I definitely think my eco-friend, Sylvie Verdant, should get a clock. I have strong suspicions that her only timepiece is a sundial in the yard of her solar-powered treehouse.

She's rarely on time. She's either early or late. And she says things like "I'll meet you tomorrow at moonrise," which may sound exotic and cool, but really!

Honestly, sometimes I just don't know how she manages.

So maybe I'll get her a Bedol water clock. I think she has a birthday coming up, and although she hates getting material things, I just might do it anyway.

This clock doesn't plug into a socket, and it doesn't require batteries. It runs on water.

I'm trying one out at my desk now. It's blue plastic, shaped like a droplet, and I've filled it with good old Philly tap water.

Behind the face of the clock are two metal plates, which the water covers.

Here's the company's explanation of how it works: Water has naturally-occurring ions. They move between the opposing metal plats, and the exchange creates energy. Enough to run the clock's digital components.  Voila!

Different water sources last for different lengths of time, the company says, but the general rule is that a single tank of water should generate 12-15 weeks of power.

When the power runs out, the company says, just water your houseplant with the old water and add clean tap water to the tank.

But it's not quite a free ride. Bedol has a request: donate the money you save on batteries to a tree planting program or wilderness conservation organization.

The clocks range in price from $19 to $39.

So now I'll put it to you: Is this a clock that would pass muster with Sylvie? Add your comments below. Is it truly green? Or should I take her out to watch fireflies for her birthday instead? She'll want to meet at moonrise, I'm sure.