水电站蓝水足迹的计算分析与探讨

为合理评估水电开发利用过程消耗水资源的问题,计算了我国已建283座大中型水电站的总蓝水足迹及其平均值,同时根据气候区域及水电基地的不同将这些水电站划分为7个气候分区和13个水电基地,并分别计算其平均蓝水足迹。结果表明,由于气候分区及所在水电基地的不同,所统计水电站的平均蓝水足迹差异较大,但总体上平均蓝水足迹较小。通过分析计算结果合理性及敏感性,得出水电站蓝水足迹的变化主要取决于水电站和水库的参数。说明蓝水足迹可作为水电站规划与运行期间的一个指标,为我国水资源的科学管理及合理开发提供了理论依据。     

The impact of global change on the hydropower potential of Europe: a model-based analysis

This study presents a model-based approach for analyzing the possible effects of global change on Europe's hydropower potential at a country scale. By comparing current conditions of climate and water use with future scenarios, an overview is provided of today's potential for hydroelectricity generation and its mid- and long-term prospects. The application of the global water model WaterGAP for discharge calculations allows for an integrated assessment, taking both climate and socioeconomic changes into account. This study comprises two key parts: First, the ‘gross’ hydropower potential is analyzed, in order to outline the general distribution and trends in hydropower capabilities across Europe. Then, the assessment focuses on the ‘developed’ hydropower potential of existing hydropower plants, in order to allow for a more realistic picture of present and future electricity production. For the second part, a new data set has been developed which geo-references 5991 European hydropower stations and distinguishes them into run-of-river and reservoir stations. The results of this study present strong indications that, following moderate climate and global change scenario assumptions, severe future alterations in discharge regimes have to be expected, leading to unstable regional trends in hydropower potentials with reductions of 25% and more for southern and southeastern European countries.     

多江汊上河床式电站过渡过程涌波特性

河床式水电站过渡过程涌波对机组运行有明显影响,当电站布置于中隔岛洲的多条江汊上时,涌波问题尤为突出。对此,采用已验证的Delft3D二维模型,模拟分析了涌波大小的影响因素、涌波组成成分、涌波传播和反射规律,回答了最大涌波产生工况、涌波影响范围、涌波主波特点等问题,并具体模拟了某两岛三江上实际水电站的涌波特性,指出多江之间往复传播的纵向涌波是最主要的涌波成分。研究成果可为类似水电站的设计和运行调度提供参考。     

水电站发电对河流水环境容量的影响分析

清理水库(水电站)对河流水环境容量的影响,对实施排污权交易、环境补偿和保护水环境等方面有重要作用,根据常用的零维、一维水环境容量计算模型和能量守恒定律,推导出水电站修建前后对河流水环境容量影响的定量判别关系式,并以广东省东江干流的12个梯级水电站和3座水库为研究对象,分析了各水库、水电站发电对东江流域水环境容量的影响。结果表明,除龙潭、枕头寨和柳城3个梯级水电站外,其余9个水库、水电站均增加了东江流域水环境容量。     

Water competition through the ‘water-energy’ nexus: Assessing the economic impacts of climate change in a Mediterranean context

The impacts of climate change on water resources availability are expected to be adverse, especially in drier climate regions such as the Mediterranean. Increased water scarcity will exacerbate competition for water resources, not only between sectors but also between countries sharing transboundary river basins. Due to the mutual dependence of the energy sector on water resources and of the water services provision sector on energy inputs, the ‘water-energy’ nexus is acknowledged as a major challenge for the near future – with hydropower representing one of the most direct links in this nexus. The aim of this paper is to assess the economy-wide impacts of the concurrent effects of climate change-driven impacts on water availability and the sectoral and regional competition for scarcer water resources. In order to accomplish that goal, an integrated modelling approach is developed, where a computable general equilibrium model including raw water as a production factor is linked to TIMES_PT, a bottom-up model of the energy sector. A case study is provided for the Mediterranean country of Portugal. Results for 2050 show that macroeconomic impacts are significant, and encompass important inter-sectoral differences that, in turn, depend on the degree of competition between sectors. Impacts are stronger when water consumption by Spanish sectors is considered, as this intensifies water scarcity in Portugal. Thus the paper allows to gain insight in the broader ‘water-energy-economy’ nexus and the additional costs that the dependence on water resources availability in transboundary river basins represents to an economy – both aspects being of utmost importance for climate adaptation and energy policy making.     

The local socio-economic impacts of large hydropower plant development in a developing country

Despite extensive discussion in the literature about the socio-economic impacts of hydropower development on surrounding communities, there is (1) a lack of quantitative studies that look at impacts over extended periods of time and (2) a lack of studies including multiple projects in the context of a developing country. Here, we use econometric methods to evaluate the relationship between county-level socio-economic indicators and hydropower development for 56 Brazilian hydropower plants built between 1991 and 2010. We find that counties that built hydropower plants had greater GDP and tax revenues during their first few years of development than a control group that consisted of counties with hydropower projects planned but not yet built. However, those positive economic effects were short lived (< 15 years). We also find that social indicators (e.g. average income, life expectancy, educational level, access to piped water and public electricity, teenage pregnancy levels, and HIV cases) in counties that built hydropower did not statistically differ from those in the control counties. The results suggest that, for Brazil, justifications for hydropower projects based on local long-term economic and social development should be questioned, and that more effective mechanisms for turning local short-term economic growth into long-term development are needed.     

An integrated reservoir-power system model for evaluating the impacts of wind integration on hydropower resources

Despite the potential for hydroelectric dams to help address challenges related to the variability and unpredictability of wind energy, at present there are few systems-based wind-hydro studies available in the scientific literature. This work represents an attempt to begin filling this gap through the development of a systems-based modeling framework for analysis of wind power integration and its impacts on hydropower resources. The model, which relies entirely on publicly available information, was developed to assess the effects of wind energy on hydroelectric dams in a power system typical of the Southeastern US (i.e., one in which hydropower makes up <10% of total system capacity). However, the model can easily reflect different power mixes; it can also be used to simulate reservoir releases at self-scheduled (profit maximizing) dams or ones operated in coordination with other generators to minimize total system costs. The modeling framework offers flexibility in setting: the level and geographical distribution of installed wind power capacity; reservoir management rules, and static or dynamic fuel prices for power plants. In addition, the model also includes an hourly ‘natural’ flow component designed expressly for the purpose of assessing changes in hourly river flow patterns that may occur as a consequence of wind power integration. Validation of the model shows it can accurately reproduce market price dynamics and dam storage and release patterns under current conditions. We also demonstrate the model's capability in assessing the impact of increased wind market penetration on the volumes of reserves and electricity sold by a hydroelectric dam.     

梯级水电站群发电运行的水足迹研究

为合理评估大型流域梯级水电站群发电运行对水资源的消耗,以金沙江中游梯级水电站群为例,提出了不同调度模式下梯级水电站群发电运行的水足迹研究方法,基于负荷曲线单独运行、负荷曲线联合运行、发电量最大联合运行三种调度模式下的短期优化调度结果,分别计算获得运行阶段的水足迹,并分析了不同调度模式对水足迹的影响。结果表明,水足迹能直观地反映梯级水电站群发电运行对水资源的消耗,梯级水电站群可改变调度模式来降低其发电运行的水足迹。     

水库诱发地震危险性定量预测与评估系统开发研究

从理论模型出发,通过系统需求分析,对水利水电工程及其周缘地区诱发地震危险定量预测与评估系统的结构体系及其开发流程进行了分析与研究,在此基础上,完成了诱震危险性概率模型构建子系统,待评工程诱震危险性概率预测与评估子系统及其相应功能模块的开发,并对系统的主要功能进行了分析。     

Sustainability deterioration of electricity generation in Brazil

The power generation sector in Brazil is usually considered to have a high level of sustainability because of its large share of hydropower, about 70%. The annual growth rate of the Brazilian power sector is about 4%/year with a growing capacity addition of fossil fuels, which indicates a deterioration regarding sustainability. This work utilizes multi-criteria analysis coupled with composite indicators to infer the sustainability evolution of the power generation sector in Brazil from 2010 to 2016. Seven criteria were considered: emission of greenhouse gases, immobilized area, use of fuel resources, water use, morbidity, energy generation reliability and energy efficiency. The assessment evidenced wind power and nuclear power plants as the most sustainable options for capacity addition after hydropower. Co-generation and combined cycle technologies should be encouraged in natural gas and biomass projects in order to reduce impacts on sustainability. The assessment is interdisciplinary and admits tradeoffs amongst different impacts and benefits, for instance, environmental impacts versus energy generation reliability. It is proposed that sustainability assessments be incorporated to the formal process of decision making in order to reduce opposition and facilitate obtaining consensus among different stakeholders.     

流量节点图在金水河流域梯级电站规划环评中的应用

流量节点图在引水式水电站开发环评影响分析中应用较多,它能直观反映出由于水电站引水(或者调水)造成的减脱水段多年平均流量的变化情况。引用"佛坪县金水河流域梯级电站规划环评",浅析了流量节点图在环评影响分析中的应用。     

A review of the potential water quality impacts of tidal renewable energy systems

The continued increase in the demand for energy, growing recognition of climate change impacts, high oil and gas prices and the rapid depletion of fossil fuel reserves have led to an increased interest in the mass generation of electricity from renewable sources. Traditionally, this has been pursed through riverine hydropower plants, with onshore wind systems growing steadily in popularity and importance over the years. Other renewable energy resources, which were previously not economically attractive or technically feasible for large scale exploitation, are now being considered to form a significant part of the energy mix. Amongst these, marine and in particular, tidal energy resource has become a serious candidate for undergoing mass exploitation in the near future, particularly in places with a tidal range of 4 m or more. Tidal renewable energy systems are designed to extract the kinetic or potential energy flow and convert it into electricity. This can be achieved by placing tidal stream turbines in the path of high speed tidal currents or through tidal range schemes, where low head turbines are encapsulated in impoundment structures, much like in low head riverine hydropower schemes. It is thought that these systems, when implemented at scales required to generate substantial amounts of electricity, have the potential to significantly alter the tidal flow characteristics, which could have knock-on impacts on the hydro-environment. This review gathers together knowledge from different research areas to facilitate an evaluation of the potential hydro-environmental impacts of tidal renewable energy systems, with a particular focus on water quality. It highlights the relevance of hydro-environmental modelling in assessing potential impacts of proposed schemes and identifies areas where further research is needed. A case study is presented of recent modelling studies undertaken for the Severn Estuary.     

二滩水电站运行后对雅砻江下游河流水文情势的影响分析

为评估二滩水电站运行后对下游雅砻江水文情势的影响程度,针对雅砻江下游小得石水文站1958～2012年期间逐日流量变化情况,采用变化范围法（RVA）求得水文变动指标（IHA）中33个水文参数的改变及水文改变程度。结果表明,二滩水电站运行后,其下游雅砻江月平均流量变化的改变不大,年最小流量的改变有所增加,年最大流量变化不大;年最大流量、年最小流量的出现时间均由建库前的30日左右增加到90日左右,偏差较大;年高低流量的频率升幅较大,但持续时间略微减少;涨水率有所上升;落水率有所下降。最终根据水文综合改变度评价雅砻江河流水文情势总体改变度为68.31%,这表明二滩水电站的运行对下游小得石水文站的水文情势的影响为高度改变。     

Life-cycle uses of water in U.S. electricity generation

Water use by the electric power industry is attracting renewed interest as periods and zones of arid weather are increasingly encountered, and various regional energy-production scenarios are evaluated. However, there is a scarcity of data on upstream water factors and discrepancies of data from different sources. We reviewed previous studies of water use in electricity generation and used full-life cycle accounting to evaluate water demand factors, both withdrawal and consumption, for conventional- and renewable-electrical power plants. Our investigation showed that moving to technologies like photovoltaics and wind offers the best option for conserving our water supply. We also emphasize the importance of employing a transparent, balanced approach in accounting life-cycle water usages.     

基于支流水温对汉江干流河道水温影响的数值模拟

由于大中型水库蓄水后改变了原天然河道水温的时空分布,因此水库下游河道的水温恢复状况是目前水电工程环境影响评价的重要指标之一。将水库下泄流量、支流流量、太阳辐射、气温、风速等作为恒定因子,以支流水温为主要变量,建立了平面二维水动力—温度数学模型,并用汉江中游河段的实测水温资料对模型进行了验证,进而分析了支流水温对水库下游有支流汇入河道水温恢复过程的影响。结果表明,支流水温越高,在纵向上河道水温恢复到平衡水温所需距离越短,而在横向上水温掺混均匀所需距离越长。     

Modelling a hydropower plant with reservoir with the micropower optimisation model (HOMER)

Hydropower with water accumulation is an interesting option to consider in hybrid systems, because it helps dealing with the intermittence characteristics of renewable energy resources. The software HOMER (version Legacy) is extensively used in research works related to these systems, but it does not include a specific option for modelling hydro with reservoir. This paper describes a method for modelling a hydropower plant with reservoir with HOMER by adapting an existing procedure used for modelling pumped storage. An example with two scenarios in southern Brazil is presented for illustrating and validating the method explained in this paper. The results validate the method by showing a direct correspondence between an equivalent battery and the reservoir. The refill of the reservoir, its power output as a function of the flow rate and installed hydropower capacity are effectively simulated, indicating an adequate representation of a hydropower plant with reservoir is possible with HOMER.     

Low natural gas prices and the financial cost of ramp rate restrictions at hydroelectric dams

Peaking hydroelectric dams that employ variable, stop-start reservoir releases can have adverse impacts on downstream river ecosystems. Efforts to mitigate these impacts have relied predominantly on the use of ramp rate restrictions, which limit the magnitude of hour-to-hour changes in reservoir discharge. Ramp rate restrictions shift hydropower production towards less valuable off-peak hours, imposing a financial penalty on dam owners that is a function of the “spread” (difference) between peak and off-peak electricity prices. This study examines how low natural gas prices in the U.S. have reduced the cost of implementing ramp rate restrictions at dams by narrowing the peak/off-peak price spread. Significantly lower costs of ramp rate restrictions could open new opportunities for improving environmental flows at dams, including the “purchase” of more natural streamflow patterns by downstream stakeholders, a type of arrangement for which there is growing precedent. We also explore the role that uncertainty in the cost of ramp rate restrictions could play in precluding downstream stakeholders from forming these types of agreements with dam owners. Results suggest that financial “collar” contracts could mostly eliminate inter-annual variability in the net cost of restrictions and provide those purchasing more natural flows with greater certainty.     

我国煤电生产水足迹评价

为识别能源产业对水资源、水环境的影响和风险,基于水足迹评估理论方法构建了煤电生产水足迹评价模型,并以2016年为例,从区域尺度定量分析了我国煤电生产各环节虚拟水消耗量和虚拟水流动格局。结果表明,2016年我国煤电生产的总水足迹为107.3×10~8 m~3,其中灰水足迹占44%,蓝水足迹占56%;伴随电力的调运,晋蒙和西北地区年虚拟水输出量约为5×10~8 m~3,该区域属于我国缺水乃至严重缺水地区,能源发展面临的水资源和水环境约束十分显著。     

潘口水库蓄水运行对黄龙滩水电厂中长期发电调度的影响

堵河中下游的潘口水库正常蓄水运行后,将会对下游的黄龙滩水电厂发电调度产生较大影响。在潘口水库调度方式确定的情况下,利用有、无对比法,采用调度图和离散微分动态规划算法,研究了潘口水库正常蓄水运行后在丰、平、枯三个典型年对黄龙滩水电厂中长期发电调度的影响。结果表明,潘口水库的调蓄可明显提高平水年黄龙滩水电厂的发电量,降低其年发电耗水率;对于丰水年和枯水年,潘口水库调度期期初水位高于345 m时也可在一定程度上提高其发电效益;在潘口水库调度期期初水位低于345 m时,黄龙滩水电厂宜采用优化调度方式,并尽量提高其期初水位至245 m以上。     

Mass flow rate prediction of shale gas considering gas diffusion and water film evaporation

Abstract

The difference between organic and inorganic matters in shale matrix has significantly influence on the transport capacity of shale gas and the total production of shale gas further. Previous studies have demonstrated that the organic pores are hydrophobic and the inorganic pores are hydrophilic. Therefore, the water film can be adsorbed on the walls of the inorganic pores. However, the evaporation of water film in inorganic pore is often overlooked due to the analytical challenge and the effect of the water film evaporation on gas transport capacity is rarely discussed. Thus, it is important to accurately predict mass flow rate of the shale gas through a single nanopore whether it is organic or inorganic. In this article, the mass flow rate prediction model of the organic pore is developed firstly, which considers the interactions of slip flow, gas adsorbed at pore walls, surface diffusion for adsorbed gas and gas diffusing from the kerogen which contains dissolved shale gas in organic pores at nanoscale. This model is then used to investigate the influences of initial pressure, pressure gradient, and thickness of kerogen on the gas mass flow rate. For inorganic pores, the mass flow rate prediction model is developed secondly and the interactions of water film and the evaporation of water film have been considered. The influence of evaporation, initial humidity, water–methane diffusivity is investigated on the gas mass flow rate. Results show that diffusion from kerogen plays an important role in the transport capacity of shale gas. Both higher pressure gradient and thicker kerogen can contribute to higher gas mass flow rate and higher diffusion from kerogen. Higher initial pressure and thicker kerogen can contribute to the lower shale gas desorption. The thicker kerogen can contribute to the higher surface diffusion. The evaporation in inorganic pore should not be ignored, because it impacts gas mass flow rate and can contribute to the higher flow rate. Experimental data was compared with our prediction model, which proves the correctness and validity of our model.