A green power building spree is on the way, and much of it will be brought to you by the same people who built the nuclear and coal-fired power plants that keep the lights on now.

What might strike casual observers or radical greens as odd can be explained by good business sense; with few other power plants in the works, big U.S. engineering and construction companies have heartily embraced renewable energy projects.

Next year, in particular, is setting up to be a banner year for clean energy, with the political winds blowing in the right direction and utilities scrambling to meet renewables targets.

But moving from solar panel installations on the roofs of the eco-minded to utility-scale projects that will power the homes of thousands requires far more planning expertise and capital, which will play into the hands of the big engineers.

If you don't have nine figures of cash on the books, people are more scared off, said Heiko Ihle, an analyst at Gabelli & Co. Especially these big projects, where there's only a handful who can do it in an efficient manner, and you don't have to worry about them running away with your money.

Ihle wondered why midsized players such as, say, Foster Wheeler Ltd and KBR Inc, had not formed joint ventures capable of taking on projects costing several billion dollars.

You don't see that very much, he added. It generally boils down to the Fluors and Jacobs and Bechtels doing it.

Steven Chan, chief strategy officer of Suntech Power Holding Co Ltd, said his company was working with a few as-yet undisclosed engineering contractors, and saw the big players entering the solar business as only a positive trend.

They can bring to bear a lot of other powerful things that are within their arsenal, Chan told the Reuters Global Climate and Alternative Energy Summit this month, citing their employee numbers, and their purchasing power in driving down costs.

CLEANTECH TRACK RECORDS

Privately held Bechtel, the largest U.S. engineering group, says it has been involved in renewable energy for 25 years, including the first utility-scale photovoltaic solar plant and operating the National Renewable Energy Laboratory.

But the San Francisco-based company only set up a renewable unit a year ago, and this month it won the contract from BrightSource for a 440-megawatt solar-thermal project in the California desert, in which Bechtel will take an equity stake.

We view it as a very attractive equity investment for us. That's simply what it is, Ian Copeland, president of Bechtel Renewables and New Technology, said in an interview, clarifying that equity stakes would not necessarily be part of future deals, even if the industry could use the financing.

Like many executives, he expects 2010 to be great for clean energy, simply because many permitting hurdles will have been cleared, on top of the loans flowing more freely from banks.

I believe that a number of projects that are in train will come to fruition next year, Copeland said.

He noted that somewhere in the range of 40 percent of new U.S. power capacity in the past few years had been wind farms. As for solar, research firm iSuppli expects installations to grow by 54 percent globally in 2010 after a weak 2009.

To capture some of the renewable energy money now flowing in Silicon Valley, Pasadena, California-based Jacobs Engineering Group Inc has been touting its services at cleantech conferences in the area out of its San Jose office.

Fluor Corp, the biggest publicly traded U.S. engineering company which carved out a renewables arm in May, sees green energy as a big part of its power revenue in the coming years given the dim outlook for other new power plants.

Renewables will be the one where we fully expect, as the market does, future growth, Dave Dunning, group president for power at Irving, Texas-based Fluor, told the Barclays Capital Global Renewables Conference in Zurich this month.

In a possible sign of the times, Fluor was addressing the clean energy confab in Switzerland while many of its rivals gathered for an annual engineering and construction conference in San Francisco, where green was also a topic on the table.

John Fees, chief executive of Houston-based McDermott International Inc, said apart from its capabilities in solar thermal and biomass, the cleaner energy push would lead to plenty of revenue opportunities in power plant retrofits.

We don't see the onslaught of environmental regulation as necessarily a negative, he told the D.A. Davidson conference.

(Reporting by Braden Reddall, editing by Matthew Lewis)