Int. Journal of Renewable Energy Development 9 (1) 2020: 119-123 Page | © IJRED – ISSN: 2252-4940.All rights reserved 119 Contents list available at IJRED website Int. Journal of Renewable Energy Development (IJRED) Journal homepage: http://ejournal.undip.ac.id/index.php/ijred Multi-Feedstock Biodiesel Production from Esterification of Calophyllum inophyllum Oil, Castor Oil, Palm Oil, and Waste Cooking Oil H. Hadiyanto 1, 2, 3 , Apsari Puspita Aini 1,3 , W. Widayat 1 , K. Kusmiyati 4 , Arief Budiman 5 , Achmad Rosyadi 6 1 Department of Chemical Engineering, Diponegoro University, Jl Prof. Soedharto, SH, Tembalang, Semarang 50275, Indonesia. 2 School of Postgraduate Studies, Diponegoro University, Jl Imam Bardjo, SH, Semarang 50275, Indonesia. 3 Center of Biomass and Renewable Energy (C-BIORE), Diponegoro University, Jl Prof. Soedharto, SH, Tembalang, Semarang 50275, Indonesia 4 Faculty of Engineering, Dian Nuswantoro University, Semarang, Indonesia 5 Department of Chemical Engineering, Gadjah Mada University, Yogyakarta, Indonesia 6 Department of Chemical Engineering, Sepuluh November Institute of Technology, Surabaya, Indonesia ABSTRACT. Biodiesel can be produced from various vegetable oils and animal fat. Abundant sources of vegetable oil in Indonesia, such as Calophyllum inophyllum, Ricinus communis, palm oil, and waste cooking oil, were used as raw materials. Multi-feedstock biodiesel was used to increase the flexibility operation of biodiesel production. This study was conducted to determine the effect of a combination of vegetable oils on biodiesel characteristics. Degumming and two steps of esterification were applied for high free fatty acid feedstock before trans-esterification in combination with other vegetable oils. Potassium hydroxide was used as a homogenous catalyst and methanol as another raw material. The acid value of C. inophyllum decreased from 54 mg KOH/gr oil to 2.15 mg KOH/gr oil after two steps of esterification. Biodiesel yield from multi-feedstock was 87.926% with a methanol-to-oil molar ratio of 6:1, temperature of 60 ℃ , and catalyst of 1%wt. ©2020. CBIORE-IJRED. All rights reserved Keywords: Multi-feedstock biodiesel, trans-esterification, Calophyllum inophyllum, palm oil, waste cooking oil. Article History: Received: Oct 19, 2019; Revised: December 22, 2019; Accepted: January 21, 2020; Available online: February 15, 2020 How to Cite This Article: Hadiyanto, H., Aini, A.P., Widayat, W., Kusmiyati, K., Budiman, A. and Rosyadi, A. (2020). Multi-Feedstock Biodiesel Production from Esterification of Calophyllum inophyllum Oil, Castor Oil, Palm Oil, and Waste Cooking Oil. International Journal of Renewable Energy Development, 9(1), 119-123 https://doi.org/10.14710/ijred.9.1.119-123 1. Introduction With the depletion of petroleum reserves as the main source of fuel, many researchers have developed other sources that are renewable and sustainable to produce biofuel. Biofuel consists of bio-gasoline, bio-avtur, and biodiesel. In 2017, the United States and Brazil were the largest biodiesel producers in the world, with a total production of 6 and 4.3 billion L, respectively, followed by Germany (3.5 billion), Argentina (3.3 billion), Indonesia (2.5 billion), France (2.3 billion), Thailand (1.4 billion), and China (1 billion) (Wang 2018). In Indonesia, the contribution of renewable energy sources in the national energy mix in 2025 is targeted to be 25%, and bioenergy including biodiesel is expected to contribute 5% to those energy needs. Biodiesel is produced by converting vegetable oil and animal fat with methanol or ethanol through trans-esterification. Vegetable oils that are commonly used for biodiesel raw material are soybean oil, rapeseed oil, corn oil, palm oil, waste cooking oil, yellow grease, and castor oil (Gokdogan et al., 2015). Homogeneous catalysts, such as potassium hydroxide, and sodium hydroxide, were used as alkaline catalysts in trans-esterification, whereas hydrochloric acid, and sulfuric acid were used as acid catalysts in esterification. Although homogeneous catalysts could not be reused and require other separation processes after trans- esterification, they have been widely used worldwide. Meanwhile, heterogeneous catalysts are still being developed to achieve optimal catalytic performance with high-selectivity biodiesel. In previous research, biodiesel has been used a single oil feedstock. It depends on the type of vegetable oil used and the country’s production and reduces the flexibility of operations. Not all countries have a large production of vegetable oils that can be used as feedstock for biodiesel. For example, soybean oil became the largest commodity used in America. However, it could not be applied as a major feedstock in Indonesia because it is classified as a food commodity. In addition, it is still imported from another country because its average production only fulfills 43% of soybean needs (Hadiyanto et al., 2018). Moreover, not all vegetable oils are Research Article *Corresponding author: hadiyanto@live.undip.ac.id