Producing diesel fuel from vegetable oil has been a boon to the transportation fuel industry. A drawback is that glycerol is left over after the conversion of triglycerides in the oil to the fatty acid methyl esters that make up the fuel. Researchers have been on the lookout for ways to use the now abundant glycerol, which does not burn well itself and is usually treated as waste. Using a life-cycle analysis approach, a team led by Cecilia Mondelli, Stavros Papadokonstantakis, and Javier Pérez-Ramírez of ETH Zurich has demonstrated the viability of a tandem bio- and chemocatalytic process to convert glycerol into lactic acid, an important chemical intermediate used to make other building block compounds and to make biodegradable polylactic acid (Energy Environ. Sci. 2014, DOI: 10.1039/c4ee03352c). Biobased lactic acid is typically made from sugar by a fermentation process. The new approach includes an enzymatic conversion of glycerol to dihydroxyacetone followed by a chemical step using a tin-based microporous zeolite catalyst to isomerize dihydroxyacetone to lactic acid. The method produces less CO2 and requires less energy than the traditional process and could help improve the economics of both biodiesel and polylactic acid production, the researchers note.