Surging oil and gas production will help North America become a net exporter of oil and gas by 2025, U.S. energy giant ExxonMobil said in its annual energy outlook released Tuesday. More than half of the growth in unconventional natural gas supply in the next two decades will be in North America, providing a strong foundation for increased economic growth across the United States, and most notably in industries such as energy, chemicals, steel and manufacturing, the Texas-based company said in its Outlook for Energy: A View to 2040. The company predicted that global energy demand in 2040 will be about 35 percent higher than in 2010. Future energy needs will be supported by more efficient energy-saving practices and technologies, increased use of less carbon intensive fuels such as natural gas, nuclear and renewables, and the development of unconventional energy sources, it said. Natural gas is expected to overtake coal by 2025 as the second most-used fuel, according to the ExxonMobil report. The company predicted that natural gas use will keep increasing, at the expense of coal. By 2040, natural gas will account for 30 percent of global electricity generation, compared with less than 25 percent today, it said.