Assessment on Energy Self-Sufficiency Rate for Building Integrated Photovoltaics and Fuel Cell System in Japan

A building integrated photovoltaic (PV) and fuel cell (FC) system is proposed for assessment of the energy self-sufficiency rate in a city in Japan. The electricity consumed in the building is mainly supplied by solar panels, while the gap between the energy demand and supply is solved by the FC that is powered by the H2 produced by water electrolysis with surplus power of PV. A desktop case study of using the proposed system in Tsu city which is located in central part of Japan, has been conducted. The results found that the self-sufficiency rates of PV system to electricity demand of households (RPV) during the daytime in April and July are higher than those in January and October. The results also reveal that the self-sufficiency rate of FC system to the electricity demand (RFC) is 15% - 38% for the day when the mean amount of horizontal solar radiation is obtained in January, April, July and October. In addition, it is found the optimum tilt angle of solar panel installed on the roof of the buildings should be 0 degree, i.e., placed horizontally.

Energy Assessment of Building Integrated Photovoltaics and Fuel Cell Systems: Design Study for Building(s) of Mie, Japan

A building integrated energy system (photovoltaic (PV) and fuel cell (FC)) is proposed for assessment of the energy self-sufficiency rate in five cities of Mie prefecture in Japan. In this work, it is considered that the electricity requirement of the building is provided by the building integrated photovoltaic (BIPV) system and the gap between the energy demand and BIPV supply is fulfilled by the FC. The FC is powered by the electrolytic H2 produced from the surplus power of PV. A design study of using the proposed system in five cities in Mie prefecture, which are in center part of Japan, has been performed. It has been observed that the monthly power production from BIPV is higher in spring and summer, while it is lower in autumn and winter at all considered locations. The self-sufficiency rate of the FC system is higher with decreasing households’ number and it has been observed that the 12 households are more suitable for full cover of the electricity demand by the combined system of PV and FC. The relationship between the households’ number and self-sufficiency rate of the FC system per solar PV installation area can be expressed by exponential curve. The coefficient of the exponential curve can predict the suitable city for the BIPV system with FC system utilizing electrolytic H2 generated by using excess energy from the PV system.

Energy Characteristics of an Integrated Power Generation System with Photovoltaic and Fuel Cell

An integrated energy system (with photovoltaic (PV) and fuel cell (FC) for building) is proposed and assessed in term of its energy self-sufficiency rate in seven cities (Nagoya, Toyota, Tajimi, Takayama, Ogaki, Hamamatsu, Shizuoka) in Tokai region in Japan in this paper. In this work, it is considered that the electricity requirement of the building for household users is provided by a building integrated photovoltaic (BIPV) system and the gap between the energy demand and BIPV supply is fulfilled by the FC. The FC is powered by the electrolytic H2 produced when PV power was in surplus. Based on the study of applying the proposed system in seven cities, which clarifies the effectiveness of the integrated BIPV, electrolytic H2 and FC power generation system, a universal system model has been developed in this paper. It has been observed that the monthly power production from BIPV as well as FC system are higher in spring and summer, while they are both lower in autumn and winter at all considered locations. The self-sufficiency rate of the FC system is higher with decreasing households’ number and it has been observed that 16 is the most appropriate number of households in a building, whose electricity demand could be fully covered by the integrated PV and FC system. Due to its climate condition, Hamamatsu is the best city in the region for installing the proposed system. The correlation between the households’ number and self-sufficiency rate of the FC system per solar PV installation area can be expressed by the regression curve in the form of y = ax-b well.

基于水足迹理论的太湖流域水资源评价研究

为了解近10年太湖流域水资源开发利用状况,以太湖流域工农业生产、人口、农产品、动物产品等为研究数据,计算太湖流域水足迹及各项指标,对太湖流域水资源可持续利用状况作出分析与评价。结果表明:太湖流域近10年平均水足迹为511.6×10^(8)m^(3),低于全国平均水平,水资源自给率为63.9%,人均水足迹为889.7 m^(3),且逐年呈下降趋势,水资源匮乏度及水资源压力分别高达228.0%、273.9%,整个水资源系统处于严重超载状态。水足迹强度为100.1 m^(3)/万元,且呈逐渐下降趋势,表明太湖流域水资源的利用效率在逐年提高。为促进太湖流域水资源可持续利用,应采取以流域生态修复和水资源优化配置为基础的区域水生态安全保障策略,逐步提高水资源有效利用率。

自压滴灌技术在农田灌溉中的应用研究

该文以自压滴灌技术作为切入点,总结自压滴灌技术原理、系统组成结构与应用作用,用于论证自压滴灌技术应用可行性。结合自压滴灌技术实际应用情况,分析当前面临的技术难题,从管网布置、系统参数选择、设备选型、安全防护和建立灌溉制度几个方面阐述自压滴灌技术的应用策略。旨在有效提高农田灌溉的效率和水资源的综合利用率。

基于粮食需求的东北三省水资源自给率地域分异研究

东北三省是我国重要的商品粮生产基地,运用虚拟水理论探讨其粮食生产与消费,可为东北三省粮食生产可持续发展、粮食贸易及居民膳食结构调整提供依据。在对东北三省1998—2013年主要粮食作物生产和消费的虚拟水量核算的基础上,分析水资源自给率、虚拟水盈亏量及其地域分异特征。结果表明,从东北三省整体上看,1998—2013年玉米、水稻、大豆生产的虚拟水量均高于消费的虚拟水量,在保证居民消费的基础上可输出;而小麦生产的虚拟水量则低于消费的虚拟水量,需要大量输入以满足居民需求。从省域角度来看,黑龙江省四种主要粮食作物生产的年均虚拟水量均高于其他两省;而从地级市的空间分异来看,粮食作物虚拟水盈余量呈"中北部高、南部低"的空间分布格局。

重庆都市区食物虚拟水核算与评价

基于虚拟水理论,核算了2001—2010年重庆都市区食物生产与消费的虚拟水,选取食物虚拟水自给率、食物虚拟水进口依赖度和食物虚拟水压力指数3个指标对其评价。结果显示:①食物虚拟水生产量逐年下降,由2001年的20.05亿m3下降到2010年的17.26亿m3;食物虚拟水消费量由2001年的35.43亿m3增长到2010年的43.54亿m3;食物虚拟水净进口量在2001—2004年之间呈下降趋势,2005年后逐年上升,由2005年的16.39亿m3增长到26.29亿m3。②重庆都市区食物虚拟水进口依赖度较高,食物虚拟水自给率逐年下降,食物虚拟水压力指数大于100%。③在保证足够的生产能力条件下,从区外进口食物虚拟水是社会经济可持续发展的保障。

大食物观:结构变化、政策涵义与实践逻辑

当前我国已经进入从中等收入迈向高收入、向全面建设社会主义现代化国家进军的新阶段。本文在分析辨识我国食物消费结构特征以及变化趋势的基础上,阐释在新发展阶段树立大食物观的现实意义与政策涵义,并初步评估我国食物安全保障现状与今后的挑战,为新发展阶段践行大食物观提出实践逻辑与政策取向。本文认为,大食物观的政策涵义在于要促进粮食安全向食物安全的深化和拓展,其实践逻辑是必须树立大资源观、大农业观和大市场观,以粮食安全、生态安全和食品安全为核心基础,应对今后我国食物自给率持续下降的挑战,确保国家食物安全,必须深入践行大食物观,抓紧建立完善我国食物安全综合保障机制。

农业综合生产能力安全与我国农业资源安全阈值测算

本文系统界定了农业综合生产能力、农业综合生产能力安全和资源安全阈值等基本概念,以耕地和水资源为重点,分别构建和应用了基于农业综合生产能力安全的资源阈值模型与资源保障评测标准。测算结果表明,2020年全国粮食安全需求量为5.14～5.42亿t,耕地和灌溉水资源阈值分别为12363.3万hm2和3417亿m3,分别存在约5%和7%的供需缺口;2030年,全国粮食安全需求量为5.51～5.82亿t,耕地和灌溉水资源阈值分别为12796.2万hm2和3242亿m3,分别存在约10%和3%的供需缺口。未来我国农业资源供给压力呈扩大趋势,应以水、土资源阈值为底线,加快制定国家农业基本资源安全战略。

新加坡再生水厂能耗目标及其技术发展方向

新加坡土地紧缺、资源匮乏,而其所创造出的经济奇迹令世界刮目相看。这其中,新加坡对水的重视是保证其经济可持续发展的坚实基础。每年一度的新加坡国际水周(SIWW)和著名的李光耀"水源大奖"吸引着全球水资源、水处理专家、学者共赴盛会。这就为新加坡再生水发展计划提供了得天独厚的技术咨询与支持条件,使他们(新加坡公用事业局,PUB)审时度势地制定出能源自给自足三阶段发展目标,并根据自身环境特点和地理优势筛选出适宜技术。至2030年,新加坡将通过改造、关闭、新建再生水厂,与国际同步,以渐进方式最终逼近碳中和运行目标。介绍了新加坡再生水厂的发展思路、技术路线、预期目标,以期对我国未来污水处理技术发展方向带来一定的思想启迪。

南水北调前后北京市某区自备井水硝酸盐等卫生指标变化分析

目的:掌握北京市某区南水北调通水前后农村地区自备井水中硝酸盐等主要指标含量及合格率的变化。方法:在某区农村地区5个乡镇设置29个自备井监测点,于2014年-2015年每年枯丰水期对出厂水和末梢水进行监测,监测指标为硝酸盐、氨氮、总硬度、溶解性总固体、耗氧量、pH值、硫酸盐、氯化物、氟化物。以2014年饮水监测结果作为南水北调前自备井水水质的基础数值,将南水北调后自备井水监测结果(2015年)与南水北调通水前(2014年)监测结果进行比较,分析南水北调通水对农村自备井水硝酸盐等指标含量及变化原因。结果:自备井水硝酸盐含量由2014年的39.2 mg/L降低至2015年的35.9 mg/L,同时总硬度含量由621 mg/L降低至581 mg/L,pH由2014年的7.17升高至2015年的7.36,差异均具有统计学意义(P<0.05),其他指标含量无明显变化。硝酸盐合格率由2014年的19.7%上升至2015年的33.6%(P<0.05),其他指标合格率无明显变化。结论:2015年某区自备井水硝酸盐、总硬度含量下降,地下水水质呈优化现象,与南水北调有一定关联性,长期水质变化及健康影响需继续研究。