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Although biogas is clean and environmentally friendly, its existence is often unsustainable, especially in rural area. Consumption of fossil fuel energy still dominates because cheaper, higher in energy efficiency and ready to use than biogas. One of the efforts to make biogas can compete with fossil fuel energy is by increasing calorific value. Reduction of carbon dioxide by adsorption enhances the calorific value that evidenced by methane enrichment. In this study, we investigated the effect three types of combined adsorbent: pure natural zeolite (Z-Z), zeolite-biochar from chicken manure (Z-B1) and zeolite-modified biochar (Z-B2) on methane content. The result showed that adsorption of biogas using Z-Z, Z-B1 and Z-B2 increased methane level with enhancement of 1,36; 28,92; and 11,27% respectively compared before adsorption. To confirm whether these results were influenced by adsorbent’s character or not as consequence adsorbent characterization have been done in this study.

It is still a challenging task to fulfill power demand of Tumba Hamlet in Tamaila Utara Village, which is an isolated area in the buffer zone of Nantu Boliyohuto Wildlife Reserve. The efforts to fulfill the demand had been carried out by the local government by distributing the Solar Home System (SHS) to all households in 2013. However, the SHS performance quickly declined because the solar panels in the rooftop covered by dense and lush trees, and then it did not work at all in 2018. This research performs pre-feasibility in building the micro-hydro powerplant (MHPP) and its sustainability potential in Tumba Hamlet to fulfill the community’s electrical energy needs without disrupting the Nantu Boliyohuto Wildlife Reserve. A basic survey was performed in exploring river resources and topographical conditions in this hamlet. Sustainability study, including technical, social, and environmental aspects, was conducted by interviewing the residents. The results show that the power needs in Tumba Hamlet are 48.5 kW. This demand can be fulfilled by the MHPP with head and water discharge of 10 meters and 0.706 m3/s, respectively. It was found that positive feedback in the technical, social, and environmental aspects of sustainability is dominant.

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This paper concerns the feasibility study of 7 classes of thermal sensation detection in Indonesia's indoor environment using a low-cost thermal camera through face skin temperature. This study is required as an initial step to build a thermal comfort sensor system of HVAC control systems to produce a comfortable indoor environment with minimum and efficient energy use. The feasibility study was started by studying the thermoregulation system of respondents in Indonesia through measuring their body and facial skin temperatures under heating and cooling conditions, including their relationship with thermal sensations. The facial skin temperature variable, which is covered by four measurement points, namely forehead, nose, cheeks, and chin, represents the MST variable by the coefficient of determination of 0.54. The thermal sensation detection algorithm based on Artificial Neural Network (ANN) is 35.7% of accuracy. The thermal sensation questionnaire with 7 class categories is unsuitable for Indonesian respondents, and the number of the category classes predicted too much compared to the number of inputs. The detection algorithm has better accuracy with a smaller number of classes, namely 52.2% and 68.70% for the 5 and 3 classes of thermal sensation. Practical application: The air conditioning buildings system is possible to influence a thermal environmental control system to meet the occupants' thermal comfort level requirement in an indoor environment if the system is equipped with a sensor that can detect the occupants' thermal sensations. The thermal camera can be used as a non-contact sensor, detecting the occupant’s thermal sensation by reading the occupant's face skin temperature in an indoor environment.