• Energy Research
• 2021-2025close
• AU close
• Energy close

Abstract To guarantee the space heating in the heating season, conventional combined heat and power (CHP) plants operate in a heat-controlled operation mode, resulting in restricted peak-shaving ability (PSA). To improve the CHP plant’s PSA, a novel solar aided CHP (SA-CHP) system is proposed and simulated in this paper. In the new system, solar heat could be flexibly used to generate power or to supply heat according to the heating and power demands, thereby realizing the heat-power decoupling. A set of models for the SA-CHP system is developed and validated. The PSA, the standard coal consumption (SCC) and the techno-economic performances of a 330 MWe SA-CHP system are comprehensively analyzed in this paper. The results show that the SA-CHP system can significantly improve (up to double) the PSA compared with the CHP plant under the same rated heating power. The feasible operation region area of the SA-CHP system is 74.7% larger than that of the CHP plant. The annual SCC of the SA-CHP system are 17378.23 t less than that of the CHP plant. The net annual revenue of the SA-CHP system is $2.24 M. Besides, techno-economic performances of SA-CHP systems with two different heat storage systems are compared.

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 In energy demand forecasting, the objective function is often symmetric, implying that over-prediction errors and under-prediction errors have the same consequences. In practice, these two types of errors generally incur very different costs. To accommodate this, we propose a machine learning algorithm with a cost-oriented asymmetric loss function in the training procedure. Specifically, we develop a new support vector regression incorporating a linear-linear cost function and the insensitivity parameter for sufficient fitting. The electric load data from the state of New South Wales in Australia is used to show the superiority of our proposed framework. Compared with the basic support vector regression, our new asymmetric support vector regression framework for multi-step load forecasting results in a daily economic cost reduction ranging from 42.19 % to 57.39 % , depending on the actual cost ratio of the two types of errors.

Abstract Using a panel data analysis of a newly developed sample of monthly data by state for January 2005 to December 2019, we estimate a series of error correction models for US residential electricity demand postulated to move with electricity price, natural gas price, income, and weather. Our key findings are as follows. First, the short-run own-price elasticity estimate is not statistically different from zero (p-value > 0.8). Second, the long-run own- and cross-price elasticity estimates are −0.054 (p-value = 0.000) and 0.019 (p-value = 0.000) under the double-log specification, smaller in size than the long-run own- and cross-price elasticity estimates of −0.120 (p-value = 0.000) and 0.069 (p-value = 0.000) under the linear demand specification. Third, price elasticity estimates have been shrinking in size over time. Fourth, erroneously ignoring the panel data's cross-sectional dependence tends to more than double the long-run price elasticity estimates. Fifth, mismatching the timing of price information's availability and consumption decision leads to anomalous price elasticity estimates. Finally, our new empirics' key takeaway of low price-responsiveness supports continuation of energy efficiency standards and demand-side management programs.

In Malaysia, palm oil mill (POM) retrofit towards pollution control is vital to receive mandatory certification. Resource, waste, energy and water integrations could be performed between POM, palm oil refinery (POR) and conventional heat and power plant (CHP) under different owners to form a sustainable integrated palm oil-based complex (POBC). A cooperative game context is applied where multi-owner POM, POR and CHP act as multiple “players” in the POBC “game”. This study presents a systematic optimisation framework to design a sustainable multi-owner POBC. Firstly, five objectives related to economic, environmental and energy potentials are balanced using fuzzy optimisation approach to yield multi-objective optimal POBCs under four facility construction scenarios. Subsequently, profit-cost allocation within the multi-owner POBC is performed via an integrated cooperative game-based approach. The four fuzzy optimal POME-eliminated POBCs achieved economic potentials at 39.71 × 106- 40.84 × 106 USD/y with maximum λ (0.652). The profit-cost allocation results show economic potential improvements at 0.12 × 106- 0.46 × 106 USD/y for the multi-owner POBC facilities. POM is the major GP receiver whereas CHP benefits the most from POBC collaboration. The optimal multi-owner POBCs are economically feasible upon decision-makers' interest and robust against investment cost variations. The increment in Feed-in Tariff and biomass-based steam price reduces the economic stability of multi-owner POBC.

Dans cet article, une étude numérique tridimensionnelle a été menée en résolvant les équations de Navier Stokes moyennes de Reynolds instables avec le modèle de turbulence k-omega de transport de contrainte de cisaillement (SST) pour étudier l'efficacité de la production d'énergie d'une éolienne à axe vertical (HDWT) H-Darrieus à trois pales utilisant un profil aérodynamique S-1046 dans des conditions de vent accéléré du système d'échappement de la tour de refroidissement. Dans le but d'extraire l'énergie perdue de l'air d'échappement, quatre HDWT ayant des rapports d'aspect différents ont été testés en faisant varier le diamètre de la turbine ; et les valeurs du moment et du coefficient de puissance ont été calculées à des rapports de vitesse de pointe (TSR) compris entre 1,5 et 3,5. Les résultats ont montré que le HDWT avec un rapport d'aspect (AR) plus petit de 0,44 donne un meilleur coefficient de puissance de 0,294 à TSR 2,5 par rapport aux autres conditions de test. En outre, une analyse détaillée du champ d'écoulement autour du HDWT pour différents AR et TSR a été fournie dans ce document pour discuter des performances de la turbine. Enfin, une étude comparative avec la condition d'écoulement en flux libre a montré que HDWT fournit une performance inférieure de 58,5% à celle du flux dans le système d'échappement à AR inférieur, indiquant un effet d'écoulement guidé positif sur la performance de la turbine dans les systèmes d'écoulement d'échappement. En este documento, se ha realizado un estudio numérico tridimensional resolviendo las ecuaciones inestables de Reynolds Averaged Navier Stokes con el modelo de turbulencia k-omega de transporte de tensión de corte (SST) para investigar la eficiencia de producción de energía de un aerogenerador de eje vertical H-Darrieus de tres palas (HDWT) utilizando el perfil aerodinámico S-1046 en condiciones de viento acelerado del sistema de escape de la torre de enfriamiento. Con el objetivo de extraer la energía residual del aire de escape, se probaron cuatro HDWT con diferentes relaciones de aspecto variando el diámetro de la turbina; y los valores de momento y coeficiente de potencia se calcularon en relaciones de velocidad de punta (TSR) en el rango de 1.5–3.5. Los resultados mostraron que el HDWT con una relación de aspecto (AR) más pequeña de 0.44 da un mejor coeficiente de potencia de 0.294 a TSR 2.5 en comparación con otras condiciones de prueba. Además, en este documento se ha proporcionado un análisis detallado del campo de flujo alrededor del HDWT para diferentes AR y TSR para analizar el rendimiento de la turbina. Finalmente, un estudio comparativo con la condición de flujo de corriente libre mostró que HDWT proporciona un rendimiento 58.5% menor que el flujo en el sistema de escape a menor AR, lo que indica un efecto de flujo guiado positivo en el rendimiento de la turbina bajo los sistemas de flujo de escape. In this paper, a three-dimensional numerical study has been conducted by solving the unsteady Reynolds Averaged Navier Stokes equations with shear stress transport (SST) k-omega turbulence model to investigate the power production efficiency of a three-bladed H-Darrieus vertical axis wind turbines (HDWT) using S-1046 airfoil under accelerated wind conditions of the cooling tower exhaust system. Aiming to extract the waste energy from the exhaust air, four HDWTs having different aspect ratios were tested by varying the turbine diameter; and the moment and power coefficient values were calculated at tip speed ratios (TSR) in the range of 1.5–3.5. The results showed that the HDWT with a smaller aspect ratio (AR) of 0.44 gives a better power coefficient of 0.294 at TSR 2.5 as compared to other testing conditions. Further, a detailed flow field analysis around the HDWT for different ARs and TSRs has been provided in this paper to discuss the turbine's performance. Finally, a comparative study with the free-stream flow condition showed that HDWT provides 58.5% lower performance than the flow in the exhaust system at lower AR, indicating a positive guided flow effect on the turbine performance under exhaust flow systems. في هذه الورقة، تم إجراء دراسة رقمية ثلاثية الأبعاد من خلال حل معادلات رينولدز نافيير ستوكس غير المستقرة مع نموذج اضطراب إجهاد القص (SST) k - omega للتحقيق في كفاءة إنتاج الطاقة لتوربينات الرياح ذات المحور الرأسي H - Darrieus ثلاثية الشفرات (HDWT) باستخدام S -1046 في ظل ظروف الرياح المتسارعة لنظام عادم برج التبريد. بهدف استخراج طاقة النفايات من هواء العادم، تم اختبار أربعة HDWTs ذات نسب عرض إلى ارتفاع مختلفة من خلال تغيير قطر التوربين ؛ وتم حساب قيم العزم ومعامل الطاقة عند نسب سرعة الطرف (TSR) في نطاق 1.5–3.5. أظهرت النتائج أن HDWT مع نسبة عرض إلى ارتفاع أصغر (AR) تبلغ 0.44 يعطي معامل طاقة أفضل قدره 0.294 عند TSR 2.5 مقارنة بظروف الاختبار الأخرى. علاوة على ذلك، تم تقديم تحليل تفصيلي لمجال التدفق حول HDWT لمختلف ARs و TSRs في هذه الورقة لمناقشة أداء التوربين. أخيرًا، أظهرت دراسة مقارنة مع حالة التدفق الحر أن HDWT يوفر أداءً أقل بنسبة 58.5 ٪ من التدفق في نظام العادم عند AR المنخفض، مما يشير إلى تأثير تدفق موجّه إيجابي على أداء التوربينات تحت أنظمة تدفق العادم.