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Abstract The tofu industry consumes a lot of energy and water for its process production and then produces wastewater in large quantities that have a negative effect on the environment. It is because tofu craftsmen still use conventional technology in the process production, and there is no SOP for the use of raw materials and energy sources, and there is also a lack of capability in waste management. This study aims to investigate the audit energy in the tofu industry, including evaluating the consumption energy in different energy sources, determining the production of wastewater in the tofu industries and determining the energy sources available in the tofu industry. The data collection method involved semi-structured interviews and questionnaire surveys carried out in 40 tofu industries in Gunung Sulah district, Bandar Lampung City, Lampung Province, Indonesia. The results showed that the highest consumption in process production in the tofu industry is for cooking that depends on the type of energy sources, namely firewood 71.1 MJ/kg, LPG 16.9 MJ/kg, and wood pellets 6.0 MJ/kg. However, the consumption of water for the production of the process is 25.2 L/kg and produces 14.5 L/kg wastewater. The tofu industry is still not efficient in consuming energy because it does not use wastewater to produce a bioenergy product that can be beneficial in economic and environmental aspects. To make energy consumption more efficient in the tofu industry, it is very useful to use wastewater to produce bioenergy material that can replace non-renewable energy as the main energy for process production. Based on the prediction that the potential for methane from tofu wastewater is approximately 0.056 m 3 /kg soybeans, the use of tofu wastewater as biogas feedstock can replace 2.82% of firewood, 11.86% LPG, and 33.39% biopellets.
Ningsih et al. (Fri,) studied this question.