The current paper describes two topics. The first is a study of the effect of fatty acid methyl ester content in biodiesel on characteristics of oxidation stability as quality parameters, including peroxide value, acid value, kinematic viscosity, and induction period obtained from a Rancimat test. The second is a study of the effect of biodiesel oxidation on diesel combustion and emission characteristics. An accelerated oxidation stability test was conducted by the Rancimat test method on methyl esters with different unsaturated fatty acid components. The unsaturated fatty acid components exert a large influence on oxidation deterioration as well as thermal and auto-oxidation stability. In addition, characteristics of oxidation were obtained from a thermal oxidation test using a tank equipped with an injection system test rig. These experiments clarified relationships between oxidation quality parameters. The autoignition characteristics of deliberately oxidized biodiesel were analysed by means of the constant-volume combustion method. Engine bench tests were also conducted on a single-cylinder engine. These experiments employed methyl ester made from soya bean oil as biodiesel. Use of an oxidized biodiesel was found to increase combustion pressure and temperatures, resulting in increased NO _x emission; however, CO emission and smoke are decreased without any loss in fuel consumption rate.

Significant concerns over energy security and environmental impact reduction will drive all stakeholders to generate proper alternative energies. Biodiesel is a prospective cleaner-burning biofuel that can contribute on addressing these concerns globally. Presently, pure biodiesel (B100) application is still facing several obstacles, principally in terms of its cold flow properties. Improvement in cold flow behavior parameters is the solution to promoting biodiesel implementation at a higher percentage and wider environmental temperature range. This study provides a detailed review of several improvement methods, both physical, chemical, and biological, from various scientific sources, to elevate the cold fluidity characteristics of biodiesel. The investigated methods convincingly offer proper enhancement in the cold flow properties of biodiesel. Mostly, this improvement is accompanied by an alleviation in oxidation stability, cetane number, and/or viscosity. However, the skeletal isomerization method presents promising cold fluidity refinement with minimal reduction in other physical properties. Therefore, the continuous development of these methods promises global sustainable application of high-quality biodiesel.

Palm oil waste is an abundant biomass resource in Indonesia that is not well utilized as a raw material for producing high value-added materials. One product that is possible to be manufactured from oil palm biomass is activated nano carbon. Characteristics of high porosity and good conductivity will lead the activated nano carbon suitable as an electrode of supercapacitor material. Preparation of activated nano carbon is conducted by two main steps namely carbonization and activation. In this research, carbonization is done by hydrothermal process while activation is done by physico-chemical activation. This study focused on manufacturing activated nano carbon from empty fruit bunches of oil palm with hydrothermal carbonization for supercapacitor applications. The activation of mesopore area of the carbon has been taken place by using ZnCl₂ and CaCl₂ as a chemical activating agent during the hydrothermal process. The activated nano carbon produced from empty fruit bunches has a surface area of 41-1571 m²/g and a pore size of 2.0–6.8 nm. In this study activated nano carbon is used as a working electrode in symmetric hybrid supercapacitor.

Palm oil waste as biomass resources in Indonesia were not fully utilized. One of the product that can be made from oil palm biomass is activated carbon. Activated carbon characteristic with high porosity and good conductivity, made activated carbon suitable as supercapacitor electrode material. Activated carbon preparation consists of two main steps that are carbonization and activation. In this research carbonization carried out by hydrothermal process while activation conducted by physcal activation. This research focused on manufacturing activated carbon from palm oil waste by hydrothermal carbonization for supercapacitor application. Activated carbon produced from empty fruit bunch have a surface area of 330 – 1181 m²/gr, pore volume of 0.19 – 0.69 cm³/gr, and pore size of 2.1 – 2.3 nm. While activated carbon produced from oil palm shell have surface area of 8 – 451 m²/gr, pore volume 0.05 – 1.064 cm³/gr, and pore size 2.9 – 20.7 nm. The crystallinity of the activated carbon obtained ranged from 46.5 to 51.9%. In this study, the activated carbon is used as a working electrode on an asymmetric hybrid supercapacitor with nickel oxide being used as second electrode. This palm oil-based supercapacitor cell has a capacitance of 1.7554 F/g.