Analysis of Inter-seasonal Heat Fluxes in Soils

AbstractAssessment of the practical implementation of systems for subsurface inter-seasonal storage and recovery of solar energy requires a modelling capability which can represent heat transfer processes at the soil surface, at depth in the soil profile, and within the energy collector system itself. This study presents initial findings related to the development of both analytical and numerical tools to represent various components of such inter-seasonal heat storage facilities. In particular two aspects are considered; firstly the use of widely available averaged meteorological data to be employed in an analytical solution of a simplified version of the problem and secondly the use of a more comprehensive finite element solution to explore the detailed thermal response of the ground in terms of seasonal energy storage. Initial comparisons against field measurements from a large scale demonstration project (undertaken by others) are presented and preliminary conclusions related to the key factors affecting the representation of the surface boundary condition made. The analytical approach developed appears to offer a representative and practical way of estimating initial conditions for both initial assessment of potential for energy collection and storage and for use in defining initial conditions in any subsequent numerical analysis of a detailed inter-seasonal heat storage facility

Vapour transfer in unsaturated compacted bentonite

Results of an experimental and theoretical investigation of heat and moisture movement in unsaturated MX-80 bentonite are presented. A thermo-hydraulic cell that allows measurement of transient temperatures and facilitates the determination of pseudo-transients of moisture content, dry density and chemical composition has been used to perform thermal gradient tests. Results of a number of tests are presented, and observation of the accumulation of chloride ions near the hot end clearly indicates that there is a cycle of vapour and liquid moisture movement, with vapour moving from hotter to cooler regions, condensing, and then moving as liquid towards the hotter regions. An empirical method is applied to calculate approximate vapour fluxes using measured variations in chloride ion concentration and moisture content with time. The vapour fluxes calculated empirically are found to be lower than those determined by some existing vapour flow theories. Subsequently, an existing vapour flow model is modified to represent the observed vapour fluxes more closely

Physicochemical composition of wastes and co-located environmental designations at legacy mine sites in the south west of England and Wales: Implications for their resource potential

© 2016 This work examines the potential for resource recovery and/or remediation of metalliferous mine wastes in the south west of England and Wales. It does this through an assessment of the physicochemical composition of several key metalliferous legacy mine waste piles and an analysis of their co-location with cultural, geological and ecological designations. Mine waste samples were taken from 14 different sites and analysed for metal content, mineralogy, paste pH, particle size distribution, total organic carbon and total inorganic carbon. The majority of sites contain relatively high concentrations (in some cases up to several % by mass) of metals and metalloids, including Cu, Zn, As, Pb, Ag and Sn, many of which exceed ecological and/or human health risk guideline concentrations. However, the economic value of metals in the waste could be used to offset rehabilitation costs. Spatial analysis of all metalliferous mine sites in the south west of England and Wales found that around 70% are co-located with at least one cultural, geological and ecological designation. All 14 sites investigated are co-located with designations related to their mining activities, either due to their historical significance, rare species assemblages or geological characteristics. This demonstrates the need to consider the cultural and environmental impacts of rehabilitation and/or resource recovery on such sites. Further work is required to identify appropriate non-invasive methodologies to allow sites to be rehabilitated at minimal cost and disturbance

Assessment of health and ecological impact of policy on a legacy contamination case study

Background and objective: to investigate the effect of policy decisions on the health and ecological impact of pollution in an industrial area.Methods: a sustainability assessment methodology is applied to study the impacts of pollution in an industrial area of Bristol, UK. The effects of several regulatory/policy-related changes on a smelting facility sited in Avonmouth are investigated. Impacts considered in the investigation relate to levels of air pollution, human health effects and impacts on the local ecology. In this study the main driver or key question addressed is: what are the implications of various emission policies on ecological and health impacts? Several scenarios which represent a suite of regulatory changes imposed on the smelter over the operating period are considered. Firstly, a scenario models fate and transport of emissions with real site data. A second scenario considering constant emissions at 2002 levels investigates the impact of the smelter if a high level of intervention had been made from the start of the operations. A third scenario with constant emissions at peak levels allows consideration of the potential impacts if none of the interventions had been implemented.Results: actual Cd, PM10, As, Zn and Pb emissions data and associated information on the operating parameters and regulatory policies during each stage of the operating period are identified. Life cycle assessment modelling is carried out to examine the environmental burdens and associated life cycle impacts of the smelting operations on the local area and the wider environment. Air dispersion/deposition modelling is performed to identify the fate and transport of pollutants in the surrounding area. Results of this modelling work are then used in ecological impact assessment and human health impact analysisConclusion: analysis of the scenarios considered allows an assessment of the impact of the policy decisions on human and ecological healt