The United States is expected to achieve energy independence by 2025 to 2030, thanks to the robust shale gas development, an energy expert said Wednesday. The most eye-catching change in the world energy industry right now is the U.S. shale story, said Kristine Klavers, senior vice president of Hart Energy. The shale gas sector will continue to grow in the United States, she told Xinhua on the sidelines of the Offshore Technology Conference. According to the U.S. Department of Energy, the proportion of the country\'s domestic energy production and the use of new energies will increase while energy import will decrease. Klavers noted that she sees the change of the U.S. domestic energy production to have an influence not only on the crude oils, but also on petro-chemical market worldwide. Meanwhile, Klavers stressed the importance of safe practices in the development of shale gas. She said energy companies need to continue to stay on top of safety and environment and ensure that no accident will give a negative picture to the market. Shale gas is natural gas trapped within shale formations and has become an increasingly important source of natural gas in the United States in the past decade. It provided around 1 percent of U.S. natural gas in 2000, and over 20 percent in 2010. The U.S. Energy Information Administration estimated that 46 percent of natural gas in the United States will come from shale gas by 2035. It is extracted through hydraulic fracturing. To release the gas from the rock, huge amounts of water along with sand and small amounts of chemicals need to be pumped in to crush the rock. Some scientists said the burning of shale gas releases fewer greenhouse gases than other fossil fuels. But some said the impact of shale gas on environment, such as the leaking of extraction chemicals and the greenhouse gas emission during the extraction, may be stronger than estimated.