Microbial fuel cells: From fundamentals to applications. A review

The Photovoltaic (PV) monitoring system collects and analyzes number of parameters being measured in a PV plant to monitor and/or evaluate its performance. In order to ensure the reliable and stable operation of any PV system, an effective monitoring system is essential. Moreover, the monitoring system keeps track on various electricity generation indices and fault occurrences. The cost and complexity of existing PV monitoring systems restricts their use to large scale PV plants. Over the past decade, different aspects of PV monitoring systems were reported in wide range of literature. In this paper, a comprehensive review of various PV monitoring systems is presented for the first time. This includes the detailed overview of all the major PV monitoring evaluation techniques in terms of their relative performances. Major aspects of PV monitoring systems which examines in this paper are: sensors and their working principles, controller used in data acquisition systems, data transmission methods, and data storage and analysis. The acquaintance of all these aspects are crucial for the development of effective, low cost, and viable PV monitoring systems for small and medium scale PV plants without compromising on the desired performance.

Monitoring system for photovoltaic plants: A review

An early warning system is important to guarantee human health and ecological safety. Microbial fuel cell (MFC) sensor can achieve a self-sustainable monitoring without additional transducer or power sources. It would not limited by the main bottleneck of other contemporary MFC technologies, i.e., the low current density output, and is believed one of the most promising applications in the niche market of MFC technologies. This review is limited to MFC sensors for water quality early warning systems only, with emphasis on biochemical oxygen demand (BOD) and toxicity sensors. A comprehensive summary and discussion on sensor fabrication, operation, data representation, and optimization are provided. The MFC sensor is particularly promising to serve as a self-powered sensing device for in-situ and on-line environmental monitoring, as proved both in laboratory and field test. In addition, the main hurdles and future perspectives are discussed, as well as potential future research, which includes the following: separately lowering the detection limit or improving the concentration range dependent on the application of MFC for organic matter monitoring; further improving the sensitivity as well as lowering the recovery time of biofilm after a certain shock; developing the kinetic and/or empirical model in combining with the detection algorithm to distinguish the signal interference of complex aquatic environment, especially when the shock of BOD and toxicity occur simultaneously.

Microbial fuel cell sensors for water quality early warning systems: Fundamentals, signal resolution, optimization and future challenges

This paper reports on the pee power urinal field trials, which are using microbial fuel cells for internal lighting. The first trial was conducted on Frenchay Campus (UWE, Bristol) from February–May 2015 and demonstrated the feasibility of modular MFCs for lighting, with University staff and students as the users; the next phase of this trial is ongoing. The second trial was carried out during the Glastonbury Music Festival at Worthy Farm, Pilton in June 2015, and demonstrated the capability of the MFCs to reliably generate power for internal lighting, from a large festival audience (∼1000 users per day). The power output recorded for individual MFCs is 1–2 mW, and the power output of one 36-MFC-module, was commensurate of this level of power. Similarly, the real-time electrical output of both the pee power urinals was proportional to the number of MFCs used, subject to temperature and flow rate: the campus urinal consisted of 288 MFCs, generating 75 mW (mean), 160 mW (max) with 400 mW when the lights were connected directly (no supercapacitors); the Glastonbury urinal consisted of 432 MFCs, generating 300 mW (mean), 400 mW (max) with 800 mW when the lights were connected directly (no supercapacitors). The COD removal was >95% for the campus urinal and on average 30% for the Glastonbury urinal. The variance in both power and urine treatment was due to environmental conditions such as temperature and number of users. This is the first time that urinal field trials have demonstrated the feasibility of MFCs for both electricity generation and direct urine treatment. In the context of sanitation and public health, an independent power source utilising waste is essential in terms of both developing and developed world.

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Pee power urinal – microbial fuel cell technology field trials in the context of sanitation

Ion transport in microbial fuel cells: Key roles, theory and critical review

Energy balance and microbial fuel cells experimentation at wastewater treatment plant Milano-Nosedo

In this paper we present the project and a first concept circuit of a wireless sensor station designed to collect and send information about the environment conditions of a photovoltaic (PV) power plant, in order to monitor on-site specific phenomena of interest. The system is battery-free and uses a 4 mm2 PV harvester chip as electronic supply. It is equipped with temperature, irradiance and humidity sensors and with a MicroController Unit (MCU) for data treatment and wireless management. The light irradiance sensor discriminates the contribute of direct and diffusive light, accounting for air mass index effects. The PV harvester is integrated using a 0.35 μm BCD SOI technology while sensors, the MCU and a 802.15.4 transmitting module are placed in a external Printed Circuit Board (PCB). The goal of this project is to realize a 1 cm2 autonomous fully-integrated device representing the single low-cost node of a Wireless Sensor Network (WSN) to be installed in each PV module of a solar power plant.

A wireless irradiance-temperature-humidity sensor for photovoltaic plant monitoring applications

In this work we describe a system optimized to use the few microwatts generated by a 4 mm2 photovoltaic energy harvester to acquire, process and wirelessly transmit information about the environment temperature and light irradiance. The energy needed for the described power-expensive operations is obtained by charging a buffer capacitor while the system is in a low-power-consumption state. A voltage level detector senses the charging status of the capacitor and wakes-up the sensing station every time enough energy is stored. Thus, the environmental parameters are monitorized and transmitted with an asynchronous and intermittent strategy. The optimization work related to this paper has persued the target of minimize the unerasable continuous power consumption of the voltage detector during the charging of the capacitor. We reached the goal of reducing it from the 50 μW of the previous version of the system to the current 5 μW, with a significant usability improvement. Simulations and experimental evidences demonstrate that our station can work totally battery-free when just illuminated with 100 W/m2 of light irradiance, transmitting data with a 802.15.4 compliant protocol and potentially occupies a volume of 1 cm3.

An improved ultra-low-power wireless sensor-station supplied by a photovoltaic harvester

In this paper we present a 4-mm2 battery-less temperature sensor, designed to collect and periodically transmit information to an ambient monitoring system. It consists of a 0.35-µm BCD SOI technology based chip including an ultra-low power integrated circuit and an energy harvesting supply unit made by 34 series-parallel connected photovoltaic cells. Each cell consists of a trench insulated p-n junction. Series connections among cells are possible because of the lack, guaranteed by the SOI insulation, of the substrate parasitic diode, typical in standard CMOS technology. The system is fully compliant with real-time applications and can work in low illumination conditions and with large variations of the photovoltaic voltage.

Integrated self-supplied system for environmental temperature sensing

In this paper, a voltage supervisor (VS) for low-voltage low-power energy harvesting systems (EHSs) is presented. The task of a VS is to change the logic state of its output when a conveniently scaled fraction of its supply voltage crosses a fixed threshold. The presented VS includes an ultra-low-voltage ultra-low-power reference, a voltage comparator, and an output latch. The circuit was specifically designed for energy scavenging applications that make use of a low-voltage source with a very limited current capability. Correct operation of the VS is ensured with a supply voltage as low as 300 mV. Current consumption is lower than 1 μA. An EHS was built to test the VS. The energy provided by the low-voltage harvester is first stored in a buffer capacitor, C IN ; then, when the voltage across C IN reaches a predetermined voltage level, the VS enables a step-up circuit, which transfers the charge from C IN to an output capacitor at a higher voltage. Experimental results from a prototype are provided and discussed.

A. Lazzarini Barnabei

Papers

Energy balance and microbial fuel cells experimentation at wastewater treatment plant Milano-Nosedo

A wireless irradiance-temperature-humidity sensor for photovoltaic plant monitoring applications

An improved ultra-low-power wireless sensor-station supplied by a photovoltaic harvester

Integrated self-supplied system for environmental temperature sensing

Ultra low voltage supervisor for energy scavenging systems