Google today is launching a fascinating experiment in clean-tech investing in the form of a worldwide search for products, services, and technologies that can advance the market for plug-in electric vehicles. And it plans to invest a total of $10 million in the ones it likes.

The request for proposal just issued by Google.org, the company’s philanthropic arm, invites “entrepreneurs and companies to show us their best ideas” with the aim of making “catalytic investments to support technologies, products and services that are critical to accelerating plug-in vehicle commercialization.” Google.org says it will invest between $500,000 and $2 million in the companies it believes stand the best chance of advancing plug-in technology.

Think of it as “The Apprentice” meets “An Inconvenient Truth.”

As the company explains in a “Googlegram”:

We realize that this type of open call for proposals is not the usual model for investment, but we wanted to use a process that was open to new ideas and new entrants. Part of our goal is to get as many people as possible to work on solutions to our vehicle emissions challenges. We welcome and expect to receive submissions from a wide variety of companies — from cutting edge battery technologies to innovative service businesses – and from companies of all sizes. We also encourage participants from all over the world to submit proposals. This is a global challenge, and it will take all of us to solve it.

Entrants are asked to submit a five-page proposal by October 15. Those entries selected will be asked to submit a more complete business plan, which will then go through the usual vetting and due diligence processes. (Read an FAQ doc here.)

The RFP is the latest in a string of efforts by Google to advance electric vehicles. Earlier this year, Google.org launched the RechargeIT Initiative that aims to “reduce CO2 emissions, cut oil use, and stabilize the electrical grid by accelerating the adoption of plug-in hybrid electric vehicles and vehicle-to-grid technology.” RechargeIT to date has focused on philanthropy, committing $1 million in donations to nonprofits, and has created a small demonstration project that, the company says, will eventually lead to 100 or more plug-in hybrids in Google’s corporate fleet. In addition, the foundation is putting its money toward advocacy and policy matters related to growing the plug-in hybrid market.

It will be interesting to watch, both to see what products and services eventually come out of this quirky experiment, but also how much the RFP investment approach itself is replicated by others. On the one hand, it seems obvious to invite the best and the brightest to compete for a relatively small but meaningful pool of money. On the other hand, like so many of Google’s other innovative initiatives, no one has done this kind of thing before — or at least done it well.