With Valentine's Day coming soon, Scientific American has a timely feature on greenhouses -- you know, those places that grow the roses you're supposed to buy on Saturday? Scientific American's angle? Dutch researchers are working on ways to make greenhouses more energy-efficient. Plastics, of course, play an important role.
Until recently, most efforts to improve them involved installing thicker insulation or blocking sunlight during summer months. But Piet Sonneveld, an agricultural engineer at Wageningen University in the Netherlands, and his colleagues designed a prototype greenhouse that creates an indoor environment ideal for the Netherlands's crops and saves energy in the process. He designed a special removable film that blocks near-infrared radiation -- a wavelength of sunlight that, unless filtered out, can overheat and damage plants during the summer. The film is just 80 microns thick (one micron equals about four one hundred-thousandths of an inch) but contains hundreds of layers of plastic polymers that filter out infrared light while allowing plant-nourishing visible light to pass through. In the wintertime, when heating is necessary, the film is removed.Sonneveld's greenhouse also features a curved roof that focuses light on clusters of photovoltaic cells to that generate electricity for the building. Pretty cool!