Abstrak Abstract The wind turbine is a device that converts wind energy into mechanical energy and then converted into electrical energy through a generator. Horizontal axis wind turbines can increase the efficiency to get the maximum power coefficient. One was using the blade numerous. Maximum efisiensi system will increase the number of watts (power) generated so as to obtain a certain number of watts by simply using the number of windmills less The object of this research is the performance testing horizontal axis wind turbine with wind speed variation and variation in terms of the number of blade Efisiensi system ( ) and Tip Speed Ratio (TSR

No abstract

The rising costs for the fossil fuel based energy and concern over the environment have caused a resurgence of interest in anaerobic treatment and subsequent use of the biogas produced during the treatment of organic waste as fuel.  Biogas from cattle dung has become a potential renewable energy source for both domestic and commercial usage especially in Lombok. Unfortunetly, due to the presence of carbon dioxide (CO2) and Hydrogen sulphide (H2S) in biogas, it has become extremely difficult to store and transport it effectively and has lower energy density.This paper presents the study in biogas purification by mean of absorbing the CO2 gas using the NaOH solution. In addition, the biogas production process used in 3 (three) kinds of cattle dung from horses dung, cows dung and buffaloes dung by the composition of 1 kg of manure to 1 Liter of water.                 The results show that generated the largest volume on the composition of C with average volume reached 72.419 liters, then the composition B reached 61.794 liters, and the lowest in the composition of A with an average volume of 51.478 liters. The highest power generated in the treatment composition A with 2.5 N NaOH solution at 108.5 watts and the lowest power generated by the composition of C without treatment of 25.67 Watts.

Savonius turbine is a type of vertical-axis wind turbines. The turbine has a potential to be developed as it has a simple construction and is suitable for low wind speeds. However, the turbine is still rarely used because of the low efficiency of the turbine compared to other turbines. The low efficiency of the turbine is due to the negative moment. Some efforts have been done to reduce the negative moment such as by adding a wind concentrator. The wind concentrator can steer the incoming wind toward the turbine blades that generate positive moments, consequently, the generated power increases. The aim of this research is to determine the effect of the number and diameter of the Savonius blade wind turbine with an additional concentrator. The concentrator had a concentration ratio of 6:1 and it was tested at the lower wind speeds of 2-5 m/s. The result shows that adding a wind concentrator can increase the rotational speed of the rotor, power coefficient, and the turbine power. The Savonius turbine with two blades has the best performance compared to the three and four blades. The Savonius blade wind turbine with the rotor diameter of 12 cm is the best Savonius turbine for the concentration ratio of 6:1.

Dalam penelitian ini dilakukan pengujian karakteristik viskositas kinematik, specific gravity, warna, kadar air dan volume hasil dari minyak pelumas hasil daur ulang untuk mengetahui variasi campuran optimal antara asam sulfat dengan tanah liat sebagai adsorben pada tahap clay treatment dan kemudian dibandingkan dengan lube base oil standar. Dari pengujian, menunjukkan bahwa campuran asam sulfat dan tanah liat terbukti efektif dalam memurnikan kembali minyak pelumas yang telah terkontaminasi (minyak pelumas bekas). Pada pengujian nilai viskositas kinematik yang mendekati dengan viskositas kinematik lube base oil diperoleh pada variasi campuran A10T400 dengan nilai 13.43 cSt, untuk Specific gravity yang mendekati dengan nilai lube base oil pada variasi campuran A10T300 dengan nilai 0.88983, untuk warna  didapatkan nilai L 4.1 pada variasi A15T500, kadar air terendah pada 0.000633 g/l pada variasi A5T500 dan volume hasil terbanyak didapatkan pada variasi campuran A10T300 yaitu 584.33 ml.