Photo: The New England Aquarium
The famous Christmas tree in Rockefeller Center made headlines when it got an eco-friendly makeover in 2007, replacing its conventional lights with 30,000 LEDs.
But that's not enough to make it the world's most eco-friendly tree: From Lima to Copenhagen and Barcelona to Pittsburgh, cities around the world have gone to extreme -- and downright wacky -- lengths to celebrate sustainability while marking the start of the holiday season.
1. Eel-Powered Christmas Tree
Bikes, solar panels, wind turbines -- these are all unusual ways to light up a Christmas tree, but none of them compare to the shocking -- literally -- plan in place at the Aqua Toto Gifu Aquarium in Japan, where an electric eel lights up the decorations on a traditional pine.
The innate electricity of the eel is conducted from the tank to the tree every time the creature brushes one of a series of copper wires in the tank. Find that unbelievable? Reuters has a video of the flashing, twinkling tree.
2. Kiss-Powered Christmas Tree
Still feel a jolt every time your significant other leans in for a kiss? Put that energy to work lighting up this 50-foot tree in Covent Garden in London.
Here's how the "interactive installation" works: Stand under the giant mistletoe, each of you with one hand on a leaf; then kiss, and watch the 50,000 red and white LEDs sparkle with as a result of your electricity. The digital number on the side of the tree counts up how many couples have smooched already; with every kiss, a donation goes to The Prince's Trust youth charity.
3. Solar-Powered Christmas Tree
Though winter holidays are characterized by cold and early evenings in the U.S., the city of Brisbane, Australia, takes full advantage of its summer season with this solar-powered tree, which is almost 70 feet high and strung with 16,000 bulbs.
Unlike trees lit by the cycling power of energetic citizens, this one relies on the giant star that crowns it: The star is made of solar panels that capture enough power to provide 50 amps every hour to the strands of glowing bulbs.
4. Wind-Powered Chrismas Tree
Last year, the district of San Borja in Lima, Peru, didn't just choose one alternative energy source for its Christmas tree: According to Green Upgrader, the town enlisted ten bicycles, two solar panels, and one wind turbine (though there was no mention of a partridge in a pear tree).
The 36-foot-high tree was covered with LED lights -- and though it's not as massive as some of the other trees around the world, the bright blue lights are a striking change from traditional shades.
5. Bike-Powered Christmas Tree
In an attempt to cut the city's holiday energy use in 2008, the Barcelona City Council installed public trees adorned with low-energy lights -- including some that used solar power and others that encouraged locals to put their own pedal power to use on stationery bikes. The 19-foot high, reusable trees (along with other initiatives) allowed the city to cut its energy cost by 14 percent for the Christmas season.
That same year, the Tate Britain museum installed a tree made from salvaged material and powered by bicycles hooked up to generators, and Copenhagen followed suit in 2009 with a 700-light tree that only lit up when enough people climbed aboard the 15 bicycles at its base to generate enough power.
6. Salvage-Powered Christmas Tree
Pennsylvania's Jim Berroth isn't in charge of putting up his town's tree -- at least, not yet -- but he did think outside the traditional light box to decorate his yard: Berroth collected more than 1,800 cans and fashioned them into these triangular structures, then decorated them with bright baubles and garland -- and lit up the entire scene with 1,600 lights, most of which, he says, he picked up at yard sales.
Cities around the world, take note: Reuse can be just as impressive as even the most majestic tree.