Does a Cleaner Thames Pass an Economic Appraisal?

Abstract

Due to substantial clean-up efforts, water quality in the River Thames in London has steadily improved over the last three decades. However, London's Victorian sewage system still discharges untreated sewage into the Thames, at times of moderate to heavy rainfall. This happens approximately 60 times every year, creating adverse environmental and amenity impacts on the river. Major and costly engineering works will be required to solve the sewage overflow problem. This paper reports the results of a stated preference study designed to value the multiple non-market benefits—eductions in sewage litter, risk to human health, and risk to fish populations—associated with a range of potential engineering solutions. Our findings indicate that household willingness to pay for these benefits is likely to be significantly greater than the projected costs per household of, at least, some potential technical solutions. Although arguably justifiable on economic grounds, the final decision on whether to proceed with such a large infrastructure project is unlikely to depend wholly on cost-benefit thinking, but involve complex trade-offs with other socially desirable criteria.     

Free convection to power‐law fluids from a vertical cone of variable surface temperature

Steady free convection laminar boundary‐layer flow about a heated vertical cone immersed in a quiescent power‐law fluid is investigated. Surface temperature is assumed to have a power‐law variation with the distance. Similarity solutions are obtained numerically for the boundary‐layer velocity and temperature profiles. Magnitudes of the velocity and temperature profiles are found to decrease with increasing values of the flow behaviour index and the surface temperature exponent. The effects of flow behaviour index and the generalized Prandtl number on the surface shear stress and heat flux are determined. Copyright © 2001 John Wiley & Sons, Ltd.     

A comprehensive review on pretreatment of microalgae for biogas production

Use of microalgal biomass for renewable energy production has gained considerable attention in the world due to increasing global energy demand and negative environmental impacts of nonrenewable fossil fuels. Anaerobic digestion is one of the renewable technologies that microalgal biomass is converted into biogas by anaerobic archea. One of the main drawbacks of using microalgal biomass for biogas production is that certain types of microalgae has rigid cell wall characteristics, which limits accessibility of anaerobic archea to microalgal intracellular organic matter during hydrolysis phase. This limitation lowers efficiency of biogas production from microalgal biomass. However, introducing pretreatment methods prior to anaerobic digestion provides disruption of rigid microalgal cell wall and improve biogas yields from microalgal biomass. The objective of this paper was to review current knowledge related to pretreatment methods applied prior to anaerobic digestion of microalgal biomass. Efficiency and applicability of pretreatment methods mainly depend on type of microalgae, cell wall characteristics, and cost and energy requirements during pretreatment process. In this review, various type of pretreatment methods applied to microalgal biomass was discussed in detail with background knowledge and literature studies in their potential on maximization of biogas yields and their cost effectiveness, which is important for large‐scale applications. In the view of current knowledge, it was concluded that each pretreatment method has a relative contribution to improvement in biogas production depending on the type of microalgae. However, energy and cost requirements are the main limitations for pretreatment. So, further studies should focus on reduction of cost and energy demand by introducing combined methods, novel chemicals, and on‐site or immobilized enzymes in pretreatment to increase feasibility of pretreatment prior to anaerobic digestion in industrial scale.     

Valuation of the historic environment: The scope for using economic valuation evidence in the appraisal of heritage-related projects

In this paper we consider the question, ‘What is the the scope for using results of economic valuation studies in the appraisal and assessment of heritage-related projects and programmes?’ This entails assessing the potential role and scope of ‘value transfer’, which is an approach to economic valuation that uses results of previous valuation studies (for example, travel cost or stated preference studies) in the appraisal of projects and programmes. A distinct appeal of value transfer is its expediency and value for money properties in relation to commissioning original valuation studies, which can enable greater use of economic values within decision making. Its potential role in the appraisal of heritage assets depends on whether it is deemed a reliable approach to economic valuation, and whether there is a sufficient body of economic valuation literature concerning the heritage sector. Correspondingly, we examine: (i) the applicability of economic valuation to the historic environment; (ii) the basis for value transfer; and (iii) the literature pertaining to the valuation of the historic environment. We also develop a case study, which demonstrates the use of value transfer in a heritage context. Overall there currently appears to be limited scope for value transfer applications in heritage-related appraisal and evaluation exercises. This is in part due to the heterogeneity and complexity of heritage assets. However, a more fundamental constraining factor is the current extent of heritage valuation literature; only 30 valuation studies were identified relating to the historic environment. We recommend that future work focuses on developing a database of valuation studies relating to the heritage sector, and on establishing a broader base of high-quality original heritage-related economic valuation studies. Moreover, where value transfer is applied in an appraisal and evaluation context to heritage assets, much emphasis should be placed on satisfying the criteria for identifying suitable valuation evidence from existing studies.     

Combustion characteristics and kinetics of diesel and canola oil samples

In this study, combustion and pyrolysis behavior of diesel and canola oil is investigated using thermal analysis techniques known as thermogravimetry (TG–DTG) and differential scanning calorimetry (DSC) at different heating rates. Reaction regions, peak temperatures, mass loss, heat flow rates, ignition temperatures, and specific heat of diesel and canola oil samples are determined using TG–DTG and DSC data. It was observed that as the heating rate of the reactions increased, peak temperatures of the reactions shift higher; implying that as the heating rate of the reactions increases the reactions lose their sensitivity. Five different kinetic methods were applied to determine combustion reaction parameters of the reactions. It was observed that averages of the activation energies of the samples are in the order of canola oil and diesel for different heating rates.     

Preparation and characterization of photocured thiol‐ene hydrogel: Adsorption of Au(III) ions from aqueous solutions

In this study, photocured a novel thiol‐ene hydrogels based on P(Penta3MP4/PEG‐DA/HEMA) were investigated for adsorption of Au(III) ions from aqueous solutions purposes. The photopolymerization kinetics of thiol‐ene‐based formulations was investigated by real‐time infrared spectroscopy. The chemical composition and surface morphology of hydrogels were also characterized. The effect of different parameters on Au(III) adsorption efficiency was examined in detail. Better adsorption behavior was achieved for Au(III) by P(Penta3MP4/PEG‐DA/HEMA) F1 hydrogels. The maximum uptake for Au(III) was at pH 0.5. Both Langmuir and Freundlich adsorption isotherm models were applied and the reusability of thiol‐ene hydrogels investigated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012