Cost-Saving through Pre-Cooling: A Case Study of Sydney

Air conditioning is responsible for a considerable proportion of households’ electricity bills. During summer afternoons when households usually run their air conditioners, the retail time-of-use electricity tariffs are highest, and there is a peak demand in the electricity network. Pre-cooling is a method to shift air conditioning demand from peak hours to hours with lower demand and cheaper electricity tariffs. In this research, the pre-cooling potential of nine different types of residential housing in Sydney constructed with different star ratings and construction weights is evaluated. Star rating is the method to represent the annual heating and cooling requirements of buildings in Australia. Results highlight that pre-cooling produces cost saving for most of the days in 6-star and 8-star buildings. For 2-star buildings, pre-cooling sometimes leads to higher electricity costs. Moreover, pre-cooling improves thermal comfort, especially in 2-star light and medium weight buildings.

Assessing Local Power Generation Potentials of Photovoltaics, Engine Cogeneration, and Heat Pumps: The Case of a Major Swiss City

In this paper, we investigate the potentials of distributed generation (DG) in a medium-sized Swiss city. We show the role of private households in the sustainable energy transition process induced by Swiss energy policy. For the analysis, we define six scenarios that enable us to study the potentials and impacts of different combinations of DG technologies in terms of costs, CO2 emissions, and amounts and shares of DG provided by non-industrial end-users (essentially private households and the services sector). Three variants are investigated, one with real electricity costs and CO2 emissions, one with increased electricity costs (e.g., construction of new power plants), and one with increased CO2 emissions (e.g., due to the planned nuclear phase-out in Switzerland). We find that non-industrial entities can play an important role as prosumers. They mitigate the need for centralized generation. Within a scenario where the non-industrial energy end-users install water-water heat pumps and photovoltaics, a total reduction of the gas procurement from the grid is possible whereas the electricity demand from the grid increases by 24%. This scenario reveals higher DG electricity costs in comparison to conventional electricity supply, but the total costs of energy supply decrease due to the elimination of gas supply, and the CO2 emissions can be reduced by 68%.

Coordination of Macro Base Stations for 5G Network with User Clustering

With the increasing amounts of terminal equipment with higher requirements of communication quality in the emerging fifth generation mobile communication network (5G), the energy consumption of 5G base stations (BSs) is increasing significantly, which not only raises the operating expenses of telecom operators but also imposes a burden on the environment. To solve this problem, a two-step energy management method that coordinates 5G macro BSs for 5G networks with user clustering is proposed. The coordination among the communication equipment and the standard equipment in 5G macro BSs is developed to reduce both the energy consumption and the electricity costs. A novel user clustering method is proposed together with Benders decomposition to accelerate the solving process. Simulation results show that the proposed method is computationally efficient and can ensure near-optimal performance, effectively reducing the energy consumption and electricity costs compared with the conventional dispatching scheme.

Modelica-Based Modeling and Simulation of District Cooling Systems: A Case Study

While equation-based object-oriented modeling language Modelica can evaluate practical energy improvements for district cooling systems, few have adapted Modelica for this type of large-scale thermo-fluid system. Further, to our best knowledge, district cooling modeling studies have yet to include hydraulics in piping network nor waterside economizers. These are critical details to include when looking to make energy and control improvements in many physical system installations. To fi?ll these gaps, this study applies newly developed open-source models from the Modelica Buildings library. For a real-world case study, we modeled and simulated a district cooling system at a college campus in Colorado, United States, with six buildings connected to a central chiller plant featuring a waterside economizer. Several energy saving strategies are pursued based on the validated model, including control setpoint optimization, equipment modification, and pump setpoint adjustments. Results indicate that optimizing the condenser water supply temperature setpoint can save 2.5% to 4.4% energy; the nonintegrated waterside economizer saves 6.4% energy while cutting down the chillers' run times by 201 days/year, reducing maintenance costs, and extending chiller life; and adjusting the condenser water pump flow settings can save 10.2% energy. Through a combinationof the studied measures, the campus can annually save 84.6 MWh of energy, 8.9% of electricity costs, and 58.0 metric tons of carbon dioxide emissions. Further, the numerical results of simulating districts from tens to hundreds of buildings are presented.

Brazil's electricity costs will rise amid supply fears

Significance The controversial privatisation comes as warnings of potential energy disruption increase due to the longest dry spell in the Central and South-east regions for 91 years. The water crisis has forced a shift to thermal power stations, whose higher costs push tariffs upwards. Impacts Higher energy tariffs will drive inflationary pressures this year. Eletrobras’s privatisation may occur early next year, but could increase energy prices. Significant energy investments are required to avoid future power disruption.

Evaluation of Production Efficiency using Data Envelopment Analysis at PT. Perkebunan Nusantara XI

This study develops an evaluation of production efficiency at PT Perkebunan Nusantara XI. Since the domestic sugarcane-based industry today faces many challenges of change. From 2017 through 2018, Indonesia became the largest importer in the world. The high demand for sugar imports is caused by national production that has not met domestic needs. PTPN XI is a state-owned enterprise (SOEs) engaged in agribusiness with the core business of producing sugar. At present, PTPN XI has a problem, which is decreasing production efficiency. This study attempts to design and identify the measurement indicators used to evaluate the production efficiency of PTPN XI using Data Envelopment Analysis. The research objective will be accomplished through the analysis of questioners filled by the expert in the company. Based on the calculations and peer group decisions obtained by several factories that are being referenced, including the Pagottan Sugar Factory, Panji, Prajekan, Wonolangan, and Wringin Anom. Variables that significantly affect the efficiency of PT Perkebunan Nusantara XI's sugar mills are labor, electricity costs, and production capacity variables.