Ruihong Zhang, a UC Davis professor of biological and agricultural engineering, has worked on anaerobic digester technology for the past decade, bringing it from the laboratory to the pilot stage in 2006. Clean World Partners, a Sacramento-based startup that licensed the technology from UC Davis, installed the biodigester at American River Packaging. It converts food waste from regional food producers and unrecyclable corrugated material from the company into natural gas. The system will generate roughly 1,300 kWh of renewable energy per day, meeting about 37 percent of the company’s electricity needs. Photo taken on Thursday, May 10, 2012.