This week's tumblights are worth clicking through to the original source. Each is an interesting story of either a environmental intervention or new ideas about energy use and creation. From Cayteano Ferrer's invisible street art to retro-looking drinking glasses that collect solar energy and can charge your smartphone, this week's tumblights are more than just pretty pictures.
Clockwise from top left:
3. Energy Trumps Cards identify environmental properties of materials via Inhabitat