Last Updated May 21, 2010 11:33 AM EDT
The latest move is by Alstom (ALO), a French company best known for its railways and trains. The company just took part in a $150 million investment for BrightSource Energy, which has a number of projects planned in the United States.
Like other companies in its sector, Alstom's investment gives it a position in a very specific type of solar power: solar thermal, in which vast fields of mirrors reflect light onto enclosed water, which boils to drive a steam turbine. The average solar thermal project is likely to cover acres of land, or even square miles, which is right up the alley of a company like Alstom.
Several of Alstom's European competitors have invested in substantially identical technology -- and all have done so within the past year. Increasingly, it looks like they're all motivated by Desertec, a proposed European mega-project that plans to dot northern Africa's deserts with solar thermal plants.
Siemens, a German firm, was the first big engineering firm to step into solar thermal power, when it paid $418 million last year for the Israeli startup Solel.
A few months later Areva, another French firm, scooped up a company called Ausra -- even though the latter company had gone from a solar darling with plans to compete with BrightSource, to a scaled-down startup that aimed at smaller industrial projects instead of huge utility-scale solar fields.
There are opportunities outside of Europe for solar thermal power, but it's questionable whether the big engineering firms would involve themselves without Desertec as a motivator. Although there are various planned sites, only a few small solar thermal plants have been built, and there are more promises that real action from governments that want to use the technology. There are also too many wild cards like eSolar, a Google-backed company with its own competing technology that it licenses to all comers.
Desertec itself is by no means certain to be built, but companies with the size and influence of Siemens and Alstom at least have the leverage to encourage Europe to go ahead with the plan. And if approved, the project would generate many billions of dollars in revenue, money that would more than than recoup and investment costs.
As for BrightSource, the company has now taken more than $300 million in financing, and still has plans to build several gigawatts worth of power plants, mainly in California. Having Alstom on its side certainly won't hurt there, either.