With so many companies "going green" these days, there's been a lot of talk about cleantech. You might wonder what that is exactly, and what its future holds.

Simply put, cleantech covers a variety of products and services that help provide high performance at lower costs; cut or eliminate negative environmental impact; and improve the responsible use of natural resources.

Cleantech industries include renewable energy generation like wind, solar, geothermal and more.* Energy storage like fuel cells, advanced batteries and hybrid systems. Energy transmission like the smart grid. And Energy efficiency in lighting, buildings, windows, and appliances.

So how is the cleantech industry faring during this recession? In Silicon Valley, investment in cleantech nearly doubled in 2008.

Energy investment is slightly down so far in 2009. But potential is there to reduce our dependance on fossil fuels while further encouraging carbon-free sources of power.