The planet's most pressing environmental problems ... may seem just too big to be solved with today's technology. But don't despair: A lot of bright minds are working on futuristic projects that promise to make the world greener. It's save-the-world stuff like toxic-waste-eating trees, smart electricity grids, oceangoing robots, and floating environmental sensors. This technology may seem far out - but it will probably be here a lot sooner than you think. 1. Try a solar-powered hydrogen fueling station in your garage. It's about the size of a filing cabinet and runs on electricity generated by standard-issue rooftop solar panels. The first version of the home fueling station is expected to produce enough hydrogen to give your runabout a range of some 100 miles without emitting a molecule of planet-warming greenhouse gas. 2. Environmental sensor networks [provide] real-time data on a variety of phenomena that affect the economy and society - climate change, hurricanes, air and water pollution. 3. Toxin-eating trees ... a technology that uses vegetation to absorb hazardous waste from industrial plants and other polluters. 4. Nuclear waste neutralizer ... a chemical technology called Urex+ that extracts reusable uranium and separates out cesium, allowing four times as much waste to be packed into nuclear burial grounds. 5. Autonomous ocean robots. 6. Sonic water purifier ... a sci-fi solution for an age-old problem that leaves 1.1 billion people without access to clean water: 7. Endangered-species tracker. 8. The interactive, renewable smart power grid ... the electricity grid of the future ... will look more like the Internet - distributed, interactive, open-source - than the dumb, one-way network of today.