Charles T. TroyOAK RIDGE, Tenn. -- Using collectors to gather sunlight and optical waveguides to transport the light, researchers at the US Department of Energy's Oak Ridge National Laboratory have put together the first pieces of a hybrid lighting system that will combine artificial light with natural light. It is expected to eventually trim the nation's electric bills -- currently estimated at $75 billion."Hybrid lighting holds great promise for improving quality and efficiency of lighting," said Art Clemons, a co-developer of the system. "Even a modest improvement could result in significant savings.""Even though there have been a lot of advances in fiber optics and other technologies critical to this effort, there has been a lack of overall coordination and integration of these technologies on a systems level," said Jeff Muhs, another developer. Muhs noted that the project is a partnership between the lab and industry.Before the technology can start cutting light bills, the lightguides that transmit sunlight from rooftop collectors to inside fixtures must be made more efficient. Current lightguides have an attenuation rate of 1 percent per foot. In tall buildings, that rate is unacceptable. "Our goal is 1 percent loss per 10 ft," Clemons said, "so we have a considerable way to go."Other areas that need improvement include optical materials, light- dispersing elements, and feedback and control systems. G