Thermal stability of slow and fast cure EVA encapsulant material for photovoltaic module manufacturing process

Ethylene vinyl acetate (EVA) is a copolymer encapsulant used as an interlayer in the industrial photovoltaic module encapsulation process. EVA serves to provide the functions of structural support, electrical isolation, physical isolation/protection and thermal conduction for the solar cell circuit. This paper focuses on thermal properties of slow and fast cure EVA encapsulant material. Phase transition and thermal stability parameters of uncured EVA materials have been studied by employing thermo gravimetric analysis, thermal differential analysis and differential scanning calorimetric. EVA fast cure encapsulant material exhibits superior thermal stability in the range of operational cell temperature.     

Distributed grid-connected photovoltaic power system emission offset assessment: statistical test of simulated- and measured-based data

This study assesses the pollutant emission offset potential of distributed grid-connected photovoltaic (PV) power systems. Computer-simulated performance results were utilized for 214 PV systems located across the US. The PV systems’ monthly electrical energy outputs were based on a performance calculator called PVWATTS. Offset emissions of sulfur dioxide (SO₂), carbon dioxide (CO₂), and nitrogen oxides (NO_x) were determined from PV system outputs and average utility emissions data from each state. For validation, the simulated monthly results were statistically compared with measurement-based data (both production and corresponding emissions data) from 29 PV systems installed at different sites across the US.

While the data shows high (geographic) variability, the substantial number of measurements allows reliable statistical analysis. The methods are found to give consistent results in spite of the necessity to employ some even quite crude input approximations—such as the use of statewide rather than specific emissions data for the systems. No significant differences between simulated and measured monthly means for any of the pollutants were noted on the basis of individual monthly analyses, though the results for NO_x suggest the possible existence of some difference in that case. A more detailed statistical modeling using all monthly data in one combined analysis (allowing improved variability estimation) confirms these conclusions. Even the shorter confidence intervals for expected offsets obtained through the combined analysis show no significant differences between simulated and measured methods for SO₂ and CO₂. The differences for NO_x are statistically significant but consistent—suggesting useful prediction by the simulations via a constant correction factor. As expected, significant differences between months are evident for both simulated and measured offsets.     

Experimental assessment of the waveform distortion in grid-connected photovoltaic installations

This paper provides a multi-faceted view on the characterization of the waveform distortion in grid-connected photovoltaic (PV) plants from experimental results. The focus is set on the characterization of the waveform distortion occurring under different operating conditions in field measurements and laboratory tests. The assessment is carried out by considering the system-based point of view, on the basis of the measurements gathered at the interface between the PV plant and the grid or the supply point in the laboratory. New methodological hints on the formulation of the experimental tests are provided. The results of the waveform distortion analysis for harmonic currents and voltages are compared to the requirements of present power quality standards, indicating that in practical cases the current distortion can be significantly higher than in normal test conditions. Furthermore, the key aspect concerning harmonic and interharmonic modelling of multiple grid-connected PV inverters is addressed. Experimental results on plant configurations with multiple PV inverters show that low-order harmonics sum up almost arithmetically, whereas the higher-order harmonics and the interharmonics sum up in an almost Euclidean way.     

Leveling the playing field of transportation fuels: Accounting for indirect emissions of natural gas

Natural gas transportation fuels are credited in prior studies with greenhouse gas emissions savings relative to petroleum-based fuels and relative to the total emissions of biofuels. These analyses, however, overlook a source of potentially large indirect emissions from natural gas transportation fuels, namely the emissions from incremental coal-fired generation caused by price-induced substitutions away from natural-gas-fired electricity generation. Because coal-fired generation emits substantially more greenhouse gases and criteria air pollutants than natural-gas-fired generation, this indirect coal-use change effect diminishes potential emissions savings from natural gas transportation fuels. Estimates from a parameterized multi-market model suggest the indirect coal-use change effect rivals in magnitude the indirect land-use change effect of biofuels and renders natural gas fuels as carbon intensive as petroleum fuels.     

Diversification in the driveway: mean-variance optimization for greenhouse gas emissions reduction from the next generation of vehicles

Modern portfolio theory is applied to the problem of selecting which vehicle technologies and fuels to use in the next generation of vehicles. Selecting vehicles with the lowest lifetime cost is complicated by the fact that future prices are uncertain, just as selecting securities for an investment portfolio is complicated by the fact that future returns are uncertain. A quadratic program is developed based on modern portfolio theory, with the objective of minimizing the expected lifetime cost of the “vehicle portfolio”. Constraints limit greenhouse gas emissions, as well as the variance of the cost. A case study is performed for light-duty passenger vehicles in the United States, drawing emissions and usage data from the US Environmental Protection Agency's MOVES and Department of Energy's GREET models, among other sources. Four vehicle technologies are considered: conventional gasoline, conventional diesel, grid-independent (non-plug-in) gasoline-electric hybrid, and flex fuel using E85. Results indicate that much of the uncertainty surrounding cost stems from fuel price fluctuations, and that fuel efficient vehicles can lower cost variance. Hybrids exhibit the lowest cost variances of the technologies considered, making them an arguably financially conservative choice.     

Performance and emissions characteristics of a lean-burn marine natural gas engine with the addition of hydrogen-rich reformate

The exhaust gas-fuel reforming technique known as reformed exhaust gas recirculation (REGR) can generate on-board hydrogen-rich gas mixture (i.e., reformate) by catalytic reforming of the exhaust gas and fuel added into the reformer and then recirculate the reformate into the engine cylinder, which can realize the combination of hydrogen-rich lean combustion and exhaust gas recirculation. The REGR technique can be employed to achieve efficient and stable lean-burn combustion for the marine engine fueled with natural gas (i.e., marine NG engine) and it is considered as an effective way to meet the stringent ship emissions regulations. In the present study, an experimental investigation into the effects of reformate addition ratio (R_re) and excess air ratio (λ) on the combustion and emissions characteristics of a marine NG engine under various loads was conducted, and the potential of applying the REGR technique in a marine NG engine to achieve low emissions (i.e., International Maritime Organization Tier Ⅲ emissions legislations for international ships) was discussed. The results indicate that the addition of the hydrogen-rich reformate gases can extend lean-burn limit. For a given λ, the flame development duration and rapid combustion duration decrease with the increase of R_re, and the combustion efficiency is improved. The brake specific NO_x emissions first increase and then decrease with the increase of R_re due to the competition between the combustion phase and total heat release value. The brake specific THC emissions decline with the increase of R_re, while the reverse holds for the brake specific CO emissions, and the behavior tends to be obvious under large λ. It is demonstrated that the combination of REGR and the lean-burn combustion strategy can improve the trade-off relationship between the NO_x emissions and brake specific fuel consumption of the marine NG engine to meet the IMO Tier Ⅲ NO_x emissions legislations and maintain relatively low brake specific fuel consumption.     

The territorial and landscape impacts of photovoltaic systems: Definition of impacts and assessment of the glare risk

The installation and operation of systems that exploit solar energy through photovoltaic conversion, recently promoted in some European countries by new sell-back tariffs, is a relevant transformation of the territory for various reasons (land use, elimination of the existing vegetation, visual impact on the components of the landscape, microclimate change, glare from the reflection of the direct sunlight). The weak energy intensity of the solar source coupled with the low conversion efficiency of the photovoltaic cells, make the physical dimensions of such systems relevant and, with them, also the environmental, territorial and landscape impacts that basically depend on the physical extent of the system. If it is well known that an incentive to the exploitation of renewable sources is one of the features of the policy of land conservation, including the one of the protected areas, at the same time the concerns of local communities and governments about the environmental, territorial and landscape impacts of this technology are increasing rapidly.Given this picture, this work is intended to clarify the territorial impacts of the ground mounted photovoltaic systems. Later, the paper concentrates on a specific impact, which is the assessment of the risk of glare by reflection of direct sunlight from the surfaces of photovoltaic modules. The methodologies that can be used to assess this impact and the outcomes of an evaluation carried out for a 5000 m² PV system currently designed on a hilly territory in Italy are presented.     

Efficiency and emissions of gas-fired industrial boiler fueled with hydrogen-enriched nature gas: A case study of 108 t/h steam boiler

Hydrogen-enriched natural gas (HENG) is a promising low-carbon fuel in the industry. The fuel flexibility of the existing natural gas-fueled industrial combustion equipment is a crucial issue for the HENG application. This study evaluates the thermal and emission performances of a large-scale industrial steam boiler fueled with HENG. Considering different operation strategies, three boiler operation scenarios were proposed, namely, the unchanged fuel/air valve opening (Scenario 1), the maintained boiler capacity with unchanged valve control logic (Scenario 2), and the maintained boiler capacity with unchanged excess air ratio (Scenario 3). A model considering the thermal equilibrium and heat transfer inside the boiler was built to study the thermal efficiency under the three scenarios, and a chemical reaction network model was established to investigate the NOx emission characteristics. The results showed that thermal efficiency and NOx emission presented a similar variation trend. Both of them decreased in Scenarios 1 and 2 while increased in Scenario 3 as hydrogen volumetric fraction in HENG increased from 0 to 0.9. The differences in decarbonization potentials among the three scenarios were limited. This study implies that the trade-off between thermal efficiency and NOx emission should be carefully concerned when applying HENG to industrial steam boilers.     

Imported palm oil for biofuels in the EU: Profitability,greenhouse gas emissions and social welfare effects

We examine the social desirability of renewable diesel production from imported palm oil in the EU when greenhouse gas emissions are taken into account. Using a partial market equilibrium model, we also study the sectoral social welfare effects of a biofuel policy consisting of a blend mandate in a small EU country (Finland), when palm oil based diesel is used to meet the mandated quota for biofuels. We develop a market equilibrium model for three cases: i) no biofuel policy, ii) biofuel policy consisting of socially optimal emission-based biofuel tax credit and iii) actual EU biofuel policy. Our results for the EU biofuel market, Southeast Asia and Finland show very little evidence that a large scale use of imported palm oil in diesel production in the EU can be justified by lower greenhouse gas emission costs. Cuts in emission costs may justify extensive production only if low or negative land-use change emissions result from oil palm cultivation and if the estimated per unit social costs of emissions are high. In contrast, the actual biofuel policies in the EU encourage the production of palm oil based diesel. Our results indicate that the sectoral social welfare effects of the actual biofuel policy in Finland may be negative and that if emissions decrease under actual biofuel policy, the emission abatement costs can be high regardless of the land use change emissions.     

Greenhouse gas emissions reduction by use of wind and solar energies for hydrogen and electricity production: Economic factors

This study addresses economic aspects of introducing renewable technologies in place of fossil fuel ones to mitigate greenhouse gas emissions. Unlike for traditional fossil fuel technologies, greenhouse gas emissions from renewable technologies are associated mainly with plant construction and the magnitudes are significantly lower. The prospects are shown to be good for producing the environmentally clean fuel hydrogen via water electrolysis driven by renewable energy sources. Nonetheless, the cost of wind- and solar-based electricity is still higher than that of electricity generated in a natural gas power plant. With present costs of wind and solar electricity, it is shown that, when electricity from renewable sources replaces electricity from natural gas, the cost of greenhouse gas emissions abatement is about four times less than if hydrogen from renewable sources replaces hydrogen produced from natural gas. When renewable-based hydrogen is used in a fuel cell vehicle instead of gasoline in a IC engine vehicle, the cost of greenhouse gas emissions reduction approaches the same value as for renewable-based electricity only if the fuel cell vehicle efficiency exceeds significantly (i.e., by about two times) that of an internal combustion vehicle. It is also shown that when 6000 wind turbines (Kenetech KVS-33) with a capacity of 350 kW and a capacity factor of 24% replace a 500-MW gas-fired power plant with an efficiency of 40%, annual greenhouse gas emissions are reduced by 2.3 megatons. The incremental additional annual cost is about $280 million (US). The results provide a useful approach to an optimal strategy for greenhouse gas emissions mitigation.     

Strategies for carbon dioxide emissions reductions: Residential natural gas efficiency,economic, and ancillary health impacts in Maryland

As part of its commitments to the Regional Greenhouse Gas Initiative (RGGI), the State of Maryland, USA, auctions emission permits to electric utilities, creating revenue that can be used to benefit consumers and the environment. This paper explores the CO₂ emissions reductions that may be possible by allocating some of that revenue to foster efficiency improvements in the residential sector’s use of natural gas. Since these improvements will require changes to the capital stock of houses and end use equipment, efficiency improvements may be accompanied by economic and ancillary health impacts, both of which are quantified in this paper.     

Policies for improving the efficiency of the Brazilian light-duty vehicle fleet and their implications for fuel use,greenhouse gas emissions and land use

The increase in greenhouse gas concentrations in the atmosphere, energy security issues and competition for land use are putting pressure on governments and policymakers. However, these three subjects are not usually treated in integrated form. This paper shows that the implementation of energy efficiency policies combined with policies to encourage use of biofuels can help reduce greenhouse gases emissions while easing land use competition from sugarcane ethanol in Brazil. By adapting the ADVISOR (Advanced Vehicle Simulator) software to evaluate vehicle efficiency, and by estimating the Brazilian light-duty vehicle market share based on historical data, this paper estimates the possible levels of GHG emissions and area planted with sugarcane in 2030 in the country. The findings indicate that reductions from 8% to 20% in greenhouse gas emissions and 0.9–1.8 million ha in sugarcane planted area are possible with no significant technological breakthroughs over the horizon to 2030 in comparison with a baseline scenario.     

Baselines for carbon emissions in the Indian and Chinese power sectors: Implications for international carbon trading

The study examines the dynamics of carbon emissions baselines of electricity generation in Indian states and Chinese provinces in the backdrop of ongoing electricity sector reforms in these countries. Two Indian states—Gujarat and Andhra Pradesh, and three Chinese provinces–Guangdong, Liaoning and Hubei have been chosen for detailed analysis to bring out regional variations that are not captured in aggregate country studies. The study finds that fuel mix is the main driver behind the trends exhibited by the carbon baselines in these five cases. The cases confirm that opportunities exist in the Indian and Chinese electricity sectors to lower carbon intensity mainly in the substitution of other fuels for coal and, to a lesser extent, adoption of more efficient and advanced coal-fired generation technology. Overall, the findings suggest that the electricity sectors in India and China are becoming friendlier to the global environment. Disaggregated analysis, detailed and careful industry analysis is essential to establishing a power sector carbon emissions baseline as a reference for CDM crediting. However, considering all the difficulties associated with the baseline issue, our case studies demonstrate that there is merit in examining alternate approaches that rely on more aggregated baselines.     

Scalable methodology for the photovoltaic solar energy potential assessment based on available roof surface area: Further improvements by ortho-image analysis and application to Turin (Italy)

The ongoing rush of the UE member states to the 2020 overall targets on the national renewable energy share (see Directive 2009/28/EC), is propelling the large exploitation of the solar resource for the electricity production. However, the incentives to the large employment of PV solar modules and the relative perspective profits, are often cause of massive ground-mounted installations. These kind of installations are obviously the preferred solution by the investors for their high economic yields, but their social impact should be also considered. Over the Piedmont Region for instance, the large proliferation of PV farms is jeopardising wide agricultural terrains and turistic areas, therefore the policy of the actual administration is to encourage the use of integrated systems in place of massive installations. For these reasons, an effort to demonstrate that the distributed residential generation can play a primary role in the market is mandatory. In our previous work “Scalable methodology for the photovoltaic solar energy potential assessment based on available roof surface area: application to Piedmont Region (Italy)”, we already proposed a basic methodology for the evaluation of the roof-top PV system potential. However, despite the total roof surface has been computed on a given cartographical dataset, the real roof surface available for PV installations has been evaluated through the assumption of representative roofing typologies and empirical coefficients found via visual inspection of satellite images. In order to overcome this arbitrariness and refine our methodology, in the present paper we present a brand new algorithm to compute the available roof surface, based on the systematical analysis and processing of aerial georeferenced images (ortho-images). The algorithm, fully developed in MATLAB®, accounts for shadow, roof surface available (bright and not), roof features (i.e. chimneys or walls) and azimuthal angle of the eventual installation. Here we apply the algorithm to the whole city of Turin, and process more than 60,000 buildings. The results achieved are finally compared with our previous work and the updated PV potential assessment is consequently discussed.     

Impact of future urban form on the potential to reduce greenhouse gas emissions from residential,commercial and public buildings in Utsunomiya,Japan

Energy-saving technologies’ applicability to making cities more environmentally sustainable can be strongly influenced by the city's form, building uses and their density pattern. Technological developments have clearly shown specific urban forms to be more conducive to installing certain mitigation technologies. In this study, the capacity for implementation and impacts on energy savings and subsequent greenhouse gas (GHG) reduction potential of mitigation technologies such as photovoltaic cells (PV) and combined heat and power (CHP) technologies were analysed with respect to three potential urban forms (high density centralised, medium density averaged and low density de-centralized) for Utsunomiya City, Japan. Given current building use patterns, scenarios for 2030 and 2050, showed the medium density averaged form, which benefits from both PV and CHP technologies, to outperform the other forms, resulting in an energy savings and GHG reduction potential of 27.6% in 2030 and 67.6% in 2050. Interestingly, GHG reduction in 2050 was primarily attributable to PV, while CHP technology had the greater influence in 2030. Despite the limitation of the analysis, the study provides a useful insight, highlighting the relationship between urban forms and GHG reduction potential by two energy-saving technologies.     

Characteristics of heat transfer and fluid flow in a channel with single-row plates array oblique to flow direction for photovoltaic/thermal system

This study has been carried out to investigate the characteristics of convective heat transfer and fluid flow for a single row of oblique plates array to the flow direction inside a channel. The flow inside the channel is laminar and the plates array have spanwise distance between the plates and heated by radiation. This configuration has been designed to be used for Photovoltaic/Thermal system (PV/T) applications. The theoretical results are validated with measured values, and a good agreement prevailed. The results show that an increase in the plate oblique angle (γ) in the range from 0 to 15 degrees, leads to an increase in the Nusselt number (Nu) up to a maximum value and then decreases. The oblique angle at the maximum value of Nu depends on the flow Reynolds Number (Re), and (?_w/?_pl), where (?_w/?_pl) is defined as the ratio of the plates’ spacing at zero oblique angle to the plate length. Furthermore, increasing (?_w/?_pl) results in a significant increase in the heat transfer coefficient depending on the values of Re, and plate oblique angle (γ). In addition, increasing (γ) from 0 to 15 degrees results in a decrease in the friction factor up to a certain value, after which the friction value approaches a constant value depending on Re value and (?_w/?_pl). It was found that for any value of the plate oblique angle (γ), the friction factor decreases with the increase of the values of (?_w/?_pl) and Re, respectively.     

Examining the link between carbon dioxide emissions and the share of industry in GDP: Modeling and testing for the G-7 countries

In this paper, the relationship between per capita CO₂ emissions and the share of industrial value added in gross domestic product (GDP) for the G-7 countries is discussed using a novel approach. It is assumed that per capita CO₂ emissions are correspondent to the share of industrial value added in GDP. A model is developed using hidden Markov process to search this initial assumption. In the model, the data for industrial share in GDP are assigned to be the observations, while the data for per capita CO₂ emissions represent the hidden process, which may be then predicted using the ratio of industrial value added to GDP. The data set covers the period from 1970 to 2008 and the model is tested for the G-7 countries. The study findings show that, except in the case of Canada, the hidden Markov model performs reasonably well in tracking per capita CO₂ emissions. The study results provide also a basis for a number of policy implications.     

Comparison of the technical potential for hydrogen,battery electric,and conventional light-duty vehicles to reduce greenhouse gas emissions and petroleum consumption in the United States

Light-duty vehicles (LDV) are responsible for a large fraction of petroleum use and are a significant source of greenhouse gas (GHG) emissions in the United States. Improving conventional gasoline-powered vehicle efficiency can reduce petroleum demand, however efficiency alone cannot reach deep GHG reduction targets, such as 80% below the 1990 LDV GHG emissions level. Because the cost and availability of low-GHG fuels will impose limits on their use, significant reductions in GHG emissions will require combinations of fuel and vehicle technologies that both increase efficiency and reduce the emissions from fuel production and use. This paper examines bounding cases for the adoption of individual technologies and then explores combinations of advanced vehicle and fuel technologies. Limits on domestic biofuel production—even combined with significant conventional combustion engine vehicle improvements—mean that hydrogen fuel cell electric or battery electric vehicles fueled by low-GHG sources will be necessary. Complete electrification of the LDV fleet is not required to achieve significant GHG reduction, as replacing 40% of the LDV fleet with zero-emission hydrogen vehicles while achieving optimistic biofuel production and conventional vehicle improvements can allow attainment of a low GHG emission target. Our results show that the long time scale for vehicle turnover will ensure significant emissions from the LDV sector, even when lower emission vehicles and fuels are widely available within 15 years. Reducing petroleum consumption is comparatively less difficult, and significant savings can be achieved using efficient conventional gasoline-powered vehicles.     

Analysis of scenarios for the reduction of energy consumption and GHG emissions in transport in the Basque Country

Fossil energy depletion and fight against climate change force humanity to decarbonize the economy. By year 2050 CO₂ emissions will have to reduce globally at least 85%, and probably over 95% in developed countries.The modeling of the transportation of people and commodities in the Basque Autonomous Community (Spain) in year 2008 has allowed us to draw some conclusions about the challenges ahead. The exploration of several scenarios modeled in order to reduce energy consumption in transport shows that mobility in a decarbonized world will have to be more efficient, electrified when moving people and freight on land, based on renewable generation, and organized in such a way that guarantees very high occupancies of vehicles. All these elements will be indispensable, and even not sufficient if they are still not complemented with a reduction of mobility in absolute terms, so that economic transportation intensity—the ratio between transportation and whole economic activity—recovers to levels seen in the world four decades ago, prior to the development of present hypermobility.     

城市垃圾焚烧飞灰物理化学性质及重金属风险分析

对7种城市垃圾焚烧飞灰的物理化学性质进行了详细表征。针对飞灰中重金属成分复杂的特点对重金属含量、形态分布和浸出毒性进行了分析,并进行了风险评估指数和风险指数计算。飞灰的化学组分和晶相结构分析显示,城市垃圾焚烧飞灰中含有大量的CaO、CaSO₄、SiO₂、Al₂O₃、NaCl和KCl等化合物,具有资源化利用的潜力。但同时飞灰中含有大量的重金属,其中Pb和Cd的生态风险高,浸出毒性高于飞灰直接处理和处置要求。研究结果表明,垃圾焚烧飞灰需进行处理至达到一定要求后才能进行资源化利用。