Overall well-to-wheel greenhouse gas emissions of various types of biofuels, compared to reference fuel

SME refers to sunflower methyl ether, which is biodiesel. RME is similar for rapeseed. GTL refers to gas-to-liquid, which is synthetic diesel made from natural gas. DME refers to di-methyl ether, which is a substitute for petrol. EtOH refers to ethanol, which is a substitute for petrol. DICI refers to a modern diesel engine and DPF to a particle filter. PISI refers to a modern petrol engine.