No abstract

Indonesia has an abundant renewable energy source. One of them is wind energy resources. Unfortunately, Indonesia's wind energy resource is not fully utilized, especially for application in high-rise buildings. The paper investigates the potential of energy production from the horizontal-axis wind turbine (HAWT) and the vertical-axis wind turbine (VAWT) on the rooftop of a university building in Indonesia. The wind speed data were measured on the rooftop of the building for seven months. The data was analyzed using Weibull distribution. Based on the probability density function of the Weibull distribution, the potential energy production was calculated using the power curves from the manufacturer. Comparing energy production between HAWTs and VAWTs has shown that VAWTs can produce more energy than HAWTs. Using six turbines, VAWTs can produce 48,476 kWh. On the other hand, with four turbines, HAWTs can produce 41,729 kWh. The reason is that VAWT requires shorter distance requirements for inter-turbine and between rows. Therefore, VAWT can use more turbines than HAWT in the limited area. In conclusion, VAWT for high-rise buildings is more preferred because VAWT can generate more energy. Further study should investigate the optimal configuration with varying the wind direction and quantifying the wake effect on power output.

Gasification process is strongly influenced by the gasifier reactor to produce syngas. This study aims to design and make an updraft type of gasifier reactor without blower so that it does not require electric power in its operation, but use power from engine suction. This gasifier design is suitable for small scale power plants which are not connected to the main electricity network (off-grid system) in rural and remote areas. Materials used in manufacturing the gasifier reactor are consist of type 304 3 mm stainless steel, 3 mm diameter of stainless steel pipe, 3 mm iron plate, and fire cement. The experiment and test results show that the highest efficient and the most optimal biomass in the gasification process is coconut shell charcoal, because coconut shell charcoal has a dense structure and at the time of the experiment, coconut shell charcoal was filled 15 cm below the gas outlet pipe hole. From the economic value of the gasifier reactor that has been produced, the lowest cost result is diesel with EFB charcoal, because in this experiment EFB is the biomass that is not purchased. The additional use of empty bunches of charcoal is able to save 50% diesel usage

Low temperature storage with a single refrigeration system only stable up to 228 K temperature. The purpose of this study is to develop a low temperature cool storage with cascade refrigeration system, with hydrocarbon refrigerants in terms of energy and exergy analysis. Experimental research in laboratories using refrigerant hydrocarbon MC22 and MC134 on the hight temperature circuit, and R404A and R502 using on low temperature circuit. Condenser heat exchanger using a type of exchanger plate. Resulting from this research, obtained that result the MC22/R404A, MC22/R502 and MC134/R404A refrigerant pair can reach a temperature of 220 K. The MC22/R404A refrigerant pair has god performance, COP, total loss exergy, and exergy efficiency is better than MC22/R502, and MC134/R04A refrigerant pairs.

In making a horizontal type wind turbine, of course, it is necessary to analyze it in depth, one of which is by predicting the production of wind energy produced by the wind turbine to estimate the wind power in the wind turbine which will later be applied. Wind energy sources that are commonly used are located in rural areas, fields and even there is such a large amount of energy that it is sometimes difficult to reach the power grid and other large areas including the roofs of high-rise buildings. There are many analytical models in wind energy estimation, one of which is often done by many researchers, namely by using the Weibull distribution method. From the measurement results that as many as 1516.37 kWh with a 1 kW wind turbine with a radius of 1 meter (capacity factor 30.09%). Modeling wind turbine blades with NACA 4412 using Qblade software to determine the torsional angle of the blade to be applied so that it is obtained that the torsion angle from the base and The tip of the blade has a tilt angle of 19.05◦ to 6.96° with a maximum Cp of 0.5 this is a pretty good value in designing wind turbine blades.