What's better than trees? I'll tell you: ROBOT TREES. Scientists at MIT have developed "artificial leaves" — small solar cells, about the size (though not the shape) of an oak leaf, that use a photosynthesis-like process to turn water into electricity. Only they do it ten times more efficiently than natural leaves, and the electricity they produce can be used to power homes in the developing world. Trees: spanked.

The leaves are cheap to produce and can operate continuously for 45 hours, which gives them a lot of potential for powering homes in countries where energy infrastructure is prohibitively expensive. But we'd also like to see them used to build energy-producing roof gardens on apartment buildings, or to garland the brow of the 2050 Robot Poet Laureate.

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