A few months ago, we wrote a list of the ten most likely companies to be bought in the near future with a list of five that would never get bought. (Greenfuel Technologies, one of the top candidates for not being sold, ceased operations the next day. Greenbox, bought by Silver Spring Networks last week, was listed as a possible impulse buy in smart grid.)

But who is going to buy? Here are the main ones. The list is based on stated strategies, company histories, current market circumstances and gut feelings. In other words, pure science.

1. General Electric: GE likes to shop. It got into wind by buying Enron's wind division in 2002 and since then has invested in, or bought, companies like Southwest WindPower and ScanWind. GE now battles Vestas for the top spot in wind.

A similar trajectory occurred in water. It entered the water industry by purchasing Glegg in 1999 and then followed up with BetzDearborn and Osmonics. GE's water group is now a $2.5 billion plus operation with long-term goals to hit $10 billion.

GE's latest obsessions are smart grid, energy storage, and components and software for energy efficient buildings. In all, GE has bought 717 companies and invested in 236, according to this site. With energy as the company's future, the wallet will be open.

2. Siemens: The German GE. Expect to see a lot of emphasis on energy services, water, smart grid, energy efficient components, wind and equipment for building biofuel refineries.  In August, it purchased majority shares in two Chinese circuit breaker makers.

3. Applied Materials: Applied is the world's largest manufacturer of semiconductor manufacturing equipment and acquisitions are simply a way of life. Startups simply can't achieve the scale they need to become commercial and the established companies don't have the R&D to spread around to try out every single idea. In a sense, the equipment business is really America's Got Talent for the vapor deposition crowd.

Applied entered the solar market with its purchase of Germany's Applied Films for $464 million in 2006. It hasn't been dreamy: many analysts believe amorphous silicon, the kind Applied's equipment is geared toward, will become marginalized. But it probably won't close the wallet. Last year, Applied started to quietly lay plans to get into the market for manufacturing equipment for batteries and energy efficient lights. Applied's VC arm has also invested in a wide variety of companies. Some companies that may go into its maw: Solaicx (ingots – it already invested in Solaicx), Plextronics (printable circuits) Kateeva (novel OLED tools) and something in CIGS.

4. Taiwan Semiconductor Manufacturing Co.: Back in the mid-1980s, investors told Morris Chang that his idea of building a chip factory for hire was nuts. Since then, TSMC has become the world's largest foundry, pulling in billions a year. In August, Chang came back as CEO, announced that TSMC wants to get into LED lights and solar panels, and would likely buy companies. Asian conglomerates, in fact, will be some of the biggest buyers in the coming years. The company is known for relentless manufacturing expertise and a highly competitive culture, like First Solar and Intel. VCs have told us that TSMC's VC unit is already in the Valley armed with a spread sheet detailing markets it would like to participate in. UMC, the little brother rival of TSMC, has launched similar plans. TSMC and UMC could also become factories-for-hire in solar.

5. Valero: Take a look at this chart. Valero doesn't go for those mega-mergers, like Chevron and Texaco. Instead, it buys lots of small items. And it's aggressive. Think of it. Seven years ago, you never saw a Valero station. Now they are a common site. This year it bought seven ethanol plants from VeraSun for nearly $500 million and several other ethanol producers want to offload facilities. If some companies can start to show cellulosic ethanol or algae fuel can scale, there is a good chance Valero will show up with a checkbook first. Chevron, BP and ExxonMobil by contrast seem more intent on forming research alliances with biofuel startups.

6. Toshiba: Batteries, flash memory, computer components, advanced materials, televisions: these are some of the green markets the 150-year old company is in. Toshiba officials said recently that it may need to start buying companies in LEDs to increase its market share. Whether by Toshiba or not, LED startups will likely begin to get snapped up in any event: it's a growing market with high capital costs. Some would-be purchases: Luminus Devices, Bridgelux and Renaissance Lighting).

7. Philips: The same arguments that apply on Toshiba largely apply here, but in LEDs it will likely focus more on lighting fixtures than the light sources, which are semiconductors. It has already bought two companies this year-Teletrol (light fixtures) and Dynalight (controls). Between 2005 and 2007 it bought $5.4 billion worth of lighting companies.

8. Cisco Systems: Not a lot of explanation needed. Cisco wants to deploy its routers and software to control the power consumed by phones, PCs and servers and later the grid, homes and commercial buildings. Just as important, the company has a history of buying lots of companies and actually making the acquisitions work. Possible Cisco buys: Verdiem, Hara, EPS (energy optimization for dairies-very interesting) Optimum Energy, Other buyers in this market: Oracle and SAP. Another plus: Cisco tends to pay higher prices than conglomerates like Siemens, according to Dave Dreesen of Battery Ventures.

9. IBM and Intel: Smart grid and energy efficient computing. Intel periodically goes through acquisition binges. Between 1999 and 2003, Intel bought 37 companies for $11 billion, most of them in communications. Later, most of them were sold off. Did that cure Intel of buying? No way, it got into consumer electronics a few years later. It has begun to plant its processors into wind turbines and smart grid equipment. Intel lately has discussed how digital technology could revolutionize building management and smart grid. History makes me think that someone like Tendril or Lumenergi could be an Intel company.

IBM gobbles up companies too. Side note: IBM has nearly 398,455 employees and $106 billion in revenue. There are probably start-ups that IBM has bought and forgot they owned.

10. SunPower: Also a top ten acquisition target. SunPower faces pressure from both directions: China's Suntech Power Holdings is moving up into the high efficiency panel market SunPower created and while First Solar is setting a low, attractive price for solar nearly everywhere. Thus, like nearly every other solar maker, SunPower will need to diversify. It has been advertising like crazy to make itself a consumer brand so perhaps it will buy an installer, someone doing a solar appliance (thermal, light and PV all in one) or one of the companies doing software for remote solar estimates like Sungevity or Global Solar Center. A BIPV company is another possibility. It has a history in acquisitions with the purchases of PowerLight and Solar Solutions.

Tags: acquisitions, applied materials, asia, biofuel, cisco, energy efficiency, general electric, ibm, intel, leds, lights, oracle, philips, siemens, solar