Harvest Waste Research Articles

Hot Spot Cooling and Harvesting Central Processing Unit Waste Heat Using Thermoelectric Modules

The increasing integration of high performance processors and dense circuits in current computing devices has produced high heat flux in localized areas (hot spots), which limits their performance and reliability. To control the hot spots on a central processing unit (CPU), many researchers have focused on active cooling methods such as thermoelectric coolers (TECs) to avoid thermal emergencies. This paper presents optimized thermoelectric modules on top of the CPU combined with a conventional air-cooling device to reduce the core temperature and at the same time harvest waste heat energy generated by the CPU. To control the temperature of the cores, we attach small-sized TECs to the CPU and use thermoelectric generators (TEGs) placed on the rest of the CPU to convert waste heat energy into electricity. This study investigates design alternatives with an analytical model considering the nonuniform temperature distribution based on two-node thermal networks. The results indicate that we are able to attain more energy from the TEGs than energy consumption for running the TECs. In other words, we can allow the harvested heat energy to be reused to power other components and reduce cores temperature simultaneously. Overall, the idea of simultaneous core cooling and waste heat harvesting using thermoelectric modules on a CPU is a promising method to control the problem of heat generation and to reduce energy consumption in a computing device.

Performance analysis of a thermally regenerative electrochemical cycle for harvesting waste heat

The performance of a (TREC) thermally regenerative electrochemical cycle for harvesting waste heat has been investigated based on finite time analysis. The impacts of cell material and heat exchangers on the maximum power extracted and its corresponding efficiency have been analyzed. Results reveal that materials with larger isothermal coefficients, specific charge/discharge capacities, and lower internal resistances correspond to larger maximum power that can be extracted from them. If both power and efficiency are considered, materials with larger isothermal coefficients, specific charge/discharge capacities, appropriate internal resistances, and lower specific heats are more appealing. A better heat exchanger performance increases maximum power output; however, it does not guarantee higher efficiency. This work is expected to contribute in choosing appropriate materials and heat exchangers to improve the performance of TREC devices.

Highly transparent triboelectric nanogenerator for harvesting water-related energy reinforced by antireflection coating.

Water-related energy is an inexhaustible and renewable energy resource in our environment, which has huge amount of energy and is not largely dictated by daytime and sunlight. The transparent characteristic plays a key role in practical applications for some devices designed for harvesting water-related energy. In this paper, a highly transparent triboelectric nanogenerator (T-TENG) was designed to harvest the electrostatic energy from flowing water. The instantaneous output power density of the T-TENG is 11.56 mW/m2. Moreover, with the PTFE film acting as an antireflection coating, the maximum transmittance of the fabricated T-TENG is 87.4%, which is larger than that of individual glass substrate. The T-TENG can be integrated with silicon-based solar cell, building glass and car glass, which demonstrates its potential applications for harvesting waste water energy in our living environment and on smart home system and smart car system.

Electrochemical Heat Engines

This brief thermodynamic analysis theoretically explores the potential of using a solid-state electrochemical heat engine (EHE) to continually harvest waste heat from available thermal energy from natural and man-made sources. These EHE systems are composed of a fuel cell hybrid (FCH) and an electrolyer hybrid (EH) which is composed of fuel cells and heat engines, and electrolysers and heat engines, respectively. These systems electrochemically utilize reversible working reactions (WR) in a manner to produce electrical energy from thermal energy. Ultimately, EHE’s in this paper exploit the change in basic thermodynamic properties with temperature. This development introduces the thermodynamic methodology for analyzing and combining EHE’s.

Sustainable entrepreneurship via energy saving: energy harvester exploiting seebeck effect in traditional domestic boiler

In this paper, energy saving solutions are being elaborated, i.e. A system to harvest waste heat and convert it into electrical energy is presented; such a system is based on thermoelectric generators (teg) modules exploiting the seebeck effect. A technical and economic feasibility study of the system is presented, the most convenient applications of thermal energy residuals recovery in residential environment (detached house, condos, isolated off-the grid house) are evaluated according to the electrical supply of typical domestic low consumption devices (i.e. Led lighting); the total yearly production of thermoelectric generator is considered in different techno-economic scenarios.

Pyroelectric Energy Scavenging Techniques for Self-Powered Nuclear Reactor Wireless Sensor Networks

Recent advances in technologies for harvesting waste thermal energy from ambient environments present an opportunity to implement truly wireless sensor nodes in nuclear power plants. These sensors could continue to operate during extended station blackouts and during periods when operation of the plant’s internal power distribution system has been disrupted. The energy required to power the wireless sensors must be generated using energy harvesting techniques from locally available energy sources, and the energy consumption within the sensor circuitry must therefore be low to minimize power and hence the size requirements of the energy harvester.Harvesting electrical energy from thermal energy sources can be achieved using pyroelectric or thermoelectric conversion techniques. Recent modeling and experimental studies have shown that pyroelectric techniques can be cost-competitive with thermoelectrics in self-powered wireless sensor applications and, using new temperature cycling techniques, have the potential to be several times as efficient as thermoelectrics under comparable operating conditions. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, is outlined. This paper outlines the modeling of cantilever and pyroelectric structures and single-element devices that demonstrate the potential of this technology for the development of high-efficiency thermal-to-electrical energy conversion devices.

Membrane-free battery for harvesting low-grade thermal energy.

Efficient and low-cost systems are desired to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). An attractive approach is the thermally regenerative electrochemical cycle (TREC), which uses the dependence of electrode potential on temperature to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying the temperature, an electrochemical cell is charged at a lower voltage than discharged; thus, thermal energy is converted to electricity. Recently, a Prussian blue analog-based system with high efficiency has been demonstrated. However, the use of an ion-selective membrane in this system raises concerns about the overall cost, which is crucial for waste heat harvesting. Here, we report on a new membrane-free battery with a nickel hexacyanoferrate (NiHCF) cathode and a silver/silver chloride anode. The system has a temperature coefficient of -0.74 mV K(-1). When the battery is discharged at 15 °C and recharged at 55 °C, thermal-to-electricity conversion efficiencies of 2.6% and 3.5% are achieved with assumed heat recuperation of 50% and 70%, respctively. This work opens new opportunities for using membrane-free electrochemical systems to harvest waste heat.

Physicochemical and Mineral Composition of Dessert Banana Peduncle Juice during Conservation at Ambient Temperature

Background Dessert banana plants produce important quantities of post harvest waste such as pseudo stems, leaf sheaths, peduncles, rachis …which are either abandoned on the farms or destroyed by incineration. This study aims at promoting peduncles used in agriculture and in food industry through their extracted juice. Methods: Peduncles of bananas (Grande naine cv.) were collected in Cameroon. Data concerning weight, length and circumference were collected on the peduncles before extraction of the juice which was analysed for its physicochemical properties and mineral contents through simple analytical methods. Results During storage at ambient temperature, some physicochemical parameters (pH, total soluble solids, dry matter content) of peduncle juice showed significant increases (p<0.05) meanwhile, a significant decrease (p<0.05) in total titratable acidity was observed. From harvest to day 28, pH, TSS and DMC increased (from 5.4 to 10, 1.8 to 6.5 g/l and 2.7 to 7.5, respectively) while TTA decreased from 20.9 to 7.5 mEq/l. Moreover, mineral analysis of the peduncle juice revealed high amounts of Nitrogen (9.6 to 17.5 mg/g), Calcium (84.67 to 116.36 mg/100g), Sodium (363.16 to 431.83 mg/100g) and Potassium (83.67 to 112.44 mg/100g) from harvest to the 28th day of conservation. During storage, there was a significant increase (p<0.05) in Nitrogen, Calcium and Sodium contents; Meanwhile, a significant reduction (p<0.05) in Iron content was observed. Phosphorus, Magnesium and Potassium contents did not vary significantly during this process. Conclusions: This study contributes considerably to the establishment of the table of composition of dessert banana peduncles, to a better understanding of mineral and physicochemical changes that occur during conservation at ambient temperature. Moreover, the increase in pH and mineral contents are interesting potentials making the peduncle juice suitable to be used either for soil quality improvement, or as manure/fertilizer supplement in the production of bananas or other crops.

Solid-State Electrochemical Heat Engine

This paper explores the potential of using solid-state electrochemical heat engines operating on reversible redox reactions to continually harvest waste heat from available thermal energy from natural and man-made sources. These systems are electrolyers/fuel cells that operate on thermal energy. These systems utilize and control the electrochemical potential of molecules undergoing redox reactions in a manner to produce electrical energy from thermal energy. The electrochemical potential of these redox pairs is a function of composition, temperature and pressure. EHE’s in this paper exploit the change in basic thermodynamic properties with temperature. Each EHE is not only an energy storage device, but an energy producer using no fuel other than waste thermal energy. The EHE technology can be deployed using fuel cell/electrolyser combinations.

Process, property and performance of chalcogenide-based thermoelectric materials

The world is facing major challenges for finding alternate energy sources that can satisfy the increasing demand for energy consumption while preserving the environment. The field of thermoelectrics has long been recognized as consisting of materials that are potentially ‘ideal’ candidates for sources of power generation that operate by harvesting waste heat. However, the relatively low conversion efficiency of thermoelectric devices has suppressed their utility on a large scale. In this study, we summarize the global efforts that have been made, in the present scenario, to enhance the figure of merit of chalcogenide-based thermoelectric materials by choosing appropriate processes and their influence on properties and performance. The most recent research approaches, to chalcogenide-based thermoelectric materials in the last decade, from single crystal to polycrystalline form and from bulk to nano dimensions, have been considered in this study. The continued gap between fundamental theoretical results and actual experimental data of figure of merit and performance continues to challenge the commercial applications of thermoelectrics.

Theoretical Investigation of Waste Heat Recovery from an IC Engine Using Vapor Absorption Refrigeration System and Thermoelectric Converter

This study proposes the preliminary simulation of a single cylinder spark ignition engine with waste heat recovery system. To harvest waste heat energy from the engine exhaust a thermoelectric generator coupled to a vapor absorption refrigeration (VAR) system was proposed in this simulation work. Parametric simulation of engine, thermoelectric generator and VAR using thermodynamic relations was carried out in MATLAB – Simulink software. An attempt has been made mathematically to integrate engine, thermoelectric generator and VAR system to study the effect of engine load, speed, equivalence ratio on thermoelectric output and coefficient of performance (COP) of a VAR system. In this study, the VAR system runs by taking heat energy from the exhaust gas and the electric power produced by a thermoelectric generator was utilized to run the pump of the refrigeration system. It was found that COP of the absorption refrigeration system depends on engine load, speed and air fuel equivalence ratio. The study also reveals that about 10% to 15% of the total exhaust energy can be harvested using this system.

Framework to Harvest Waste Heat from Microprocessor using MEMS Thermoelectric Generator

The world primary energy consumption has been growing steadily. Therefore, there is a need to improve the overall energy application. There is a lack of investigation on harvesting waste heat from microprocessor as an alternative energy source. This study focuses on the framework required to harvest the energy from the microprocessor. Thermal profiling of the microprocessor integrated with an MEMS Thermoelectric Generator (TEG) using shunt configuration is developed. Additionally, a non-uniform energy model is derived to estimate the amount of energy that can be harvested from the microprocessor in the shunt configuration. MATLAB simulation based on the thermal and energy model is presented with two types of heat spreader material, copper and pyrolytic graphite with ideal and non-ideal contacts. The advantages and their shortfalls with respect to the microprocessor heat dissipation and the effectiveness to generate a temperature gradient at the MEMS TEG are discussed.

Characterization of Pyroelectric Materials for Energy Harvesting from Human Body

Pyroelectric energy harvesting is one of the feasible ways to harvest waste heat from human body. Heat is constantly lost from human body to maintain a constant temperature through a process known as thermoregulation. The maximum heat lost from the human body to the environment occurs through the skin. The heat loss varies throughout the human body, but, the most at the feet, the palms, and the exterior back which are the optimal areas for pyroelectric energy harvesting. In this paper, we investigate the feasibility of harvesting energy from the human body to power portable electronic devices such as computer mice. Current computer mice use either batteries or USB ports for power and run continuously, consuming significant amount of power. We present the design of a pyroelectric computer mouse, that uses the heat of the user's palm to power or supplement the energy demand of the mouse. Important parameters such as the heat generation rate of users, the design of the pyroelectric system, and the optimal operating conditions that provides highest power output, will be briefly discussed using commercially available materials.

ORGANIC MATTER APPLICATION IN LETTUCE AND POTATO CROPS

Trials were established in two vegetable crops, ‘Iceberg’ lettuce and ‘Russet Burbank’ potato to demonstrate the effect of incorporating organic amendments (compost or mulch) into soils under different farming conditions in Tasmania, Australia. Three treatments consisting of compost or amended compost applied at 10 t/ha, or hemp mulch were compared with a control treatment which consisted of the grower’s regular fertiliser regime. The fertiliser regime was also applied to the compost and hemp treatments, but not the amended compost treatment. Soils were assessed for a range of physical and chemical characteristics and soil fauna was assessed. Treatment effects on crop yield and quality were also examined. In the lettuce trial, compost and hemp mulch treatments exhibited the highest levels of microbial biomass carbon, while amended compost reduced microbial biomass carbon. Both soil moisture and temperature were increased by the addition of organic matter, but there was no effect on infiltration rate or soil bulk density. Available nitrogen was highest in the hemp mulch treatment. Marketable yield was reduced in the amended compost treatment. The hemp mulch application produced the lowest amount of field waste and total harvest waste. There was no difference between treatments in root mass. Compost application in the potato trial resulted in higher yields. The level of misshapen potatoes was highest in the control and amended compost treatments, while the hemp mulch treatment had the lowest incidence of scab. Both soil and leaf nitrogen and phosphorous levels were the same in all treatments, however, hemp mulch increased available soil potassium and the level of leaf potassium. There was no treatment effect on soil moisture content or bulk density. With limited information available on the impact of soil amendments on crop yield and quality, this work has provided farmers with scientific information as well as a visual display of the benefits of improved soil management practices.

Effective Piezoelectric Response of Substrate-Integrated ZnO Nanowire Array Devices on Galvanized Steel

Harvesting waste energy through electromechanical coupling in practical devices requires combining device design with the development of synthetic strategies for large-area controlled fabrication of active piezoelectric materials. Here, we show a facile route to the large-area fabrication of ZnO nanostructured arrays using commodity galvanized steel as the Zn precursor as well as the substrate. The ZnO nanowires are further integrated within a device construct and the effective piezoelectric response is deduced based on a novel experimental approach involving induction of stress in the nanowires through pressure wave propagation along with phase-selective lock-in detection of the induced current. The robust methodology for measurement of the effective piezoelectric coefficient developed here allows for interrogation of piezoelectric functionality for the entire substrate under bending-type deformation of the ZnO nanowires.

Prototype Combined Heater/Thermoelectric Power Generator for Remote Applications

This study presents a prototype thermoelectric generator (TEG) developed for remote applications in villages that are not connected to the electrical power grid. For ecological and economic reasons, there is growing interest in harvesting waste heat from biomass stoves to produce some electricity. Because regular maintenance is not required, TEGs are an attractive choice for small-scale power generation in inaccessible areas. The prototype developed in our laboratory is especially designed to be implemented in stoves that are also used for domestic hot water heating. The aim of this system is to provide a few watts to householders, so they have the ability to charge cellular phones and radios, and to get some light at night. A complete prototype TEG using commercial (bismuth telluride) thermoelectric modules has been built, including system integration with an electric DC/DC converter. The DC/DC converter has a maximum power point tracker (MPPT) driven by an MC9SO8 microcontroller, which optimizes the electrical energy stored in a valve-regulated lead–acid battery. Physical models were used to study the behavior of the thermoelectric system and to optimize the performance of the MPPT. Experiments using a hot gas generator to simulate the exhaust of the combustion chamber of a stove are used to evaluate the system. Additionally, potential uses of such generators are presented.

Identifying the physical distribution form and supply chain issues in marketing F&amp;V products by organised supermarkets: a case on reliance distribution model

The organised trade in its innovative 'avatar' began its growth story in the country only subsequent to the liberalisation of the economic policies. The agri-food retailing accounts for 18% of the organised retail today and is likely to have a lower share of 12% by 2020 (NABARD, 2011). Blocked by its major structural issues like inefficient distribution system and unscientific sourcing, there is a need to study the physical distribution model with the objectives of assessing its existing status as well the problems and prospects of the industry. The government has accorded it a soaring priority, with numeral fiscal reliefs, incentives and minimising pre/post harvest waste. Developing a revised model based on its core growth strategy of backward integration and progressing towards building an entire value chain starting from the farmers to the end consumers is the major focus area of the paper.

Production of Bio-organic fertilizer from sawdust after mushroom harvest and livestock wastes

Agricultural production requires high quality organic fertilizer. Bio-organic fertilizers are products of the compost consisting of organic matter, heterotrophic microbiota, and trace elements which are required to plant growth. In this study, bio-organic fertilizer obtained from sawdust after mushroom harvest and livestock waste was investigated. The mixture sawdust:swine waste (w:w) or sawdust: poultry waste (w:w) was incubated with 1% of Tribio product containing Trichoderma T1 and 5% of molasses. 30 days later, 1% of Tribio product and 1% of A-N fixing containing Azotobacter were added. The incubation process was ended 12 days later. All mixtures were mixed once per week during incubation. Our results showed that the ratio sawdust:swine waste (1 : 1) and sawdust: poultry waste (1 : 1.5) gave fertilizer products which have C/N ratio = 15-17, moisture = 48-49%, total organic C = 25-34%, total N = 1.5-2.2%, total P = 0.7-1.5%, humic acid = 5.1-5.9%, and total beneficial Trichoderma T1 &gt; 1 × 107 CFU/g and Azotobacter &lt; 1 × 105 CFU/g. These parameters get the standard levels of Vietnam Ministry of Agriculture and Rural Develoment.

Pyroelectric energy converter for harvesting waste heat: Simulations versus experiments

This paper is concerned with numerical simulations of a pyroelectric converter for direct energy conversion of waste heat into electricity. The simulated prototypical device consisted of a hot and cold source separated by a series of vertical microchannels supporting pyroelectric thin films made of co-polymer P(VDF-TrFE) and undergoing the Olsen cycle. A piston was used to vertically oscillate a working fluid back and forth between the thermal sources. The experimental device was instrumented with thermocouples and a pressure sensor. The two-dimensional transient mass, momentum, and energy equations were solved numerically using finite element methods to determine the local and time-dependent temperature at various locations inside the device microchannels. The operating frequency varied from 0.025 to 0.123Hz and the working fluid was 1.5 or 50cSt silicone oil. Good agreement was found between the simulated and experimentally measured local mean temperatures for both working fluids at all operating frequencies considered. The local temperature swings were underestimated slightly for 50cSt silicone oil and significantly more for 1.5cSt silicone oil. Overall, this study confirms our previous numerical results. Moreover, this numerical model could be used to design and operate the next generation of pyroelectric energy converters based on oscillatory convective heat transfer.

Rapid assessment of rice seed availability for wildlife in harvested fields

AbstractRice seed remaining in commercial fields after harvest (waste rice) is a critical food resource for wintering waterfowl in rice‐growing regions of North America. Accurate and precise estimates of the seed mass density of waste rice are essential for planning waterfowl wintering habitat extents and management. In the Sacramento Valley of California, USA, the existing method for obtaining estimates of availability of waste rice in harvested fields produces relatively precise estimates, but the labor‐, time‐, and machinery‐intensive process is not practical for routine assessments needed to examine long‐term trends in waste rice availability. We tested several experimental methods designed to rapidly derive estimates that would not be burdened with disadvantages of the existing method. We first conducted a simulation study of the efficiency of each method and then conducted field tests. For each approach, methods did not vary in root mean squared error, although some methods did exhibit bias for both simulations and field tests. Methods also varied substantially in the time to conduct each sample and in the number of samples required to detect a standard trend. Overall, modified line‐intercept methods performed well for estimating the density of rice seeds. Waste rice in the straw, although not measured directly, can be accounted for by a positive relationship with density of rice on the ground. Rapid assessment of food availability is a useful tool to help waterfowl managers establish and implement wetland restoration and agricultural habitat‐enhancement goals for wintering waterfowl. © 2011 The Wildlife Society.