Google announced today on it’s company blog that is was launching a $100 Million venture capital fund, “to support innovation and encourage promising new technology companies.”

The fund will be run by managing partners William Maris, a former entrepreneur, and Rich Miner, a former executive in its mobile unit.

The partners said there would be very few companies within the fund’s core sectors that would be off limits for consideration. Miner said the partners have been given a green light to invest in technology that is competitive and potentially disruptive to Google’s core search advertising business.

Maris said the fund would be governed by Google’s “Don’t be evil” motto. The partners will also limit their investments to U.S.-based start-ups to make sure they were close at hand to help build the companies.

“We have huge number of people, many of whom have PhDs, who can help evaluate companies and perform due diligence,” said Miner. “That’s a key asset we have.”

But he stressed there would be a “one-way mirror” between the fund and Google, which would allow start-ups to benefit from Google’s expertise without concern about the security of their intellectual property.

The fund has already invested in two start-ups, including Silver Spring Networks, a company that uses technology to improve the efficiency of power grids, and has also offered a term sheet to a third.

Here is the announcement:

“”””Today we’re excited to announce Google Ventures, Google’s new venture capital fund. This is Google’s effort to take advantage of our resources to support innovation and encourage promising new technology companies. By borrowing the best practices of top-tier, financially focused venture capital firms and bringing to bear Google’s unique technical expertise and brand, we think we can find young companies with truly awesome potential and encourage their development into successful businesses.

At its core, Google Ventures is charged with finding and helping to develop exceptional start-ups. We’ll be focusing on early stage investments across a diverse range of industries, including consumer Internet, software, clean-tech, bio-tech, health care and, no doubt, other areas we haven’t thought of yet. Central to our effort will be our fellow Googlers, whom we view as a critically important resource to help educate us about potential investments areas and evaluate specific companies.

Economically, times are tough, but great ideas come when they will. If anything, we think the current downturn is an ideal time to invest in nascent companies that have the chance to be the “next big thing,” and we’ll be working hard to find them. If you think you have the next big idea, or if you just want to to learn more, please see our website at www.google.com/ventures””””