Can you take the heat? – Geothermal energy in mining

In 2013, there are less than 20 documented examples of operational geothermal systems on mine sites worldwide. This is surprising, since on remote mine sites, where fuels may have to be shipped in over great distances, heating and cooling from low-enthalpy geothermal sources may have a significant advantage in operational cost over conventional energy sources. A review of factors affecting the feasibility of geothermal systems on mining projects has been undertaken, and has identified the possible configurations of geothermal systems suitable for the exploration, operational and closure phases of mine development. The geothermal opportunities associated with abandoned or legacy mines are also discussed. The potential categories of heat reservoirs associated with mine sites are: natural ground; backfilled workings; mine waste; dewatering pumping; and flooded workings/pit lakes. The potentially lower operational costs for heating and cooling must be offset against the capital cost of a geothermal system. The focus for mine operators should therefore be on identifying at feasibility stage those projects where conditions are favourable for geothermal systems, the potential risks are understood, the economics are likely to be beneficial, and geothermal systems can be established while minimising additional capital costs

With Gay Greetings and Lesbian Solidarity: Transnational AIDS-activism and the Danish National Organization for Gays and Lesbians 1981-1994

AIDS-activism is an understudied area of Danish history, and the previous research made has only focused on the Danish government’s response to the epidemic. Using Signild Vallgårda’s theories of ‘problematization’ and ‘path dependency’, and Sidney Tarrow and Donatella della Porta’s theories of transnational activism, this article examines how the Danish National Organization for Gays and Lesbians developed AIDS-activism strategies at international conferences. By analyzing conference notes, meeting minutes, and campaign materials, this article finds that the AIDS-epidemic was mainly problematized as a discriminatory problem within the international organizations The Nordic Council for Homosexuals and the International Lesbian and Gay Association. This was caused by the organizations’ previous work with discrimination. A diffusion of AIDS-prevention strategies evolved within these international forums and while the diffusion of AIDS-prevention strategies mainly happened between European homosexual organizations, Danish AIDS-activists used American symbols to frame the AIDS-epidemic, such as the NAMES Project AIDS Memorial Quilt. The use of American symbols in the Danish AIDS-activism, might have made the American influence in the Danish AIDS-activism seem bigger.With Gay Greetings and Lesbian Solidarity: Transnational AIDS-activism and the Danish National Organization for Gays and Lesbians 1981-1994. AIDS-activism is an understudied area of Danish history, and the previous research made has only focused on the Danish government’s response to the epidemic. Using Signild Vallgårda’s theories of ‘problematization’ and ‘path dependency’, and Sidney Tarrow and Donatella della Porta’s theories of transnational activism, this article examines how The Danish National Organization for Gays and Lesbians developed AIDS-activism strategies at international conferences. By analyzing conference notes, meeting minutes, and campaign materials, this article finds that the AIDS-epidemic was mainly problematized as a discriminatory problem within the international organizations The Nordic Council for Homosexuals and the International Lesbian and Gay Association. This was caused by the organizations’ previous work with discrimination. A diffusion of AIDS-prevention strategies evolved within these international forums and while the diffusion of AIDS-prevention strategies mainly happened between European homosexual organizations, Danish AIDS-activists used American symbols to frame the AIDS-epidemic, such as the NAMES Project AIDS Memorial Quilt. The use of American symbols in the Danish AIDS-activism, might have made the American influence in the Danish AIDS-activism seem bigger

Water from abandoned mines as a heat source: practical experiences of open- and closed-loop strategies, United Kingdom

Pilot heat pump systems have been installed at two former collieries in Yorkshire/Derbyshire, England, to extract heat from mine water. The installations represent three fundamental configurations of heat exchanger. At Caphouse Colliery, mine water is pumped through a heat exchanger coupled to a heat pump and then discharged to waste (an open-loop heat exchange system). The system performs with high thermal efficiency, but the drawbacks are: (1) it can only be operated when mine water is being actively pumped from the colliery shaft for the purposes of regional water-level management, and (2) the fact that the water is partially oxygenated means that iron oxyhydroxide precipitation occurs, necessitating regular removal of filters for cleaning. At Markham Colliery, near Bolsover, a small amount of mine water is pumped from depth in a flooded shaft, circulated through a heat exchanger coupled to a heat pump and then returned to the same mine shaft at a slightly different depth (a standing column arrangement). This system’s fundamental thermal efficiency is negatively impacted by the electrical power required to run the shaft submersible pump, but clogging issues are not significant. In the third system, at Caphouse, a heat exchanger is submerged in a mine water treatment pond (a closed-loop system). This can be run at any time, irrespective of mine pumping regime, and being a closed-loop system, is not susceptible to clogging issues

Studying the impact of construction dewatering discharges to the urban storm drainage network(s) of Doha city using infoworks integrated catchment modeling (ICM)

The discharge of construction dewatering flows to the storm drainage network for disposal is a common activity in Qatar. The Dupuit empirical approach was utilized to establish various hypothetical dewatering scenarios on the basis of site classifications, which were modeled on 4 Case Study Areas of Doha’s Existing Surface Drainage Network in order to study the impact of dewatering discharge against an established baseline. The simulations were undertaken using InfoWorks Integrated Catchment Modeling (ICM) software for critical and non-critical rainfall events. The results indicated significant localized flooding in excess of the baseline conditions for scenarios exceeding 0.5 m3/sec flows, while individual catchments demonstrated variations and sensitivities on the basis of catchment properties and rainfall events. It is evident that dewatering discharge under unpredictable rainfall events poses various levels of risk to the city’s infrastructure, which is further exacerbated due to the massive scale of construction activity in the country and the rising ground water table in Greater Doha Area basin

Assessment of settlements caused by groundwater control

Lowering of groundwater levels by pumping increases vertical effective stress in the soil around an excavation. The resulting ground settlements are normally small, but in certain circumstances may be large enough to cause damage to surrounding structures. This paper describes the mechanism of these settlements and presents a simple risk assessment methodology for initial identification of zones where buildings may be at varying degrees of risk of damage. These risk zones can help to determine the extent of preconstruction building condition surveys needed, or to assess the need for settlement mitigation or avoidance measures. Potential uncertainties in the assessments are discussed. </jats:p