Hydrogen production using solar radiation

Various water-splitting methods using solar energy are reviewed and compared to each other. Direct thermal method has the highest efficiency, however it poses difficulties because of the need for heat-resisting materials. Thermochemical method becomes promising if corrosion-resisting materials are found. Electrolytic method is straightforward and conventional. However, a hybrid system combining electrolytic method with thermochemical and/or photochemical methods looks promising and is believed to result in optimum conversion efficiencies in the near future. Photolysis and biochemical methods are environmentally most acceptable, but are of low conversion efficiencies presently.     

Calculation of solar radiation using a methodology with worldwide potential

Surface meteorological observations from the DATSAV2 database provide the capability to use the METSTAT (meteorological/statistical) model to calculate hourly values of direct normal, diffuse horizontal, and global horizontal solar radiation for locations throughout the world. Opaque cloud cover, a key input parameter to the METSTAT model, is derived from the DATSAV2 layered cloud cover information. Resulting multiyear data sets include solar radiation and other meteorological data such as dry bulb temperature, dew point temperature, wind speed, and atmospheric pressure. Data filling procedures ensure that the multiyear data sets are serially complete. A minor revision to METSTAT improved solar radiation estimates for conditions of high cloud amounts and low ceiling heights. The methodology was applied to regions of Southern Africa and Saudi Arabia.     

A heat-resistant ceramic with increased mechanical strength on the basis of aluminum titanate synthesized with concentrated solar radiation

The mechanical properties of an aluminum titanate-based ceramic are increased by decreasing the grain growth kinetic of the initial material, which is synthesized by melting in a solar furnace. The thermomechanical properties are improved if the following additives are introduced: mullite, spinel, and a eutectic of Al₂O₃-ZrO₂.     

Investigations of solar radiation detectors using a laboratory test facility for solar radiation meteorological instruments

A laboratory test facility for solar radiation detectors has been built and is in operation at the Aerological Station of the Swiss Meteorological Institute (SAP/SMI). This installation is conceived as a universal test bed for solar radiation exposed meteorological instruments, and consists of a commercially available solar simulator, a laser alignment system, a translation mechanism with instrument mounts, and an adjustable projection mirror. The solar simulator produces a well characterized radiation beam which can be filtered to match the terrestrial or outer space solar spectrum with an irradiance of up to one solar constant (1367 Wm⁻²). The instrument mounts and a HeNe laser beam provide a precise and easy alignment of the reference and the test instruments in the radiation beam, allowing for incident angles in the range of 15°–75°. The measurement is based on a comparison of the response of an active cavity absolute radiometer PMO6 with the signal of the test instrument.Detailed investigations of the Haenni Solar 111B type heliometer have revealed important irregularities in the sunshine threshold irradiance angular distribution. Measurements performed with and without the protection glass cover prove the exceedingly high threshold values at large declination angles to be a consequence of enhanced reflections due to the incident angle and inhomogeneities in the glass cover.Very satisfactory results have also been obtained on characterization measurements of pyranometers showing the mean values of the responsivity to be within 0.8% of the calibration values measured at the world radiation center (WRC) at Davos.     

Forecasting hydrogen production potential in islamabad from solar energy using water electrolysis

The focus of this study is the use of Machine Learning methods to forecast Solar Hydrogen production potential for the Islamabad region of Pakistan. For this purpose, we chose a Photovoltaic-Electrolytic (PV-E) system to forecast electricity and, hence, hydrogen production. The weather data used for forecasting and simulation were recorded with precise meteorological instruments stationed in Islamabad, over the course of 13 and a half months. Out of the three tested algorithms, Prophet performs the best with Mean Absolute Percentage Error of 3.7%, forecasting a daily average Hydrogen production of 93.3 × 10³ kg/Km². Although, the forecast in this study is made for the month of August and September, during which the local season moves towards winter, this study demonstrates solar hydrogen production, as a green energy source, has a tremendous potential in this region.     

Analysis of solar radiation data using cubic splines

Cubic spline regression is used to study the relationship between total solar radiation and sunshine duration. The least square cubic splines function with a linear segment is computed for each month for three major towns in Peninsular Malaysia, viz Kuala Lumpur, Penang and Kota Baru which represent three regions of different climatic and geographical conditions. Extrapolation to other towns shown that the erros between the estimated radiation and the measured values are more uniform than those obtained by linear regression.     

Synthesis of aluminum nitride and oxynitride during combustion of powder-like metallic aluminum in the field of concentrated solar radiation

We investigated characteristics of synthesis of nitrides and oxynitrides during combustion of disperse powders of aluminum in air in radiant heating furnaces. Processes of the formation of oxynitride ceramics in the Al₂O₃-AlN-Al₃O₃N system are considered. Solid microporous samples with a pore size of 1–2 μm was made.     

Enhancement of solar radiation absorption using nanoparticle suspension

The radiation absorption characteristics of a Ni nanoparticle suspension were investigated by spectroscopic transmission measurement. It was demonstrated that the absorption coefficient of the nanoparticle suspension is much higher than that of the base liquid for visible to near-infrared wavelengths. Radiation characteristics predicted by the Mie theory showed good agreement with the increase of absorption coefficient in wavelengths where the base liquid is transparent. It was also confirmed that a new transmittance measurement technique for a liquid sample using a liquid cell with no spacer was quite useful for evaluating a material possessing an extremely strong absorption band. The proposed measurement method and successive Kramers-Kronig analysis were validated by measuring the optical properties of water. The measurement and prediction process of the thermal radiation properties of nanoparticle suspensions developed here could be used in developing direct absorption solar collectors.     

Spatial estimation of global solar radiation using geostatistics

The number of radiation data collection stations is limited due to economic reasons. Hence, there is a need for the spatially continuous mapping of solar radiation by estimation. This paper utilizes a geostatistical technique for the estimation of solar radiation in Saudi Arabia. This technique includes five steps: (i) data collection, (ii) univariate analysis, (iii) experimental variogram calculations and model fitting, (iv) estimation using kriging, and (v) plotting contour maps. Variogram models are fitted to measured variograms for each month of the year. Estimates were obtained at 1500 grid points (30 × 50) between a longitude of 36.58°E and 50.00°E, and latitude of 17.17°N and 31.33°N for a grid resolution of 55 × 33 km. These values were used to plot the contour maps of solar radiation for each month of the year. To test the performance of the technique, estimates were obtained at the 41 known locations by systematically excluding one of these points from the known data. The error analysis showed a maximum mean deviation between measured and estimated values of 0.0037 (January) and a minimum of 0.0013 (March and October). The mean percent errors were found to vary between a minimum of 0.5% and a maximum of 1.7%. This technique may be expanded for the spatial estimation of solar radiation on regional and continental scales.     

A study of water electrolysis with photovoltaic solar energy conversion

The performance of the hydrogen production system consisting of the photovoltaic array and the water electrolysis unit is studied. The results of the calculation are compared with available experimental data and the performance of a hydrogen production plant by means of photovoltaic solar energy conversion is determined for two typical locations. A method for the estimation of the power matching conditions of the system solar array electrolysis unit is formulated to allow conclusions of general validity.     

Reliability analysis of solar photovoltaic system using hourly mean solar radiation data

This paper presents the hourly mean solar radiation and standard deviation as inputs to simulate the solar radiation over a year. Monte Carlo simulation (MCS) technique is applied and MATLAB program is developed for reliability analysis of small isolated power system using solar photovoltaic (SPV). This paper is distributed in two parts. Firstly various solar radiation prediction methods along with hourly mean solar radiation (HMSR) method are compared. The comparison is carried on the basis of predicted electrical power generation with actual power generated by SPV system. Estimation of solar photovoltaic power using HMSR method is close to the actual power generated by SPV system. The deviation in monsoon months is due to the cloud cover. In later part of the paper various reliability indices are obtained by HMSR method using MCS technique. Load model used is IEEE-RTS. Reliability indices, additional load hours (ALH) and additional power (AP) reduces exponentially with increase in load indicates that a SPV source will offset maximum fuel when all of its generated energy is utilized. Fuel saving calculation is also investigated. Case studies are presented for Sagardeep Island in West Bengal state of India.     

太阳能地板辐射采暖

低温热水地板辐射采暖具有舒适、节能和有利于装饰等优点，在北京地区逐渐得到广泛的应用。低温热水地板辐射采暖是采用铝塑复合管、交联聚乙烯（PE-X）等新型管材敷设于室内地面垫层内，管道内通入低温热水达到室内采暖的目的。在设计室内温度为16℃时，就可以达到其他采暖方式18℃时的舒适度，而且采暖供回水温度最高可以是60／50℃，最低可以是40／30℃。     

Hydrogen production through solar energy water electrolysis

Various methods of making hydrogen from water have been proposed, but at the present time the only practical way to make hydrogen from water without fossil fuel is electrolysis. The development of a new, advanced, water electrolyser has become necessary for use in hydrogen energy systems and in electricity storage systems. All the new possible electrolysis processes, suitable for large-scale plants, are being analysed, in view of their combination with solar electricity source. A study of system interactions between large-scale photovoltaic plants, for electrical energy supply, and water electrolysis, is carried out. The subsystems examined include power conditioning, control and loads, as they are going to operate. Water electrolysis systems have no doubt been improved considerably and are expected to become the principal means to produce a large amount of hydrogen in the coming hydrogen economy age. Thus, the present paper treats the subject of hydrogen energy production from direct solar energy conversion facilities located on the earth's oceans and lakes. Electrolysis interface is shown to be conveniently adapted to direct solar energy conversion, depending on technical and economical feasibility aspects as they emerge from the research phases. The intrinsic requirement for relatively immense solar collection areas for large-scale central conversion facilities, with widely variable electricity charges, is given. The operation of electrolysis and photovoltaic array combination is verified at different insolation levels. Solar cell arrays and electrolysers are giving the expected results during continuously variable solar energy inputs. Future markets will turn more and more towards larger scale systems powering significantly bigger loads, ranging from hundreds of kW to several MW in size. Detailed design and close attention to subsystem engineering in the development of high performance, high efficiency photovoltaic power plants, are carried out. An overall design of a 50 MWp photovoltaic central station for electricity and hydrogen co-generation is finally discussed.     

Production of hot air with quasi uniform temperature using concentrated solar radiation

The design of a hot air solar generator for different uses has been simulated while investigating the flow induced by a hot disc placed at the entrance of the open ended vertical cylinder. Ambient air (Pr = 0.7) enters the bottom of the cylinder with constant velocity and temperature, and flows up through the cylinder as a result of natural convection. The cylindrical wall is heated by thermal radiation emitted by the disc. The pressure drop due to acceleration of the flow to the cylinder-inlet causes the appearance of thermosyphon effect around the thermal plume. At the top part of the cylinder, the flow exploration shows the full development of the turbulence and the uniformity of thermal and hydrodynamic fields. The study of the thermal spectral density indicates that the turbulent structures seem to be sufficiently small not to be sensitive to viscosity, but large enough to be sensitive to Archimedes effects.     

Study of a water electrolysis system using a compact solar cell module with a plant shoot configuration

The system proposed in this paper produces hydrogen by supplying photovoltaic power to a water electrolyzer and then supplying this gas to a fuel cell with a time shift. The objective of this system is to supply power to an individual house or apartment building with only green energy. However, the solar cell module installation area is large in the proposed system. Therefore, this paper considered installing a solar cell module with a plant shoot configuration. As a result of this modification, the power generation area of the proposed system is 33–52% smaller than that of a conventional flat solar cell module. From these results, it should be possible to introduce the proposed system into an individual house.     

Estimation of global solar radiation using artificial neural networks

This paper introduces a neural network technique for the estimation of global solar radiation. There are 41 radiation data collection stations spread all over the kingdom of Saudi Arabia where the radiation data and sunshine duration information are being collected since 1971. The available data from 31 locations is used for training the neural networks and the data from the other 10 locations is used for testing. The testing data was not used in the modeling to give an indication of the performance of the system in unknown locations. Results indicate the viability of this approach for spatial modeling of solar radiation.     

Prediction of global daily solar radiation using higher order statistics

The main concern of the present paper is to present and to analyse two procedures for modelling daily global solar radiation. The first one uses the clearness index techniques and the second one uses a totally different type of approach for taking in consideration important properties of such data, including non-Gaussian shape and non-stationarity. This procedure uses the difference between the extraterrestrial and the observed daily global radiation denoted “lost solar component”. Both procedures are based on higher order statistics for generating the global solar radiation using mainly a random process. The prediction results show that the sequences of values generated have the same statistical characteristics as those of sequences observed. The comparison between the two methods used indicates that the developed model based on the “lost solar component” is better than the model obtained using the conventional procedure based on the clearness index.     

PV system sizing using observed time series of solar radiation

Sizing represents an important part of photovoltaic system design. This paper describes a sizing procedure based on the observed time series of solar radiation. Using a simple geometrical construction, the sizing curve is determined as a superposition of contributions from individual climatic cycles of low daily solar radiation. Unlike the traditional methods based on loss-of-load probability, the reliability of supply enters in this method through the length of the time series of data used in the analysis. The method thus resembles techniques used in other branches of engineering where extreme values are considered as functions of certain recurrence intervals.     

Solar electricity prospects in Oman using GIS-based solar radiation maps

This paper discusses solar power prospects in Oman. First, the geographic and topographic information about Oman are presented. The methodology of producing solar radiation maps using GIS tools is then discussed. The results obtained show very high potential of solar radiation over all the lands of Oman during the whole year. A slope analysis has allowed calculating the yearly electricity generation potential for different Concentrated Solar Power (CSP) technologies such as the parabolic trough, parabolic dish, tower, and concentrated PV. For instance if only 10% of the land of Oman with a slope less than 1% is considered an exploitable land for the parabolic trough CSP technology, then the total calculated potential of yearly electricity generation would be about 7.6 million GWh, which is many multiples of (680 times) the current generation supply in Oman which was about 11,189 GWh in 2007.