|
Affiliation |
Engineering educational research section Research & Development Center for Sustanable Energy and Environmental Engineering |
|
Title |
Associate Professor |
|
External Link |
|
OTA Yasuyuki
|
|
|
Research Areas 【 display / non-display 】
-
Energy Engineering / Earth resource engineering, Energy sciences / 太陽光発電、P2G
Papers 【 display / non-display 】
-
Analysis of Climate Conditions upon Driving Distance of Vehicle Integrated Photovoltaics-Powered Vehicles Reviewed International coauthorship
Yamaguchi M., Nakamura K., Ozaki R., Kojima N., Ohshita Y., Masuda T., Okumura K., Mabuchi T., Satou A., Tanimoto T., Tomita Y., Zushi Y., Nakado T., Yamada K., Thiel C., Tsakalidis A., Jaeger-Waldau A., Takamoto T., Araki K., Ota Y., Nishioka K.
Energy Technology 12 ( 1 ) 2024.1
Language：English Publishing type：Research paper (scientific journal) Publisher：Energy Technology
The development of the vehicles powered by photovoltaic (PV) is desirable and very important for reducing CO2 emissions from the transport sector to realize a decarbonized society. Although long-distance driving of vehicle-integrated PV (VIPV)-powered vehicles without electricity charging is expected in sunny regions, driving distance of VIPV-powered vehicles is affected by climate conditions such as solar irradiation and outside temperature, and the power consumption of the air conditioners. In this article, analytical results for system efficiency of VIPV-powered vehicles and the effects of usage of air conditioner are presented by using power losses estimated from the electric mileage by using the driving distance data for Toyota Prius and Nissan Van demonstration cars installed with high-efficiency InGaP/GaAs/InGaAs three-junction solar cell modules with a module efficiency of more than 30%. The potential of VIPV-powered vehicles to be deployed in major cities in Japan and the world is also analyzed. Mild weather cities such as Miyazaki in Japan and Sydney in Australia are thought to have longer driving range even under usage of air conditioners. The other power losses for the VIPV such as temperature rise of VIPV modules and partial shading estimate the previous data and some reference as well as effects of usage of air-conditioners are also discussed in this article.
-
Shwe Sin P.P., Wai S.H., Ota Y., Nishioka K., Suzuki Y.
International Journal of Hydrogen Energy 53 86 - 92 2023.12
Authorship：Corresponding author Publishing type：Research paper (scientific journal) Publisher：International Journal of Hydrogen Energy
Hydrogen production from renewable electricity offers an eco-friendly alternative to fossil fuels. Proton exchange membrane (PEM) electrolysis is a well-known method for this purpose. Studies have primarily focused on reducing costs of noble catalysts, improving efficiency, managing system degradation, and addressing membrane thinning caused by contaminated cations. However, techniques for PEM recovery post-degradation are still under development. This study investigated the effects of cations on PEM cells using artificial soft water, and analyzed two recovery methods to restore cell performance. Our findings indicate a significant rise in cell operating voltage and a decrease hydrogen production over 8 h of operation with soft water. After introducing both recovery methods, the initial operating value was reinstated in both cases. Only nitric acid treatment, however, achieved hydrogen production levels comparable to those of ultrapure water.
-
Prediction of PPFD (photosynthetic photon flux density) under transparent CPV modules Reviewed
Toyoda T., Yajima D., Kirimura M., Araki K., Ota Y., Nagaoka A., Nishioka K.
AIP Conference Proceedings 2841 ( 1 ) 2023.9
Language：English Publishing type：Research paper (scientific journal) Publisher：AIP Conference Proceedings
Recently, the agro-photovoltaic (agri-photovoltaic) system is expected to penetrate the market due to its advantages in some crops and significant potential installation areas. In principle, the agro-photovoltaic system shares solar energy with PV and agriculture, and its appropriate and controlled distribution is the key for the economy. Accurate and reproducible optimization design is essential. Any PV modules can be used for the agro-photovoltaic system. The best may be the transparent CPV that uses direct sunlight to concentrate onto solar cells and diffused sunlight to illuminate the farming light through a transparent backplane. The diffused sunlight for typical CPV modules is not used for electricity generation, and the transparent CPV is utilized as the secondary light source to crops. The diffused sunlight does not create shadow and improves the inhomogeneity of PPFD (Photosynthetic Photon Flux Density) from the stripe of shadows by PV modules, thus improving the yield. This paper predicts PPFD by the transparent CPV modules and the effectiveness of its use for the agro-photovoltaic system.
DOI： 10.1063/5.0146145
-
Shimizu R., Ota Y., Nagaoka A., Araki K., Nishioka K.
Applied Sciences (Switzerland) 13 ( 18 ) 2023.9
Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Sciences (Switzerland)
Featured Application: Solar panel fire accident diagnosis, analysis, and prediction. Fires in photovoltaic modules are caused by hot spots, which are typically monitored by thermal images. This method helps visualize the hot spot, but it is affected by the environment (solar irradiance, wind, ambient temperature) and is not reproducible. Assessing the heat dissipation of the hot cell can be used for alternative assessment of the fire risk. This method was validated by comparing the value measured by the surface potential meter and the module potential measured directly by adding a bypass measurement circuit. The substantial reverse-bias voltage caused by mismatching or partial shading (depending on the operating conditions) leads to local heat consumption of the partially shaded solar cells and potentially causes fire. The fire risk can be assessed in the worst-case conditions (ex. 1380 W/m2 solar irradiance) by non-contact measurement of the reverse-bias voltage and calculating the heat dissipation and temperature rise. This work suggested that −13 V is the criterion and was close to the known value of reverse voltage for Si cells. The current technology inspects solar cells before assembly to the module, and there is no way of inspecting in the product test or detecting after degradation that can be covered by the proposed method in this work.
DOI： 10.3390/app131810391
-
Araki K., Ota Y., Nagaoka A., Nishioka K.
Energies 16 ( 11 ) 2023.6
Language：English Publishing type：Research paper (scientific journal) Publisher：Energies
Building-integrated photovoltaics (BIPVs) and vehicle-integrated photovoltaics (VIPVs) receive solar irradiance through non-uniform shading objects. Standard scalar calculations cannot accurately determine the solar irradiance of BIPV and VIPV systems. This study proposes a matrix model using an aperture matrix to accurately calculate the horizontal and vertical planes affected by non-uniform shading objects. This can be extended to the solar irradiance on a VIPV by applying a local coordinate system. The 3D model is validated by a simultaneous measurement of five orientations (roof and four sides, front, left, tail, and right) of solar irradiance on a car body. An accumulated logistic function can approximate the shading probability. Furthermore, the combined use of the 3D solar irradiance model is effective in assessing the energy performance of solar electric vehicles in various zones, including buildings, residential areas, and open spaces. Unlike standard solar energy systems, the energy yield of a VIPV is affected by the shading environment. This, in turn, is affected mainly by the location of vehicle travel or parking in the city rather than by the climate zones of the city.
DOI： 10.3390/en16114414
Presentations 【 display / non-display 】
-
Testing and rating of VIPV: Scientific background International conference
Kenji Araki, Sho Kuranaga, Yasuyuki Ota, Kensuke Nishioka
PVinMotion 2024
Event date： 2024.3.6 - 2024.3.8
Language：English Presentation type：Oral presentation (general)
-
Optimum Clustering of VIPV Strings: Statistical and Probability Approach International conference
Kenji Araki, Yasuyuki Ota, Kensuke Nishioka
PVinMotion 2024
Event date： 2024.3.6 - 2024.3.8
Language：English Presentation type：Poster presentation
-
PV on HAPS (High Altitude Platform Station): PV modeling International conference
Kensuke Nishioka, Kohei Okada, Kenji Araki, Seiichi Kiyama, Yasuyuki Ota, Koji Nishiyama
PVinMotion 2024
Event date： 2024.3.6 - 2024.3.8
Language：English Presentation type：Poster presentation
-
PV on Heavy Duty Vehicles (HDVs) project in Japan International conference
Kenji Araki, Takumi Konuma, Makoto Tanaka, Yasuyuki Ota, Shiro Sakamoto, Kensuke Nishioka
PVinMotion 2024
Event date： 2024.3.6 - 2024.3.8
Language：English Presentation type：Poster presentation
-
Outdoor evaluation of total cross tied (TCT) Si module under driving conditions International conference
Yasuyuki Ota, Keiya Tamada, Kyotaro Nakamura, Masafumi Yamaguchi, Yoshio Ohshita, Kenji Araki, Kensuke Nishioka
PVinMotion 2024
Event date： 2024.3.6 - 2024.3.8
Language：English Presentation type：Oral presentation (general)
Grant-in-Aid for Scientific Research 【 display / non-display 】
-
太陽光由来メタン合成システムのシステム最適化および製造コスト削減
Grant number：22K05008 2022.04 - 2025.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
-
システム最適化した高効率集光型太陽電池水素生成機構の高精度コスト試算モデルの構築
Grant number：18K05015 2018 - 2021.03
科学研究費補助金 基盤研究(C)
Authorship：Principal investigator