Your kids may not thank you now, but the Hydrocar Educational Clean Energy Kit carries a timely message about renewable energy that will hopefully last longer than car's power source. It is a collection of parts that users assemble into a working car that runs completely on renewable energy.

The hydrogen-gathering process sounds great on paper. You put water into a tank and use a solar panel to run electricity through the water to extract hydrogen. This is then put through a special "reversible Proton Exchange Membrane" that turns hydrogen into electricity.

The renewable energy that comes from this process is ready to be pumped through cars and homes without the need for fossil fuels or dangerous nuclear power and its potential for glowing bunny rabbits.

This kit points out both the exciting potential and major problems that stop the widespread use of hydrogen fuel.

With its $129 price tag, the Hydrocar isn't cheap. At this price, the less green-conscious consumer could get themselves a nifty set of EyeClops Night Vision Infrared Stealth Goggles.

Nor is it exciting, with a very slow speed and a short life-span. In our tests the Hydrocar lasted between 1min 24sec and 2min for each full "tank" of hydrogen. The sensors on the front of the vehicle are inaccurate and often try to drive the kit straight off the edge of a table, suggesting yet another secret conspiracy to force us to use petrol-power.

But all of this is largely irrelevant. The kit uses clear tanks filled with water to explore the potential of hydrogen power, and putting it together is a hands-on process.

Once you're finally ready, after a long wait filled with watching and waiting as bubbles of gas enter the tank, there's an undeniable thrill that comes as the car starts up and the lights turn on.

So while your kids would probably prefer to find a stocking with a Nintendo DS, they might appreciate your geeky parenting down the track when they're driving hydrogen cars and living in solar-powered tree houses.