We’ve all heard claims of green inventions that are too good to be true: the zero-point energy generator, the water-powered car, the device for talking with dolphins to achieve world peace. Sometimes they amuse us; sometimes they confuse us, as we try to determine whether they’re legitimate or not; and sometimes they just annoy us. But can they ever help us? Yes: by keeping our imaginations open, and by honing our evaluation skills — skills which are useful both when deciding between existing technologies, and when thinking about technologies on the