scholarly journals Evaluation of Continuous Power-Down Schemes

Information ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
James Andro-Vasko ◽  
Wolfgang Bein

We consider a power-down system with two states—“on” and “off”—and a continuous set of power states. The system has to respond to requests for service in the “on” state and, after service, the system can power off or switch to any of the intermediate power-saving states. The choice of states determines the cost to power on for subsequent requests. The protocol for requests is “online”, which means that the decision as to which intermediate state (or the off-state) the system will switch has to be made without knowledge of future requests. We model a linear and a non-linear system, and we consider different online strategies, namely piece-wise linear, logarithmic and exponential. We provide results under online competitive analysis, which have relevance for the integration of renewable energy sources into the smart grid. Our analysis shows that while piece-wise linear systems are not specific for any type of system, logarithmic strategies work well for slack systems, whereas exponential systems are better suited for busy systems.

As the demand for electrical energy increases continuously, we cannot rely on the existing conventional source for continuous power supply, as they are diminishing fast. The renewable energy sources are the best alternative for this energy crisis. We have different types of renewable energy sources and choice of source depends on location and load requirement. The most prominent source is the solar energy because of its own advantages. The nature of supply from this source is DC and it is to be converted into AC for supply to consumers. However, inverters are used for this conversion but produces harmonics. The Multilevel inverters are the alternate choice over conventional inverters due to the advantages of Low dv/dt and lower switching losses. Out of various multilevel inverters, cascaded H bridge (CHB) MLI topology is a well known solution for reducing the harmonics, which needs more number of switches and isolation power supplies which further increases the cost. This paper describes a proposed hybrid H-bridge topology with reduced switches. The proposed topology is implemented in Matlab/Simulink and results for 5, 7, 9 and 11 level are analyzed with their THD in output voltage. Hardware model for 5-level inverter is developed using 8051 micro-controller and results are presented


Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3599 ◽  
Author(s):  
Martinez-Fernandez ◽  
deLlano-Paz ◽  
Calvo-Silvosa ◽  
Soares

Carbon mitigation is a major aim of the power-generation regulation. Renewable energy sources for electricity are essential to design a future low-carbon mix. In this work, financial Modern Portfolio Theory (MPT) is implemented to optimize the power-generation technologies portfolio. We include technological and environmental restrictions in the model. The optimization is carried out in two stages. Firstly, we minimize the cost and risk of the generation portfolio, and afterwards, we minimize its emission factor and risk. By combining these two results, we are able to draw an area which can be considered analogous to the Capital Market Line (CML) used by the Capital Asset Pricing model (CAPM). This area delimits the set of long-term power-generation portfolios that can be selected to achieve a progressive decarbonisation of the mix. This work confirms the relevant role of small hydro, offshore wind, and large hydro as preferential technologies in efficient portfolios. It is necessary to include all available renewable technologies in order to reduce the cost and the risk of the portfolio, benefiting from the diversification effect. Additionally, carbon capture and storage technologies must be available and deployed if fossil fuel technologies remain in the portfolio in a low-carbon approach.


2019 ◽  
Vol 32 ◽  
pp. 385-389 ◽  
Author(s):  
Pavel Atănăsoae ◽  
Radu Dumitru Pentiuc ◽  
Dan Laurențiu Milici ◽  
Elena Daniela Olariu ◽  
Mihaela Poienar

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Innocent Okwanya ◽  
Abdulkareem Alhassan ◽  
Job Pristine Migap ◽  
Simon Adeka Sunday

Purpose This study aims to examine the effects of policy incentives and cost on the choice and use of renewable energy in North-Central Nigeria. Design/methodology/approach The data for this study are collected from a sample of 290 respondents drawn from across 6 states in North-Central Nigeria, including the Federal Capital Territory. This study uses descriptive statistics and multinomial logistic regression to analyze the data. Findings The findings reveal that there is a huge potential demand for renewable energy sources (particularly solar photovoltaic) in the rural communities in Nigeria. It also indicates a positive and highly significant relationship between the level of awareness, availability and income and the use (consumption) of renewable energy sources among the rural communities. Furthermore, the cost of installation and maintenance of renewable energy, its reliability and availability are significant determinants of renewable energy choices among rural inhabitants in Nigeria. Practical implications The authors submit that inefficient policy strategies, high cost of installation and lack of awareness remain the major hindrances to the use of more efficient renewable energy sources. From a policy point of view, a viable strategy for effective use of renewable energy sources is the involvement of government, development partners and agencies for the funding of renewable energy technology in the rural sector of the country. The usage of modern renewable energy would increase if policy incentives are aimed at covering parts of the maintenance and installation cost of renewable energy users. The authors recommend that apart from creating awareness on the benefits of renewable energy, policymakers should provide a desirable policy environment for private energy firms to supply renewable energy at an affordable cost to the rural communities in Nigeria. Social implications A majority of the rural households in Nigeria, as shown in this article, are poor and therefore use firewood as their main source of cooking energy because of the cost of renewable energy. Originality/value Despite the abundance of renewable energy sources and government effort at improving renewable energy use, more than 15 million people live without access to electricity and 54 million are without modern energy services for cooking and lightening in Nigeria. A total of 61% of these people live in rural areas. Therefore, this study is novel in providing energy policy insights for rural communities in North-Central Nigeria.


2020 ◽  
Author(s):  
Aleksandr Ivakhnenko ◽  
Beibarys Bakytzhan

<p>In global socioeconomic development facing climate change challenges to minimize the output of greenhouse gas (GHG) emissions and moving to a more low-carbon economy (LCE) the major driving force for success in achieving Sustainable Development Goals (SDGs) is the cost of energy generation. One of the main factors for energy source selection in the power supply and energy type generation process is the price parameters often influenced at different degree by government policies incentives, technological and demographic challenges in different countries. We research the energy sources situation and possible development trends for developing country Kazakhstan with resource-based economy. In general, the economic aspects affect the quality and quantity of energy generated from different sources with incentives for environmental concern. Traditional energy sources in Kazakhstan, such as coal, oil and natural gas remain low-cost in production due to high reserve base, which leads to steady growth in this area. In general, the cost for generating 1 kWh of energy from the cheapest carbon source of energy sub-bituminous coal is about 0.0024 $, for natural gas 0.0057 $, conventional oil 0.0152 $ (conventional diesel is 0.0664 $) and for expensive unconventional oil 0.0361 $, whereas renewable hydrocarbons could potentially become more competitive with unconventional oil production (methanol 0.0540 $, biodiesel 0.0837 $, bioethanol 0.1933 $ for generating 1 kWh). Furthermore, we consider the main non-traditional and renewable energy sources of energy from the sun, wind, water, and biofuels, hydrogen, methane, gasoline, uranium, and others. There is a difference between the breakeven prices of conventional gas and biomethane (0.0057 $ and 0.047 - 0.15 $ respectively averaging 0.0675 $ per 1 kWh for biomethane) which is often related to the difference in their production methods. The main advantage of biomethane is environmentally friendly production. We also propose an assessment of fuel by environmental characteristics, where one of the hazardous sources Uranium is forth cheap 0.0069 $ per kWh, but the environmental damage caused by its waste is the greatest. At the same time hydropower is seven times more expensive than uranium, but it does not cause direct health damage issues, however influencing significantly ecosystem balance. Hydrogen fuel is the most expensive among others. Overall in Kazakhstan energy-producing from the sun, wind and biogas is more expensive comparing with global trends from 0.4 to 5.5 cents per 1 kWh, but remains cheaper for hydropower. In addition, based on the research findings we analyzed the potential for sustainable non-renewable and renewable energy development in the future for the case of the resource-based economy in Kazakhstan. </p>


Author(s):  
Pavlin Pavlov ◽  

Renewable energy sources provide a perspective for reducing the harmful effects on the environment. They also help to reduce the cost of meeting energy needs after the return on investment in alternative energy. The tourism sector and in particular the hotel business use significant amounts of energy resources. Therefore, the purpose of this report is to present the nature of RES and the ways of application in the hotel industry. Barriers and opportunities for overcoming them are outlined. Some good practices of using alternative energy sources in the hotel business are presented.


2020 ◽  
Vol 10 (9) ◽  
pp. 3142 ◽  
Author(s):  
Girolama Airò Farulla ◽  
Maurizio Cellura ◽  
Francesco Guarino ◽  
Marco Ferraro

Power systems in the future are expected to be characterized by an increasing penetration of renewable energy sources systems. To achieve the ambitious goals of the “clean energy transition”, energy storage is a key factor, needed in power system design and operation as well as power-to-heat, allowing more flexibility linking the power networks and the heating/cooling demands. Thermochemical systems coupled to power-to-heat are receiving an increasing attention due to their better performance in comparison with sensible and latent heat storage technologies, in particular, in terms of storage time dynamics and energy density. In this work, a comprehensive review of the state of art of theoretical, experimental and numerical studies available in literature on thermochemical thermal energy storage systems and their use in power-to-heat applications is presented with a focus on applications with renewable energy sources. The paper shows that a series of advantages such as additional flexibility, load management, power quality, continuous power supply and a better use of variable renewable energy sources could be crucial elements to increase the commercial profitability of these storage systems. Moreover, specific challenges, i.e., life span and stability of storage material and high cost of power-to-heat/thermochemical systems must be taken in consideration to increase the technology readiness level of this emerging concept of energy systems integration.


Sign in / Sign up

Export Citation Format

Share Document