The CEO of ExxonMobil Corp. says alternative fuels will grow but that oil will remain the world's leading source of energy for another quarter century.

Speaking Wednesday at the company's annual shareholder meeting, CEO Rex Tillerson said natural gas will surpass coal as the second most heavily used fuel.

About 15 people protested outside the meeting hall, charging that Exxon was not doing enough to reduce climate change and develop alternative sources of energy to burning oil and natural gas. Shareholders were scheduled to vote on a resolution urging Exxon to set emission-reduction goals from both its own operations and the use of its products.

Tillerson said that the Irving, Texas, company has reduced greenhouse gas emissions over the past five years, which he said was equal to taking nearly 2 million cars off the road.

ExxonMobil earned $32.6 billion last year, a decline of 26% from 2012. Revenue fell 9% to $438.3 billion. Exxon shares gained 17% last year; they have been flat in 2014.

But, as it has for several years, the environmental debate crowded out the financial one at the annual meeting of the nation's largest oil company.

A dissident shareholder and Dominican sister from New Jersey, Pat Daley, said that Exxon was making a long-term business mistake by not moving more aggressively into alternative fuels. She said the company was betting "that the nations of the world will continue to do nothing about climate change for the next 30 years."

Tillerson responded that he was confident technology will provide an answer to climate change, and he said ideas such as hard emissions-reduction goals were simplistic.

"There is not going to be a ready set of solutions that are going to fit the world's peoples" because, Tillerson suggested, people in developing countries will want to achieve the same living standards as those in the developed world, which will drive higher global demand for energy.

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