• Energy Research
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Abstract To understand the relationship between green building energy performance and regional commercial estates, this study analysed Australia’s Commercial Building Disclosure (CBD) program database. This database discloses the annual energy use intensity (EUI) and the corresponding energy rating (1–6 stars) of 2460 National Australian Built Environment Rating System (NABERS) certified office buildings. The study selected for analysis Australia’s six largest cities and then used panel data regression, where commercial estate factors (total stock of office buildings, vacancy rate, average gross face rent, and government incentives such as financial support) served as independent variables and the EUI was the dependent variable. The p-values of all the models are below 0.05, indicating that the results are statistically significant. Results showed the commercial real estate factors were significantly related to the EUI for buildings with a rating of 1 star and above. The correlation between EUI and commercial real estate factors became less strong with the rating level increasing. The effect of ‘green building’ branding makes the office buildings more attractive with regard to tenancy and their energy performance more reflective of the variation in the commercial real estate market. This study is a frontrunner in contextualising green building energy performance and ratings in the context of regional commercial estate, and the regression models employed in the study could be used to define regional baselines for energy ratings in future studies.

Abstract Biodiesel is an environmental friendly liquid fuel similar to conventional diesel in combustion properties. It has received international attention in recent times, as that biodiesel is renewable, non-toxic and safe to store. In this study, high grade biodiesel was produced from microalgae ( Nannochloropsis oculata ) derived lipids via transesterification reaction with methanol in the presence of heterogeneous Ca(OCH 3 ) 2 (calcium methoxide) catalyst. The biodiesel was produced with high yield; (92%) at 60 °C compared to the highest yield reported as 22% with the use of a Mg–Zr catalyst. The product exhibited excellent performances. The catalyst was characterized by TG/DTA (thermogravimetric-differential thermal analyses), XRD (X-ray diffraction), BET (Brunauer – Emmett – Teller), FTIR (Fourier transform infrared), SEM-EDX (scanning electron microscopy-energy dispersive spectrometer) and TEM (transmission electron microscopy) analysis. The effect of different reaction parameters including reaction time, methanol/oil molar ratio and catalyst dosage on the yield of FAME (fatty acid methyl ester) was studied. Interestingly, the catalyst can be reused five times successively without affecting the biodiesel yield. Biodiesel produced from microalgae oil consists of high levels of polyunsaturated fatty acids, making it highly suitable as winter grade biodiesel.

Biomass represents a renewable source for transport fuels when processed by gasification, followed by catalytic conversion of the syngas to liquids. The efficiency of biomass gasification can be improved by supplying process heat from concentrated solar systems, which can attain the required temperature of 900 °C. Various chemical routes and contacting configurations are reviewed. The challenges related to biomass-based processes are discussed. Heat and material balances are then deduced. The area of land required for growing biomass can be reduced using the application of thermal solar to one half of that needed for a standard gasification system. If hydrogen is generated by solar means in order to reduce carbon dioxide emissions to zero, the figure becomes one third. Examples of the land requirements for three different biomass materials are presented.

Abstract A techno-economic feasibility of a stand-alone hybrid power generation for a remote community in Bangladesh is carried out in this study. The proposed system integrates a combination of biogas generator, PV modules, diesel generators, wind turbines, and lead acid battery to meet the electric load requirements using Hybrid Optimization Model for Electric Renewables (HOMER) software tool. The designated system would satisfy the energy requirements of 248 kWh/day primary load with 44.41 kW peak load. The optimized hybrid system consists of a biogas generator (9 kW), PV modules (10 kW), 2 diesel generators (10 kW each), 72 batteries (390Ah each), and 15 kW inverters. This configuration gives the COE of $0.28/kWh and total Net Present Cost (NPC) of $612280 with a renewable fraction of 60%. Additionally, the system has potential benefit to reduce CO 2 emission by nearly 59.6% per year as compared to a diesel-based system and by 40.5% compared to the grid electricity. Furthermore, the results also indicate that it is fairly impossible to reach grid electricity price parity even with full government support for the project capital cost. However, the proposed system is found as an economical option than supplying electricity to the remote community with solar home systems (SHSs).

Abstract The building sector is responsible for significant energy demands. An understanding of where this occurs across the building life cycle is critical for optimal targeting of energy reduction efforts. The energy embodied in a building can be significant, yet is not well understood, especially the on-going ‘recurrent’ embodied energy associated with material replacement and building refurbishment. A key factor affecting this ‘recurrent’ embodied energy is a building's service life. The aim of this study was to investigate the relationship between the service life and the life cycle embodied energy of buildings. The embodied energy of a detached residential building was calculated for a building service life range of 1–150 years. The results show that variations in building service life can have a considerable effect on the life cycle embodied energy demand of a building. A 29% reduction in life cycle embodied energy was found for the case study building by extending its life from 50 to 150 years. This indicates the importance of including recurrent embodied energy in building life cycle energy analyses as well as integrating building service life considerations when designing and managing buildings for improved energy performance.

Abstract Thermochemical energy storage (TCES) systems are a promising alternative to conventional molten salt systems for integration with solar thermal power plants. TCES systems can offer high storage densities and high storage temperatures. Thus, they have the potential to increase the efficiency and reduce the levelized cost of electricity of solar thermal power plants. The present study investigates reacting systems with alkaline carbonates and hydroxides and metal oxides performing redox and chemical looping combustion reactions for their near-term deployment potential. 17 solid–gas TCES systems are identified from the initial set of 21 systems for techno-economic assessment. A quantitative assessment methodology based on techno-economic performance indicators (TPIs) is proposed for the comparative analysis. The techno-economic analysis indicates that energy consumption by auxiliary equipment and the cost of the feedstock are the most important factors affecting the system capital cost. Eight TCES systems are identified as competitive with molten salts in the near term, with an estimated capital cost lower than $25 MJ−1: hydroxide looping with Ca(OH)2/CaO, Sr(OH)2/SrO and Ba(OH)2/BaO; carbonate looping with CaCO3/CaO and SrCO3/SrO; redox with BaO2/BaO and chemical looping combustion with Fe3O4/FeO and NiO/Ni.

Abstract Coal use is expected to increase substantially in many parts of the world during the next few decades. Several of the major producers or consumers of coal are in Asia and around the Pacific Ocean. The production, shipment, and burning of such large quantities of coal can have significant environmental implications throughout the region. In this article, we discuss these implications in general, as well as for some of the countries individually. We conclude with a recommendation for a collaborative study involving policy-makers and scientists from the different countries in the region.

Green roofs could act as a thermal buffer in buildings and offer potential energy savings. However, the energy benefits from green roofs are not usually properly recognised by traditional building energy regulations. Building energy regulations are traditionally over-simplistic during the assessment of the energy performance of complex building constructions. In the case of green roof designs, it is essential that the assessment mechanisms should not ignore the complex heat and moisture balances within the green roof layers. In this paper, dynamic energy modelling that considers the complexity within the green roof layers is adopted to guide policy makers in China on the relationship between using specific thicknesses of roof insulation against green roof layers. Simulations are run for a residential building type by also considering different thermal envelope characteristics across eight large Chinese cities and within the five main climatic zones of China. Results that link the green roof characteristics with respective traditional insulation layers are produced for all cities and it is found that optimising the plant and soil characteristics of green roofs in some climates could substitute more than 125 mm of roof insulation, while less optimum green roof types could only replace about 25 mm of roof insulation.