Aug 4 (Reuters) - Cheniere Energy Inc, the largest U.S. liquefied natural gas (LNG) exporter, on Thursday reported second-quarter profit that topped forecasts, and raised its full-year earnings outlook.

Western sanctions imposed on Moscow in response to its war on Ukraine has fueled a scramble for alternatives to Russian gas, sending global gas prices soaring, with forecasts for LNG demand expected to double by 2040.

Cheniere has become a top LNG supplier by rapidly expanding production. It recently approved an $8 billion addition to a Corpus Christi, Texas, facility and earlier completed an expansion at Sabine Pass, Louisiana.

"Both of those sites are ripe and ready for much larger expansions," Chief Executive Jack Fusco said on a conference call. U.S. regulatory reforms could accelerate "projects like ours and what we're about to propose longer term," he said.

Fusco downplayed an air-pollution ruling that could require expensive changes to its facilities. Testing results for formaldehyde emissions from gas turbines are due in early September.

If those tests find changes are required, Cheniere "would be able to develop a solution that would enable compliance without a material financial or operational impact," said Fusco.

Cheniere has sold out much of its LNG production this year, said finance chief Zach Davis and has struck deals for future output from facilities not yet authorized.

Shares fell slightly to $145.29 in afternoon trading.

Higher profits have allowed the company to accelerate debt repayments and will allow a bigger share of future earnings to go toward shareholder returns, Davis said.

"There's going to be quite a bit of money allocated to share buybacks over time," he said with providing details. A new plan for using its cash for debt and returns will be disclosed by year-end, he said. The United States, which has committed to deliver additional liquefied natural gas (LNG) to European countries, became the top exporter of the supercooled fuel in the first half of 2022.

It raised its full-year earnings outlook for a second time this year to adjusted earnings of between $9.8 billion and $10.3 billion, up from guidance of $7-$7.5 billion earlier in the year.

Cheniere posted second-quarter net to common stockholders of $741 million, or $2.90 per share, compared with a loss of $329 million, or $1.30 per share, a year earlier.

(Reporting by Rithika Krishna in Bengaluru, additional reporting by Gary McWilliams; Editing by Vinay Dwivedi and Shinjini Ganguli)