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What will the hydrogen economy do with all that water?

The obvious solution is to sequester the water, in the car, much as you sequester urine in your bladder, and dump it into the local water system when you fill up again. Filling the car with hydrogen might be like going to the bathroom, with pressurized gas on one side of a bladder pushing water out the other side.

In yesterday's story about Robert Dopp and his amazing electrolyzer we failed to discuss the unintended consequences.

If you have cars running on hydrogen, combining it with oxygen in fuel cells, what do you do with the pollution? What do you do with the water?

Dopp notes that if a fuel cell car gets the equivalent of 75 miles per gallon equivalent of hydrogen it's producing 2.2 gallons of water.

A trip between Dopp's home in Marietta and Hilton Head Island, SC, which is a little more than the distance between Los Angeles and Las Vegas, would create 17.5 gallons!

That's a lot of pollution. Notice how, in the picture above from Wikimedia Commons, the water is simply vented, allowed to go up toward the Sun as vapor.

Big mistake there.

The net amount of water used in the translation is zero, but it is in effect being transported from place-to-place. You need water to power an electrolyzer but that water could come from a very wet place. It might be deposited in a very dry place.

We are talking about climate change on a massive scale, or an enormous boon to places that are currently water poor -- like Las Vegas.

You can already see a small version of this effect if you drive along a desert highway today that has a lot of car traffic. Notice the small plants by the roadside, which peter out as you get further from the road? They are living off the water thrown off by car exhaust and air conditioners. What I'm writing about is not science fiction.

The obvious solution is to sequester the water, in the car, much as you sequester urine in your bladder, and dump it into the local water system when you fill up again. Filling the car with hydrogen might be like going to the bathroom, with pressurized gas on one side of a bladder pushing water out the other side.

Right now all the fuel cell cars I know of vent their water. They just let it go into the atmosphere. That's fine when there are very few of them, but what if there are millions, or hundreds of millions, of fuel cell cars.

The water being created is pure, pollution free. For safety's sake you might still want to get it into a city system where it can be treated with chlorides and other chemicals that make it potable. But it's pure stuff -- just oxygen and hydrogen.

Shouldn't we think about these problems now rather than waiting for the hydrogen revolution to overtake us so our kids end up on Earth Day 2070, at protest marches in the jungles of Arizona and Nevada?

This post was originally published on Smartplanet.com