There’s been a push to wean vehicles from petroleum, but fossil fuels will continue to power the transportation field for the next few decades, according to the ExxonMobil researcher who advises the company’s corporate executives.

“Oil will provide about 90% of transportation usage though 2040,” said Tahmid Mizan, Senior Technical Advisor at ExxonMobil Corp.

The keynoter at the 2015 SAE World Congress focused on mobility as he detailed the company’s long-term view of global energy consumption and supply Wednesday morning. His talk, “The Outlook for Energy: A View to 2040,” included many factors that will impact energy supply and demand.

One is that the global population is growing rapidly, as is the number of middle-class people who have the wherewithal to purchase vehicles. That will drive up the demand for vehicles as the new middle class buys cars and businesses buy trucks to deliver goods needed by the burgeoning population. Much of this growth will come in emerging nations.

“Transportation will be largely flat in developed countries, but there will be significant growth in undeveloped countries,” Mizan said. “Overall demand grows about 40%, with most growth in heavy-duty vehicles.”

Though the number of vehicles on roads will soar, fuel consumption won’t. That’s largely because internal-combustion powertrains will continue to enhance efficiency. Electrification will also have some impact.

“Light-duty consumption will be essentially flat to declining, which is remarkable because the number of vehicles will double through 2040,” Mizan said. “The share of hybrid vehicles will grow to about 33% by 2040.”

He predicted that plug-ins and fuel-cell vehicles won’t grow beyond mid-single-digit percentages. Skeptical engineers at the SAE World Congress asked Mizan about ExxonMobil’s prognostication track record. He responded that demand forecasts have been pretty good, but the company has underestimated on the supply side. He said 1981 estimates were for about 2 trillion barrels of oil, rising to 3.3 trillion in 2000. Now, researchers say there’s 5.5 trillion barrels available.

“That’s equivalent to about 150 years supply,” Mizan said. “It’s likely that five years from now, the oil reserve expectations will continue to expand. The technology to find and produce resources, through horizontal drilling and other technologies, continues to improve.”

It’s important for ExxonMobil to understand how the global supply and demand for energy will change over the long term. The company spends $30-40 billion annually on capital assets that often remain operational for several years.

In his non-transportation discussion, he said natural gas will see very solid growth, which bodes well for reducing emissions. Solar power will be one of the fastest-growing energy sources, with a 10x growth rate. It will account for roughly 6% of energy consumed in 2040, Mizan predicted.

“It’s got the fastest growth rate, but it started from a very small base,” he said.