The following are some of the research topics. Please see “Funded Projects” for more information.
1. Ocean Wave Energy Harvesting with a Novel Power Takeoff
Ocean wave energy potential in the US is 64% of the total electricity generated from all sources in 2010. Over 53% of the US population lives within 50 miles of a coast, so ocean waves offer exceptional opportunity. For wave energy generation equipment alone, the annual worldwide market is over $150B. Quite different from wind energy, the ocean wave energy is concentrated at low frequencies and at low, alternating velocities. Ocean wave energy harvesting remains in relative infancy. One of the most important challenges is the power takeoff mechanism, which “…is possibly the single most important element in wave energy technology, and underlies many (possibly most) of the failures to date.”
This project seeks a revolutionary advance by designing, prototyping, and validating an innovative ocean wave power takeoff based on a mechanical motion rectifier (MMR). This mechanism, patented by Lei Zuo, directly converts the irregular oscillatory wave motion into unidirectional generator rotation. By solving the challenges caused by irregular, bi-directional wave motion, the MMR will yield high-energy conversion efficiency, enhanced reliability, unmatched compactness, and optimal electrical grid integration. A multiple disciplinary approach is being taken for fundamental research in marine hydrodynamics, mechanical design, vibration dynamics, control system, power electronics, and environment assessment. This project won the 2014 EPA P3 Award and was selected as the 2014 Winner of Best Technology Development of Large-Scale Energy Harvesting. (NSF, EPA, DOE)
The objective of this project is to develop a dual-functional approach to efficiently harvest utility-scale energy and at the same time to effectively mitigate the wind-induced vibrations of large structures like high-rise buildings. Tall buildings, slender towers, and long bridges, being susceptible to dynamic wind load effects, can experience large vibrations. To reduce these vibrations in a building, a popular approach is to utilize a large mass at the top as a tuned mass damper which absorbs some energy in its own motion and dissipates the rest as wasted heat in a damper. In this project, a unique approach is proposed to provide enhanced structural response suppression by converting the dissipated vibration energy into electricity by using a series of optimally configured electricity-generating tuned mass dampers.
To optimize the performance of the dampers in energy harvesting and structural control, the project will conduct a comprehensive study of the dynamics and energy analysis of structures with proposed tuned mass dampers, will design efficient electromagnetic energy transducers for harvesting and connecting to the building’s or structure’s power grid, and will develop a complete semi-active self-powered vibration control system. The proposed research is multi-disciplinary as it blends concepts of structural, mechanical, power system, and electrical engineering for designing an optimal system for energy harvesting to enhance sustainability in structural designs, and for controlling structures to enhance their safety and reliability. (NSF)
In the USA there are over 255 million ground vehicles, which consume 170 billion gallons of fuel per year, or 44% of US oil (DOT data 2011). However, only 10-16% energy of the fuel burned by cars is used to drive the vehicles – to overcome the resistance from road friction and air drag (DOE and EPA data). Besides the thermal inefficiency of the engines, one important mechanism of energy loss in automobiles is the dissipation of kinetic energy during vehicle vibration and motion.
We estimated that for a middle-size vehicle, 100W and 400W of average power is available for harvesting from the regenerative shock absorbers while driving on Class B (good) and C (average) roads at 60 mph, which is comparable with the car alternators (500-600W). And the energy potential for trucks, rail cars, and off-road vehicles is on the order of 1kW-10kW. This represents a potential of 1-6% fuel efficiency increase. The objective is to establish an energy-harvesting vehicle suspension technology to improve the fuel efficiency and to significantly enhance the ride comfort and vehicle safety through self-powered suspension control. We have designed both linear and rotational electromagnetic shock absorbers with high energy density, and demonstrated 15W average and 100 peak power from one shock absorber of a SUV on the smooth paved road. Our work has been highlighted by several public news media including, PhysOrg, IOPscience, New York Times, MIT Technology Review and Winner of the prestigious R&D 100 Award by the R&D Magazine in 2011. We also won the Award of Best Technology Development of Energy Harvesting in the conference of Energy Harvesting and Storage USA. (NYSERDA, CIT, Ford Motor)
(PI: Lei Zuo)
The railroad transportation, including freight rail, intercity passenger train, commuter rail and subway, plays a very important role in the economy and quality of life for the people. To facilitate policy makers and transportation agencies to make informed decisions on operating and managing the transportation system, electric infrastructures are necessary along the railway tracks, such as the signal lights, road crossing gates, wireless communication, train and track monitoring, positive train control, etc. Unfortunately, the cost-effective and reliable power supply needed for the electrical infrastructures remains a challenge, since significant portion of the rails are in relative remote areas, in the underground tunnels, or on the bridges, where the energy needed to power electric infrastructure is uneconomical to install and maintain. This project aims at developing an advanced technology of energy harvesting from railway track vibrations to meet the regional and industry-wide need of access to cost-effective and reliable power supply for the track-side electrical infrastructures of rail transportation. The proposed method is to design and integrate an innovative energy harvesting mechanism, fly wheel, electric generator, power electronics and energy storage to produce high-quality DC power up to hundred watts from the irregular and pulse-like track deflections. Full-scale prototypes have been developed and demonstrated. This project won the award of Best Application of Energy Harvester and has been covered in many news medias, including ASME Mechanical Magazine. (US DOT/UTRC, NYSERDA, CIT)
A variety of studies have shown that recovering vehicle waste heat can be successfully used to produce electricity using solid state thermoelectric generators (TEG) to supplement the vehicle’s electrical demands, resulting 5-10% fuel savings. The exhaust system, however, presents unique challenges for integrating thermoelectric devices, including materials, thermal manage es in a rapid, economical, and industrially scalable manner. The proposed approach is based on the recent progress developed by an interdisciplinary team, including non-equilibrium material synthesis of bulk materials with rapid quenching, thermal spray of thick films, laser micromachining for feature patterning, and integrated thermal and mechanical design. The central concept is to fabricate TE structures directly onto exhaust system components, which will result in excellent interface adhesion between material layers that is intrinsically strong, and with no adhesives or mechanical clamping required. Cylindrical exhaust components are readily fabricated with the process, making integration into existing vehicle exhaust systems straightforward and inexpensive. The non-equilibrium material process is expected to enable high figure-of-merit TE couples economically manufactured from abundant materials at low-cost. (NSF, DOE)
6. High Throughput MEMS based Miniaturized Calorimeter for Biomolecular Characterization
Differential scanning calorimetry (DSC) is one of the few techniques that allow direct determination of enthalpy values for binding reactions and conformational transitions in biomolecules. It provides the thermodynamics information of the biomolecules which consists of Gibbs free energy, enthalpy and entropy in a straightforward manner that enables deep understanding of the structure function relationship in biomolecules such as the folding/unfolding of protein and DNA, ligand bindings, etc. In this project, we propose a high performance power compensation micro-DSC for biomolecular characterization. The optimized PDMS chamber (1 µL) and polyimide film led to low heat conduction and low evaporation. Ultrasensitive vanadium oxide thermistors monitored a slight temperature difference between the reference and sample region. A well-designed heating stage was built for linear scanning and shielding. A power compensation system achieved by LabVIEW program was made to maintain a constant temperature difference during the scanning process. The proposed MEMS DSC has a resolution of 250 nJ/K under the scanning rate of 40oC/min. (NSF, AbbVie)
7. Energy harvesting for self-powered wireless through-wall data communication system in nuclear environment
In the nuclear industry many important components, such as nuclear reactor pressure vessels (RPV) and spent fuel storage canisters, exist which are completely enclosed by metal and surrounded by thick concrete walls. Monitoring temperature, pressure, radiation, humidity, structural health, ect. within these enclosed vessels is crucial to ensure the safety of the reactor, and fuel containment safety and security. Thick shielding however presents unique challenges to sensing and instrumentation since these metal enclosures and thick concrete shields block electromagnetic waves preventing the transmission of data wirelessly from internals. Wiring through holes in the vessel walls is undesirable, and generally largely unfeasible. External monitoring for internal health is undesirable, and there is currently no internal sensing and instrumentation system that could provide direct measurements of these critical data, because (1) there is no long-lasting electricity power for the sensor inside the enclosed canisters, (2) one cannot transfer the data out of the enclosed steel canister using wires or RF wireless, and (3) the harsh environment of high temperature (175 °C on the wall) and high radiation inside the enclosed vessel creates challenges for electronics and sensors. Similar sensing needs and challenges exist for the nuclear reactor vessels of Boiling Water Reactors (BWR) and Pressurized Water Reactors (PWR).To combat these issues, we are committed to develop and demonstrate an enabling technology for the data communications for nuclear reactors and fuel cycle facilities using radiation and thermal energy harvesters, through-wall ultrasound communication, and harsh environment electronics. The task of our lab is to produce electrical energy from gamma rays through gamma-ray material heating and build electrical management circuit for the powering system. The package will be able to harvest tens of mW or more power from the nuclear radiations directly. The energy will be stored and used to power sensors and ultrasound data transmission inside the vessels. (DOE)
Energy harvesting for the smart tire has been an influential topic for researchers over the past several years. In this project, we developed an energy harvester for smart tire under modulated noise excitations by taking advantage of self-tuning stochastic resonance with particular application to powering smart tires. Compared to existing tire energy harvesters, it has larger power output and wider bandwidth. The former is achieved by stochastic resonance while the latter is by passively tuning the stochastic resonance frequency to track the time varying rotating speeds of the tire via a centrifugal stiffening effect; thus, the harvester maintains optimal power generation over a wide range of vehicle speed. It is an electromagnetic energy harvester consisting of an inward oriented rotating beam subjected to centrifugal force induced buckling. The compressive centrifugal force induces bistability to the harvester. Maximum power of 45 mW is achieved in the simulation while 1.8mW acheived in the ⅓ scale experiment. The half-power bandwidth of the harvester is around 52~111 km/h (32 mph ~ 70 mph), which corresponds to a typical speed range for a car in general road and highway.
9. Energy harvesting from human body to power mobile and wearable devices
The energy stored in human body is equal to the energy stored in 1000 kg of AAA battery . Daily activities consume several hundreds of power. At the same time, mobile devices (such as smart phone) consumes only 1~5W of energy . It is possible to harvest energy from human body to power the mobile and wearable devices. However, conventional energy harvesting devices such as hand crank generators burdens and exhausts the human body. It is desirable for the energy harvesting devices to be low burden and incorporate into everyday activities. Two energy harvesting devices were developed in the lab.
We have developed a mechanical Motion Rectification (MMR) based energy harvesting backpack, which weighs only 1.7 lb. The energy harvesting backpack is able to harvest 3W of power when walking at 3 mph. Treadmill experiments show that MMR backpack have nearly six-fold improvement in bandwidth. MMR backpack can have two- to ten-fold increase in specific power.
Energy harvesting shoes
With the rapid development of low-power devices, wearable electronics are booming in sports, healthcare, and entertainment industries. Traditional way to charge these devices inevitably interrupts their use. Human walking offers sufficiently harvestable and convertible energy sources that can be harvested to continuously power wearable sensors in health monitoring and low-power devices. In particular, the foot motion could produce large force excitations due to heel strike and leg swing. This project proposes an embedded piezoelectric footwear energy harvester by exploring the dynamic force excitation in a heel. The harvester is constituted of several piezoelectric stacks integrated in the well-designed and optimized force amplification frames and sandwiched by two heel-shaped aluminum plates. A survey investigation is implemented to disclose the dynamic force distribution in the heel induced by body weight and heel-strike at different walking speeds. An optimal force amplification frame is obtained by parameter optimization to achieve a large force amplification factor and efficient energy transmission. The measured average power of the prototype with six piezoelectric tacks is 9.3 mW/shoe at the walking speed of 3.0 mph (4.8 km/h). The simulated average power of the footwear harvester with four piezoelectric stacks is 20.4 mW/shoe based on the experimentally validated model.
10. Harvesting energy from pedestrians to power smart infrastructure
Energy harvesting paver (tile)
Harvesting energy from pedestrians can be used to power sensors in smart infrastructure, monitor structural health, and provide environmental sensing data. We developed an energy harvesting tile that can harvest 1.8J per step. The average electrical power output is 3.6W. The size is compatible with commercial tiles. The energy harvesting tile can scale up and deployed as normal tiles to pave the ground. The tile top panel movement is limited to 6mm (1/4 in.) to have least affect on human gait.