This paper presents a review of R&D of novel next-generation, high-efficiency photovoltaic solar cells based on III-V compound semiconductors, particularly tandem multi-junction cells, intermediate band cells, hot-carrier cells, and multiple exciton generation cells. These cells are predicted to have the potential to yield conversion efficiencies of over 50%, and research toward their realization has been accelerated worldwide after the east Japan earthquake disaster. It is expected that gigawatt-scale solar power generation plants will be constructed mainly in the low latitude desert areas by making use of these high-efficiency solar cells and sunlight concentrator optics.
Wind power is renewable and is regarded as one of the main countermeasures of global warming. Offshore wind power can harness more energy since offshore wind is stronger than onshore wind and is less turbulent above the sea surface. Furthermore，the ocean space has no bounds whereas there are many restrictions on the land. Recently，some studies report that the potential energy of offshore wind around Japan is many times greater than the country’s domestic demand for electric power. In this report，the current situation of R&D towards the utilization of offshore wind power is described for bottom mounted offshore wind turbines and for those on floating piles， structures or platforms.
Tidalpower has a potential for future electricity generation same as wind energyand solar energy. Difference is that tidal energy is more stable and predictable than wind energyand solar power. Among sources ofrenewable energy, tidal power has beentreated as a systemwith highcost and limited sites where we can find sufficiently high tidal energy. However, many recent technological developments improve its profitabilityby using these advantages compared with other renewable energies. To obtain the maximumefficiencyoftidal turbine, the conventional blade element momentum method (BEM) has been used and manycorrectionfactors were developed. Inthis paper, calculation methods whichhave been used inthe area of marine propellers are applied tothe designoftidal turbines and evaluated indetail based oncomparison withthe conventional BEM used in wind turbine field.
Performance analysis of a power system utilizing waste heat energy from marine engines was conducted with Trifluoroethanol (TFEA) as the working fluid. The power system performance analysis was carried out using two methods. One involved the evaluation of the Rankine cycle thermal efficiency, and the other is the objective function for inlet and outlet temperature difference of waste heat gas. In the latter method, the maximum net power was obtained by minimizing the heat transfer area of the heat exchangers. The minimum value of the objective function was about 4 m2/kW when the inlet temperature of waste heat gas was 450 degrees Celsius. The marine engine power output was obtained from a performance analysis of a power system utilizing waste heat energy.
Particulate matter (PM) exhausted from diesel engines has several serious effects on human health and the environment. The strong health effects of the fine particles, in particular, have been reported recently. In this paper, the measurement of the particle size distribution was performed with a 4-stroke marine diesel engine. A three-cylinder high speed 4-stroke marine diesel engine (3L13AHS) was used as the test engine. The effect of the dilution ratio and the dilution air temperature in the dilution tunnel on particle size distribution was examined using Scanning Mobility Particle Sizer (SMPS) and Electrical Low Pressure Impactor (ELPI). The results show that the number of particles increases with an increase in the dilution ratio or the temperature of dilution air. The dilution ratio and the temperature of dilution air have a strong effect on the generation process of nuclei mode particles.