This study is motivated by the depletion of fossil fuels in nature, which is inversely proportional to the higher level of fuel oil consumption, so the need for alternative fuels, namely biodiesel. Biodiesel can be made using waste cooking oil because of its abundant quantity, low price, and not being reused. One of the efforts to achieve energy conservation and improve fuel quality is using bioadditives. A lemon essential oil can be used as a bio-additive because it is easily soluble in fuel and its oxygen-rich content can reduce the rate of fuel consumption. The process in this study is to produce biodiesel with waste cooking oil (WCO) using a transesterification process. Biodiesel samples containing the bioadditive lemon essential oil on B20 biodiesel with varying volume fraction (0%; 0.1%; 0.15%; 0.2%). In general, this research can be done in three steps. The first step is the characterization of the compound composition (GCMS) and functional group (FTIR) of diesel fuel, biodiesel, and lemon essential oil bioadditive. The second step is the characterization of the physicochemical properties (density, viscosity, flash point, calorific value) of B20 biodiesel with various concentrations of lemon essential oil bioadditive, then compared with SNI 7182:2015. The third step is determining the rate of fuel consumption in diesel engines. The results show that Biodiesel B20 with a volume fraction of 2% lemon essential oil bioadditive has a high ability to reduce the rate of fuel consumption. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

This research is motivated by the decreasing of fossil fuels in the earth while the level of consumption of fossil fuels is getting higher from year to year, so the need for alternative fuels increases, one of which is biodiesel. The existence of studies in preparing biodiesel as an alternative fuel is essential. This study aimed to determine the effect of bioadditive essential oils (lemon, lemongrass, and eucalyptus) on biodiesel fuels’ thermophysical properties. The method used in this study is using esterification and transesterification step for making biodiesel. The character of biodiesel can be recognized by testing the physicochemical properties which consist of kinematic viscosity, density, flash point, and low heating value tests. The results show that the density of all samples is not significantly different in value. Increased density occurs in each sample due to the higher concentration of essential oils. As the concentration of essential oil increases, flashpoint tends to decrease. Low heating value tends to decrease with the increase concentration of essential oil. Kinematic viscosity has a value that tends to decrease with the addition of essential oil concentrations.

Long-term electricity demand in Indonesia for the period 2003 to 2020 increased to 275 TWh. The demand for electricity in Java Island in the same period from 2003 to 2020 reached 200 TWh. Alternative and renewable energy is needed to support the electricity needs of the Indonesian. The potential for water energy is one of the alternative energies that can be maximized to obtain electrical energy, among others, it can be obtained from river water flow without falling heads or free water flow. A turbine innovation that can be used in rivers with free water flow is the goose foot water turbine. This research is focused on calculating the efficiency of the goose foot water turbine based on the variation of the number of fins and the depth of the turbine in order to obtain maximum performance. Performance analysis was conducted using the Computational Fluid Dynamics (CFD) method. The CFD results show that the highest value is obtained at the number of blades is 6, the number is fins 17, and the turbine depth is 0.35 m, namely the highest torque is 1593 Nm, the highest rotational speed is 11,705 rpm, the highest power is 1951.602 W, and the highest efficiency of 86.738%.

Waste is a wordlwide problem including in Indonesia. The increasing amount of waste is caused by the increasing human population. Proper waste management must be applied to avoid detrimental health and environmental consequences. One way to manage waste is to design a device that could convert waste into electrical energy. This research aimed to provide a solution so that the volume of waste in Indonesia can be reduced and used as renewable energy. The methods used in this research were (1) identifying previous research on waste incineration and (2) designing a waste incinerator as appropriate technology and equipped with a system of utilizing the generated heat into electrical energy. The result of this research is the design of a device that can produce electricity from smoke and thereby reduce air pollution. Smoke from waste burning in a furnace was first filtered using a carbon cloth material to reduce air pollution. The heat from combustion was used to boil the water and change it into fumes above 100ºC. The steam produced had potential energy which was converted into kinetic energy through a turbine that can move the shaft to produce mechanical energy. Mechanical energy was then used to rotate the generator shaft that generated electric current and was then used to charge the battery. The battery power was then distributed for regualr use using a power converter. Keywords: combustion, design, electricity, environment, health, waste

This research is geared by the depletion of the availability of fossil fuels in nature. This is inversely proportional to the level of fossil fuel consumption, which is getting higher from year to year. Thus, there is a need for alternative fuels. One of which is biodiesel. The existence of an assessment in preparing biodiesel as an alternative fuel is significant. This study aims to determine the effect of the addition of bioaditive essential oil (eucalyptus) on the performance of diesel engines. The method used in this research was the manufacture of biodiesel through esterification and transesterification steps, then testing the diesel engine to determine the performance and gas emissions were also carried out. The results show that brake torque has decreased along with the loading at each engine speed. The value of brake power increases from 1700 rpm to 1900 rpm and then decreases to 2300 rpm. Brake fuel consumption increases with increasing engine speed, and thermal brake efficiency decrease with increasing engine speed. The CO emission is constant, but in the B20 biodiesel sample with 0.1% eucalyptus oil additive, the CO emission increases to 2100 rpm. CO2 and HC emissions fluctuate with an increasing trend with increasing engine speed. O2 emissions fluctuate with a decreasing trend along with the increase in engine speed, the O2 content produced by pure biodiesel B20 is lower than B20 with additives