Can you take the heat? – Geothermal energy in mining

Abstract

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, where the potential risks are understood, and where the economics are likely to be beneficial, where geothermal systems can be established while minimising additional capital costs. KEYWORDS Energy, Geothermal, Minewater INTRODUCTIONThe use of geothermal technologies to extract heat energy from the sub-surface environment, to provide heating and cooling or to generate electricity, is well established outside of the mining industry, yet to date it has seen relatively little uptake within the sector. As it relies on the same blend of geological and engineering skills which mining demands, this omission is rather puzzling, and begs the question whether it represents a considered rejection or merely oversight. In appropriate geological settings, with the correct engineering, geothermal energy can be an economic source of low carbon energy, able to displace traditional fossil fuelbased energy sources, either for use within a mine, for supply to living quarters or working areas on mine sites or for sale to third parties. This paper examines the proposition that the mining industry is ripe for a significant expansion of geothermal energy use.

Hydrochemical characterization of a mine water geothermal energy resource in NW Spain

“…The thermal resource potential of mine water is widely recognised, and a number of geothermal investigations at former mining sites (particularly coal mines) have either been completed, or are underway (Burnside et al, 2016a and b;Peralta et al, 2015;Preene and Younger, 2014;Hall et al, 2011;Hamm and Bazargan, 2010;Raymond and Therrien, 2007;Watzlaf and Ackman, 2006, among others).…”

A simple, low-cost approach to predicting the hydrogeological consequences of coalfield closure as a basis for best practice in long-term management

“…Beyond environmental protection issues, flooded mine workings may also represent resources, inasmuch as (where water quality permits) they may be used as water reservoirs (Ordoñez et al 2012) and / or as water sources for heat-pump systems providing lowcarbon space heating and cooling (e.g. Renz et al 2009;Preene and Younger 2014). …”

“…The insights into system behaviour gained from such exercises could well be valuable in future re-use of flooded voids as resources, for instance as water resource reservoirs (Ordoñez et al 2012) or as water sources for heat recovery / disposal as part of low-carbon heating systems (e.g. Renz et al 2009;Preene and Younger 2014).…”

A combined pumping test and heat extraction/recirculation trial in an abandoned haematite ore mine shaft, Egremont, Cumbria, UK

“…Mine water has been used for several decades for heating and cooling; reviews have been provided by Banks et al (2003Banks et al ( , 2004, Watzlaf and Ackman (2006), Hall et al (2011), Preene and Younger (2014), Ramos et al (2015), Bracke and Bussmann (2015) and Banks et al (2017). Among a number of mine water, heat pump systems operating worldwide can be listed: Park Hills, Missouri, USA (Watzlaf and Ackman 2006;DOE 2015), Springhill, Nova Scotia, Canada (Jessop 1995;Jessop et al 1995;Raymond et al 2008), Marywood University, Pennsylvania, USA (Korb 2012), several in Saxony, Germany (Ramos et al 2015), Henderson molybdenum mine, Empire, Colorado, USA (Watzlaf and Ackman 2006), Saturn coal mine, Czeladz, Poland (Malolepszy et al 2005;Tokarz and Mucha 2013), and Novoshakhtinsk, Russia (Rostov Regional Government 2011; Ramos et al 2015).…”