Making the Red One Green – Renewable Heat from Abandoned Flooded Mines

Abandoned mines are often allowed to flood, sometimes overflowing at the surface to form discharges of potentially contaminated (often ochreous, acidic or metal-rich) mine water. Other such mines are actively pumped and managed to prevent contaminated water overspilling at the surface. They are usually regarded as environmental or economic liabilities. At increasing numbers of locations throughout the world, the huge reservoir of warm(ish) water contained in these mines is being utilised as a thermal resource or store, providing “green” space heating or cooling. The underground network of tunnels and shafts provides a heat exchange interface with the rocks in the mined area. In this way, it is possible to convert an ochreous reddish-orange environmental liability into a green renewable energy asset. Five main factors hinder the adoption of mine water as a thermal resource: (i) the lack of proven heating and cooling demand in the vicinity of some mines; (ii) the major investment required in district heating/cooling systems to optimally utilise the resource; (iii) legislative and licensing uncertainty; (iv) the perceived risk of ochre/metal precipitate clogging of heat exchangers and injection wells; (v) the perceived risk of rapid thermal breakthrough of re-injected thermally spent water at the production well. This paper examines how these issues have been tackled at a number of European mine water sites. “Will all great Neptune's ocean wash this blood clean from my hand? No; this my hand will rather the multitudinous seas incarnadine, making the green one red" William Shakespeare, Macbeth, Act II, Scene

UIEGA and the rise and rise of gaming and gambling in the UK

The paper explores gaming and gambling cultures in the UK and US arguing that they are ripe for a renewed sociological and criminological attention

Modelling dynamic decision making with the ACT-R cognitive architecture

This paper describes a model of dynamic decision making in the Dynamic Stocks and Flows (DSF) task, developed using the ACT-R cognitive architecture. This task is a simple simulation of a water tank in which the water level must be kept constant whilst the inflow and outflow changes at varying rates. The basic functions of the model are based around three steps. Firstly, the model predicts the water level in the next cycle by adding the current water level to the predicted net inflow of water. Secondly, based on this projection, the net outflow of the water is adjusted to bring the water level back to the target. Thirdly, the predicted net inflow of water is adjusted to improve its accuracy in the future. If the prediction has overestimated net inflow then it is reduced, if it has underestimated net inflow it is increased. The model was entered into a model comparison competition-the Dynamic Stocks and Flows Challenge-to model human performance on four conditions of the DSF task and then subject the model to testing on five unseen transfer conditions. The model reproduced the main features of the development data reasonably well but did not reproduce human performance well under the transfer conditions. This suggests that the principles underlying human performance across the different conditions differ considerably despite their apparent similarity. Further lessons for the future development of our model and model comparison challenges are considered

Sums and Products with Smooth Numbers

We estimate the sizes of the sumset A + A and the productset A $\cdot$ A in the special case that A = S (x, y), the set of positive integers n less than or equal to x, free of prime factors exceeding y.Comment: 12 page

Social choice theory, game theory, and positive political theory

We consider the relationships between the collective preference and non-cooperative game theory approaches to positive political theory. In particular, we show that an apparently decisive difference between the two approachesthat in sufficiently complex environments (e.g. high-dimensional choice spaces) direct preference aggregation models are incapable of generating any prediction at all, whereas non-cooperative game-theoretic models almost always generate predictionis indeed only an apparent difference. More generally, we argue that when modeling collective decisions there is a fundamental tension between insuring existence of well-defined predictions, a criterion of minimal democracy, and general applicability to complex environments; while any two of the three are compatible under either approach, neither collective preference nor non-cooperative game theory can support models that simultaneously satisfy all three desiderata

Sustainability of thermal energy production at the flooded mine workings of the former Caphouse Colliery, Yorkshire, United Kingdom

Abandoned, flooded, coal mine workings are an artefact of fossil fuel exploitation that can be repurposed as a renewable energy resource. The warm subsurface waters that fill former workings can be developed to provide efficient and low-carbon heat generation using ground source heat pumps. In order to determine the long-term suitability of flooded mine workings as a sustainable thermal resource we have to understand the hydrological components of the system and how they interact in response to exploitation-related disturbance. We investigate pump induced mixing dynamics at the former Caphouse Colliery, which has been pumped since 1996 for regional water level management but only recently started to be explored as a thermal resource. Initial findings from the first 6 months of study show virtually no variation in physiochemical, major ion or stable isotope values. However, placed in context with archived values from 2004 to the present, we see a general pattern of mine water quality recovery punctuated by a doubling of Cl− values (150 mg/l to > 300 mg/l) which may suggest recent ingress of deeper-sourced saline waters. This is supported by O and H isotopic values, which are indicative of ancient, perhaps Late Pleistocene, confined waters. Sulphur isotope values (19.7–23.8‰) are abnormally high as compared to typical values for Carboniferous Coal Measures (0–10‰). There is no simple explanation, so further data collection and investigation are required, though we note that these values are similar to Lower Carboniferous seawater values. The relative stability of recent parameters suggests that Caphouse waters represent a dependable thermal resource. However, much about the hydrogeology of the Caphouse system is still uncertain, so further work is required to check the persistence of recent trends

Data Mining in Electronic Commerce

Modern business is rushing toward e-commerce. If the transition is done properly, it enables better management, new services, lower transaction costs and better customer relations. Success depends on skilled information technologists, among whom are statisticians. This paper focuses on some of the contributions that statisticians are making to help change the business world, especially through the development and application of data mining methods. This is a very large area, and the topics we cover are chosen to avoid overlap with other papers in this special issue, as well as to respect the limitations of our expertise. Inevitably, electronic commerce has raised and is raising fresh research problems in a very wide range of statistical areas, and we try to emphasize those challenges.Comment: Published at http://dx.doi.org/10.1214/088342306000000204 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Characterisation of hydraulic and hydrogeochemical processes in a reducing and alkalinity-producing system (RAPS) treating mine drainage, South Wales, UK

A series of tracer tests has been carried out in the compost and limestone Tan-y-Garn Reducing and Alkalinity-Producing System (RAPS), designed to treat iron-rich net acidic mine water (mean pH 6.18, Fe = 47 mg L-1, alkalinity 1.70 meq L-1 and mineral acidity 1.82 meq L-1) in South Wales, UK. Conservative tracer breakthrough time in the RAPS basal effluent is approximately inversely related to throughflow rate. Repeat tracer tests indicate a long term decrease in hydraulic conductivity, but not in total porosity. A specific sodium chloride tracer test from June 2008 is reported, when 15 kg salt was added to a raw mine water inflow rate of 0.87 L s-1. Electrical conductivity and major ion chemistry were monitored for a 170 hour period. Sodium exhibited a retardation of 1.15 to 1.2 in the RAPS medium relative to chloride, due to cation exchange. Simple 1-D advection-diffusion analytical modelling succeeded in simulating the early portion of tracer breakthrough in the RAPS effluent. More complex analytical modelling, accounting for (i) mixing and dilution effects in the supernatant water input signature and (ii) matrix diffusion effects, was found to be required to adequately simulate the later-stage tail of the breakthrough curve in the RAPS effluent