Well, well, Bill Gates.

Today came news that the Microsoft founder, philanthropist and green investor has invested in a $60 million round for NEOS GeoSolutions, a Houston-based firm that uses data analysis and geophysical sensors to help oil and gas companies decide where to drill. NEOS’s backers also include Goldman Sachs, Kleiner Perkins, Passport Capital and, now, Saudi-based oil and industrial conglomerate Energy Capital Group, which joined as a new investor with Gates.

It’s a fairly surprising and — dare we say — hypocritical move for Gates, considering that he’s been a vocal champion of green energy in the past. He’s chairman of the board of alternative energy advocacy group American Energy Innovation Council, which includes business leaders like GE’s Jeffrey Immelt and Xerox’s Ursula Burns.

“The innovation that would be the most important for the world is a way of generating electricity that’s less than half as expensive as the way we do it today but has no bad environmental effects, and, in particular, emits no CO2,” Gates says (italics mine) in an AEIC video embedded below. I’ve reached out to the AEIC for comment, but haven’t heard back.

In fact, the AEIC’s recommendations includes a call for the U.S. to invest $16 billion a year in innovative energy research and development, even hinting that the U.S. spends too much money — $16 billion every 16 days — overseas for oil.

Gates is also an investor in cleantech venture capitalist Vinod Khosla’s green fund. He has backed biofuels company Sapphire Energy, nuclear plant designer TerraPower, low-emissions car motors startup EcoMotor, and Pacific Ethanol. And the Bill and Melinda Gates Foundation headquarters was designed as a green building, with a roof that doubles as a natural habitat for birds and is sustained via rainwater.

On the flip side, calling Gates a hyprocrite may be a little harsh. For one, he’s likely diversifying his portfolio of investments. For another, it’s not easy — or even realistic — to be 100 percent green when most of the world still runs on fossil fuels and the majority of renewable energies are still more expensive than traditional fuel sources. Immelt’s GE, for all of its investment in cleantech, still makes jet engines and traditional lightbulbs (though it studiously markets greener versions of both).

And on the bright side, while NEOS supplies oil companies, it also counts gas companies among its clients. Natural gas is a much cleaner fossil fuel than coal, is forecast to oust coal in the next few decades, and big oil companies like Chevron and Exxon have invested in natural gas acquisitions and projects. So smart investors are looking to bet on the commodity, which isn’t as bad for the environment as coal.

I’d venture that Gates’s green contributions and high-profile role in green advocacy probably outweighs this one deal, but it’ll be interesting to see  if he’ll continue to bang the drum for alternative energy with one hand and bet on oil and gas exploration with the other.

[Top image via Green Diary]