Kenneth McEnaney

Bio: Kenneth McEnaney is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Thermoelectric effect & Thermoelectric generator. The author has an hindex of 16, co-authored 29 publications receiving 2468 citations.

High-performance flat-panel solar thermoelectric generators with high thermal concentration

Abstract: The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. A highly efficient solar to electric energy conversion device based on nanostructured thermoelectric materials and high solar concentration is now demonstrated. The results show potential for cost effective solar thermoelectric generation.

A review of cermet-based spectrally selective solar absorbers

Abstract: Spectrally selective solar absorbers harvest solar energy in the form of heat. Solar absorbers using cermet-based coatings demonstrate a high absorptance of the solar spectrum and a low emittance in the infrared (IR) regime. Extensive work has been done to optimize cermet-based solar absorbers to achieve high performance by exploring different cermet (ceramic–metal composite) materials and film configurations through different preparation techniques such as electrodeposition, sputtering, pulsed laser deposition, and solution-based methods. In this article, we review the progress of cermet-based spectrally selective absorbers with high solar absorptance and low thermal emittance, such as Cr2O3, Al2O3, AlN, SiO2, and ZrO2 based cermets as absorption layers. We also present an outlook for cermet-based spectrally selective absorbers with high thermal stability and high conversion efficiency from sunlight to heat.

Concentrating solar thermoelectric generators with a peak efficiency of 7.4

Abstract: Concentrating solar power normally employs mechanical heat engines and is thus only used in large-scale power plants; however, it is compatible with inexpensive thermal storage, enabling electricity dispatchability. Concentrating solar thermoelectric generators (STEGs) have the advantage of replacing the mechanical power block with a solid-state heat engine based on the Seebeck effect, simplifying the system. The highest reported efficiency of STEGs so far is 5.2%. Here, we report experimental measurements of STEGs with a peak efficiency of 9.6% at an optically concentrated normal solar irradiance of 211 kW m−2, and a system efficiency of 7.4% after considering optical concentration losses. The performance improvement is achieved by the use of segmented thermoelectric legs, a high-temperature spectrally selective solar absorber enabling stable vacuum operation with absorber temperatures up to 600 ∘C, and combining optical and thermal concentration. Our work suggests that concentrating STEGs have the potential to become a promising alternative solar energy technology. Solar thermoelectric generators are a promising technology for converting solar energy into electricity, however their efficiency has been limited to 5.2%. Kraemer et al. report a solar thermoelectric generator with an efficiency of 9.6%, resulting in 7.4% efficiency in a concentrating solar thermoelectric system.

Studies on the Bi2Te3–Bi2Se3–Bi2S3 system for mid-temperature thermoelectric energy conversion

Abstract: Bismuth telluride (Bi2Te3) and its alloys have been widely investigated as thermoelectric materials for cooling applications at around room temperature. We report a systematic study on many compounds in the Bi2Te3–Bi2Se3–Bi2S3 system. All the samples were fabricated by high energy ball milling followed by hot pressing. Among the investigated compounds, Bi2Te2S1 shows a peak ZT ∼0.8 at 300 °C and Bi2Se1S2 ∼0.8 at 500 °C. The results show that these compounds can be used for mid-temperature power generation applications. The leg efficiency of thermoelectric conversion for segmented elements based on these n-type materials could potentially reach 12.5% with a cold side at 25 °C and a hot side at 500 °C if appropriate p-type legs are paired, which could compete well with the state-of-the-art n-type materials within the same temperature range, including lead tellurides, lead selenides, lead sulfides, filled-skutterudites, and half Heuslers.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Ultrahigh power factor and thermoelectric performance in hole-doped single-crystal SnSe

Abstract: Thermoelectric technology, harvesting electric power directly from heat, is a promising environmentally friendly means of energy savings and power generation. The thermoelectric efficiency is determined by the device dimensionless figure of merit ZT(dev), and optimizing this efficiency requires maximizing ZT values over a broad temperature range. Here, we report a record high ZT(dev) ∼1.34, with ZT ranging from 0.7 to 2.0 at 300 to 773 kelvin, realized in hole-doped tin selenide (SnSe) crystals. The exceptional performance arises from the ultrahigh power factor, which comes from a high electrical conductivity and a strongly enhanced Seebeck coefficient enabled by the contribution of multiple electronic valence bands present in SnSe. SnSe is a robust thermoelectric candidate for energy conversion applications in the low and moderate temperature range.

Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human-Activity Monitoringand Personal Healthcare.

Abstract: Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as ultrathinness, low modulus, light weight, high flexibility, and stretchability. These flexible and stretchable physical sensors conformally attached on the surface of organs or skin can provide a new opportunity for human-activity monitoring and personal healthcare. Consequently, in recent years there has been considerable research effort devoted to the development of flexible and stretchable physical sensors to fulfill the requirements of future technology, and much progress has been achieved. Here, the most recent developments of flexible and stretchable physical sensors are described, including temperature, pressure, and strain sensors, and flexible and stretchable sensor-integrated platforms. The latest successful examples of flexible and stretchable physical sensors for the detection of temperature, pressure, and strain, as well as their novel structures, technological innovations, and challenges, are reviewed first. In the next section, recent progress regarding sensor-integrated wearable platforms is overviewed in detail. Some of the latest achievements regarding self-powered sensor-integrated wearable platform technologies are also reviewed. Further research direction and challenges are also proposed to develop a fully sensor-integrated wearable platform for monitoring human activity and personal healthcare in the near future.

Rationally Designing High-Performance Bulk Thermoelectric Materials

Abstract: There has been a renaissance of interest in exploring highly efficient thermoelectric materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk thermoelectric materials. We begin with the fundamental stratagem of achieving the greatest thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization. We proceed to discuss ways of maximizing ZT at a constant doping level, such as increase of band degeneracy (crystal structure symmetry, band convergence), enhancement of band effective mass (resonant levels, band flattening), improvement of carrier mobility (modulation doping, texturing), and decrease of lattice thermal conductivity (synergistic alloying, second-phase nanostructuring, mesostructuring, and all-length-scale hierarchical architectures). We then highlight the decoupling of th...

Research opportunities to advance solar energy utilization

Abstract: Major developments, as well as remaining challenges and the associated research opportunities, are evaluated for three technologically distinct approaches to solar energy utilization: solar electricity, solar thermal, and solar fuels technologies. Much progress has been made, but research opportunities are still present for all approaches. Both evolutionary and revolutionary technology development, involving foundational research, applied research, learning by doing, demonstration projects, and deployment at scale will be needed to continue this technology-innovation ecosystem. Most of the approaches still offer the potential to provide much higher efficiencies, much lower costs, improved scalability, and new functionality, relative to the embodiments of solar energy-conversion systems that have been developed to date.