Overall global energy demand is expected to be 30% greater than the current level by 2040, while energy needs in developing nations are predicted to soar by 60% during the same period. This is according to The Outlook for Energy: A View to 2040, an Exxon-Mobil report released in mid-December.

During the next three decades, the major expects natural gas to be the fastest-growing major energy source. By 2025, natural gas is forecast to become the second-most widely used source of energy worldwide.

The demand for coal, however, should peak around 2025 and then begin to decline, as improved efficiency combines with a shift to less carbon-intensive energies, particularly in the electricity-generation sector. The shift will be led by countries belonging to the Organization for Economic Cooperation and Development (OECD).

Even China, which today accounts for close to 50% of global coal demand, will see its use fall by more than 10% through 2040, according to the report. This would mark the first long-term decline in global coal use since the start of the Industrial Revolution.

Nonetheless, oil, gas and coal combined will account for about four-fifths of the fuel mix through 2040. Global demand for the least carbon-intensive fuels—natural gas, nuclear and renewable—will rise at a faster-than-average rate.

Oil will remain the world’s top energy source, led by a 70% growth in liquid petroleum demand in developing countries such as China and India. In countries belonging to the OECD, “We see energy use remaining essentially flat, even as these countries achieve economic growth and even higher living standards,” the report states.

By contrast, the energy demands of non-OECD nations—which are primarily developing countries—will expand during the next two decades and then gradually flatten as economies and populations mature. Elsewhere, billions of people will be working to advance their living standards, requiring more energy. The need for energy to make electricity will remain the biggest driver of demand.

The report provides perspective about the development of unconventional resources. “For both oil and natural gas, an increasing share of global supply will come from unconventional sources such as those produced from shale formations.”

From an environmental perspective, some favorable news will be coming during the next three decades, according to the report . “Gains in efficiency through energy-saving practices and technologies—such as hybrid vehicles and new, high-efficiency natural gas power plants—will temper demand growth and curb emissions. Global energy-related carbon dioxide (CO2 ) emissions will grow slowly, then level off around 2030. In the U.S. and Europe, where a shift from coal to less carbon-intensive fuels such as natural gas already is under way, emissions will decline through 2040.”

By 2040, the world will have 2.8 billion households, according to the report—a nearly 50% increase from 2010. These households will need energy for lighting, heating, cooking, hot water and refrigeration, as well as electricity to run everything from computers to air conditioners.

Every region of the world will see a net increase in households through 2040, but growth will be particularly strong in Africa, China, India and Latin America. Africa is expecting a sharp rise in population; China will have fewer multifamily or shared households; and India and Latin America are both expected to have growing populations and fewer shared homes. By 2040, these four regions will account for about 60% of all households in the world, according to the report.

“Through 2040, global growth in households will more than offset projected improvements in residential energy efficiency, resulting in rising demand in this sector. Yet in terms of the relationship between people, their homes and their energy use, it is important to remember that significant differences exist between regions.”

Despite the projected population growth in the four regions, average energy use per household in non-OECD nations will remain relatively low. Even by 2040, it will be only about two-thirds of the level of the average household in OECD countries.

As conventional oil production holds relatively flat through 2040, demand growth will be met by newer sources. The biggest gains will come from global deepwater production, which will more than double through 2040, notes the report.