Solid Oxide Fuel Cells (SOFCs) are an electrochemical energy converter that receives the world's attention as a power generation system of the future owing to its flexibility to consume various types of fuels, low emission of greenhouses gases, and having high efficiency reaching over 70%. A conventional SOFCs operates at high temperature, typically ranges between 800 to 1000°C. SOFCs use yttria-stabilized zirconia (YSZ) as the electrolyte, which exhibits excellent oxide ion conductivity in this temperature range. However, this temperature range poses an issue to SOFCs durability, as it leads to the degradation of the cell components. In addition, SOFCs application is limited and difficult to implement for the transportation sector and portable appliance. A viable solution is to lower the SOFCs operating temperature to intermediate (600 to 800°C ) or low (<600°C) operating temperature. The benefit of this way, cell durability will improve, as well as other advantages such as facilitates handling, assembling, dismantling, cost reduction, and expanded the SOFCs application. Nonetheless, the key challenge for the issue is finding suitable electrolyte, as YSZ have lower ionic conductivity at low and intermediate temperature range. The aim of this paper is to review the status and challenges in the attempts made to modify YSZ electrolyte within the past decade. The resulting ionic conductivity, microstructure, and densification, mechanical and thermal properties of these 'new' electrolytes critically reviewed. The targeted conductivity of modification of YSZ electrolyte must be exceeded >0.1 S cm -1 to enable high performance of SOFCs power generation systems to be realized for transportation and portable applications. Based on our knowledge, this paper is the first review which focused on the recent status and challenges of YSZ electrolyte towards lowering the operating temperature.

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Energy analysis is important to analyze energy consumption pattern, monitoring on how the energy used varies with time in the building and how the system element interrelate. In this case study, a preliminary energy audit is done on lighting and air-conditioning system. The lighting and airconditioning system consume the highest amount from the total building energy usage. The study was conducted in the Faculty of Mechanical Engineering Building, Universiti Teknikal Malaysia (UTeM) Technology Campus. From the result shows  that the air-conditioning system has contributed approximately 48.8% from the total monthly energy usage. The estimation of Building Energy Index (BEI) for the cooling load is 655.19 kWh/m²/year. Meanwhile, the BEI for lighting system is found approximately 150 kWh/m2/year.

The characteristics of tar generated from tropical-plant-based biomass with different chemical compositions during high temperature gasification are crucial to understand the tar formation. In this paper, lignin-rich palm kernel shell (PKS) and hemicellulose and cellulose-rich coconut shell (CS) were gasified in a downdraft fixed-bed reactor at 900 °C. Fourier transform infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC-MS) were used to examine the functional groups and tar compounds. The results of FT-IR indicate that the PKS tar has a lower intensity peak in the fingerprint region than that of CS. The GC-MS results exhibits that the higher molecular weight of tar compounds, such as polycyclic aromatic hydrocarbons (PAHs) are higher in CS tar compared to that in PKS tar. PKS tar is susceptible to create a lighter molecular weight of tar compounds, such as phenolics. Both of the materials have a great potential to be used for renewable energy feedstock.