To utilize the municipal solid waste (MSW), PT Semen Indonesia has a program to convert waste into three useful products. One of the product is named Refuse Derived Fuel (RDF). The RDF has claimed that it had a caloric value about 5178 kcal/kg. However, currently, RDF could not be used for the combustion process in the cement kiln since RDF has higher moisture content and lower caloric value. In this research, a solar dryer with greenhouse type is designed to reduce the moisture content. The performance is tested using two variations and compared to the conventional method. The variations are a solar dryer with one fan and with no fan. The general results show that variation with one fan has the highest drying rate among all. There is a significant reduction of moisture content after drying process using a solar dryer. The moisture content could be reduced to 16.25 % and 17 % using one fan and no fan, respectively. Furthermore, variation with 1 fan has higher solar dryer efficiency than that of one fan.

This study aims to increase the calorific value of woody cutting waste briquette by adding activated carbon. The previous experiments showed that the highest calorific value of woody cutting waste briquette reached only 3 630 kCal kg–1. In this research, activated carbon was made of Palmyra palm fiber using H3PO4 as an activator solvent. There are four different proportion of activated carbon used in the experiment, for example, 5 %, 10 %, 15 %, and 20 % with 10 % tapioca flour binder. The woody cutting waste were carbonized and sieved into 50 mesh to 100 mesh. The briquette performance was tested using proximate analysis, bomb calorimeter, and combustion analysis. The addition of activated carbon in briquette could increase the calorific value from 3 630 kCal kg–1 to around 4 500 kCal kg–1.

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An impulse turbine uses drag force on its blades to produce torque on its rotor. As fluid flows over the blades, pressure changes occur at the nozzle, which increases the fluid's velocity and reduces the static pressure at the nozzle outlet. The high-momentum fluid then impinges on the rotor blades, generating frictional force and resulting in torque production. To study the impact of blade shape and number on the turbine's performance, simulations were conducted. The results indicate that blades with an angle of 0° and 180° are optimal for creating high-pressure vortices on the concave surface of the blade. Addition-ally, more blades always result in higher torque and power out-put by increasing the active area of the blades. However, in the case of blades with an angle of 0° and 180°, 8 blades produced more torque than 12 blades with an angle of 0° and 90°. There-fore, blades with an angle of 0° and 180° are highly effective at generating drag force and producing torque.