Reviewing optimisation criteria for energy systems analyses of renewable energy integration

The utilisation of fluctuating renewable energy sources is increasing world-wide; however, so is the concern about how to integrate these resources into the energy systems. The design of optimal energy resource mixes in climate change mitigation actions is a challenge faced in many places. This optimisation may be implemented according to economic objectives or with a focus on techno-operational aims and within these two main groupings, several different criteria may potentially be applied to the design process.In this article, a series of optimisation criteria are reviewed and subsequently applied to an energy system model of Western Denmark in an analysis of how to use heat pumps for the integration of wind power.The analyses demonstrate that the fact whether the system in question is modelled as operated in island mode or not has a large impact on the definition of the optimal wind power level. If energy savings and CO₂ emission reductions beyond the system boundary are not included in the analysis, then it is either not feasible to expand wind power to a high degree or it is conversely more feasible to install relocation technologies that can utilise any excess production. The analyses also demonstrate that different optimisation criteria render different optimal designs.     

Grid integration of intermittent renewable energy sources using price-responsive plug-in electric vehicles

Plug-in electric vehicles (PEVs) are expected to balance the fluctuation of renewable energy sources (RES). To investigate the contribution of PEVs, the availability of mobile battery storage and the control mechanism for load management are crucial. This study therefore combined the following: a stochastic model to determine mobility behavior, an optimization model to minimize vehicle charging costs and an agent-based electricity market equilibrium model to estimate variable electricity prices. The variable electricity prices are calculated based on marginal generation costs. Hence, because of the merit order effect, the electricity prices provide incentives to consume electricity when the supply of renewable generation is high. Depending on the price signals and mobility behavior, PEVs calculate a cost minimizing charging schedule and therefore balance the fluctuation of RES. The analysis shows that it is possible to limit the peak load using the applied control mechanism. The contribution of PEVs to improving the integration of intermittent renewable power generation into the grid depends on the characteristic of the RES generation profile. For the German 2030 scenario used here, the negative residual load was reduced by 15–22% and the additional consumption of negative residual load was between 34 and 52%.     

Assessment of practices and technologies of energy saving and renewable energy sources in hotels in Crete

This study aims to assess the state of the art of practices and technologies of energy saving and renewable energy sources in hotels. This will contribute to determining the potential of efficient and sustainable energy technologies integration. Hotel managers were interviewed face to face and information sessions were provided. Special energy and environmental awareness campaigns, sectoral tourism programs for climate change mitigation and adaptation, supportive policies and hotel energy investments and renovation programs are some recommendations elicited from the results of this study.     

国内可再生能源新闻

太阳能中国环境标志太阳能标准颁布,首批21家企业获得认证(本刊记者王廷飞)继不久前有关领导透露太阳能热水器行业国家标准将有所提高之后,国家环保总局也出新举措,于日前颁布了专门针对太阳能     

可再生能源发电

可再生能源是指不会随人类的开发利用而衰减的能源,如风能、太阳能、生物质能、小水电（指设计能力低于２５兆瓦的工程）、海洋能、垃圾再利用能源、垃圾掩埋沼气、污水处理沼气、地热能等。我国的自然资源总量排世界第７位,能源资源总量居世界第３位。其中可再生能源资源尤其丰富,可开发风能资源２．５亿千瓦,水能资源７５４０万千瓦,生物质能１．２５亿千瓦,地热能６７０万千瓦,另外还有数量巨大的太阳能及城市垃圾利用潜力。１我国太阳能资源我国地处北半球欧亚大陆的东部,幅员辽阔,有着十分丰富的太阳能资源。我国各地的太阳辐…     

Techno-economic analysis of the integration of hydrogen energy technologies in renewable energy-based stand-alone power systems

A large number of stand-alone power systems that are based on fossil fuel or renewable energy (RE) based, are installed all over Europe. Such systems, often comprising photovoltaics (PV) and/or diesel generators provide power to communities or technical installations, which do not have access to the local or national electricity grid. The replacement of conventional technologies such as diesel generators and/or batteries with hydrogen technologies, including fuel cells in an existing PV-diesel stand-alone power system providing electricity to a remote community was simulated and optimised, using the hybrid optimisation model for electric renewables (HOMER) simulation tool. A techno-economic analysis of the existing hybrid stand-alone power system and the optimised hydrogen-based system was also conducted. The results of the analyses showed that the replacement of fossil fuel based gensets with hydrogen technologies is technically feasible, but still not economically viable, unless significant reductions in the cost of hydrogen technologies are made in the future.     

Barriers to dissemination of renewable energy technologies for cooking

A preliminary effort to identify the barriers to dissemination of renewable energy technologies in developing countries has been made.     

Comparative analysis of support mechanisms for renewable energy technologies using probability distributions

In this paper, a probabilistic model is developed to assess the effects of different support mechanisms on the financial return of small-scale hydroelectric, wind energy and solar PV systems. Besides, the results from this model are used to compare the economic effectiveness of each mechanism in increasing the profitability of these projects. We focus on three renewable energy support mechanisms: governmental grants, feed in tariffs (FiT) and renewable energy certificates (RECs). We also consider the effect of the carbon credits on the net present value of renewable projects and compare it with the other support mechanisms. The simulation results demonstrate that the feed in tariffs is the best mechanism to increase the profitability of solar PV systems and wind energy projects. Conversely, green certificate mechanism favors the most competitive technology as the hydropower. In addition, it is shown that the governmental grants and carbon credits are secondary support mechanisms compared to FiT and RECs. And, the carbon credits play a more important role than governmental grants as the energy output of the system increase. Finally, it can be concluded that the efficiency of the support mechanisms varies depending on stage of development of the renewable technologies that are implemented.     

Exergy analysis of renewable energy sources

Oil crises in the past years made more obvious the dependency of economies on fossil fuels. As a consequence, the need for new energy sources became more urgent. Renewable energy sources could provide a solution to the problem, as they are inexhaustible and have less adverse impacts on the environment than fossil fuels. Yet, renewable energy sources technology has not reached a high standard at which it can be considered competitive to fossil fuels. The present study deals with the exergy analysis of solar energy, wind power and geothermal energy. That is, the actual use of energy from the existing available energy is discussed. In addition, renewable energy sources are compared with the non-renewable energy sources on the basis of efficiency.     

适应可再生能源消纳的储能技术经济性分析

低成本储能技术是碳中和目标下高渗透率可再生能源系统的重要支撑技术.现有储能技术经济性研究一般基于储能产品技术参数评估平准化充放电成本(LCOS),缺少结合具体应用工况的储能技术路线对比分析.在未来以新能源为主体的新型电力系统中,储能的运行工况将发生明显变化,技术经济性定量预测研究是储能技术路线选择和激励政策设计的重要参...     

More accurate sizing of renewable energy sources under high levels of electric vehicle integration

Electric vehicles (EVs) and distributed generation are expected to play a major role in modern power systems. Although many studies have introduced novel models to integrate distributed generation into high levels of EV-adoption scenarios, none has considered EV-embedded battery performance degradation and its economic effect on system planning. Based on well-established models and data to emulate the capacity fading of lithium-ion batteries, the current work presents a mixed-integer linear programming optimization framework with decision variables to size renewable energy resources (RESs) in modern microgrids. The objective function aims to minimize the total cost of the system while guaranteeing a profitable operation level of vehicle-to-grid (V2G) application, narrowing the gap between design stage and real-life daily operation patterns. Stochastic modeling is used to incorporate the effect of different uncertainties involved in the issue. A case study on a residential system in Okinawa, Japan, is introduced to quantitatively illustrate how a profitable V2G operation can affect RES sizing. The results reveal that accounting for the economic operation of EVs leads to the integration of significantly higher capacities of RESs compared with a sizing model that excessively relies on V2G and does not recognize battery-fading economics.     

Developing markets for renewable energy technologies

Although renewable energy resources are now being utilised more on a global scale than ever before, there is no doubt their contribution to the energy economy can still be greatly increased. Recently international support for developing these relatively new sources of energy has been driven by their benefits as assessed by reduced environmental impact, particularly reduced greenhouse gas emissions.After several decades of continuous but somewhat erratic funding for research and development of renewables, it is time to take stock of the key issues to be addressed in terms of implementation of major renewable energy programmes on a large scale worldwide. One of the first steps in this process is the identification and encouragement of reliable continuous markets both in developed and developing nations. Future energy policy and planning scenarios should take into account the factors necessary to integrate renewables in all their diverse forms into the normal energy economy of the country.Other critical factors in market development will include the mass production of high quality, reliable and reasonable cost technical products and the provision of adequate finance for demonstrating market ready and near market renewables equipment.Government agencies need to aid in the removal of legislative and institutional barriers hindering the widespread introduction of non-conventional energy sources and to encourage the implementation of government purchasing schemes.Recent moves by companies in Australia to market ‘green energy’ to customers should also aid in the public awareness of the ultimate potential of renewables leading to greater use in the industrial, commercial and domestic sectors.     

Control strategies for single-phase grid integration of small-scale renewable energy sources: A review

Small-scale renewable energy sources, such as small hydro turbines, roof-mounted photovoltaic and wind generation systems, and commercially available fuel cells are usually connected to the single-phase distribution grid through a voltage source converter. To regulate the power exchange with the single-phase grid, and at the same time, reduce the harmonic distortions in the ac current, different current control structures have already been proposed, among which the current hysteresis control, the voltage oriented control, and the proportional-resonant based control have found more attentions. This paper provides an overview of the main characteristics of these control strategies. Also, some implementation aspects such as the fictitious signal generation and the single-phase grid synchronization techniques are discussed. Finally, through extensive simulations a comparative study of the presented control strategies is presented. The simulations are supported by experiments.     

Cyprus energy system and the use of renewable energy sources

Cyprus is an island state whose energy production is almost completely dependent on imported hydrocarbon fuels. Its electricity production sector is more than 90% dependent on oil products while the remaining 9% are covered by imports of coal (4.5%) and by solar energy (4.5%). Because Cyprus will become a full member of the European Union (EU), it becomes essential to follow the EU white paper rules and insert renewable energy sources (RES) as part of its energy production system. Solar, wind energy and biomass are the three available forms of RES. This paper will examine and analyze the energy system of Cyprus. It will examine the RES available and the extent of the energy needs could be satisfied by them.     

Seawater desalination using renewable energy sources

The origin and continuation of mankind is based on water. Water is one of the most abundant resources on earth, covering three-fourths of the planet's surface. However, about 97% of the earth's water is salt water in the oceans, and a tiny 3% is fresh water. This small percentage of the earth's water—which supplies most of human and animal needs—exists in ground water, lakes and rivers. The only nearly inexhaustible sources of water are the oceans, which, however, are of high salinity. It would be feasible to address the water-shortage problem with seawater desalination; however, the separation of salts from seawater requires large amounts of energy which, when produced from fossil fuels, can cause harm to the environment. Therefore, there is a need to employ environmentally-friendly energy sources in order to desalinate seawater.After a historical introduction into desalination, this paper covers a large variety of systems used to convert seawater into fresh water suitable for human use. It also covers a variety of systems, which can be used to harness renewable energy sources; these include solar collectors, photovoltaics, solar ponds and geothermal energy. Both direct and indirect collection systems are included. The representative example of direct collection systems is the solar still. Indirect collection systems employ two sub-systems; one for the collection of renewable energy and one for desalination. For this purpose, standard renewable energy and desalination systems are most often employed. Only industrially-tested desalination systems are included in this paper and they comprise the phase change processes, which include the multistage flash, multiple effect boiling and vapour compression and membrane processes, which include reverse osmosis and electrodialysis. The paper also includes a review of various systems that use renewable energy sources for desalination. Finally, some general guidelines are given for selection of desalination and renewable energy systems and the parameters that need to be considered.     

国际可再生能源会议信息

2004/1/17-21欧洲可再生能源学术讨论会会议地点:德国柏林联系人:Eufores,EuropeanForumforRenew-ableEnergySources,RenewableEnergyHouse,26RuedeTrone,B-1000Brussels,Belgium.电话:+3225461948传真:+3225461934电子邮件:eufores@eufores.org网址:www.eufores.org2004/1/19-21欧洲可再生能源讨论会会议地点:德国柏林联系人:ChristineLins,SecretaryGeneral,EREC,EuropeanEenewableEnergyCouncil,26,RueduTrone,B-1000Brussels,Belgium电话:+3225461933传真:+3225461934电子邮件:berlin2004@erec-renewables.org网址:www.ere…