* July-December underlying profit rises 5 pct to A$381 mln
* Power demand from new LNG plants to make up for car plant closures
* Sees FY2014 profit around same level as FY2013
* Sees strong growth from 2015 onward as LNG exports start
MELBOURNE, Feb 20 (Reuters) - Origin Energy Ltd, Australia's biggest energy retailer, expects little impact on power demand from a string of closures of car plants and an aluminium smelter, as new gas liquefaction plants would take up the slack.
Only if newer, larger aluminium smelters were shut would there be a big hit to power demand, Chief Executive Grant King said at a news conference on Thursday after the company reported a 5 percent rise in first-half underlying profit.
U.S. aluminium giant Alcoa Inc announced this week it was going to close its Point Henry smelter and two rolling mills in August, following plans by car makers Toyota Motor Corp , General Motors Co and Ford Motor Co to close their Australian plants by 2017.
King said liquefied natural gas (LNG) plants in the state of Queensland, due to launch operations within the next two years, would easily make up that lost power demand.
"That demand growth from LNG probably exceeds the impact in the market of the general things that are happening in manufacturing," King told reporters.
While aluminium smelters are huge consumers of electricity, he said the closure of Point Henry would not have much impact on power demand as it was small compared with Rio Tinto Ltd's Tomago smelter and Alcoa's Portland smelter, which remain open.
"At the moment it doesn't seem to us that those larger, more modern plants are at threat, nor is it a surprise that some of the smaller, older plants have been shut down," King said.
Origin is poised for strong growth starting next year, when it will start selling gas to its rivals who are due to begin exporting from their LNG plants in Queensland, ahead of Origin's neighbouring Australia Pacific LNG project.
However for the year to June 2014, Origin said it expected results to be roughly in line with 2013 after it reported underlying profit of A$381 million for the six months ended December up from A$362 million a year earlier.
That compared with an average of three analysts' forecasts at A$387.2 million, according to Thomson Reuters Starmine.
Origin said heavy competition in power retailing was continuing to hurt margins, but that it expected its energy markets division to post a better result in the six months to June than in the first half.
Analysts expect the group's full-year profit will rise 3 percent to A$782 million, according to Thomson Reuters I/B/E/S.
Origin also said its biggest project, the A$24.7 billion Australia Pacific LNG project, remains on track to start exporting in mid-2015, within budget.
The company's shares have gained 21 percent over the past year, heavily outperforming the broader market, but fell 3.2 percent to A$14.375 on Thursday after the earnings release against a 0.1 percent fall in the benchmark.