This article was originally published on Mining.com
Geothermal can be the energy solution for the Peruvian mining sector to optimize their energy management plan, reduce costs, enhance ESG and prioritize water consumption
Geothermal Energy: A Case for the Mining Sector in Peru
Mining has never been considered a "green” industry. The industry has made great bounds over the last decade but still struggles with public opinion, government policies, and societal shift toward green energy initiatives. The mining industry as a whole is very energy intensive, with one source stating that nearly 80 percent of the world's electricity is used by the mining industry, equivalent to the total sum of Australia, Mexico, South Korea, Italy, and Canada's energy use (The World Counts, 2022). While this figure is debatable (and certainly embodies a number of underlying assumptions), the overarching fact is that the mining industry is one of the most energy intensive industries in the world and most of this energy comes from burning fossil fuels, making the industry one of the largest sources of all CO2 emissions.
In an ever-changing global climate, with more pressure than ever to prioritize sustainable business operations, the mining sector must explore energy efficient solutions to offset energy consumption and optimize water resources.
In theory, mining may reduce its energy use and GHG emissions by utilizing a variety of clean energy options, including energy efficiency, energy recovery, renewable energy, and carbon capture. To completely address energy-related difficulties facing the mining industry, a combination of energy solutions will be needed.
Solar and wind have seen increased investment from the mining sector and are the most common renewable energy technology application in mining operations today. While both have advantages and contribute the industry, they both have significant setbacks as well. Both solar and wind require a backup energy source or expensive energy storage during intermittency (weather primarily), oftentimes defaulting to fossil fuels. However, geothermal as an energy source can circumvent these issues and has the potential to provide a sustainable, baseload means to offset consumption at a high-capacity factor. Geothermal development expands access to otherwise unobtainable water sources, as well as providing a mechanism for reinjection of water for optimization and waste reduction. This can reduce a mine’s reliance on diminishing freshwater supplies that are already highly sought after and vital to sustain local populations.
As outlined in our previous article, Mining’s Energy Challenge: A Case for Geothermal [link] there is a locational correlation between precious minerals being formed over time and geothermal resources which are produced from the same volcanic systems. In other words, the map of commercial scale geothermal power generation and opportunity closely overlaps existing mining infrastructure, and presents a compelling case for geothermal development.
A Deeper Look at Peru
There are at least 16 active volcanos in Southern Peru which indicates there is an accessible amount of heat to explore for geothermal applications. A gold or copper mine operating in Southern Peru could explore geothermal for power generation and energy independence. The capital exploration expenses associated with this would be further justified knowing that the mine can diversify the resource for applications such as heap leaching, desalination or perhaps become the next region for lithium extraction from geothermal brines. For the mining industry with operations in southern Peru, identifying the feasibility of geothermal would help determine the value it could yield in their efforts get in front of the energy transition.
Studies show geothermal potential of more than 3,000 MW in Peru (The Master Plan for Development of Geothermal Energy in Peru Final Report, JICA, 2012). For perspective, if even 60% of that potential was developed, Peru would rank in the top 5 countries worldwide with total geothermal power generation capacity, trailing behind world leaders such as the United States (3,722MW) and Indonesia (2,286MW) and the Philippines (1,928MW) (ThinkGeoEnergy, 2021).
Figure 1: Map overlay of Geothermal Potential in relation to major Mining Operations
Energy Development Company, a geothermal leader in the Philippines, has a vested interest in developing geothermal in Peru (EDC Peru). The company has plans to invest more than $1B USD to construct at least two geothermal plants in Arequipa and Moquegua. The tentative plan will be to initially produce 200 MW with potential to expand to up 350MW in future installments. Estimates show that the power plant in Arequipa alone can supply electricity to 385 thousand households, that is almost 90% of the families in Arequipa. Any additional plants would have the potential to directly supply mining operations or other industries in the area.
More than 50% of the geothermal energy potential in Peru is concentrated in the southern region of the country. Geothermal plants in this region could add up to 2% additional economic growth each year in the Arequipa region; directly impacting poverty reduction and community advancement. Estimates indicate this project alone would generate between 25% and 43% of additional, sustainable employment and dramatically enhance the well-being of the region, including the mining communities.
However, for this to be possible, public policies are required. These policies would include adding geothermal energy into the country’s energy plans and allow Peruvians to take advantage of the resource and the indirect benefits.
One way to fast track these policies would be to include the Peruvian mining sector as influential off-takers or produces of the geothermal energy.
Geothermal and Mining
The applications for geothermal in the mining industry are enormous, and vary based on the operation and exploited minerals. The following Lindal Diagram outlines some of the many applications as it correlates to the temperature of the resource (saturated steam or hot water).
Figure 2: Lindal Diagram - Mining Applications Using Geothermal Resources, Patsa 2015
The following will go into more detail on several applications for geothermal with examples including, heap leaching, desalination and lithium extraction.
Heap Leaching
Heap leaching is a low-cost process used in over 120 mines across the world to extract minerals from the raw ore. The chemical reactions involved in the process can be expedited through heating the heap. In many mines this may be done using gas/oil boilers where large quantities of the fuel are required and must be constantly transported over long distances to the mine. There are examples of mines using geothermal fluid as a heat source such as the Florida Canyon Mine in the state of Nevada, US.
Figure 3: Florida Canyon Mine operated by Argonaut Gold (https://www.argonautgold.com/English/assets/operations/Florida-Canyon/default.aspx)
Other mines have considered this as well such as the Collahuasi Copper Mine in Chile. They conducted a feasibility study using geothermal fluids for enhancing heap leaching on site. It was identified that a higher temperature geothermal resource could bring improvements to their current system which was heating raffinate to 35 degrees using diesel. The study indicated that Copper output levels could increase by an average of 1.2% per degree Centigrade change in the raffinate temperature. A separate study identified that heating cyanide could increase extraction by 5-7% in gold and silver mines depending on the temperature it is heated to (Bloomquist, 2006).
Desalination
Not only is freshwater required for various processes throughout mining operations, but it is also required to sustain the large numbers of mine workers in remote locations that often have restricted access to drinking water. More and more mines are turning to desalination to provide the required volumes of potable water for example, at Escondida, El Abro and Chuquicamata in Chile.
Geothermal can be used either to generate electricity to power a desalination plant, or the geothermal fluids themselves can be used to produce potable water. This type of solution is gaining interest as freshwater supplies are coming under increased pressure around the world. It could also be seen in mining regulations in the near future with countries such as Chile trying to make it a requirement for mines consuming more than 150 L/s to include desalination in their mining processes. Magnuvis, a clean-tech start up from New Zealand is pioneering a modular system that leverages geothermal and waste heat to generate power and desalinate water for multiple commercial or community use.
Lithium Extraction
Extracting lithium from geothermal waters has been found in Cornwall, Germany, New Zealand and the US. There has been recent development of geothermal projects focused on extracting lithium for the electric vehicle (EV) market in the Salton Sea of southern California which is widely recognized as a mature geothermal region.
Figure 4: Lithium Extraction from Geothermal Brines diagram in Salton Sea area of California (Controlled Thermal Resources)
Researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory published a review of past and current technologies for extracting minerals from geothermal brine. The review finds that geothermal brines in the Salton Sea region of California are expected to be a major domestic source of lithium in the future albeit with some significant infrastructure challenges to be optimized.
Beyond Electricity
If the development lifecycle of geothermal power generation seems unjustifiable, or the resource is just not hot enough, do not write it off entirely. Geothermal can be leveraged for more than just power generation. The diversity of applications that can be vetted for commercial viability might be more suited for heating and cooling, agriculture, and industrial process heating as illustrated below.
The benefits and applications of geothermal stretch far beyond electricity generation. Whether these aid in the bottom line of the mining operation or are made available to the neighboring communities to generate the coveted social license to operate, the benefits are glaring.
Regardless of whether the resource produces electricity or heat, and or the end use, the investment in this sustainable resource can lead to profitable outcomes such as renewable energy tax credits, or country-specific sustainability incentives. This is true before even considering the cost savings associated with offsetting expensive power purchases, fuel consumption or potential new revenue streams stemming from the heat or water.
Figure 5: Geothermal benefits beyond electricity
With so many mines/companies positioned to capitalize on geothermal resources, what is stopping them? Often it is found that without the appropriate expert advice, many people are either unaware of the benefits that could be provided by geothermal, or they have difficulty bringing it to the table as a credible solution with appropriate figures to support it. Other times people tend to write geothermal off as they associate it with high capital costs and therefore decide, without proper consideration of the business case, that they cannot afford it. With CDP’s analysis indicating that reported exposure to water-related risks in the mining sector amounted to $24.9 billion in 2018, and energy prices at their highest levels in decades, the real question should be - can they afford not to?
Applications
An example of a system that could be considered (depending on the resource available) would be a geothermal power plant to generate electricity for all of the mine’s electrical demands, with the spent geothermal fluid from the plant being used in a cascading system for heap leaching, desalination and space heating/cooling.
Figure 6: Cuajone mine complex was developed by Southern Pern Copper Corporation (Flour.com)
The politics of water use are sensitive and polarizing issues for Peru. In the context of resource development, such as mining, energy, and water management, water is one of the most contentious commodities. The mining sector has been known to consume significant amounts of water for ongoing operations. Initial geothermal development requires water as well, however, once developed can be a continuous source of water optimization, access, desalination, repurposing and wastewater management.
Water is used at every stage of the mining process, especially in hard rock mines, from removing waste from valuable minerals to cooling machinery to regulating dust. According to Ban Ki-moon, the Secretary-General of the United Nations, "water and energy are inexorably intertwined" in the energy sector. Energy generation, delivery, and usage all require water. Energy, on the other hand, is essential for the extraction and supply of potable water as well as for the security of water itself. When access to either is restricted or undermined, people worldwide - but especially the most disadvantaged and disenfranchised - suffer significant risks.
Many significant mining projects, including Conga (a $5 billion investment in gold), Ta Maria (a $1 billion investment in copper), and hydroelectric projects like Puno's Inambari (2,030 MWe), have been put on hold or delayed as a result of disputes with local communities, who cite water demand and the resulting socio-environmental impact as their primary concerns.
Many of the most desirable geothermal resources are found in places with significant mining potential and sparse water supplies. The societal difficulties resulting from the link between resource development/utilization and water conservation may be helped by geothermal developments' relatively low water demand. (Carmonal Geothermal Development Opportunities in Peru).
What if the mining companies developed geothermal resources within their existing leases and operations? They could provide access to the water obtained and repurposed from geothermal, and use this tangential operation to boost their ESG status, reduce emissions, power consumption, and provide employment for locals. We believe this could be the key to breaking through community resistance and expedite the social license to operate that often stands in the way of operations.
Furthermore, the multiple uses of the geothermal resource in this scenario would enhance the business case for the project significantly, with benefits being seen all through the mine’s operations. For example, the advantage of faster chemical recovery of the precious metals through heated heap leaching would boost operational efficiencies. Additionally, with the temperature enhancement, a mine company can operate a leaching pad throughout the year (typically stopping in the winter months due to freezing temperatures). This helps the operator generate more revenues and will give year-round employment opportunities to locals.
This is just an example case, however similar opportunities could be identified in mines all over the world such as in Peru, the US, and Australia. The processes involved in a mine’s operations will vary; however, all processes require energy or heat in some form so there will always be a demand for energy independence.
JRG Energy is a renewable energy, project management, engineering consulting firm with a rich history of geothermal experience. Our team can help mining operators navigate the wave of energy transition, help identify pathways of energy independence through renewable energy generation, specifically geothermal. For more information, visit: https://www.jrgenergy.com/geothermal-solutions-for-mining
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