Biodiesel merupakan bahan bakar alternatif yang berasal dari bahan bakar nabati dan hewani yang tergolong dapat diperbarui. Bahan nabati yang dapat digunakan sebagai bahan baku contohnya seperti biji alpukat. Biji alpukat yang melalui proses pengepresan menghasilkan minyak dan getah (gum). Proses degumming dilakukan untuk memisahkan minyak dan getah dengan menggunakan asam phospat 0,5%v/v. Kandungan FFA dapat digunakan pada proses transesterifikasi untuk menghasilkan metil ester dengan perbandingan minyak dan metanol serta lama waktu transesterifikasi. Penelitian ini bertujuan untuk mengetahui pengaruh perbandingan minyak dan metanol serta pengaruh waktu terhadap rendemen biodiesel dan menentukan karakteristik biodiesel yang dihasilkan sesuai dengan standar SNI 04-7182-2015. Penelitian ini dirancang dengan menggunakan metode Rancang Acak Lengkap (RAL) dengan 2 faktorial yaitu perbandingan minyak dan metanol (1:4, 1:6, 1:8) dan lama waktu transesterifikasi yaitu (30 menit, 60 menit, 90 menit). Parameter karakteristik biodiesel yang dianalisis meliputi densitas, viskositas, bilangan asam, angka setana, nilai kalor, angka iodin dan kadar metil ester yang sesuai dengan SNI 04-7182-2015. Hasil penelitian menunjukkan bahwa rendemen tertinggi terdapat pada sampel A3T1 (perbandingan 1:8 dengan lama waktu transesterifikasi 30 menit). Hasil pengujian mutu A3T1 yaitu densitas 968 kg/m3, viskositas 4,6037 mm2/s, bilangan asam 0,4 mgKOH/gr, angka setana 44,77, nilai kalor 48,81 MJ/kg, angka iodine 8,10 gram/100gram dan kadar metal ester 94,05%.Kata kunci: Biji alpukat; biodiesel; pemurnian Utilizing Avocado Seed Extraction  (Persea americana Mill) as Bioidesel Raw Material by Purifying Water WashingABSTRACTBiodiesel is an alternative fuel derived from vegetable and animal fuels that is classified as renewable resource. Vegetable materials that can be used as raw materials for example are avocado seeds. Through the pressing process, avocado seeds will produce oil and gum. The degumming process is carried out to separate the oil and the gum using 0.5% v/v phosphoric acid. FFA content can be used in the transesterification process to produce methyl esters with a ratio of oil and methanol and the length of transesterification time. This research aims to determine the effect of the ratio of oil and methanol as well as the effect of time on the yield of biodiesel and to determine the characteristics of biodiesel in accordance with SNI 04-7182-2015 biodiesel standards.The research was designed using Complete Randomized Design (CRD) method with 2 factorial comparisons of oil and methanol (1:4, 1:6, 1:8) and the length of transesterification time (30 minutes, 60 minutes, 90 minutes). The analyzed parameters of biodiesel characteristics include density, viscosity, acid number, cetane number, calorific value, iodine number and metal ester content in accordance with the Indonesian National Standard number 04-7182-2015. The results showed that the highest yield was in the A3T1 sample (1:8 ratio with 30 minutes transesterification time). A3T1 quality test results showed the density of 968 kg/m3, 4.6037 mm2/s viscosity, 0.4 mgKOH/gr acid number, 44.77 cetane number, 48.81 MJ/kg calorific value, 8.10 gram/100gram iodine number and 94.05% of ester metal content.Keywords: Avocado seed; biodiesel; purification

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Batu bara merupakan bahan bakar yang tidak dapat diperbarui dan masih mendominasi peran sebagai bahan bakar utama Pembangkit Listrik di Indonesia. Sumber energi yang dapat diperbarui seperti matahari mulai dikembangkan sebagai alternatif. PLTS merupakan sistem yang mampu mengkonversi energi radiasi cahaya matahari menjadi listrik menggunakan modul semikonduktor fotovoltaik. Gedung Teknik Politeknik Negeri Jember memiliki PLTS di atapnya yang terdiri dari 4 kWp PLTS off-grid dan 6 kWp PLTS on-grid. Namun, hanya sistem off-grid sebesar 4 kWp saja yang sudah dioperasikan. Pada penelitian ini dilakukan studi evaluasi pada PLTS off-grid terkait berdasarkan Panduan Studi Kelayakan PLTS dan IEC 61724. Pengujian dilakukan selama 3 hari mulai pukul 09.00 – 14.30 dengan interval 30 menit menggunakan 2 lampu halogen dengan total daya 800 W. Berdasarkan penelitian yang telah dilakukan, PLTS memiliki nilai efisiensi PV 43 %, inverter 92 %, SCC 95 %, dan rasio performansi 44%. Selama proses pengujian tidak didapati kendala yang fatal dan kondisi fisik komponen secara keseluruhan baik. Optimasi yang dapat dilakukan adalah maintenance seperti cleaning secara berkala, penambahan perangkat monitoring seperti pyranometer yang terintegrasi dengan sistem PLTS untuk memudahkan pemantauan sistem. Untuk meningkatkan efisiensi modul surya, penambahan alat pembuang panas pada modul atau sistem pendinginan dapat dilakukan.

The vibration of the secondary cooling system the Kartini reactor works to remove heat from the primary cooling system so that the heating element stays below the safety limit of the specified operating temperature. One component that is supported is a pump that is needed one of them by the vibration analysis method. By using vibration analysis, the type of cause of damage to the pump can be detected without dismantling the pump, so that it can provide predictability of maintenance time, scheduling repairs, picking up damaged equipment before hazardous needs. Vibration measurement with vibration meter (Lutron VB 8202) is carried out on the bearing housing of the secondary cooling pump motor housing in the direction: vertical, horizontal and axial. The value of the vibration compared with the vibration pump standard (ISO 10816-3). From the results of pump vibration measurements, there are several pump parts whose conditions are classified as vibrations that can cause damage to these components, namely the pump motor section. The average vibration on the pump motor is 5.74 mm / s greater than 4.5 mm/s that is classified as a vibration velocity value which can cause damage to other pump components. The results of the symptom analysis of variations in the vibration of abnormal values in the pump motor are caused by looseness of rotation and damage to roller bearings.

Distance Learning which is currently being implemented as a result of the Covid-19 pandemic which has lasted for almost 1.5 years has caused psychological problems for students. The problems that arise include boredom due to monotonous learning, less interactive, and piling tasks. The level of education that is quite affected due to the implementation of Distance Learning is elementary school education. To overcome these problems, it is necessary to do a learning that is able to restore student motivation in learning. Mutiara Bunda Jember Foundation in collaboration with Renewable Energy Engineering lecturers at the Politeknik Negeri Jember held an interesting and interactive lesson entitled "Fun Physics Experiment". This activity was attended by 30 participants from various grade levels at the elementary school level. The results of the pretest and posttest questionnaires showed that there was an increase in participants' knowledge of light refraction, air pressure, combustion and pressure processes, heat transfer and density. In addition, after the "Fun Physics Experiment" activity, it was found that the level of interest of participants in Physics lessons increased, there were 7 participants who were very interested in Physics lessons and 23 participants were interested in Physics lessons.