Origin Energy says it had to act after agreeing to fork out up to $US800 million ($A865.57 million) for a stake in a new gas project off the Western Australian coast. The company, Australia's largest electricity retailer and generator, has taken on a potential second major liquefied natural gas (LNG) project a year before its flagship $24.7 billion Queensland project comes online. Origin has struck a deal to buy junior Karoon Gas's 40 per cent interest in the Poseidon discovery in WA's Browse Basin. Origin managing director Grant King said investors were already asking what the company planned to do with the extra $1 billion in cash flow its Australia Pacific LNG project would eventually start delivering. "The answer is we are setting ourselves up through this investment and have a very good opportunity to reinvest part of those cashflows for continued development," he told reporters.