* European, Asian companies announce plant investments
* Especially steel, chemicals sectors step up spending
* Cheap natural gas means low power prices, cheap feedstock
* Some U.S. companies bring back jobs
FRANKFURT/VIENNA, March 26 (Reuters) - When Wolfgang Eder and his team started looking around for a site for a new plant for Voestalpine, the Austrian steelmaker he heads, they had 17 sites in eight countries on their list.
This month, after more than a year of looking, they settled on the U.S. state of Texas, after a boom in the production of natural gas from shale extraction brought gas prices down to just a quarter of what companies paid in Europe.
"In the USA, re-industrialisation is being promoted very consistently, ambitiously and with great conviction," Eder told Reuters. "Low energy prices gave us the final - and not insignificant - push."
With cheap shale gas making the United States a magnet for industrial companies like Voestalpine, many economists are positing a return to industrialisation for the world's biggest economy after more than a decade of consumption-led growth.
"America is currently seeing a renaissance of production," said Felix Schuler, a partner at Boston Consulting Group (BCG) based in Germany who specialises in the industrial goods sector.
U.S. natural gas prices are $4 per million British thermal units - having touched a decade low of $2 last year - well below its 10-year average of about $5.70 and prices of around $14 in Britain and almost $17 in Asia.
Voestalpine will use natural gas at its new plant, its biggest investment to date at 550 million euros ($712 million), to turn iron ore into sponge iron, which will later be used to make crude steel.
Cheap natural gas not only cuts costs for companies that use it as a raw material or feedstock for other products such as chemicals, it also means lower power prices as utilities use more gas to generate electricity.
Industrial companies pay about $40 per megawatt-hour of electricity on the U.S. East Coast, where prices have dropped sharply since mid-2008. That compares with about 45 euros ($58) in Germany, 60 euros in Austria and more than 65 pounds ($98) in Britain, creating incentives for energy-hungry firms in the steel and chemicals sectors to invest in new plants and expand existing facilities in the United States.
"The idea that energy costs in North America would always be more expensive no longer holds true. The new reality is that natural gas has turned that equation on its head," Peter Loescher, the chief of executive of German engineering conglomerate Siemens, said in Detroit last month.
The National Association of Manufacturers in the United States estimates the shale boom will add 1 million manufacturing jobs in the country by 2025 as long as natural gas price increases remain moderate and industry regulation is favourable.
"I've spoken to several manufacturers from Europe and Asia who are interested in the shale revolution," said Chad Moutray, the association's chief economist.
Austrian fireproof materials maker RHI is also mulling a new U.S. plant, while it cuts production capacity in Europe due to lower levels of growth.
Tough targets designed to reduce greenhouse gas emissions in Europe can also act as a push from the old continent.
RHI's chief executive told journalists this month that the idea the company could cut its energy use by 5 percent a year to meet EU targets was "in the realm of fairy tales".
"We set ourselves these challenges, but at some point one must realise that European industry employs many people and helps economic growth. What is the alternative? Shall we turn Europe into a financial centre?" asked Franz Struzl.
U.S. manufacturing output was at its highest level since mid-2008 in February, fuelled by a pickup in demand for cars and homes as well as cheap energy. Manufacturers' new orders - an indicator for future revenues - rose 3 percent in 2012.
U.S. companies including General Electric and Boeing are also starting to bring back home some of the jobs they had moved abroad to cut costs, helped by the availability of cheap shale gas. Apple said late last year it planned to move some production of Macintosh computers to the United States from China this year.
"Two years ago, it was uncertain whether the pick-up in the United States was just a catch-up effect. But by now there is significant confidence in the sector that this is not a flash in the pan," said Ulrich Ackermann, head of German engineering association VDMA's Foreign Trade department.
Lower energy and feedstock prices help narrow the production cost gap with countries such as China to make exports more competitive.
According to research and analysis firm IHS, a number of large chemicals companies have announced plans to spend a total of about $95 billion to build or expand facilities in North America for exports, lured by cheap feedstock.
They are mainly in the production of ethylene, a basic hydrocarbon used to make solvents, plastics and detergents.
South African petrochemicals group Sasol is considering spending up to $7 billion on an ethane cracker complex in the United States, Egypt's Orascom Construction Industries is building a $1.4 billion fertiliser plant in Iowa, and Taiwan's Formosa Plastics has expanded plans for a new ethylene plant in Texas.
Japanese oil refiner Idemitsu Kosan and trading house Mitsui & Co are looking into running a petrochemical plant in the United States, which would export 30 percent of its production to Asia and Europe.
Austria's Voestalpine aims to send half the annual output of its new plant in Texas back to its mills in Austria and use the rest as a strategic reserve.
U.S. President Barack Obama last month laid out a plan in his State of the Union address to bring manufacturing jobs back to the country, including a network of institutes that would teach new industrial skills.
In last year's address, he praised Germany's Siemens for job training efforts at its gas turbine plant in Charlotte, North Carolina, opened in 2011.
The investment by Siemens, which has a total U.S. workforce of about 60,000, is tapping booming demand for gas turbines as the U.S. power industry switches to natural gas from coal.
German speciality chemicals company Wacker Chemie has also cited government incentives such as infrastructure grants and tax credits as key reasons for its decision to invest $2 billion in a new polysilicon plant in Cleveland, Tennessee.
Voestalpine's Eder said a secure energy supply, ease of logistics and the availability of trained workers were important in the company's investment decision, but the fact that his company was "welcomed with open arms" played a major role.
"We miss comparable efforts for industrial activities in Europe," Eder said.