When Bill Barrett Corp, a small US natural gas producer, first went to Utah's Nine Mile Canyon in 2002 to begin drilling, it sought permission to drill fewer than 100 wells. But the price of natural gas has rocketed in the intervening years and now Bill Barrett is seeking approval for 800 more. In the last year alone, Devon Energy, an oil and gas explorer, has grown production by more than one-third to more than 1bn cubic feet equivalent a day in the Barnett Shale, its largest asset and one of the largest gas fields in the US. And, in the past few weeks, BP, the UK oil group, bought about 90,000 acres of natural gas properties in Oklahoma. The list of those eager to capitalise on the US's gas resources goes on. PFC Energy, the consultancy, said natural gas production in the US grew by 4.3 per cent last year, up from a 2.3 per cent increase in 2006. "No country in the world increased its natural gas production more than the United States in 2007 - not even Russia, Qatar or Azerbaijan," said Bob MacKnight, a PFC lead analyst. This year's percentage increase will be in double digits. Production data through this April showed a more-than-10-per-cent growth rate compared with the same time frame in 2007, Mr MacKnight said. US natural gas production was widely believed to have passed its peak. Yet high prices have encouraged companies to employ new and expensive technologies to access resources that were off-limits only a few years ago. While much of US natural gas production is obtained from conventional sources, most of the recent growth has been in unconventional resources, such as gas from shale, dense sandstone and coalbeds - which are known respectively as shale gas, tight gas and coalbed methane. Growth in these sources has been made possible by new technology advancements in horizontal drilling and fracturing. Ed Kelly, vice-president of north American natural gas and power for Wood Mackenzie, the consultancy, said much of the focus was on shale, which is plentiful in the US and only in the early stages of being developed. He believes there is potential for growth through the middle of the next decade. The rush is so overwhelming that Standard & Poor's, the ratings agency, suspects those engaged in US natural gas production are setting themselves up for future difficulties if expanded future supply pushes down prices. Yet the industry wants the US government to open the 60 per cent of federal land off-limits to the industry, in hopes of growing production still further. Ken Cohen, ExxonMobil spokesman, said: "We have the financial resources and the technical strength to develop new energy supplies here in the US in an environmentally responsive way. Let me emphasise this point: we want to do more." Marc Smith, executive director of the Independent Petroleum Association of Mountain States, a trade association, said that putting limits on domestic oil exploration held back "both energy independence and reducing the carbon intensity of our economy". The most charged fight brewing is over the US outer-continental shelf, most of which has been off-limits to drilling since the 1980s. President George W. Bush and John McCain, Republican presidential candidate, have pressed Congress to lift its moratorium on offshore drilling, but have faced opposition from Nancy Pelosi, House speaker, and Barack Obama, Democratic presidential candidate. However, both Ms Pelosi and Mr Obama at the weekend signalled willingness to accept a bipartisan compromise on the issue. Anadarko Petroleum underlines how quickly opening a new area can yield resources. In 2001, the US government opened new acreage 125 miles off the coast of Florida. Six years later, Anadarko's project there recovers 1bn cubic feet a day of natural gas - enough to heat 5m-10m American homes. "This is a frontier area," said Stuart Strife, Anadarko's vice-president of exploration for the Gulf of Mexico. "It's a great testament to what we can do when we are given access." Copyright The Financial Times Limited 2008