Dr Nadine Upton, Post-doctoral Scientist | Curation made possible by Deep Science Ventures
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Abstract: Sustainably produced biofuels are being discussed intensively as one possible component in the energy scenarios for future ground transportation, especially when they are derived from lignocellulosic biomass. Traditionally, research activities on their production focus on the synthesis process, while leaving their combustion properties to subsequent evaluation by a different community. The present article adopts an integrative view of engine combustion and fuel synthesis, focusing on the chemical aspects as the common denominator. We wish to demonstrate that fundamental understanding of the combustion process can be instrumental to derive design criteria for the molecular structure of fuel candidates that can then be targets for the analysis of synthetic pathways and the development of catalytic production routes. With such an integrative approach to fuel design, it will be possible to improve systematically the entire system, spanning biomass feedstock, conversion process, fuel, engine, and pollutants with a perspective to improve the carbon footprint, increase efficiency, and reduce emissions of the transportation sector along the whole value chain.
Pub.: 12 Feb '17, Pinned: 21 Feb '17
Abstract: Irradiating a flame via microwave radiation is a plasma-assisted combustion (PAC) technology that can be used to modify the combustion chemical kinetics in order to improve flame stability and to delay lean blow-out. One practical implication is that combustion engines may be able to operate with leaner fuel mixtures and have an improved fuel flexibility capability including biofuels. Furthermore, this technology may assist in reducing thermoacoustic instabilities, which is a phenomenon that may severely damage the engine and increase NOX production. To further understand microwave-assisted combustion, a skeletal kinetic reaction mechanism for methane–air combustion is developed and presented. The mechanism is detailed enough to take into account relevant features, but sufficiently small to be implemented in large eddy simulations (LES) of turbulent combustion. The mechanism consists of a proposed skeletal methane–air reaction mechanism accompanied by subsets for ozone, singlet oxygen, chemionization, and electron impact reactions. The baseline skeletal methane–air mechanism contains 17 species and 42 reactions, and it predicts the ignition delay time, flame temperature, flame speed, major species, and most minor species well, in addition to the extinction strain, compared to the detailed GRI 3.0 reaction mechanism. The amended skeletal reaction mechanism consists of 27 species and 80 reactions and is developed for a reduced electric field E/N below the critical field strength (of ∼125 Td) for the formation of a microwave breakdown plasma. Both laminar and turbulent flame simulation studies are carried out with the proposed skeletal reaction mechanism. The turbulent flame studies consist of propagating planar flames in homogeneous isotropic turbulence in the reaction sheets and the flamelets in eddies regimes, and a turbulent low-swirl flame. A comparison with experimental data is performed for a turbulent low-swirl flame. The results suggest that we can influence both laminar and turbulent flames by nonthermal plasmas, based on microwave irradiation. The laminar flame speed increases more than the turbulent flame speed, but the radical pool created by the microwave irradiation significantly increases the lean blow-out limits of the turbulent flame, thus making it less vulnerable to thermoacoustic combustion oscillations. Apart from the experimental results from low-swirl flame presented here, experimental data for validation of the simulated trends are scarce, and conclusions build largely on simulation results. Analysis of chemical kinetics from simulations of laminar flames and LES on turbulent flames reveal that singlet oxygen molecule is of key importance for the increased reactivity, accompanied by production of radicals such as O and OH.
Pub.: 18 Jan '17, Pinned: 21 Feb '17
Abstract: Life cycle assessment (LCA) is used extensively to assess the greenhouse gas (GHG) implications of biofuels. Some argue that the common treatment of biogenic carbon emissions as being carbon neutral in LCA is flawed. From this divergent perspective, biofuels have potential benefits only if additional atmospheric CO2 is captured or feedstocks that would otherwise quickly decompose (e.g. agricultural residues) are utilized. An alternative method, Annual Basis Carbon (ABC) accounting, has recently been demonstrated for a single ethanol facility comparing the year-over-year GHG impacts of the cropland supplying the facility, the fuel production processes (gasoline prior to construction and ethanol after), and vehicle tailpipe emissions. Our review of the ABC method identifies inconsistencies in the treatment of the non-fuel products: corn, soybeans, and distiller's dried grain solubles (DDGS). While these products are also consumed annually, the GHG emissions were not considered in evaluating the system performance. Furthermore, GHG impacts, both in terms of burdens from inputs and crop CO2 uptake, were not allocated to the products leaving the system. Thus in the initial state, the petroleum-fueled system received a substantial benefit from crop CO2 uptake, but none of the subsequent emission burdens associated with the consumption of non-fuel (i.e., food/feed) ‘exports’. In the final state, conversely, most biomass was combusted as ethanol and captured within the considered system. A system expansion is needed to better account for impacts. While concerns about the degree of carbon additionality have some merit, consequential LCA methods provide for more consistent and comprehensive approaches for evaluating biofuel GHG performance. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd
Pub.: 07 Feb '17, Pinned: 21 Feb '17
Abstract: Fruit processing industries contribute more than 0.5billion tonnes of waste worldwide. The global availability of this feedstock and its untapped potential has encouraged researchers to perform detailed studies on value-addition potential of fruit processing waste (FPW). Compared to general food or other biomass derived waste, FPW are found to be selective and concentrated in nature. The peels, pomace and seed fractions of FPW could potentially be a good feedstock for recovery of bioactive compounds such as pectin, lipids, flavonoids, dietary fibres etc. A novel bio-refinery approach would aim to produce a wider range of valuable chemicals from FPW. The wastes from majority of the extraction processes may further be used as renewable sources for production of biofuels. The literature on value addition to fruit derived waste is diverse. This paper presents a review of fruit waste derived bioactives. The financial challenges encountered in existing methods are also discussed.
Pub.: 15 Feb '17, Pinned: 21 Feb '17
Abstract: Clean tech entrepreneurs have struggled to gain investor confidence because of some particular characteristics and circumstances of the industry. This research combines network and sustainable development literature in the clean tech context to support the logic of a new investment approach that may stimulate sustainable investing in clean tech. Theory is proposed to suggest that there may be an advantageous social capital paradox where strong ties in a cluster lead to dynamism rather than decay. The clean tech industry provides a context where strong ties offer network stability in a small world cluster such that it is a value-creating organizational form offering greater dynamism. Two related propositions are developed to support the social capital paradox. They lead to a theoretical conclusion that long term integrated partner solutions where partners are also resource constrained lead to successful alliances supporting a dynamic cluster that will grow over time. A practical conclusion is that investing in a connected cluster of firms might be less risky compared to investing in a new firm or even a portfolio of well diversified assets. De-risking clean production investments may be achievable through a small world network cluster-backed security.
Pub.: 20 Aug '16, Pinned: 21 Feb '17
Abstract: We test for evidence that energy efficiency features are capitalized into home prices in three U.S. metropolitan areas. Using hedonic regressions and multiple matching procedures, we find that Energy Star certification is associated with higher sales prices in two of the markets: the Research Triangle region of North Carolina and Portland, Oregon. We find that local “green” certifications in Portland and in Austin, Texas, are also associated with higher prices and that the estimated price impacts are larger than those from Energy Star. Matching on observables proves to be important in some cases, reducing the estimated impacts compared with models without matching. We calculate the implied energy savings from the estimated premiums and find that, in the Research Triangle market, the Energy Star premiums approximately equal the savings that program is designed to achieve, but in Portland, the premiums are slightly greater than the program's savings due to low energy costs in the region.
Pub.: 22 Nov '16, Pinned: 03 Feb '17
Abstract: Manipulating the flow of energy in nanoscale and molecular photonic devices is of both fundamental interest and central importance for applications in light energy harvesting optoelectronics. Under erratic solar irradiance conditions, unregulated power fluctuations in a light-harvesting photocell lead to inefficient energy storage in conventional solar cells and potentially fatal oxidative damage in photosynthesis. Here, we compare the theoretical minimum energy fluctuations in nanoscale quantum heat engine photocells that incorporate one or two photon-absorbing channels and show that fluctuations are naturally suppressed in the two-channel photocell. This intrinsic suppression acts as a passive regulation mechanism that enables the efficient conversion of varying incident solar power into a steady output for absorption over a broad range of the solar spectrum on Earth. Remarkably, absorption in the green portion of the spectrum provides no inherent regulatory benefit, indicating that green light should be rejected in a photocell whose primary role is the regulation of energy flow.
Pub.: 10 Nov '16, Pinned: 03 Feb '17
Abstract: The management of distributed energy resources (DER) in power distribution systems and the concept of demand side management (DSM) are becoming increasingly important in recent years, provided that emerging communication technologies contribute to the formation of smart distribution networks of the future. Several methods have been proposed in the literature for the optimal operation of smart distribution networks (OOSDN) with renewables and/or non-renewable DER, DSM and energy storage systems. The main scope of this paper is to review the most significant papers in the area of OOSDN and to introduce a taxonomy of models and optimization methods that are applied to the OOSDN problem. Moreover, the basic schemes for active network management are briefly presented. The article also discusses challenges and areas for future research in the field of OOSDN.
Pub.: 13 Jul '16, Pinned: 02 Feb '17
Abstract: A future smart grid must fulfill the vision of the Energy Internet in which millions of people produce their own energy from renewables in their homes, offices, and factories and share it with each other. Electric vehicles and local energy storage will be widely deployed. Internet technology will be utilized to transform the power grid into an energy-sharing inter-grid. To prepare for the future, a smart grid with intelligent periphery, or smart GRIP, is proposed. The building blocks of GRIP architecture are called clusters and include an energy-management system (EMS)-controlled transmission grid in the core and distribution grids, micro-grids, and smart buildings and homes on the periphery; all of which are hierarchically structured. The layered architecture of GRIP allows a seamless transition from the present to the future and plug-and-play interoperability. The basic functions of a cluster consist of ① dispatch, ② smoothing, and ③ mitigation. A risk-limiting dispatch methodology is presented; a new device, called the electric spring, is developed for smoothing out fluctuations in periphery clusters; and means to mitigate failures are discussed.
Pub.: 16 Mar '16, Pinned: 02 Feb '17
Abstract: Using data from a survey of households in 11 OECD countries, this paper investigates the determinants of preferences for a completely green residential electricity system. Three important questions are addressed: (i) how much are households willing to pay to use only renewable energy? (ii) does willingness-to-pay (WTP) vary significantly across household groups and countries? and (iii) what drives the decision to enter the (hypothetical) market for green energy and, given entry, what drives the level of WTP? The analysis here differs from previous studies on green energy in two ways: first, data and analyses are comparable across countries and second, a comprehensive attempt is made to understand 0 WTP, and to accommodate—using a censored quantile regression (CQR) framework—unobserved heterogeneity. The survey data indicate a low WTP, at 11–12 % of current electric bill. This study also addresses a key question: how important is income for understanding WTP, relative to more “attitudinal” determinants? The effect of income overall appears ambiguous, with Tobit-like models indicating that income is not significant while the CQR indicates that income exerts a significant effect near the center of the distribution of WTP. Across all frameworks used, a key determinant of WTP appears to be environmental attitudes, particularly membership in an environmental organization.
Pub.: 04 Jan '15, Pinned: 02 Feb '17
Abstract: Publication date: November–December 2016 Source:Renewable Energy Focus, Volume 17, Issue 6 Author(s): Martin Pickard Martin Pickard, investment director at Low Carbon, looks at the opportunities for renewable energy investment projects at home and abroad.
Pub.: 26 Dec '16, Pinned: 02 Feb '17
Abstract: With a global market share of about 90%, crystalline silicon is by far the most important photovoltaic technology today. This article reviews the dynamic field of crystalline silicon photovoltaics from a device-engineering perspective. First, it discusses key factors responsible for the success of the classic dopant-diffused silicon homojunction solar cell. Next it analyzes two archetypal high-efficiency device architectures – the interdigitated back-contact silicon cell and the silicon heterojunction cell – both of which have demonstrated power conversion efficiencies greater than 25%. Last, it gives an up-to-date summary of promising recent pathways for further efficiency improvements and cost reduction employing novel carrier-selective passivating contact schemes, as well as tandem multi-junction architectures, in particular those that combine silicon absorbers with organic–inorganic perovskite materials.
Pub.: 12 Feb '16, Pinned: 02 Feb '17
Abstract: Renewables will soon dominate energy production in our electric power system. And yet, how to integrate renewable energy into the grid and the market is still a subject of major debate. Decentral Smart Grid Control (DSGC) was recently proposed as a robust and decentralized approach to balance supply and demand and to guarantee a grid operation that is both economically and dynamically feasible. Here, we analyze the impact of network topology by assessing the stability of essential network motifs using both linear stability analysis and basin volume for delay systems. Our results indicate that if frequency measurements are averaged over sufficiently large time intervals, DSGC enhances the stability of extended power grid systems. We further investigate whether DSGC supports centralized and/or decentralized power production and fi?nd it to be applicable to both. However, our results on cycle-like systems suggest that DSGC favors systems with decentralized production. Here, lower line capacities and lower averaging times are required compared to those with centralized production.
Pub.: 11 Feb '16, Pinned: 02 Feb '17
Abstract: Abstract The dominating view in the literature is that renewable electricity production increases the price variance on spot markets for electricity. In this paper, we critically review this hypothesis. Using a static market model, we identify the variance of the infeed from intermittent electricity sources (IES) and the shape of the industry supply curve as two pivotal factors influencing the electricity price variance. The model predicts that the overall effect of IES infeed depends on the produced amount: while small to moderate quantities of IES tend to decrease the price variance, large quantities have the opposite effect. In the second part of the paper, we test these predictions using data from Germany, where investments in IES have been massive in the recent years. The results of this econometric analysis largely conform to the predictions from the theoretical model. Our findings suggest that subsidy schemes for IES capacities should be complemented by policy measures supporting variance absorbing technologies such as smart-grids, energy storage, or grid interconnections to ensure the build-up of sufficient capacities in time.AbstractThe dominating view in the literature is that renewable electricity production increases the price variance on spot markets for electricity. In this paper, we critically review this hypothesis. Using a static market model, we identify the variance of the infeed from intermittent electricity sources (IES) and the shape of the industry supply curve as two pivotal factors influencing the electricity price variance. The model predicts that the overall effect of IES infeed depends on the produced amount: while small to moderate quantities of IES tend to decrease the price variance, large quantities have the opposite effect. In the second part of the paper, we test these predictions using data from Germany, where investments in IES have been massive in the recent years. The results of this econometric analysis largely conform to the predictions from the theoretical model. Our findings suggest that subsidy schemes for IES capacities should be complemented by policy measures supporting variance absorbing technologies such as smart-grids, energy storage, or grid interconnections to ensure the build-up of sufficient capacities in time.
Pub.: 01 Jul '16, Pinned: 02 Feb '17
Abstract: In today's world, the prices of fossil fuels are increasing day-;by-;day, the availability of non-;renewable fuels is depleting and pollution is causing major harm to the environment and health of living organisms. There is a crucial need for using new ecofriendly and renewable fuels. Bioenergy production from microalgae has attracted the most attention as increasing energy access and energy security are seen as key actions for reducing poverty, and access to modern energy services as electricity or liquid fuels is a basic requirement to improve living standards. Biophotovoltaics are "living solar panels" which generate electricity by capturing sunlight. They are biological electrochemical systems that function in a way similar to microbial fuel cell. Biophotovoltaics use photosynthesis of algae and moss along with light and water to generate electricity or renewable energy along with some by-;products. Algae based solar panels and algae covered lily pads can play a significant role in offshore power generation. As algal cells have excess electrons being stored inside during daylight hours, biophotovoltaics power station can generate energy during the night also. This article discusses the potential of algae, moss, lotus and lily as biosubstrate for hydrogen and green electricity production.
Pub.: 30 Jun '16, Pinned: 02 Feb '17
Abstract: Roadmaps towards sustainable bioeconomy, including the production of biofuels, in many EU countries mostly rely on biomass use. However, although biomass is renewable, the efficiency of biomass production is too low to be able to fully replace the fossil fuels. The use of land for fuel production also introduces ethical problems in increasing the food price. Harvesting solar energy by the photosynthetic machinery of plants and autotrophic microorganisms is the basis for all biomass production. This paper describes current challenges and possibilities to sustainably increase the biomass production and highlights future technologies to further enhance biofuel production directly from sunlight. The biggest scientific breakthroughs are expected to rely on a new technology called "synthetic biology", which makes engineering of biological systems possible. It will enable direct conversion of solar energy to a fuel from inexhaustible raw materials: sun light, water and CO2. In the future, such solar biofuels are expected to be produced in engineered photosynthetic microorganisms or in completely synthetic living factories.
Pub.: 17 Dec '15, Pinned: 02 Feb '17
Abstract: The U.S. shared solar market is poised for growth, boosted by initiatives supported by state and federal agencies, customers, contractors, and utilities. Full-scale adoption will require addressing political and economic barriers, which vary between states and program models. Investor-owned utilities will be working with regulators to define enabling policies in the coming years, while municipal and cooperative utilities will continue to pilot programs.
Pub.: 28 May '16, Pinned: 02 Feb '17
Abstract: The acceleration of new technology venture launch and growth is an important and rapidly growing field of practice for university-based accelerators, incubators, and technology transfer offices. Based on four comparative case studies of fast-launching clean tech startups in the USA (two of which were university-affiliated), this paper explains how some technology startups are able to develop innovative products, form organizations, internationalize, and release products into global markets very rapidly, and highlights implications for university-sourced ventures. Findings show that two processes, “product emergence” and “organization emergence,” have to be managed strategically, with time as a critical variable to be considered. This paper suggests that there are dynamic tensions between temporal, financial, and human resources in the technology startup process. To start up quickly, the new international technology venture compresses two parallel timelines: product launch and organization launch, which can also accelerate the internationalization process. This study identifies the organizational formation pivot as a risky but necessary transition from a lean, informal, fast-paced technology development project to a structured, legally compliant organization, in the case of a university-sourced venture fully independent from the university that spawned it, that can be trusted for transactions and investment.
Pub.: 19 Jul '16, Pinned: 31 Jan '17
Abstract: There are currently strong incentives for increased use of renewable fuels in the transport sector worldwide. However, some bioethanol and biodiesel production routes have limitations with regard to resource efficiency and reduction of greenhouse gases. More efficient biofuel systems are those based on lignocelluloses and novel conversion technologies. A complementary strategy to these is to increase the production of biogas from the digestion of organic residues and energy crops, or from byproducts of ethanol and biodiesel production. Compared with other biomass-based vehicle fuels available so far, biogas often has several advantages from an environmental and resource-efficiency perspective. This provides the motivation for further technological development aiming to reduce costs and thereby increased economic competitiveness of biogas as a vehicle fuel.
Pub.: 27 Nov '07, Pinned: 01 Feb '17
Abstract: Climate change mitigation, economic growth and stability, and the ongoing depletion of oil reserves are all major drivers for the development of economically rational, renewable energy technology platforms. Microalgae have re-emerged as a popular feedstock for the production of biofuels and other more valuable products. Even though integrated microalgal production systems have some clear advantages and present a promising alternative to highly controversial first generation biofuel systems, the associated hype has often exceeded the boundaries of reality. With a growing number of recent analyses demonstrating that despite the hype, these systems are conceptually sound and potentially sustainable given the available inputs, we review the research areas that are key to attaining economic reality and the future development of the industry.
Pub.: 27 Jul '10, Pinned: 01 Feb '17
Abstract: This paper aims to identify the lessons that should be learnt from how biofuels have been envisioned from the aftermath of the oil shocks of the 1970s to the present, and how these visions compare with biofuel production networks emerging in the 2000s. Working at the interface of sustainable innovation journey research and geographical theories on the spatial unevenness of sustainability transition projects, we show how the biofuels controversy is linked to characteristics of globalised industrial agricultural systems. The legitimacy problems of biofuels cannot be addressed by sustainability indicators or new technologies alone since they arise from the spatial ordering of biofuel production. In the 1970-80s, promoters of bioenergy anticipated current concerns about food security implications but envisioned bioenergy production to be territorially embedded at national or local scales where these issues would be managed. Where the territorial and scalar vision was breached, it was to imagine poorer countries exporting higher-value biofuel to the North rather than the raw material as in the controversial global biomass commodity chains of today. However, controversy now extends to the global impacts of national biofuel systems on food security and greenhouse gas emissions, and to their local impacts becoming more widely known. South/South and North/North trade conflicts are also emerging as are questions over biodegradable wastes and agricultural residues as global commodities. As assumptions of a food-versus-fuel conflict have come to be challenged, legitimacy questions over global agri-business and trade are spotlighted even further. In this context, visions of biofuel development that address these broader issues might be promising. These include large-scale biomass-for-fuel models in Europe that would transform global trade rules to allow small farmers in the global South to compete, and small-scale biofuel systems developed to address local energy needs in the South.
Pub.: 22 Apr '14, Pinned: 01 Feb '17
Abstract: Social and economic indicators can be used to support design of sustainable energy systems. Indicators representing categories of social well‐being, energy security, external trade, profitability, resource conservation, and social acceptability have not yet been measured in published sustainability assessments for commercial algal biofuel facilities. We review socioeconomic indicators that have been modeled at the commercial scale or measured at the pilot or laboratory scale, as well as factors that affect them, and discuss additional indicators that should be measured during commercialization to form a more complete picture of socioeconomic sustainability of algal biofuels. Indicators estimated in the scientific literature include the profitability indicators, return on investment (ROI) and net present value (NPV), and the resource conservation indicator, fossil energy return on investment (EROI). These modeled indicators have clear sustainability targets and have been used to design sustainable algal biofuel systems. Factors affecting ROI, NPV, and EROI include infrastructure, process choices, and financial assumptions. The food security indicator, percent change in food price volatility, is probably zero where agricultural lands are not used for production of algae‐based biofuels; however, food‐related coproducts from algae could enhance food security. The energy security indicators energy security premium and fuel price volatility and external trade indicators terms of trade and trade volume cannot be projected into the future with accuracy prior to commercialization. Together with environmental sustainability indicators, the use of a suite of socioeconomic sustainability indicators should contribute to progress toward sustainability of algal biofuels.
Pub.: 10 May '16, Pinned: 01 Feb '17
Abstract: Publication date: Available online 7 January 2017 Source:International Journal of Hydrogen Energy Author(s): Mehdi Mehrpooya, Mohammad Mehdi Moftakhari Sharifzadeh, Mahsa Rajabi, Mortaza Aghbashlo, Meisam Tabatabai, Soleiman Hosseinpour, Seeram Ramakrishna This study was aimed at proposing a novel integrated process for co-production of hydrogen and electricity through integrating biomass gasification, chemical looping combustion, and electrical power generation cycle with CO2 capture. Syngas obtained from biomass gasification was used as fuel for chemical looping combustion process. Calcium oxide metal oxide was used as oxygen carrier in the chemical looping system. The effluent stream of the chemical looping system was then transferred through a bottoming power generation cycle with carbon capture capability. The products achieved through the proposed process were highly-pure hydrogen and electricity generated by chemical looping and power generation cycle, respectively. Moreover, LNG cold energy was used as heat sink to improve the electrical power generation efficiency of the process. Sensitivity analysis was also carried out to scrutinize the effects of influential parameters, i.e., carbonator temperature, steam/biomass ratio, gasification temperature, gas turbine inlet stream temperature, and liquefied natural gas (LNG) flow rate on the plant performance. Overall, the optimum heat integration was achieved among the sub-systems of the plant while a high energy efficiency and zero CO2 emission were also accomplished. The findings of the present study could assist future investigations in analyzing the performance of integrated processes and in investigating optimal operating conditions of such systems.
Pub.: 13 Jan '17, Pinned: 01 Feb '17
Abstract: Deliberate halide exchange between unstable intermediate HPbI2Br and nonstoichiometric FAI is employed to produce high-quality FAPbI3–xBrx (x ≈ 0.44), which eliminates the use of antisolvent dripping and other post-treatment techniques. The obtained perovskite thin film demonstrates high crystallinity and a large and compact crystal domain up to 2–3 µm. The corresponding device shows power conversion efficiency of up to around 19.0%, with reliable stability and reproducibility.
Pub.: 30 Jan '17, Pinned: 01 Feb '17
Abstract: The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules in hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si. Copyright © 2017 John Wiley & Sons, Ltd.
Pub.: 30 Jan '17, Pinned: 01 Feb '17
Abstract: The replacement of fossil fuels by biofuels could be an important means of reducing net carbon dioxide (CO2) emission. An estimation of the CO2 mitigation efficiency of biofuel systems depends on the method and assumptions used. Here, different parameters and methods are discussed for comparing fossil-fuel- and biofuel-based systems. Three parameters are suggested: the monetary cost, the primary energy cost and the biofuel cost of CO2 mitigation. They are defined as the difference in monetary expenditure, primary energy use and biofuel use between the compared systems, divided by the difference in net CO2 emission between the systems. Cogeneration and separate production of electricity and heat is then compared using these parameters and the methods of multi-functional products or subtraction. In both methods, either electricity or heat is regarded as the main product and the other is regarded as a by-product. The multi-functional method is preferable due to its transparency as both the main product and the by-product are part of the functional unit. Using heat as the main product illustrates the typical situation that the heat demand limits the use of cogeneration. When comparing systems the output from them should not differ. If the by-product is not fully, cogenerated part of the by-product has to be produced separately. A logical choice for producing this part of the by-product is to use a similar fuel and technology as used for cogeneration.
Pub.: 20 May '06, Pinned: 01 Feb '17
Abstract: Two p-type conjugated polymers with disparate optical and electronic properties, PB3T and PB2T, were developed and applied in fullerene-free polymer solar cells (PSCs). The photovoltaic performance of the PB3T-based PSC device processed by anisole achieved a high power conversion efficiency of 11.9% with a Jsc of 18.8 mA cm−2 and Voc of 1.00 V.
Pub.: 23 Jan '17, Pinned: 01 Feb '17
Abstract: Abstract Renewable energy technology (RET) projects face many difficulties and challenges during their development process, especially in terms of securing financing. In an effort to address these challenges, the International Renewable Energy Agency has developed different tools such as the Project Navigator, which provides developers with the necessary skills and knowledge to identify and plan a successful RET project, and prepare high-quality project proposals which are attractive to financing institutions.AbstractRenewable energy technology (RET) projects face many difficulties and challenges during their development process, especially in terms of securing financing. In an effort to address these challenges, the International Renewable Energy Agency has developed different tools such as the Project Navigator, which provides developers with the necessary skills and knowledge to identify and plan a successful RET project, and prepare high-quality project proposals which are attractive to financing institutions.
Pub.: 06 Jan '17, Pinned: 31 Jan '17
Abstract: A simple and robust suction technique is proposed for vacuum cleaning based on an innovative water filtration method for dry, wet, and water swab modes. The technique relies on applying vacuum above the free surface of water to drive the dust-laden airstream to be released at constant depth below the water surface. Unlike conventional vacuum cleaner types, experimental measurements revealed that a high negative suction pressure availability and low exhaust air temperature with negligible and irrelevant increase in humidity levels were maintained regardless of the filling state. The proposed technique thus ensures more efficient utilization and conservation of energy.
Pub.: 01 Jan '16, Pinned: 31 Jan '17
Abstract: The objective of this study was to evaluate the potential of near-infrared (near IR) spectroscopy associated with multivariate statistics to distinguish charcoal produced from wood of planted and native forests in Brazil. Timber forest species from the Cerrado (Cedrela sp., Aspidosperma sp., Jacaranda sp., and Apuleia sp.) and Eucalyptus clones from forestry companies (Vallourec steel producer and Cenibra pulp producer) were pyrolyzed under well controlled laboratory scale conditions at the final temperatures of 300 (573,15), 500 (773,15) and 700 °C (973,15 K), respectively. Fifteen charcoals of each species were produced for each temperature leading to heighten controlled pyrolysis treatments and finally 270 charcoal samples (3 treatments × 15 repetitions × 6 materials). Principal component analysis (PCA) and partial least-squares regression (PLS-R) were carried out in the spectra recorded from charcoal specimens. Near IR spectroscopy associated with PCA was not able to differentiate the charcoals produced from native and planted woods if the 270 samples were considered in the same analysis. However, the separation of native and planted charcoal was achieved when the samples were analyzed separately by final pyrolysis temperature. Thus, the prediction of native or planted classes by PLS-R presented better performance for samples pyrolyzed at 300 °C, followed by those at 500 °C, 700 °C, and all together.
Pub.: 03 Jan '17, Pinned: 31 Jan '17