The nuclear industry warns that without continued support for nuclear energy, President Obama's goal of achieving his newly announced clean energy goal will be next to impossible to achieve.

The president, together with the leaders of Canada and Mexico, announced Wednesday a goal of achieving 50 percent clean energy by 2025 for the whole of North America. The three countries said the goal will be achieved by building on low-emission power plants, including nuclear, solar, wind and even clean coal.

The Nuclear Energy Institute, representing the nuclear power industry in Washington, applauded the goal, but warned that if nuclear power plants continue to be forced to close due to market and policy factors, the goal will not succeed.

"The United States is adding five new nuclear plants that all will be on line by 2020, but any reduction in nuclear energy's role — specifically the premature closure of nuclear plants due to unintended consequences of federal or state energy policies or flawed electricity markets — makes it impossible to achieve the 50 percent clean energy target by 2025," said the group's President and CEO Marvin Fertel.

Exelon, the largest nuclear utility in the U.S., was the most recent company to announce it will be closing two of its facilities in the Midwest. Other power producers are considering similar action throughout the country. Despite the threat of closure, the U.S. nuclear power fleet comprises about 100 reactors, which is the largest of any one country.

Fertel said the biggest chunk of clean energy in the U.S. and Canada comes from nuclear and hydroelectric power plants.

"North America needs zero-carbon nuclear energy, and lots of it," Fertel said. "That's the biggest takeaway from the ambitious commitment to achieve a 50 percent clean electricity supply in North America only nine years from now."

He said nuclear energy facilities operate in 30 states and produce 62 percent of our carbon-free electricity. In Canada, nuclear power provides the bulk of electricity, second only to hydropower. And in Mexico, it comprises 18 percent of the clean energy mix.

But the White House appears to be working on the assumption that nuclear power will not grow beyond providing 19 percent of the nation's total electricity output, a senior administration official told reporters earlier this week. In fact, the administration sees the possibility of nuclear energy losing its share of the mix due to a number of plants being at risk of closing.

"Nuclear represents about 19 percent to the generation mix now," said the president's senior adviser Brian Deese. "Our projections going forward do not assume that that increases, and they do take into account the potential for some of the at-risk existing nuclear capacity. And in terms of our projections and our scenarios, we take into account the fact that that might come down."

Deese says clean energy development in the U.S. "is principally driven by the expansion of renewables and by energy efficiency."

He said a landmark five-year extension of tax credits for solar and wind last year will help that increase, along with the Environmental Protection Agency's climate rules.

Wind and solar power have increased dramatically in the last few years, but they still occupy just a sliver of America's total electricity system when compared to the bulk that is provided by coal and natural gas.

Renewable energy provided roughly 13 percent of the nation's electricity generation in 2015, according to the Energy Information Administration. Of that number, solar and wind energy provided less than half of the total.

Wind provided 4.7 percent of total U.S. electricity production in 2015. Solar provided 0.6 percent of total electricity, while conventional hydropower provided the biggest share of renewable power production at 6 percent.

Coal advocates said Wednesday that the 50 percent clean energy goal includes coal only if it includes special advanced technologies that have not been commercialized yet. Pro-coal groups say to include coal in the target is disingenuous because there is not one such plant in commercial use anywhere in the world.

"Today's joint commitment to generate 50 percent of North America's electricity via low or zero-carbon sources by 2025 not surprisingly raises more questions than it does answers," said Laura Sheehan, senior vice president of communications for the American Coalition for Clean Coal Electricity.

"The administration says one of the ways it will meet its goal is by utilizing energy from power plants with [carbon capture and storage (CCS)]. The problem with that assertion, however, is that there are no scalable plants anywhere in the world with CCS and none will ever be built in this country thanks to regulations promulgated by this administration," Sheehan says.

She asks: Where would the bulk of low or zero-carbon energy come from, if not from cleaner fossil fuels? "Certainly not rainbows and unicorns, which one would have to [have] pockets full of to meet these pie in-the-sky commitments," she says.