A new study says that the U.S. and Canada could produce 80 percent of its energy from renewable energy sources by 2030, and one academic thinks its forecast is way off.

The Solutions Project, an environmental group promoting renewable energy, recently released a paper outlining how renewable energy could produce electricity and fuel transportation through solar, wind, and other renewable sources. Gary Wolfram, a professor of economics and public policy at Hillsdale College, says that the data shows the group is not presenting a realistic forecast.

Wolfram cites Tony Seba, an entrepreneur and lecturer at Stanford University, who has forecasted that within 15 years all energy will be from renewable sources. The U.S. will no longer need oil, coal, or nuclear power, and all non-electric vehicles will be eliminated, according to Seba.

“While interesting paths to these goals can be drawn, the probability of achieving them are very small for a number of reasons,” according to Wolfram.

Wolfram documents the current state of electricity generation in the U.S. – with 33 percent coming from natural gas, 33 percent from coal, and 20 percent from nuclear. Even though it has been increasing in capacity, only 13 percent comes from renewable energy. Solar power has a big opportunity to see consumption growth with its dramatic drop in price. The levelized cost of solar fell by 78 percent from 2009 to 2014, and is currently lower than coal with carbon capture and peak load natural gas.

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Offsetting gains from renewables has been the price of oil and natural gas falling steeply in recent years. That’s come from the use of horizontal drilling and other new technologies, which has been part of the U.S. becoming the world’s largest producer of oil.

Another challenge renewable energy has in competing with fossil fuels is that the generated power is intermittent and can be reduced on days with less blowing wind and sunshine. Battery technology will need to improve dramatically to store the energy in batteries when wind and solar isn’t being generated.

Gasoline-powered vehicles will likely to continue to see demand in 15 years for at least two reasons, Wolfram said. There are more than 200 million gasoline-powered light duty vehicles on U.S. roads, with 31 million new gas-powered cars sold in the past two years. “To think all the owners of all these cars will replace them in a 15-year period is not reasonable,” he said.

Another reason gasoline-powered cars have a real advantage is access to fueling stations. That breaks out to 168,000 gasoline stations and over 13,000 electric vehicle charging stations in the U.S.

Even with the significant improvements in renewable energy and charging stations, it’s going to take more than 15 years to see a complete transition away from fossil fuels, according to Wolfram.

The Detroit News