says leaders at all levels of government should act to accelerate the U.S. transition to 100% renewable energy, and the following five key principles should guide the country’s energy policy:

1. Prioritize energy savings. Conserving energy and using it more efficiently can ease the transition from dirty fuels to clean, renewable energy.

2. Promote steady and swift deployment of clean renewable energy sources. Solar and wind energy are poised to play a major role in every vision of a 100% renewable energy system.

3. Transition those portions of the U.S. economy that rely on direct combustion of fossil fuels to electricity and other zero-carbon energy carriers.

4. Provide reliable access to renewable energy by modernizing the electricity grid and enabling community microgrids and grid-connected energy storage.

5. To protect the global climate and people’s health, keep much of the country’s coal, oil and gas reserves in the ground and cease construction of new fossil fuel infrastructure.

The full report is available here.