This research focused on evaluating the technical viability of using biodiesel with a blending ratio of 40% v/v, which is expected to be implemented soon in Indonesia. Two kinds of biodiesel blends were prepared, a blend of 60% diesel fuel and 40% biodiesel (B40) and a blend of 60% diesel fuel, 30% biodiesel, and 10% hydrogenated vegetable oil (HVO) (B30D10). The fuels were tested on EuroII vehicles without any engine modifications through a 50,000 km endurance road test. Laboratory tests were also performed at certain traveled distances to evaluate various engine parameters, including power, fuel economy, exhaust emissions, and used engine oil properties. Engine components were inspected upon the completion of the road test. Cold-start ability was also examined to confirm the suitability of the investigated biofuels at low-temperature operating conditions in Indonesia. The road test results showed that vehicles fuelled with B40 and B30D10 could reach a distance of 50,000 km without encountering any technical issues. The laboratory evaluation during the road test indicated that B30D10 had a higher power and fuel economy than B40, with a maximum difference of 2%. Furthermore, B30D10 emitted lower CO, HC, and PM emissions than B40 throughout the distance traveled, with maximum differences of 11.4%, 14.7%, and 22.6%, respectively, but led to 15% higher NOx. Engine component inspection and used engine oil analysis confirmed the fulfillment of the manufacturer's recommendations for both B40 and B30D10. Finally, B40 and B30D10 were suitable for operating at low ambient temperatures in Indonesia, confirming them as practical options to be implemented in the nationwide 40% biodiesel blend fuel.

Based on the Indonesian road map on achieving renewable energy fuels, the use of 30% palm biodiesel (B30) with mono-glyceride contents of 0.5% maximum has been applied nationally. Determination of this mono-glyceride value is to prevent biodiesel precipitation if it is exposed to low temperatures, moreover the excessive precipitate formed can block a fuel filter. Blocking fuel filter cause a vehicle difficult to be started. Cold start ability of the use B30 and precipitation tests in low temperatures ambient is one of considerations of the government's decision. The cold start ability test used diesel passenger vehicles fuelled by B30, while the precipitation test used samples of B30 which were placed in an open area close to cloud point temperature of palm biodiesel. After soaking for 3 to 21 days, the test vehicles fuelled by B30 with mono-glyceride content of 0.5% and 0.4 % can be turned on around 1 second as well as fuelled by pure diesel. The precipitation of B30 0.5% mono-glyceride content was higher than 0.4% mono-glyceride content ones. While, the pure diesel took the lowest place. The variation of soaking time didn't effect on the precipitate formed of the test fuels.

As a tropical country, Indonesia has various plants that can be used as alternative energy sources, including palm oil as a biodiesel material. The use of biodiesel at a relatively high ratio continues to be encouraged by the government through various policies. The application of high concentrations of biodiesel in diesel engines needs to be supported by a series of studies to solve some of the problems that may occur and to ensure that no negative impacts occur. Oxidation stability and deposit formation are the main concerns in biodiesel use. In this study, an evaluation of B100 and B100+1000 ppm BHT fuel was carried out to determine its oxidation stability and its effect on the formation of deposits in the combustion chamber. Deposit evaluation is carried out on a stationary engine running for 70 hours (10 hours per day) with a constant load of 70% for each fuel. The addition of 1000 ppm BHT to B100 increased the oxidation stability by 171%, reduced smoke emissions by 24%, and lowered total deposit formation in the combustion chamber by 25%. A decrease in deposits was observed on the piston (32%), cylinder head (8%), and exhaust valve (23%). However, a slight increase in deposits was noted on the intake valve (11%) and injector tip, as seen from the photographic comparison. Importantly, the increase in injector tip deposits did not affect engine performance during the 70 hours of testing.

The depletion of petroleum reserves as the basic raw material for gasoline production has driven studies into alternative fuels. One of the alternative fuels is alcohol, both ethanol and methanol. Due to their liquid form and physical-chemical properties similar to gasoline, small modifications to the engine are required. This paper will explain the effect of using a mixture of gasoline (in this case, RON 98 gasoline with methanol or methanol on engine performance and emissions. The fuel mixtures are as follows: G100, E10, E20, E30, M10, M20, M30. AVL Boost simulation software was used as a tool for 1-dimensional engine modelling, where the modeling is based on engine testing with G100 fuel. The results show that with increasing ethanol-methanol composition, torque and power decrease, and SFC increases. On the emission side, CO, CO2, and HC were decreased and NOx increased.

The automotive and non-automotive sectors have followed the Indonesian government's policy regarding applying high concentration biodiesel use. Some issues arise from the effects of using a high biodiesel concentration on engine components, such as filter blocking or degradation. Therefore, various parties have challenged to improve both in terms of fuel quality and engine components. Meanwhile, testing of high concentration biodiesel fuel (blending ratio above 10 %) was still rarely published in the rail transport sector. Therefore, the rail test aimed to evaluate the effect of B20 fuel on locomotive engine components. The test was conducted during two periodic maintenance (6 months) using two trains with B20 and B0 fuels as a comparison. This study discusses the effect of B20 on fuel filters by performing tests on used filters for one periodic maintenance (3 months). The morphological analysis of deposits was conducted using a digital microscope, while TGA, GC-MS, FTIR, and elemental analysis were used to determine its components. The results showed that biodiesel filtration in the main filter was higher, and the subsequent filtration showed fewer deposits than that of pure diesel. Various types of fuel filter deposits have been identified, such as hydrocarbons and fatty acid methyl esters.