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This week at Treehugger: A smoke alarm that recharges its batteries when you turn on the lights, aerial thermal imaging to detect wasteful houses in the UK, a tip to stop paying for wasted electricity, car tires made out of corn-based bio-plastic and a cool educational solar robot kit for the kids this Christmas.

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No batteries required for this smoke alarm. Instead, it connects directly into ceiling-mounted light sockets, automatically recharging whenever the light is turned on. Not bad—it involves less maintenance and saves batteries from the landfill. Of course, it probably shouldn't be your only kind of smoke detector in the house, but it is a good addition.

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Could big brother be getting green? British company BlueSky is helping improve energy efficiency in UK homes by using aerial thermal imaging to pinpoint areas and homes that are leaking too much energy. Local energy authorities can then use this information to help advise homeowners on how to improve their energy efficiency in accord with the mandated 30 percent increase in domestic efficiency by 2006, helping them save on bills and have a more comfortable house along the way.

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So much electricity is completely wasted, and people pay for it both on their utility bill and with the degradation of nature that comes with energy production (especially where coal is used). Do something about it. Have you ever noticed that your cellphone charger stays warm even when you are not charging your phone with it? That's because it is still draining electricity, and that doesn't just apply to cellphone chargers; most electronics have phantom loads. Only 5% of the power drawn by cell phone chargers is actually used to charge phones. The other 95% is wasted. The lesson? Unplug your charger when you are not using it or plug everything on a power strip and use the switch to turn it off...

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Tire giant Goodyear and Italian eco-bio-chemical firm Novamont have collaborated to produce bio-tires using non-GMO corn starch. These tires reduce rolling resistance, noise and emissions while increasing fuel efficiency and reducing the energy needed in the production process. BMW has even approved them to be used on its new cars.

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Pictured here is a Solabeast robot kit. This kit allows you to assemble your own solar-powered "Beast" machine. It comes with a solar cell and pre-punched wooden boards, gears, shafts and motors. Cool educational project for kids and would-be engineer daddies and mommies.

Treehugger s EcoModo column appears every Tuesday on Gizmodo.