Review on multi-criteria decision analysis aid in sustainable energy decision-making

Multi-criteria decision analysis (MCDA) methods have become increasingly popular in decision-making for sustainable energy because of the multi-dimensionality of the sustainability goal and the complexity of socio-economic and biophysical systems. This article reviewed the corresponding methods in different stages of multi-criteria decision-making for sustainable energy, i.e., criteria selection, criteria weighting, evaluation, and final aggregation. The criteria of energy supply systems are summarized from technical, economic, environmental and social aspects. The weighting methods of criteria are classified into three categories: subjective weighting, objective weighting and combination weighting methods. Several methods based on weighted sum, priority setting, outranking, fuzzy set methodology and their combinations are employed for energy decision-making. It is observed that the investment cost locates the first place in all evaluation criteria and CO₂ emission follows closely because of more focuses on environment protection, equal criteria weights are still the most popular weighting method, analytical hierarchy process is the most popular comprehensive MCDA method, and the aggregation methods are helpful to get the rational result in sustainable energy decision-making.     

The role of tidal asymmetry in characterizing the tidal energy resource of Orkney

When selecting sites for marine renewable energy projects, there are a wide range of economical and practical constraints to be considered, from the magnitude of the resource through to proximity of grid connections. One factor that is not routinely considered in tidal energy site selection, yet which has an important role in quantifying the resource, is tidal asymmetry, i.e. variations between the flood and ebb phases of the tidal cycle. Here, we present theory and develop a high-resolution three-dimensional ROMS tidal model of Orkney to examine net power output for a range of sites along an energetic channel with varying degrees of tidal asymmetry. Since power output is related to velocity cubed, even small asymmetries in velocity lead to substantial asymmetries in power output. We also use the 3D model to assess how tidal asymmetry changes with height above the bed, i.e. representing different device hub heights, how asymmetry affects turbulence properties, and how asymmetry is influenced by wind-driven currents. Finally, although there is minimal potential for tidal phasing over our study site, we demonstrate that regions of opposing flood- versus ebb-dominant asymmetry occurring over short spatial scales can be aggregated to provide balanced power generation over the tidal cycle.     

Economic evaluation of reverse osmosis desalination system coupled with tidal energy

A reverse osmosis (RO) desalination system coupled with tidal energy is proposed. The mechanical energy produced by the tidal energy through hydraulic turbine is directly used to drive the RO unit. The system performances and the water cost of the conventional and tidal energy RO systems are compared. It is found that the proposed tidal energy RO system can save water cost in the range of 31.0%-41.7% in comparison with the conventional RO system. There is an optimum feed pressure that leads to the lowest water cost. The tidal RO system can save more costs at a high feed pressure or a high water recovery rate. The optimum feed pressure of the tidal energy RO system is higher than that of the conventional RO system. The longer lifetime of the tidal energy RO system can save even more water cost. When the site development cost rate is lower than 40%, the water cost of the tidal energy RO system will be lower than that of the conventional RO system. The proposed technology will be an effective alternative desalination method in the future.     

Air co-gasification process of LDPE/HDPE waste based on thermodynamic modeling: Hybrid multi-criteria decision-making techniques with sensitivity analysis

Gasification process is an efficient thermochemical disposal technique and is growing fast in the plastic waste field, nowadays. Co-gasification of low-density and high-density polyethylene waste with different composition ratios was developed in this study and subjected to a hybrid multi-criteria decision-making (MCDM) techniques after validation by comparing with experimental data. A comprehensive parametric study was conducted by considering interaction effects of gasification parameters on the outputs. The MCDM problem involved eleven alternatives and five energy, environmental and economic criteria of gasification performance indicators including hydrogen production, energy efficiency, carbon dioxide emission, heating value of syngas and purchasing cost. The criteria weighting was performed using analytical hierarchy process, Shannon entropy technique and their composite weighting method. TOPSIS and VIKOR techniques were coupled by criteria weighting methods for alternative ranking. L0H100 alternative, i.e. composition of 0 wt% of low-density polyethylene waste and 100 wt% of high-density polyethylene waste, was the best alternative in almost all cases. This alternative had the minimum CO₂ emission of 4.98 g/mol, the minimum purchasing cost of 0.96 $/kg and led to the maximum heating value of 126.8 kJ/mol. The findings revealed that VIKOR technique was sensitive to the criteria weights; however, TOPSIS method was independent from the changing the criteria weights.     

GIS based multi-criteria decision making for solar hydrogen production sites selection in Algeria

Hydrogen production from renewable energy sources appears to be an interesting solution for reducing greenhouse gas emissions and ensuring the energy security supply. This paper develops an integrated framework to evaluate land suitability for hydrogen production from solar energy site selection that combines multi-criteria decision making (MCDM) with geographical information systems (GIS); an application of the proposed framework for Algerian country. In GIS two types of criteria will be taken: constraints and weighting criteria. Constraints criteria will make it possible to reduce the area of study by discarding those areas that prevent the implementation of installing solar hydrogen production systems. These criteria will be obtained from the legislation (land use, water bodies, waterways, roads, railways, power lines, and also their buffer around them). Weighting criteria will be chosen according to the objective to be reached, in this case they will be the hydrogen demand, potential solar hydrogen production, digital elevation models (DEMs), slope, proximity to roads, railways, and power lines. Through the use of MCDM the criteria mentioned will be weighted in order to evaluate potential sites to locate a solar hydrogen production installation system. Analysis and calculation of the weights of these criteria will be conducted using Analytic Hierarchy Process (AHP). As a result, the final index model was grouped into four categories as “very low suitability”, “low suitability”, “moderate suitability” and “high suitability” with a manual interval classification method. The results indicate that 10.34% (246,272.02 km²), of the study area has very low suitability, 60.75% (1,446,907.65 km²) has low suitability, 6.68% (159,100.3 km²) has moderate suitability and 0.49% (11,669.21 km²) has high suitability for a solar-powered hydrogen production installation system. The other 21.74% (517,790.5 km²) of the study area is not suitable for such projects. The sensitivity analysis highlights that the suitable sites for solar hydrogen production installation system are dependent on the weights of the criteria that influence the decision. The MCDM methodology integrated with GIS is a powerful tool for effective evaluation of the solar-powered hydrogen production sites selection.     

The economics of tidal energy

Concern over global climate change has led policy makers to accept the importance of reducing greenhouse gas emissions. This in turn has led to a large growth in clean renewable generation for electricity production. Much emphasis has been on wind generation as it is among the most advanced forms of renewable generation, however, its variable and relatively unpredictable nature result in increased challenges for electricity system operators. Tidal generation on the other hand is almost perfectly forecastable and as such may be a viable alternative to wind generation. This paper calculates the break-even capital cost for tidal generation on a real electricity system. An electricity market model is used to determine the impact of tidal generation on the operating schedules of the conventional units on the system and on the resulting cycling costs, emissions and fuel savings. It is found that for tidal generation to produce positive net benefits for the case study, the capital costs would have to be less than €510,000 per MW installed which is currently an unrealistically low capital cost. Thus, it is concluded that tidal generation is not a viable option for the case system at the present time.     

Performance of OWC wave energy converters: influence of turbine damping and tidal variability

The performance of oscillating water column (OWC) systems depends on a number of factors in a complex manner. The objective of this work is to analyse the influence of the wave conditions, the damping caused by the turbine and the tidal level on the efficiency of the conversion from wave to pneumatic energy that occurs in the OWC chamber. To achieve this, a comprehensive experimental campaign is carried out, involving in total 387 tests of a model OWC under varying wave conditions (both with regular and irregular waves), damping coefficients and tidal levels. It is found that the damping exerted by the turbine is the factor that most affects the chamber efficiency—even more than the wave conditions. It follows that a proper selection of the turbine is crucial not only to the performance of the turbine itself but also to that of the chamber, which reflects the importance of the turbine–chamber coupling in OWC systems. The next factor in order of importance is the wave period. Finally, we find that the influence of the tidal level, which is examined in this work for the first time, is significant under certain conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Renewable energy in India: Historical developments and prospects

Promoting renewable energy in India has assumed great importance in recent years in view of high growth rate of energy consumption, high share of coal in domestic energy demand, heavy dependence on imports for meeting demands for petroleum fuels and volatility of world oil market. A number of renewable energy technologies (RETs) are now well established in the country. The technology that has achieved the most dramatic growth rate and success is wind energy; India ranks fourth in the world in terms of total installed capacity. India hosts the world's largest small gasifier programme and second largest biogas programme. After many years of slow growth, demand for solar water heaters appears to be gaining momentum. Small hydro has been growing in India at a slow but steady pace. Installation of some of the technologies appears to have slowed down in recent years; these include improved cooking stoves (ICSs) and solar photovoltaic (PV) systems. In spite of many successes, the overall growth of renewable energy in India has remained rather slow. A number of factors are likely to boost the future prospects of renewable energy in the country; these include global pressure and voluntary targets for greenhouse gas emission reduction, a possible future oil crisis, intensification of rural electrification program, and import of hydropower from neighbouring countries.     

Supporting energy initiatives in small communities by linking visions with energy scenarios and multi-criteria assessment

Many decisions about future energy systems in small communities are based on the visions of several key actors about the ideal-type system. Although meaningful, such visions may not inclusively represent the objectives of all relevant actors. Moreover, the visions are mostly intuitively judged by these actors and reflect their experiences and concerns. Yet, analytical expertise provides essential information about the required decisions and their consequences. We argue that coming up with a number of alternative visions about a future energy system and addressing these visions from both intuitive and analytical perspectives leads to better-quality decisions. This paper presents a case study in the small Swiss community of Urnäsch, where actors from practice and academia collaborated in a transdisciplinary process to address the future energy system. Visions of these actors about the ideal-type energy system were linked both with energy scenarios that analytically specified options to implement these visions and with stakeholder-based multi-criteria assessment of the consequences. As a result, most of the involved actors adjusted their initial vision preferences. Thus, we believe this approach could lead to capacity building and formation of stable, informed preferences, which are necessary to support a transition in the coming decades.     

中国海洋能专利研究

专利是除论文外的又一非常重要的科技成果.目前专利申请工作并未得到足够重视,并且文献中对专利技术成果的反映甚少.文章对中国国家知识产权局(SIPO)专利数据库中海洋能专利授权情况进行了分类统计.介绍了波浪能、潮汐能、温差能的最新专利,并指出了该领域专利申请的热点和空白领域.最后根据统计数据从专利的角度分析了中国海洋能研究的进展和前景.     

固定偏角垂直轴潮流能水轮机叶片安装位置试验研究

叶片安装位置是影响固定偏角垂直轴潮流能水轮机水动力性能的关键参数之一,为了研究其对水轮机性能影响的基本规律,建立了垂直轴水轮机水槽模型试验系统,设计了垂直轴水轮机性能和载荷测试方法。通过试验结果的分析,得到了叶片安装位置对水轮机能量利用率、推力系数、侧向力系数和合力系数的影响规律,为水轮机设计提供了试验依据。     

水平轴潮流能水轮机尾流特性研究

文章以水平轴潮流能水轮机为研究对象,采用CFD方法对水轮机的尾流特性进行分析。通过网格无关性验证与已发表文献的比对,验证了CFD方法的精度。通过不同叶尖速比下的水轮机性能曲线,进一步分析了水轮机的尾流场速度分布特征。通过分析尾流场中轴向、径向和切向速度的分布特点,研究了水平轴潮流能水轮机尾流的微观结构特征及其演化规律。研究结果表明:尾流横向影响范围在以中心轴线为中心的1D范围内;在近尾流处,尾流速度具有周期性,轴向速度随着尾流下移而逐渐减小;在尾流旋转过程中,径向速度向外扩散并逐渐衰减,切向速度分量沿轴向逐渐衰减。     

太阳能在建筑节能中应用的探讨

论述了太阳能在建筑中的应用形式，对不同的形式做了必要的分析。提出了使用中应注意的问题，并得到一些结论。     

Econometric analysis of the R&D performance in the national hydrogen energy technology development for measuring relative efficiency: The fuzzy AHP/DEA integrated model approach

Hydrogen energy technology can be one of the best key players related to the sector of the United Nations Framework Convention on Climate Change (UNFCCC) and the hydrogen economy. Comparing to other technologies, hydrogen energy technology is more environmentally sound and friendly energy technology and has great potential as a future dominant energy carrier. Advanced nations including Korea have been focusing on the development of hydrogen energy technology R&D for the sustainable development and low carbon green society. In this paper, we applied the integrated fuzzy analytic hierarchy process (Fuzzy AHP) and the data envelopment analysis (DEA) for measuring the relative efficiency of the R&D performance in the national hydrogen energy technology development. On the first stage, the fuzzy AHP effectively reflects the vagueness of human thought. On the second stage, the DEA approach measures the relative efficiency of the national R&D performance in the sector of hydrogen energy technology development with economic viewpoints. The efficiency score can be the fundamental data for policymakers for the well focused R&D planning.     

A Multi—Criteria Decision Making Procedured for the Analysis of an Energy System

In the course of improving and/or designing an energy system,either purely economic criteria,although theoverriding criteria,or purely energy-based criteria,although the emphasized criteria,can not separately handlereal-world situations in a satisfactory manner.The economic effectiveness and the energy efficiency mustbe considered simultaneously to demonstrate the conflicting and non-commensurable characteristics of thesemultiple criteria.An iterative and interactive approach to formulating and solving non-linear multi-criteria decision makingproblems for the analysis of an energy system is proposed.It allows the decision maker(DM)to learn fromthe available information and dynamically change his mind.Criterion functions can be treated as objectivefunctions,as constraints or as something in between by the DM.After a series of iterations and interactiveprocedures,a preferred solution can be made among the non-inferior sets considering thermodynamic criteriaand economic criteria simultaneously.A simple example for design of a heat exchanger is used to illustrate theprocedure.     

Potential of building-scale alternative energy to alleviate risk from the future price of energy

The energy used for building operations, the associated greenhouse gas emissions, and the uncertainties in future price of natural gas and electricity can be a cause of concern for building owners and policy makers. In this work we explore the potential of building-scale alternative energy technologies to reduce demand and emissions while also shielding building owners from the risks associated with fluctuations in the price of natural gas and grid electricity. We analyze the monetary costs and benefits over the life cycle of five technologies (photovoltaic and wind electricity generation, solar air and water heating, and ground source heat pumps) over three audience or building types (homeowners, small businesses, large commercial and institutional entities). The analysis includes a Monte Carlo analysis to measure risk that can be compared to other investment opportunities. The results indicate that under government incentives and climate of Toronto, Canada, the returns are relatively high for small degrees of risks for a number of technologies. Ground source heat pumps prove to be exceptionally good investments in terms of their energy savings, emission, reductions, and economics, while the bigger buildings tend also to be better economic choices for the use of these technologies.     

A comparative multi-disciplinary policy review in wind energy developments in Europe

Over recent decades, European Union countries have committed to increasing their electricity production from renewable energy sources (RESs). Wind energy plays a significant role in a sustainable future. This paper presents a political, economic, social, technological, legal and environmental analysis. Although these countries have made many improvements in their legal frameworks aiming to attract investors and boost the RE sector, there are still challenges. The UK focuses on offshore wind energy, adjusts the economic strategy and changes the legislation context. Germany has the healthiest economic conditions, as it keeps following its initiative to design a new programme for an energy transition from conventional to RESs with emphasis on the onshore. Greece has only a few installations and much room for development but needs to make further changes in the legislation and economy so as to attract more investors in the long term. The purpose of this research is to analyse, highlight and discuss vital aspects of these countries as well as the European environment, with reference to their current wind energy activities. Ultimately, it attempts to give a wider perspective and to serve as a guide for future studies on the wind energy sector.     

Tidal stream energy resource assessment in the Qiantang River Estuary,China

A tidal stream energy resource assessment can be achieved through direct measurements of tidal elevations or flow velocities, theoretical formulas, and numerical models. This paper first described the development of renewable energy in China. Then, the tidal stream energy resource in the Qiantang River Estuary was assessed. The present work established a 2D numerical model for calculating the power density in the estuary and validated it with in situ water level, tidal current, and suspended sediment concentration measurements. Three possible sites found near the Hangzhou Bay Bridge were selected for detailed resource assessment. The results indicated that if only 50 turbines are deployed to each site, the tidal stream energy output by all turbines would be 7.5?GWh/year. Finally, building a tidal stream power generation device into an existing bridge structure was proposed at the Qiantang River Estuary.     

A dynamic risk aversion model for virtual energy plant considering uncertainties and demand response

To full use clean energy to meet load demand of electrical and thermal, the paper proposed a novel concept of virtual energy plant (VEP) including wind power plant (WPP), photovoltaic power generation (PV), combined heat and power generation (CHP), solar collectors (SC), electric boiler (EB), heat storage tank (HSK), and incentive‐based demand response (IBDR). Firstly, the basic structure of VEP is designed, including three subsystems, namely, electricity, heating, and energy storage. Then, a basic scheduling model is constructed under the objective of maximizing operating revenue without considering uncertainty. Thirdly, the conditional value at risk (CVaR) method and the robust optimization theory are used to handle the uncertainty factors in objective functions and condition constraints, and the risk aversion scheduling model is proposed. Finally, industrial park group in northern China are chosen, for example, analysis results show (1) VEP could convert the abandoned clean energy, use HSK to store heating energy during the valley load period, and supply heating energy in the peak period to obtain the excess economic benefits. (2) Lower‐prediction accuracy will amplify the uncertainty risk, when the robust β∈[0.8,0.825]&(0.925,1], the increase of confidence level β will lead to larger increase in CVaR. Especially when β∈(0.925,1), decision makers are extremely disgusted with the risks brought by the uncertainty factors, and correspondingly, the output of clean energy becomes minimum. (3) When the capacity ratio of HSK, EB and the electricity price of peak, valley are lower than 3, the values of revenue, VaR and CVaR change faster, but the ratios are larger than 3, the values change slower, which indicates that the scale of HSK capacity needs to be properly controlled to optimize the use of clean energy, and price‐based demand response could improve the operation profit while controlling risk properly. In general, the proposed scheduling model can maximize the use of clean energy to obtain economic benefits while rationally controlling risks.     

The link between political decision-making and energy options: Assessing future role of renewable energy and energy efficiency in Finland

European Union and Finland are confronted with much the same kind of challenges in energy policy. Because of much higher importance on energy, these issues escalated earlier in Finland including vital political decision-making. Several alternative energy paths to the future can be identified with fairly similar projected costs. The more in-depth analysis in the Finnish case suggests that, e.g., an integrated approach consisting of renewable energy sources and energy efficiency measures would be one competitive alternative to satisfy both increasing energy demand and CO₂ emission reductions already by 2020. The study shows that meeting environmental, energy security and economical targets may not as such be adequate for the future success of an energy option. There is a more profound link between the energy options and the political decision-making, implying a much broader range of criteria than just the 3 Es reflecting thus politicians’ priorities and concerns. For example, in the Finnish case renewable energy sources and energy efficiency did not match optimally the parliamentary majority's preferences when deciding on future electricity direction in 2002. The methodology suggested here can be used to improve the strategic positioning of alternative energy paths.