3.6. Mass balance of biodiesel and bioethanol production from Chlorella sp. KR-1 microalgae A mass balance of biodiesel and bioethanol production from 1 kg of Chlorella sp. KR-1 biomass was analyzed (Fig. 3). Whole cells contain total lipids and carbohydrates of 38.0% and 36.1% (w/w), respectively. From this sample, 0.3 kg of biodiesel and 0.62 kg of the lipid-extracted residual biomass were produced. The residual biomass contained 49.7% carbohydrates (82.4% fermentable sugar and 17.6% non-fermentable sugar). Approximately 98.2% of the total carbohydrates were converted into monosaccharides (fermentable+ non-fermentable sugar) using dilute acid saccharification. The fermentable sugars were then subsequently fermented into bioethanol with a fermentation yield of 79.3% using the SHF process. In this study, bioethanol was sequentially produced using the lipid-extracted residual biomass of Chlorella sp. KR-1 asfermentation feedstock. The lipid-extracted residual biomass was directly saccharified and fermented with high efficiency since the cell wall was disrupted during lipid extraction step in biodiesel production process. In another manner, the saccharification broth generated by enzymatic method was directly used for bioethanol fermentation without any pretreatment. The waste residual biomass generated from biodiesel production process could be used as feedstock for bioethanol fermentation, which contributes to economic feasibility of biofuel production from microalgae.