On the potential change in solar radiation over the US due to increases of atmospheric greenhouse gases

Solar radiation is the most important source of renewable energy available to reduce fossil CO₂ atmospheric emissions and also is an important factor in heating, ventilation, and air conditioning (HVAC) energy considerations. Solar radiation may be affected by climate changes induced by CO₂ emissions. In this study, a refined regional climate model was used to generate seasonal global radiation climatologies for the US under the present and mid 21st century enhanced atmospheric CO₂ level. Simulated seasonal-mean daily global radiation (direct plus diffuse incident radiation on a horizontal surface) under the present climate showed overall reasonable agreement with observed patterns but with negative biases in most locations. In most of the US, the enhanced CO₂ simulation (future climate) showed a trend of decreased seasonal-mean daily global radiation availability in the range of 0–20%. The most noticeable decrease was simulated in the western US during fall, winter, and spring. In small areas in the southern and northwestern US some increase in global radiation was simulated. Changes in global radiation during summer were relatively low.     

Possible future scenarios for atmospheric concentration of greenhouse gases: A simplified thermodynamic approach

Most of the increase in concentrations of greenhouse gases in the Earth's atmosphere is mainly due to anthropogenic activities. This is particularly significant in the case of CO₂. The atmospheric concentration of CO₂ has systematically increased since the Industrial Revolution (260 ppm), with a remarkable raise after the 1970s until the present day (380 ppm). If this increasing tendency is maintained, the last report of the Intergovernmental Panel on Climate Change (IPCC) estimates that, for the year 2100, the CO₂ concentration can augment up to approximately 675 ppm. In this work it is assumed that the quantity of anthropogenic greenhouse gases emitted to the Earth's atmosphere is proportional to the quantity of heat rejected to the environment by internal combustion heat engines. It is also assumed that this increasing tendency of CO₂ due to men's activity stems from a mode of energy production mainly based on a maximum-power output paradigm. With these hypotheses, a thermoeconomic optimization of a thermal engine model under two regimes of performance: the maximum-power regime and the so-called ecological function criterion is presented. This last regime consists in maximizing a function that represents a good compromise between high power output and low entropy production. It is showed that, under maximum ecological conditions, the emissions of thermal energy to the environment are reduced approximately up to 50%. Thus working under this mode of performance the slope of the curves of CO₂ concentration, for instance, drastically diminishes. A simple qualitative criterion to design ecological taxes is also suggested.     

A theoretical analysis of the capture of greenhouse gases by single water droplet at atmospheric and elevated pressures

Gas absorption by droplets is an important route to reduce greenhouse gas emissions, especially for carbon dioxide. To recognize the fundamental absorption processes of greenhouse gases by single droplets, the mass transport phenomena of greenhouse gas uptake by a quiescent water droplet at atmospheric and elevated pressures are analyzed theoretically and four common greenhouse gases of CO₂, N₂O, CH₄ and O₃ are taken into consideration. On account of piecewise function encountered at the droplet surface, it is impossible to obtain a fully analytical solution for describing the mass transfer process. Instead, a semi-analytical method is developed to predict the mass diffusion between the gas phase and the liquid phase. The obtained results indicate that, by virtue of the four greenhouse gases characterized by low mass diffusion number, the entire mass transfer is controlled by the liquid phase. A unified formula has been successfully established to aid in estimating the dimensionless solute uptake process and the dimensionless aqueous diffusion time of 0.45 is sufficiently long the implement the absorption process. For the ambient temperature and pressure in the ranges of 280–350 K and 1–20 atm, respectively, it is found that increasing the two parameters will intensify the solute absorption amount significantly and the absorption process can be accelerated by increasing temperature.     

Degradation of [D-Leu]-Microcystin-LR by solar heterogeneous photocatalysis (TiO2)

The present study investigates the use of solar heterogeneous photocatalysis (TiO₂) for the destruction of [D-Leu]-Microcystin-LR, powerful toxin of widespread occurrence within cyanobacteria blooms. We extracted [D-Leu]-Microcystin-LR from a culture of Microcystis spp. and used a flat plate glass reactor coated with TiO₂ (Degussa, P25) for the degradation studies. The irradiance was measured during the experiments with the aid of a spectroradiometer. After the degradation experiments, toxin concentrations were determined by HPLC and mineralization by TOC analyses. Acute and chronic toxicities were quantified using mice and phosphatase inhibition in vitro assays, respectively. According to the performed experiments, 150 min were necessary to reduce the toxin concentration to the WHO’s guideline for drinking water (from 10 to 1 μg L^?1) and to mineralize 90% of the initial carbon content. Another important finding is that solar heterogeneous photocatalysis was a destructive process indeed, not only for the toxin, but also for the other extract components and degradation products generated. Moreover, toxicity tests using mice have shown that the acute effect caused by the initial sample was removed. However, tests using the phosphatase enzyme indicated that it may be formed products capable of inducing chronic effects on mammals. The performed experiments indicate the feasibility of using solar heterogeneous photocatalysis for treating contaminated water with [D-Leu]-Microcystin-LR, not only due to its destruction, but also to the significant removal of organic matter and acute toxicity that can be achieved.     

Potential for large-scale solar collector system to offset carbon-based heating in the Ontario greenhouse sector

In the Ontario greenhouse sector the misalignment of available solar radiation during the summer months and large heating demand during the winter months makes solar thermal collector systems an unviable option without some form of seasonal energy storage. Information obtained from Ontario greenhouse operators has shown that over 20% of annual natural gas usage occurs during the summer months for greenhouse pre-heating prior to sunrise. A transient model of the greenhouse microclimate and indoor conditioning systems is carried out using TRNSYS software and validated with actual natural gas usage data. A large-scale solar thermal collector system is then incorporated and found to reduce the annual heating energy demand by approximately 35%. The inclusion of the collector system correlates to a reduction of about 120 tonnes of CO₂ equivalent emissions per acre of greenhouse per year. System payback period is discussed considering the benefits of a future Ontario carbon tax.     

On the potential change in wind power over the US due to increases of atmospheric greenhouse gases

Wind power (WP) is a likely source of renewable energy to reduce fossil CO₂ atmospheric emissions. However, WP availability might be affected by climate changes induced by such emissions. In this study a refined regional climate model, appropriate for resolving near-surface flows, was used to generate WP climatologies for the US consistent with present and mid-21st century enhanced atmospheric CO₂ level. In both cases the regional climate simulation was forced by lateral boundary conditions based on simulations of the Hadley Centre general circulation model. Simulated present WP showed reasonable general agreement with patterns observed in most locations. In most of the US the enhanced CO₂ simulation showed a trend of decreased daily average WP availability in the range of 0–30%. However, in limited areas in the southern and northwestern US, an increase in WP, peaking at 30%, was simulated. Under the enhanced CO₂ climate scenario, the present relatively high WP availability in northern Texas and western Oklahoma, as well as in the northwest US, are almost unaffected. A decline in WP is simulated in the north–central US and the western mountainous region.     

Pilot-plant treatment of olive mill wastewater (OMW) by solar TiO2 photocatalysis and solar photo-Fenton

Olive mill wastewater (OMW), a highly polluted wastewater from the olive oil industry, was treated by solar photocatalysis and solar photo-Fenton. Among the tested systems the application of titanium dioxide alone was not successful. The addition of peroxydisulphate as an electron acceptor had only limited effect on degradation performance and led to high salt concentrations (30 g/l sulphate generated) and a pH value near zero. The photo-Fenton method successfully removed up to 85% COD and up to 100% of phenol index of OMW with different initial concentrations and from different sources. Two solar photocatalytic pilot-plant reactors were used; one of conventional CPC type and an open non-concentrating Falling Film Reactor. The latter, newly designed reactor worked properly and yielded comparable results to the CPC in terms of degradation rate referred to incident UV radiation energy per solution volume. The suspended solids in the OMW hinder light from entering the reactor. Therefore, flocculation induced by a commercial flocculation agent was successfully applied to remove suspended solids. Application of this pre-treatment led to considerable increase of degradation rates and decrease of hydrogen peroxide consumption.     

现代农业技术--太阳能温室设施农业

＠吴静怡＠王如竹一、太阳能温室设施农业及其关键技术农作物的生长发育，一方面决定于作物本身的遗传特性，另一方面决定于外界环境条件。太阳能温室设施农业是在不适宜露地栽培农作物的季节或地区，利用特定的太阳能温室设施创造出适于农作物生长发育的人工小气候环境，从而达...     

Concentrated solar photocatalysis for hydrogen generation from water by titania-containing gold nanoparticles

Photocatalysis is an effective way to utilize solar energy to produce hydrogen from water. Au/TiO₂ nanoparticles (NPs) have a better performance in photocatalytic hydrogen generation because of the localized surface plasmon resonance (LSPR) effect of Au/TiO₂ NPs. In the photocatalytic hydrogen generation experiments, it was found that light intensity plays a key role in the photocatalytic reaction rate of Au/TiO₂ NPs. At a light intensity of 0–7 kW/m², the reaction rate has a super-linear law dependence on the light intensity (Rate ∝ Intensityⁿ, with n > 1). However, at a light intensity of 7–9 kW/m², the dependency becomes sub-linear (n < 1). This means that the increase rate of photocatalytic rate is smaller than that of light intensity when the light intensity exceeds 7 kW/m². In addition, the finite element method (FEM) was utilized to further elucidate the role of light intensity by calculating the absorption power and nearfield intensity mapping of a Au/TiO₂ nanoparticle. The variation trend of the calculated total absorption power agrees with the photocatalytic experimental results for different light intensities. These results shed light on the utilization of concentrated solar photocatalysis to increase the solar-to-hydrogen performance of Au/TiO₂ NPs.     

太阳能多用可调控温室研制

一引言20世纪80年代以来,具有中国特色的新型保护地设施——节能日光温室在我国北方地区逐渐普及。近十年来,温室在我国各地包括西南等地区的发展也很快。节能温室面积逐年扩大,取得了显著     

东北型节能日光温室--辽沈Ⅰ型温室地下热交换系统试验研究

温室的地下热交换系统是为提高太阳能的利用率，达到节能增温的目的而研究设置的，本文运用传热学的基本理论，通过对日光温室地下热交换系统土壤温度场的分析。提出了日光温室地下热交换系统的设计原理，地下热交换系统的设计的一般方法，并结合测试结果进行分析。     

Considerations for the calculation of greenhouse gas reduction by photovoltaic solar energy

A CO₂ comprehensive balance within the life-cycle of a photovoltaic energy system requires careful examination of the CO₂ sinks and sources at the locations and under the conditions of production of each component, during transport, installation and operation, as well as at the site of recycling. Calculations of the possible effect on CO₂ reduction by PV energy systems may be incorrect if system borders are not set wide enough and remain on a national level, as can be found in the literature. For the examples of Brazil and Germany, the effective CO₂ reductions have been derived, also considering possible interchange scenarios for production and operation of the PV systems considering the carbon dioxide intensity of the local electricity grids. In the case of Brazil also off-grid applications and the substitution of diesel generating sets by photovoltaics are examined: CO₂ reduction may reach 26,805 kg/kW_p in that case. Doing these calculations, the compositions of the local grids and their CO₂ intensity at the time of PV grid injection have to be taken into account. Also possible changes of the generation fuel mix in the future have to be considered: During the operation time of a PV system, different kinds of power plants could be installed that might change the CO₂ intensity of the grid. In the future also advanced technologies such as thin films have to be considered.     

日光温室节能墙体的选择

为探讨日光温室墙体对室内热环境的影响，对两组温室室内外温度进行了测试对比，并针对目前常见的单一材料墙体及异质复合墙体，在厚度相同的情况下进行了传热分析。测试结果显示，异质复合墙体温室内的夜间温度比单一材料墙体温室夜间温度高3℃左右。在考虑墙体的蓄热和传热情况下，温室墙体以内部砖外部聚苯板异质复合墙体为宜。     

Reduction of greenhouse gases using renewable energies in Mexico 2025

This study presents three scenarios relating to the environmental futures of Mexico up to the year 2025. The first scenario emphasizes the use of oil products, particularly fueloil, and represents the energy policy path that was in effect until 1990. The second scenario prioritizes the use of natural gas, reflecting the energy consumption pattern that arose in the mid-1990s as a result of reforms in the energy sector. In the third scenario, the high participation of renewable sources of energy, in particular renewable hydrogen, is considered feasible from a technical and economic point of view. The three scenarios are evaluated up to the year 2025 in terms of greenhouse gases (GHG), acid rain precursor gases (ARPG), and environment–energy intensity factors.     

温室技术在太阳热水器的应用

利用物体表面对太阳辐照的表面积累效廊设计，多霞温摩，使受光面积远超过太阳能热水器的集热面积，大幅度地提高了集热器的环境温度，减小了太阳热水器与环境的温差，提高了热水器的使用效果。此方法代替了现已应用的真空技术、蜂窝技术等抑制太阳能集热板（管）顶部散热的方法。提出了利用“矮墙多重温室法”产生廉价热水的技术方案。     

Off-season cultivation of cucumbers in a solar greenhouse

The use of solar energy for growing cucumbers in pots and the ground has been studied under controlled environments in a solar greenhouse. Forced and evaporative cooling were employed. An average of 7 cucumbers per pot (1342.4 g) was produced. Linear and multiple regression analyses were used to analyze the data. Correlations are proposed for predicting the yield as a function of the number, length and perimeter of cucumbers. A cost/benefit analysis is included.     

德国大型太阳能装置在工业中的应用

太阳能作为一种开发潜力巨大的可再生能源,早已引起世界各国的广泛关注。德国是世界上太阳能利用市场规模最大的国家。据德国太阳能工业协会2009年底发表的统计数字,截至2008年底,德国共有约200家太阳能企业,约7.8万名从业人员,全年销售额达110亿欧元,共有170万个     

A large-scale solar greenhouse dryer using polycarbonate cover: Modeling and testing in a tropical environment of Lao People’s Democratic Republic

A large-scale solar greenhouse dryer with a loading capacity of 1000 kg of fruits or vegetables has been developed and tested at field levels. The dryer has a parabolic shape and the dryer is covered with polycarbonate sheets. The base of the dryer is a black concrete floor with an area of 7.5 × 20.0 m². Nine DC fans powered by three 50-W solar cell modules are used to ventilate the dryer. The dryer was installed at Champasak (15.13 °N, 105.79 °E) in Lao People’s Democratic Republic (Lao PDR). It is routinely used to dry chilli, banana and coffee. To assess the experimental performances of the dryer, air temperature, air relative humidity and product moisture contents were measured. One thousand kilograms of banana with the initial moisture content of 68% (wb) was dried within 5 days, compared to 7 days required for natural sun drying with the same weather conditions. Also three hundred kilograms of chilli with the initial moisture content of 75% (wb) was dried within 3 days while the natural sun drying needed 5 days. Two hundred kilograms of coffee with the initial moisture content of 52% (wb) was dried within 2 days as compared to 4 days required for natural sun drying. The chilli, coffee and banana dried in this dryer were completely protected from insects, animals and rain. Furthermore, good quality of dried products was obtained. The payback period of the dryer is estimated to be 2.5 years. A system of partial differential equations describing heat and moisture transfer during drying of chilli, coffee and banana in the greenhouse dryer was developed. These equations were solved by using the finite different method. The simulated results agree well with the experimental data. This model can be used to provide the design data for this type of dryer in other locations.     

Thermo-catalytic conversion of greenhouse gases (CO2 and CH4) to CO-rich hydrogen by CeO2 modified calcium iron oxide supported nickel catalyst

In this study, the thermo-catalytic conversion of two principal greenhouse gases (methane and carbon dioxide) to carbon monoxide (CO)-rich hydrogen (H₂) is investigated over cerium oxide (CeO₂) promoted calcium ferrite supported nickel (Ni/CaFe₂O₄) catalyst. The CeO₂ promoted Ni/CaFe₂O₄ catalyst was prepared using wet-impregnation technique. To ascertain the physicochemical properties, the as-prepared catalyst was characterized using various instrument techniques. The characterization of the catalysts reveals that CeO₂-Ni/CaFe₂O₄ possesses suitable physicochemical properties for the conversion of methane (CH₄) and carbon dioxide (CO₂) to CO-rich H₂. The thermo-catalytic reaction revealed that the CeO₂ promoted Ni/CaFe₂O₄ catalyst displayed a higher CH₄ and CO₂ conversions of 90.04% and 91.2%, respectively, at a temperature of 1073 K compared to the unpromoted catalyst. The highest H₂ and CO yields of 78% and 76%, respectively, were obtained over the CeO₂-Ni/CaFe₂O₄ at 1073 K and CH₄/CO₂ ratio of 1. The CeO₂ promoted Ni/CaFe₂O₄ catalyst remained stable throughout the 30 hours time on stream (TOS) while that of the unpromoted Ni/CaFe₂O₄ catalyst sharply decreased after 22 hours TOS. The characterization of the used catalysts confirms the evidence of carbon depositions on the unpromoted Ni/CaFe₂O₄ which is solely responsible for its deactivation. Whereas, there was a slightly gasifiable carbon deposited on the CeO₂ promoted Ni/CaFe₂O₄ catalyst which could be ascribed to the interaction effect of the CeO₂ promoter on the Ni/CaFe₂O₄ catalyst.