On the Feasibility of Indoor Light Energy Harvesting for Wireless Sensor Networks

AbstractThis paper presents the important issues about the design of a low cost, micro power, indoor light energy harvesting system to supply a node of a wireless sensor network (WSN). Possible technology options, available for the photovoltaic (PV) cells, are discussed. Light power and irradiance measurements, in a real indoor environment, are performed and results are presented. From these results, a possible solution for cell sizing is described

On the Feasibility of GPON Fiber Light Energy Harvesting for the Internet of Things

The emerging concept of smart cities demands for a large number of electronic devices, like sensors and actuators, distributed over several public spaces and buildings. The Internet of Things (IoT) has a key role in connecting devices to the Internet. However, the significant number of devices makes the maintenance task of the entire network difficult and expensive. To mitigate this problem, considerable research efforts have been made to develop energy-aware devices capable of self-sustainable operation, by harvesting their energy from various sources. In this paper, we study the possibility of harvesting energy from the light flowing in the Gigabit Passive Optics Network (GPON) to supply low-power devices. Since most cities already have a working GPON installation, using this installation to interconnect and power IoT devices can be a viable and less expensive solution, instead of installing new dedicated networks. This is also an interesting solution to convey communications and energy to low-power applications where access to the power grid is unfeasible. This study is focused in the 1550 nm wavelength, whose available optical power, in residential premises, is between -7 dBm and +2 dBm. With this range of optical power, and with a 30% efficiency photodiode, we show, for the worst-case scenario of the GPON, how it is possible to harvest 62 µW of energy at the Maximum Power Point (MPP)

Key distribution and distributed intrusion detection system in wireless sensor network

This thesis proposes a security solution in key management and Intrusion Detection System (IDS) for wireless sensor networks. It addresses challenges of designing in energy and security requirement. Since wireless communication consumes the most energy in sensor network, transmissions must be used efficiently. We propose Hint Key Distribution (HKD) for key management and Adaptive IDS for distributing activated IDS nodes and cooperative operation of these two protocols. HKD protocol focuses on the challenges of energy, computation and security. It uses a hint message and key chain to consume less energy while self-generating key can secure the secret key. It is a proposed solution to key distribution in sensor networks. Adaptive IDS uses threshold and voting algorithm to distribute IDS through the network. An elected node is activated IDS to monitor its network and neighbors. A threshold is used as a solution to reduce number of repeated activations of the same node. We attempt to distribute the energy use equally across the network. In a cooperative protocol, HKD and Adaptive IDS exchange information in order to adjust to the current situation. The level of alert controls the nature of the interaction between the two protocols

CMOS indoor light energy harvesting system for wireless sensing applications

Dissertação para obtenção do Grau de Doutor em Engenharia Electrotécnica e de ComputadoresThis research thesis presents a micro-power light energy harvesting system for indoor environments. Light energy is collected by amorphous silicon photovoltaic (a-Si:H PV) cells, processed by a switched-capacitor (SC) voltage doubler circuit with maximum power point tracking (MPPT), and finally stored in a large capacitor. The MPPT Fractional Open Circuit Voltage (VOC) technique is implemented by an asynchronous state machine (ASM) that creates and, dynamically, adjusts the clock frequency of the step-up SC circuit, matching the input impedance of the SC circuit to the maximum power point (MPP) condition of the PV cells. The ASM has a separate local power supply to make it robust against load variations. In order to reduce the area occupied by the SC circuit, while maintaining an acceptable efficiency value, the SC circuit uses MOSFET capacitors with a charge reusing scheme for the bottom plate parasitic capacitors. The circuit occupies an area of 0.31 mm2 in a 130 nm CMOS technology. The system was designed in order to work under realistic indoor light intensities. Experimental results show that the proposed system, using PV cells with an area of 14 cm2, is capable of starting-up from a 0 V condition, with an irradiance of only 0.32 W/m2. After starting-up, the system requires an irradiance of only 0.18 W/m2 (18 mW/cm2) to remain in operation. The ASM circuit can operate correctly using a local power supply voltage of 453 mV, dissipating only 0.085 mW. These values are, to the best of the authors’ knowledge, the lowest reported in the literature. The maximum efficiency of the SC converter is 70.3% for an input power of 48 mW, which is comparable with reported values from circuits operating at similar power levels.Portuguese Foundation for Science and Technology (FCT/MCTES), under project PEst-OE/EEI/UI0066/2011, and to the CTS multiannual funding, through the PIDDAC Program funds. I am also very grateful for the grant SFRH/PROTEC/67683/2010, financially supported by the IPL – Instituto Politécnico de Lisboa

Urubu: energy scavenging in wireless sensor networks

For the past years wireless sensor networks (WSNs) have been coined as one of the most promising technologies for supporting a wide range of applications. However, outside the research community, few are the people who know what they are and what they can offer. Even fewer are the ones that have seen these networks used in real world applications. The main obstacle for the proliferation of these networks is energy, or the lack of it. Even though renewable energy sources are always present in the networks environment, designing devices that can efficiently scavenge that energy in order to sustain the operation of these networks is still an open challenge. Energy scavenging, along with energy efficiency and energy conservation, are the current available means to sustain the operation of these networks, and can all be framed within the broader concept of “Energetic Sustainability”. A comprehensive study of the several issues related to the energetic sustainability of WSNs is presented in this thesis, with a special focus in today’s applicable energy harvesting techniques and devices, and in the energy consumption of commercially available WSN hardware platforms. This work allows the understanding of the different energy concepts involving WSNs and the evaluation of the presented energy harvesting techniques for sustaining wireless sensor nodes. This survey is supported by a novel experimental analysis of the energy consumption of the most widespread commercially available WSN hardware platforms.Há já alguns anos que as redes de sensores sem fios (do Inglês Wireless Sensor Networks - WSNs) têm sido apontadas como uma das mais promissoras tecnologias de suporte a uma vasta gama de aplicações. No entanto, fora da comunidade científica, poucas são as pessoas que sabem o que elas são e o que têm para oferecer. Ainda menos são aquelas que já viram a sua utilização em aplicações do dia-a-dia. O principal obstáculo para a proliferação destas redes é a energia, ou a falta dela. Apesar da existência de fontes de energia renováveis no local de operação destas redes, continua a ser um desafio construir dispositivos capazes de aproveitar eficientemente essa energia para suportar a operação permanente das mesmas. A colheita de energia juntamente com a eficiência energética e a conservação de energia, são os meios disponíveis actualmente que permitem a operação permanente destas redes e podem ser todos englobados no conceito mais amplo de “Sustentabilidade Energética”. Esta tese apresenta um estudo extensivo das várias questões relacionadas com a sustentabilidade energética das redes de sensores sem fios, com especial foco nas tecnologias e dispositivos explorados actualmente na colheita de energia e no consumo energético de algumas plataformas comercias de redes de sensores sem fios. Este trabalho permite compreender os diferentes conceitos energéticos relacionados com as redes de sensores sem fios e avaliar a capacidade das tecnologias apresentadas em suportar a operação permanente das redes sem fios. Este estudo é suportado por uma inovadora análise experimental do consumo energético de algumas das mais difundidas plataformas comerciais de redes de sensores sem fios

Modelado y optimización de energía en redes de sensores inalámbricas para la medida de parámetros medioambientales

Las redes de sensores inalámbricos forman un reciente campo de investigación. Están formadas por una serie de nodos que realizan una determinada tarea. Los nodos suelen ser pequeños dispositivos electrónicos, autónomos, alimentados por baterías y con capacidad para comunicarse entre ellos inalámbricamente. Las características del tamaño y la alimentación con batería hacen que el consumo de energía sea un factor clave en su diseño. A partir de la necesidad de optimizar el consumo de energía aparecen nuevos tópicos de investigación como la recolección de energía y la optimización del consumo. Esta tesis se enmarca dentro de estos campos, tratando de estudiar, proponer soluciones e implementarlas. En la primera parte se estudiará el comportamiento y arquitecturas de los dispositivos y sistemas operativos más utilizados en el ámbito de las redes de sensores. El análisis se enfocará en los sistemas operativos TinyOS, MantisOS y Contiki y en los dispositivos Tmote Sky y MICAz. En la siguiente parte se estudiará el estado del arte de los modelos teóricos sobre el consumo de energía en redes de sensores desde diferentes perspectivas: el transceiver, un nodo completo, toda una red, etc. Después se propondrá una metodología para obtener modelos para mejorar el conocimiento sobre estado de carga de un nodo sensor, teniendo en cuenta factores tales como la temperatura o el desgaste de las baterías. Aplicando este método se propondrán varios modelos basados en regresiones lineales y redes neuronales que puedan ser ejecutados por un nodo final. Los resultados se validarán con medidas experimentales y comparativas con otros dispositivos hardware. Se propondrá una arquitectura de fuente de alimentación basada en recolección de energía solar. Además esta fuente permitirá reducir el desgaste de las baterías recargables mediante el empleo de supercondensadores. Para ello la fuente de alimentación cuenta con un sistema que automáticamente conmuta entre ambas fuentes y prioriza la del supercondensador respecto a la de la batería. El diseño permitirá operar a un nodo típico exclusivamente desde un supercondensador durante varios días, entrando la batería en funcionamiento únicamente cuando las condiciones climatológicas impiden obtener la suficiente energía del sol. Después se estudiará la posibilidad de utilizar otra fuente de recolección de energía: la energía proveniente de ondas de radio comerciales. Para ello se estudiarán diversos circuitos y se compararán sus resultados. Este método de obtención de energía, si bien proporciona poca corriente, puede ser suficiente para un nodo con un consumo extraordinariamente reducido, o como apoyo a otra fuente de energía, sobre todo teniendo en cuenta que su disponibilidad no depende de condiciones climatológicas. En la última parte de la tesis se realizarán varias aplicaciones. En primer lugar se implementará un nodo inalámbrico para controlar sistemas de regadíos mediante electroválvulas. El nodo tendrá un sistema de alimentación y disparo de las electroválvula combinando condensadores y supercondensadores. Además se implementará un protocolo de acceso al medio que mantiene el sincronismo entre nodos adyacentes mediante un sistema hardware que permite reducir el consumo del nodo sin perder la temporización. La segunda aplicación será un sistema medidor de parámetros medioambientales que utilizará la fuente de alimentación diseñada anteriormente. Además el consumo de este nodo se aproxima a la energía que podría proporcionar un sistema de recolección mediante ondas de radio. Se podrá acceder a los parámetros medioambientales recogidos a través de internet.Lajara Vizcaíno, JR. (2014). Modelado y optimización de energía en redes de sensores inalámbricas para la medida de parámetros medioambientales [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39371TESI

Renewable Energy

Renewable Energy is energy generated from natural resources - such as sunlight, wind, rain, tides and geothermal heat - which are naturally replenished. In 2008, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood burning. Hydroelectricity was the next largest renewable source, providing 3% (15% of global electricity generation), followed by solar hot water/heating, which contributed with 1.3%. Modern technologies, such as geothermal energy, wind power, solar power, and ocean energy together provided some 0.8% of final energy consumption. The book provides a forum for dissemination and exchange of up - to - date scientific information on theoretical, generic and applied areas of knowledge. The topics deal with new devices and circuits for energy systems, photovoltaic and solar thermal, wind energy systems, tidal and wave energy, fuel cell systems, bio energy and geo-energy, sustainable energy resources and systems, energy storage systems, energy market management and economics, off-grid isolated energy systems, energy in transportation systems, energy resources for portable electronics, intelligent energy power transmission, distribution and inter - connectors, energy efficient utilization, environmental issues, energy harvesting, nanotechnology in energy, policy issues on renewable energy, building design, power electronics in energy conversion, new materials for energy resources, and RF and magnetic field energy devices