Drivers who are buffing their gleaming new Japanese-made hybrid cars and relishing the environmental benefits might consider how their cars got here: most likely via marine shipping, which emits more carbon dioxide than aviation and spews more sulfur dioxide than all the cars, trucks, and buses of the world combined. Plenty (Aug./Sept. 2007) reports that some innovative shipping companies are trying to green up their acts. Hamburg-based SkySails uses a combination of conventional engines and giant, computer-maneuvered kites to power ships. With kites ranging in size from 160 to 5,000 square meters, the systems can cost a few million dollars to install, but can save between 10 percent and 35 percent in fuel costs, paying for themselves in three to five years. Competing California firm KiteShip notes some reluctance by shipping firms to embrace the unfamiliar technology, with many planning to address pollution by installing exhaust-scrubbing systems that cost up to $6 million and eat up even more fuel. It might be easier to clean up smaller watercraft. To that end, Canada’s Tamarack Lake Electric Boat Company has developed a solar-assisted pontoon boat, according to Canadian Geographic (July/Aug. 2007). Overhead solar panels power an electric motor, allowing green pleasure cruisers to glide around without wasting fuel or dumping pollutants in the water.