I love electronic gadgets that work without batteries or needing to be plugged in. Sure, with many of them the savings are more symbolic than meaningful, but with the Timeless Garden clock, you get a double dose of eco friendly symbolism.
Using organisms in the soil to create a chemical reaction that results in a tiny electric charge, the Timeless Garden should work as long as the plant life is kept alive. A side benefit is that the grass will also extract a tiny amount of carbon from the air, while releasing a minute amount of oxygen. Still, I wonder whether the amount of greening over the lifetime of the clock is sufficient to cover the carbon generated by making it and shipping it from China.