Among the renewable biomass fuel alternatives, microalgae are the most important future choices owing to its fast growth rate and great capability for CO2 fixation. There are various species in the world, in which each species has its characteristics. This work presents a prospect of marine microalgae Isochrysis galbana for renewable fuel feedstock regarding its biomass abundance, physicochemical properties, and thermal characteristic. The seawater medium in the Erlenmeyer flask was used for the algal culturing. The biomass abundance, in term of specific growth rate and doubling time, was assessed by calculating the culture medium cells number with a hemocytometer and optical microscope. Harvesting was done by precipitating biomass with caustic soda, subsequently filtering, and washing it with distilled water. The biomass sediment had been sun-dried for three days, and then dried biomass was crushed by using the mortar to be a powder. The proximate analysis was arranged by conducting an experiment in according to the test method of ASTM D 3173-11, ASTM D 3175-11, ASTM D 3172-13 and ASTM D 3174-12 for specifying the content of moisture, volatile matter, fixed carbon, and ash of the sample, respectively. The heating value was estimated by using adiabatic bomb calorimeter. The chemical composition of biomass was determined by Energy-dispersive X-ray (EDX) spectrometry. The biomass cellular macromolecular compounds were also evaluated by Fourier transform infrared (FTIR) spectroscopy and compared with its residue. Through eight days observation, it was noticeable that Isochrysis galbana has a specific growth rate of 0.18 d-1 and a doubling time of 3.85 d. The respective moisture, volatile matter, fixed carbon, and ash content were 12.98, 40.10, 7.47, and 39.45 (%, air-dried basis). The energy content algal biomass was 16.22 MJ kg-1. This current investigation encourages that Isochrysis galbana can be viable as one of a future sustainable solid biofuel feedstock.

The impact of MgCO3 and Al2O3 additives on the thermal behavior of Spirulina platensis (SP) biomass during combustion in a thermal analyzer was evaluated to understand their catalytic effect in the decomposition process. The samples were pure SP and a mixture of SP and additives at mass fractions of 3, 6, and 9 (wt,%). Each sample of around 8.5 mg was mounted in a thermobalance and subjected to a furnace on a heating program of 10 o C/min. The 100 ml/min air atmosphere was kept continuously flowing during the combustion process from 30-1200 o C. The thermal behavior of the sample was then characterized from the thermogravimetric (TG) and derivative thermogravimetric (DTG) curves, those were recorded by a computer during the experiment. The Horowitz-Metzger method was used to evaluate the impact of additives on the kinetic parameters of the samples. The results indicated that the presence of additives shifted the main decomposition stage toward a lesser temperature. The rate of mass loss (ML) in the main decomposition zone decreased in the 1 st peak and increased in the 2 nd , in accordance with the increase in the fraction of additives. This indicates that additives play different roles during the decomposition process. The mass mean activation energy (Em) increased at the additive fraction of 3% for both MgCO3 and Al2O3, as well as at 6% MgCO3 compared to combustion with no additives. Conversely, the presence of greater additives promoted a shift in Em toward smaller values. These results confirm that both additives significantly influenced the thermal behavior and kinetics of the SP combustion.

Thermogravimetric analysis experiment to understand thermal decomposition behavior of water hyacinth during the pyrolysis has been performed. Water hyacinth was taken randomly from 2 places, i.e., Selorejo and Sengguruh Dam, district of Malang, Indonesia. Those raw materials were thoroughly cleaned by using the water, then cut and dried in an oven with a temperature range of 80-90 o C for 6 hours. Subsequently, the dried samples were crushed and then filtered to a mesh size of 60. Thermal behavior of the sample was observed through the instrumentality of thermal analyzer at a constant heating rate of 10 °C/min with a nitrogen flow rate of 100 ml/min and a temperature range of 25-1000 °C. The kinetics of active pyrolysis zone were evaluated by Coats-Redfern integral method. The thermogravimetric test results show that the water hyacinth biomass decomposed into four stages during the pyrolysis process. The kinetic parameters in term of activation energy (E), logarithmic frequency factor (log A) and reaction order (n) were 60.74 kJ/mol, 4.77/min and 1.9, respectively.

Indonesia is one of the countries with the third highest air pollution in the world. The biggest contributor air pollution is produced by motorbikes by 60-70%. One the causes of increased exhaust emission is widespread use absorptive exhaust that designed without catalytic converter. The aims of this research is to determine the effect of copper-based catalytic converter with circular tube shape on exhaust emission of Yamaha Vixion 1PA. This study used an experimental research design. The objective of this research is copper catalyst with circular tube shape model. The research instrument used the gas analyzer HG-510 as a test tool for data collection of exhaust emission. Data analysis using inferential statistical techniques paired sample T test through the SPSS 24 statistical analysis application. The results showed that the addition of copper catalytic converter with a circular tube shape model can reduce CO exhaust emission by 16.67%, whereas for exhaust emission HC can be reduced by 32.54%.

Penelitian ini bertujuan untuk mengetahui apakah ada pengaruh dari perubahan panjang alur roller terhadap daya dan akselerasi pada sepeda motor Honda Vario 125 cc PGM-FI CBS ISS. Pendekatan penelitian yang digunakan dalam penelitian ini adalah pendekatan penelitian kuantitatif dengan desain quasi-experiment yang melibatkan variabel bebas dan variabel terikat. Berdasarkan hasil penelitian ini daya yang dihasilkan oleh primary pulley standard pada putaran rpm 8000 ialah sebesar 10,281 HP sedangkan dengan menggunakan primary pulley yang sudah di custom menghasilkan daya sebesar 10,905 HP. Sementara untuk akselerasi kendaraan yang dihasilkan ketika menggunakan primary pulley standard dari kecepatan 0-100 km/jam ditempuh dengan percepatan 2,05 m/  sedangkan untuk primary pulley custom dengan kecepatan yang sama ditempuh dengan percepatan 2,09 m/ . Dengan demikian perubahan panjang alur roller ini tidak menghasilkan perbedaan daya dan akselerasi yang signifikan.