A review of the potential benefits and risks of photovoltaic hybrid mini-grid systems

Photovoltaic hybrid mini-grid systems (PVHMS) are expected to play a major role in facilitating rural electrification in the developing world, however these systems still face significant barriers to adoption. The technology occupies a middle ground of electrification options – between traditional network extension and individual home systems, possessing elements of each yet also their own distinctive characteristics. Given this, and their relatively limited application to date, such systems are the focus of a growing body of literature. This work has highlighted a range of potential benefits and risks associated with the technology. However, there still hasn't been a comprehensive review of these documented benefits and risks; an understanding of which is crucial for informed project investment and implementation decision making. This paper presents a preliminary review of the existing literature to identify claimed and demonstrated benefits and risks. The most commonly identified benefits are those that are easy to measure: reduced cost and provision of improved electrical services. Other benefits such as the social or environmental benefits are less commonly demonstrated, but are frequently claimed. The major risks identified included incorrect system sizing due to load uncertainty, challenges related to community integration, equipment compatibility issues, inappropriate business models and risks associated with geographical isolation. For all of these types of risks, associated mitigation strategies were also identified in the literature. Further research including industry surveys and additional case studies will be required to validate what has been observed in the literature to date, and identify progress as the technology matures, costs fall and stakeholders learn from these previous experiences.     

The Brazilian experience of rural electrification in the Amazon with decentralized generation - The need to change the paradigm from electrification to development

There are at least 607 thousand households in the Brazilian Amazon that need to be attended with some form of regular electricity service. These households are not attended by the electricity sector through its electricity distribution companies and most of them have some form of precarious decentralized electricity generation that is not registered or regulated in the institutional framework. Diverse initiatives were taken by Brazilian government to attend these household through alternatives that relied on locally available renewable energy. This paper accesses this initiatives of rural electrification in the Brazilian Amazon. First an overview of the problems of rural electricity are discussed and its specificities in the Brazilian Amazon. Then the Brazilian institutional framework that organizes the decentralized electricity generation is described with its various limitations. The diverse initiatives undertaken to attend the rural communities in the Amazon since the 1990s are described, as well as how these initiatives are linked to the policies for rural electrification. The results shows that it can be inferred that sole market mechanisms are not sufficient to guarantee economic sustainability of these projects. This can be one of the reasons why traditional electricity distribution companies showed the lack of interest in promoting rural electrification with other means than grid extension. The most successful projects had financed efforts to integrate the generation of electricity into local development initiatives in order to guarantee sustainability and used substantial part of funding for local mobilization and organization. It needs a paradigm chance by treating these initiatives as local development initiatives and promoting alternative ways for its implementation through partnership between local new actors in the electricity sector and government and implementing policy on a local municipal level.     

基于电子商务的县域就地城镇化与农村发展新模式研究

文章从电子商务的内涵和县域电子商务的发展概况谈起,分析了电子商务对我国城镇化格局的影响,探讨了在互联网时代电子商务普及的影响下,人才和经济体在各级城市中获得的机会将更加平等化,我国大城市的中心性地位受到挑战,县域及其所管辖的农村地区迎来了前所未有的机遇,农村地区可以实现由工业化带动到信息化带动的跃迁式发展的城镇化新形势。文章进一步指出在这种新形势下,电子商务所驱动的县域就地城镇化和农村发展是当前新型城镇化的一种新思路,并深入分析了县域就地城镇化的内涵和路径以及基于电子商务的农村发展的三种新模式,分别是延伸式("赶街"模式)、介入式("聚土地"模式)和内生式("沙集"模式),为我国信息化时代背景下的新型城镇化发展提供了一定的参考。     

Enabling off-the-grid telephony: An adaptive probabilistic model for broadcasting in ad-hoc mobile phone networks

Ad-hoc peer-to-peer mobile phone networks (phone-MANETs) can enable village level telephony for cash-strapped, off-the-grid communities in developing regions. Broadcasting is a fundamental operation in such MANETs (Mobile Ad-hoc Networks) and is used for route discovery. Cost and power consumption optimizations are critical for such systems. Hence, lightweight broadcast techniques which can operate on basic devices and incur low overheads are more pragmatic than their more complex counterparts. This paper proposes a new broadcast technique for rural phone-MANETS that is lightweight, efficient and incurs low latency. Using extensive simulations, the proposed technique is compared to existing lightweight broadcast protocols. The results show that the new technique is successful in outperforming existing lightweight techniques on multiple criteria that are important for a phone-MANET.     

论接续型乡村规划及实践要点

我国曾长期是一个农业社会，农 村是整个社会的主体，尽管现在仍处在向 城市时代过渡的高峰期，但乡村规划及其建 设依然具有重要意义。综合各种情况，接续 型乡村规划应成为当代中国乡村规划的主流 模式。这种兼顾继承与创新的规划，具有 延续文脉、有机更新、成本低廉等优势。在 运用该种规划模式时，要尊重乡村的内在空 间肌理及历史沿革，突出与彰显人文特征， 使用与乡村规模相适宜的小尺度，关注乡村 社会经济的当代转型等。     

建筑学介入下的乡村营造及相关思考 ——当代建筑师乡村实践中的启示

城市化的单向进程导致了乡村的边 缘化，而建筑学正在积极介入乡村营造改变 这一现实。为让建筑学更好地应用于乡村营造 工作，通过分析建筑学介入乡村营造带来的 积极影响以及所面临的问题，肯定了建筑师主 导模式对于乡村营造的借鉴价值，从建筑师 在乡村的实践案例中总结出价值观、地域表 达和建筑师3个方面的乡村营造新思路。     

居民参与利益分配的自然资源型旅游小城镇规划设计初探

本文分析了旅游小城镇总体规划中居民利益缺失的源头,并以重庆市南川区黎香湖镇总体规划为例,提出了从当地居民利益出发、促进当地居民参与利益分配的具体规划措施,如合理的城乡空间开发模式和城镇建设模式、复合的旅游产业规划设计、具有当地特色的农业发展策略,等等。     

建筑标准知识库系统设计与实玛

本文通过对目前村镇住宅设计需求的深入调研分析,设计实现了村镇住宅建筑标准设计知识库系统,迅速提高村镇住宅设计水平。针对农村设计队伍现状,建立村镇住宅模块化设计集成应用平台,通过互联网为村镇住宅设计人员提供及时、快捷技术服务。     

S7-200PLC无功补偿装置在小型变电站中的应用

根据目前农网改造工程中农村小型变电所电容器无功补偿存在的问题,以一所小型变电站为例,根据它的运行方式和控制方式,设置了电容器的投切判据,并依此设计了一款基于S7 - 200PLC的可靠性高、功能灵活的无功补偿控制装置.把它应用于小型变电站无功补偿方案中,对提高农村电网的供电能力、保证电压质量、降低农网损耗有重要作用.     

Optimization and life-cycle cost of health clinic PV system for a rural area in southern Iraq using HOMER software

This paper addresses the need for electricity of rural areas in southern Iraq and proposes a photovoltaic (PV) solar system to power a health clinic in that region. The total daily health clinic load is 31.6 kW h and detailed loads are listed. The National Renewable Energy Laboratory (NREL) optimization computer model for distributed power, “HOMER,” is used to estimate the system size and its life-cycle cost. The analysis shows that the optimal system’s initial cost, net present cost, and electricity cost is US$ 50,700, US$ 60,375, and US$ 0.238/kW h, respectively. These values for the PV system are compared with those of a generator alone used to supply the load. We found that the initial cost, net present cost of the generator system, and electricity cost are US$ 4500, US$ 352,303, and US$ 1.332/kW h, respectively. We conclude that using the PV system is justified on humanitarian, technical, and economic grounds.