Cyanobacteria are an attractive candidate for renewable production of microbe-derived chemicals, thanks to their plantlike power that converts sunlight and carbon dioxide to energy. But scaling up production is difficult, partially because of sunlight limitations in large industrial facilities. Shota Atsumi at the University of California, Davis, is seeking to bypass that problem by engineering the cyanobacteria species Synechococcus elongatus to metabolize a second carbon source, glycerol: a cheap and abundant by-product of biodiesel production. “Glycerol provides an energy source at nighttime; otherwise, we can only use half the day,” Atsumi says. He previously engineered the species to produce 2,3-butanediol, a common polymer precursor (Proc. Natl. Acad. Sci.USA 2013, DOI: 10.1073/pnas.1213024110). In the new study, Atsumi inserted genes for enzymes that enable glycerol digestion in cyanobacteria, allowing them to produce 2,3-butanediol both day and night, approximately quadrupling the previous output (ACS Synth. Biol. 2016, DOI: 10.1021/acssynbio.6b00239). “New uses for glycerol are always good for the development of a sustainable society, since glycerol is a major by-product of the biodiesel industry,” says Ethan I. Lan of National Chiao Tung University. “They made cyanobacterial biochemical production one step closer to industrialization,” Lan says.