This paper presents a low power boost converter for thermoelectric energy harvesting that demonstrates an efficiency that is 15% higher than the state-of-the-art for voltage conversion ratios above 20. This is achieved by utilizing a technique allowing synchronous rectification in the discontinuous conduction mode. A low-power method for input voltage monitoring is presented. The low input voltage requirements allow operation from a thermoelectric generator powered by body heat. The converter, fabricated in a 0.13 μm CMOS process, operates from input voltages ranging from 20 mV to 250 mV while supplying a regulated 1 V output. The converter consumes 1.6 (1.1) μW of quiescent power, delivers up to 25 (175) μW of output power, and is 46 (75)% efficient for a 20 mV and 100 mV input, respectively.

A 20 mV Input Boost Converter With Efficient Digital Control for Thermoelectric Energy Harvesting

The microbial fuel cell (MFC) technology offers sustainable solutions for distributed power systems and energy positive wastewater treatment, but the generation of practically usable power from MFCs remains a major challenge for system scale up and application. Commonly used external resistors will not harvest any usable energy, so energy-harvesting circuits are needed for real world applications. This review summarizes, explains, and discusses the different energy harvesting methods, components, and systems that can extract and condition the MFC energy for direct utilization. This study aims to assist environmental scientists and engineers to gain fundamental understandings of these electronic systems and algorithms, and it also offers research directions and insights on how to overcome the barriers, so the technology can be further advanced and applied in larger scale.

Practical Energy Harvesting for Microbial Fuel Cells: A Review

Energy-nutrients-water nexus: integrated resource recovery in municipal wastewater treatment plants.

Microbial electrochemical technologies have gained much attention in the recent years during which basic research has been carried out to provide proof of concept by utilizing microorganisms for generating bioenergy in an electro redox active environment. However, these bio-electrocatalyzed systems pose significant challenges towards up-scaling and practical applications. Various parameters viz., electrodes, materials, configuration, biocatalyst, reaction kinetics, fabrication and operational costs, resistance for electron transfer etc. will critically govern the performance of microbial catalyzed electrochemical systems. Majorly, the surface area of electrode materials, biofilm coverage on the electrode surface, enrichment of electrochemically active electrode respiring bacteria and reduction reactions at cathode will aid in increasing the reaction kinetics towards the upscaling of microbial electrochemical technologies. Enrichment of electroactive microbial community on anode electrode can be promoted with electrode pretreatment, controlled anode potential or electrical current, external resistance, optimal operation temperature, chemical additions and bioaugmentation . Inhibition of the growth of methanogens also increases the columbic efficiency, an essential parameter that determines the efficacy of bioelectricity generation. Considering the practical implementation of these microbial electrochemical technologies, the current review addresses the challenges and strategies to improve the performance of bio-electrocatalyzed systems with respect to the operational, physico-chemical and biological factors towards scale up. Besides, the feasibility for long term operation, the scope for future research along with the operational and maintenance costs are discussed to provide a broad spectrum on the role of the system components for the implementation of these bio-electrochemical technologies for practical utility.

Microbial electrochemical technologies with the perspective of harnessing bioenergy: Maneuvering towards upscaling

This communication reports for the first time the charging of a commercially available mobile phone, using Microbial Fuel Cells (MFCs) fed with real neat urine. The membrane-less MFCs were made out of ceramic material and employed plain carbon based electrodes.

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Waste to real energy: the first MFC powered mobile phone

Electrical energy generation from a large number of microbial fuel cells operating at maximum power point electrical load

In this paper, an autonomous low voltage and ultra-low power DC-DC converter is presented. This novel topology is inspired from the classical Armstrong oscillator structure. In addition to be self-powered and autonomous, this converter is suitable for high-impedance sources. Theoretical and simulation-based optimizations are used in order to design the converter. A fabricated prototype is tested. It harvests RF energy from a low power rectenna (rectifying antenna). High output voltage and good performances are achieved in the range of 4μW to 1mW of input power.

/pdf/self-powered-ultra-low-power-dc-dc-converter-for-rf-energy-4bq2yqq500.pdf

Self-powered ultra-low power DC-DC converter for RF energy harvesting

This paper describes and evaluates an original boost converter able to harvest energy from low-power and low-voltage power sources. Design and sizing are made according to specifications issued from the stringent characteristics of microbial electric generators such as microbial fuel cells and microbial desalination cells. The harvested power is 10mW under input voltage Vin=0.3V (33mA input current). The design of the converter is adapted from a classical boost topology. It includes a self-oscillating circuit for autonomous operation, and a simple analog maximum power point regulation. Measurements of the conceived discrete realization enable evaluation of the circuit. Best global efficiency of 74% is achieved under realistic harvesting conditions.

/pdf/self-starting-dc-dc-boost-converter-for-low-power-and-low-2tntstgz7y.pdf

Self-starting DC:DC boost converter for low-power and low-voltage microbial electric generators

In this paper, an ultra-low voltage and power DC/DC converter is presented. This converter harvests energy from a Microbial Fuel Cell (MFC) in order to feed another circuit such as an autonomous wireless sensor. The MFC behaves as a voltage generator of 475mV open-circuit voltage with a 600Ω serial internal impedance. The maximum delivered power is therefore around 100μW. The DC/DC converter provides output voltage in the range 2–7.5V and performs impedance matching with source. The converter achieves when associated with the MFC, 60% peak efficiency. Furthermore, this DC/DC converter is self-operating without the need for external power source of start-up assistance.

/pdf/autonomous-ultra-low-power-dc-dc-converter-for-microbial-88mjoxsteo.pdf

Autonomous ultra-low power DC/DC converter for Microbial Fuel Cells

The embedding of components in Printed Circuit Board (PCB) material is an attractive solution to improve the performance of power converters in the 1 W–100 kW range by increasing the power density (exploitation of unused volume in the PCB), reducing circuit parasitics (strip-line approach to current distribution, shorter interconnects), and improving manufacturability (rationalization of the manufacturing process, automation). This paper presents a review of the embedding technologies, with a special focus on power components (passive, active) and thermal mangement. The second part of the article is dedicated to the design process, and proposes a new design approach, inspired from microelectronics. The ambition is to simplify the design process by using "design toolkits". These toolkits would provide the designer with elements such as design rules, libraries or models. The objective is to enable automatic design validation, and to ensure the design can be produced directly.

/pdf/application-of-the-pcb-embedding-technology-in-power-2dr5kyw37q.pdf

Nicolas Degrenne

Papers

Electrical energy generation from a large number of microbial fuel cells operating at maximum power point electrical load

Self-powered ultra-low power DC-DC converter for RF energy harvesting

Self-starting DC:DC boost converter for low-power and low-voltage microbial electric generators

Autonomous ultra-low power DC/DC converter for Microbial Fuel Cells

Application of the PCB-Embedding Technology in Power Electronics – State of the Art and Proposed Development