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GEOTHERMAL ENERGY IN MINING

Dr Martin PreenePreene Groundwater ConsultingJune 2014

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SYNOPSIS

Synopsis

• What are geothermal systems?

• Conventional applications of geothermal systems

• Mining geothermal applications to date

• Potential geothermal applications on mining projects

• Challenges and business opportunities

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PRACTICE PROFILE

Preene Groundwater Consulting is the Professional Practice of Dr Martin Preene and provides specialist advice and design services in the fields of dewatering, groundwater engineering and hydrogeology to clients worldwide

Dr Martin Preene has more than 25 years’ experience on projects worldwide in the investigation, design, installation and operation of groundwater control and dewatering systems. He is widely published on dewatering and groundwater control and is the author of the UK industry guidance on dewatering (CIRIA Report C515 Groundwater Control Design and Practice) as well as a dewatering text book (Groundwater Lowering in Construction: A Practical Guide to Dewatering)

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GEOTHERMAL SYSTEMS

• Geothermal systems are an established method of producing low carbon and cost effective heating, cooling and sometimes electricity by exchanging heat energy with the ground

• Opportunities for exploitation of geothermal energy are controlled by the nature of the heat reservoir, including peak available temperature.

• The vast majority of opportunities for geothermal energy from mines will be for heat energy, not electricity

• Conventional applications outside of the mining industry are typically divided into two types

– Open loop systems– Closed loop systems

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OPEN LOOP GEOTHERMAL SYSTEMS

• Geofluid (groundwater, brine or steam) is extracted via ground collectors in the form of wells or intakes

• Fluid is passed through heat transfer system and is then disposed of (at a different temperature) either to waste or by re-injection back into the original reservoir

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CLOSED LOOP GEOTHERMAL SYSTEMS

• No fluid is extracted from the heat reservoir

• Ground collectors take the form of a loop of pipework through which heat transfer fluid is circulated

• Heat is exchanged between the ground and the ground collector

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MINING GEOTHERMAL APPLICATIONS TO DATEDate Location DescriptionEarly 1980s USA – Henderson molybdenum mine Minewater used for direct heating of mine ventilation air to prevent icing of shafts and equipment

and to control mine working temperatures

1984 Germany – Heinrich coal mine 350 kW capacity, used to heat nursing home

Late 1980s Canada – Springhill, Nova Scotia Flooded underground coal mine workings used to heat and cool several buildings

1994 Germany – abandoned tin mine Used to heat a high school

1995 USA – Park Hills, Missouri Production bore penetrating to a flooded lead mine. Used to heat and cool a Municipal Building

1997 Germany – abandoned tin mine Used to heat a museum building for mine visitors

1998 Norway – Folldal Mine, Hedmark County

Underground cavern in disused mine heated by a closed loop ground collector in a 600 m deep flooded shaft

1999 UK – Shettleston, Scotland Borehole drilled into flooded underground coal mine workings to heat 16 residential properties

2000 UK – Lumphinan, Scotland Borehole drilled into flooded underground coal mine workings to heat 16 residential properties

2000 Germany – Zollverein coal mine, Katernberg, Essen

Used to heat a school of design

2007 Germany – Shaft 302, Marienberg Mine, Sachsen

Minewater extracted from disused uranium mine used to heat a swimming pool

2006 Canada – Goyer Quarry, Quebec Open loop system in a flooded open pit, feeding 36 apartments

2009 Russia – Novoshaktinsk Three wells, up to 400 m deep supplying heat pumps.2009 Netherlands – Heerlen Mine water from a flooded coal mine is supplied to a district heating energy station

2010 Spain – Hunosa Pumping system installed in shaft at mine closure stage and used to cool university buildings

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POTENTIAL APPLICATIONS ON MINING PROJECTS

Heat reservoir

Natural ground Backfilled workings

Mine waste Dewateringpumping

Flooded workings/pit

lakes

Phase

Exploration X

Operation X X X X

Closure X X X* X

Legacy X* X

Notes: * Where pumping is required as part of closure or environmental management measures

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APPLICATIONS – DEWATERING PUMPING

Underground workings

Open pit workings

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APPLICATIONS – FLOODED UNDERGROUND WORKINGS

Water pumped to disposal (suitable where active pumpingis needed to control minewaterlevels)

Water re-injected to workings

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APPLICATIONS – FLOODED PIT LAKES

Open loop system

Closed loop system

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CHALLENGES AND BUSINESS OPPORTUNITIES

• It seems a simple technology transfer exercise to apply geothermal technologies to mining projects, to give cost and carbon savings

• But less than 20 systems exist worldwide

• Lots more academic studies on geothermal potential, and some community projects at various stages of development

• The vast majority of current applications are on legacy or abandoned mines, not led by mining companies

• Very few applications on operational mining projects or led by mining companies

• Not clear why this is

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CHALLENGES AND BUSINESS OPPORTUNITIES

• Possible reasons for lack of uptake– Unit cost (kWh) is not competitive with existing sources of energy– Capital cost is problematic– Mining companies not focused on-site mine energy issues– Mine site demand for heating and cooling is limited– Unfamiliar technologies, lack of track record in mining industry

• Opportunity to promote the use of geothermal technology, either on individual sites or for clients with portfolios of sites

• The required skills are:– Energy management/demand assessment– Hydrogeology and geochemistry– Geothermal and M&E– Permitting and environmental assessment– Engineering and contracting

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BUSINESS OPPORTUNITIES

• Two types of potential clients – communities located over legacy mines and mining companies

• Communities– Funding issues– Have clear demand for heating and cooling– Track record of successful projects– Pit lakes as well as underground workings

• Mining companies– Need to understand/find demand for heat– Need to understand drivers – cost, carbon, community links– Easy wins are dewatering systems and exploration camps

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GEOTHERMAL ENERGY IN MINING

Dr Martin PreenePreene Groundwater ConsultingJune 2014