China recently announced its climate neutrality for 2060, while this is rising plenty of questions regarding Chinas future and existence of their hard coal mining industry. With an annual production of 4 bn t of hard coal, China remains the biggest producer of this resource. The consequences for the environment are tremendous and not just a national issue. It is a global one affecting everyone. Climate neutrality poses new challenges for this country with its abundance of resources. Hard coal is still the easiest and safest way to guarantee the supply of energy to its citizens, whereby energy security is a high priority (1). The switch to and the integration of renewable energies has already started and, according to the latest five-year plan, should become the main driver of growth in the coming years. The transition to a green development with a low carbon economy as one of the most important objectives is imminent (2). These developments will have a decisive impact on the next few years and will drive structural change forward. Since China also has large reserves of rare earths, which are required in particular for the construction of regenerative energy options (electric cars, solar panels and windmills). This presents the market for trade with new challenges. China has a market share of up to 97 % and is therefore clearly the dominant player in this trade area, which will become increasingly important worldwide in the future. But here, too, only one environmental problem is shifted to the next, since the recycling of rare earths is not really well developed and the factor of sustainability is a big question mark (3).
2 Mining around rare earths in China
A recently published case study of the environmental and social impacts of rare earth extraction in the Bayan Obo mine in Baotou, located in the western part of the Jiuyan area in Inner Mongolia/China, shows that in order to enable the construction of new, supposedly sustainably generating energy in one country or place, in other large areas pollutions are accepted over entire stretches of land (4). Generally speaking about China or anywhere else on earth, where 1 t of rare earth elements are produced, it can be stated that 60,000m³ of waste gas containing hydrochloric acid is also produced, as well as 200 m³ of acid-containing sewage water and 1 to 1.4 t of radioactive waste. Now thinking about the amounts that are produced in China – up to 85 to 90 % of the global production – the destroyed vegetation in intensive producing areas in China can be imagined (5).
Another example of Baotou shows that an artificial lake has been created there by discharging the polluted and toxic wastewater. The place is primarily known for refining and processing ores, which, among other things, creates the so-called bastnäsite concentrate. The processing of this ore is explained later in this article in more detail. The wastewater left over from this process destroys the vegetation of the soil and possible living beings (3, 4). In addition, the wastewater seeps into the groundwater, where it also pollutes the drinking water and causes possible diseases for the people living there (4). Even though there are attempts to put huge amounts of money into new wastewater recycling equipment, the recycling of rare earth itself is just at the beginning and far not advanced enough. Additionally to China’s own problems with non-recyclable waste, other countries, e. g., South Korea, member states of the EU, the USA and Japan, also send their waste illegally to China. In this way, they seemingly only have to deal with the positive leftover, while China gets more waste to handle (5).
Besides that, the occupational safety measures in China are known to be very low, especially in the mining sector. This often ends in accidents or even the death of employees and has an impact on the surrounding environment (6). This is just one of many examples, especially for this area. Another, recent study has focused on the effects of water-soluble particulate matter generated during rare earth processing. Here, the effects on human health were investigated, and it was found that there is a deterioration or inhibition of the development of cells and proteins within the lung. This can even lead to a standstill of the cell cycle and increase the development of diseases such as lung cancer (7).
Because China has the biggest resources of rare earths, its global share of renewable energies is currently estimated at 13.5 % (2018) of the global primary energy consumption and is expected to double by the year 2050 (8). The different applications of 17 known rare earths can be found in table 1.
3 The Life Cycle Assessment (LCA)
As rare earths continue to gain traction in the coming years as an alternative to, e. g., hard coal and lignite, it is impossible to imagine the transformation process toward decarbonization without this resource. According to the current state of scientific knowledge, the increasing production of alternative energy products such as hybrid vehicles or wind turbines mainly requires the use of rare earths, which are difficult to recycle. The consequences arising from the manufacturing and extraction processes have already been briefly described in the chapter before. Therefore, it makes sense to look at these processes from a Life Cycle Assessment (LCA) perspective. This enables a classification of the precipitation on the environment by passing through the life cycle of a product in the holistic dimension (9).
The life cycle assessment method thus represents an instrument for assessing product development and its optimization. Because of this, it is not only an integral part of political decisions or strategic action, but also standardized according to DIN EN ISO 14040/44 (10, 11). Basically, the LCA analyzes the existing energy flows of a specific product over its entire life cycle. All emissions to the environment with regard to soil, air and water are included. These emissions are then assessed in terms of their impact, primarily the negative impact, on the environment. This can be expressed by acidification, greenhouse effect, smog and much more (Figure 1).
The implementation of the LCA is to be divided into four phases:
- Phase 1: The goal and scope are determined, as well as the definition of systematic boundaries and necessary requirements for the required data.
- Phase 2: In the second step, the extent of the data can be summarized and the so-called inventory of the life cycle can be determined individually (LCI). This includes all required substances and generated emissions or waste in the production process.
- Phase 3: Now the life cycle impact assessment takes places through the environmental compatibility assessment (LCIA). This is done by using a software-protected procedure, taking into account possible risks to human health. At the same time, the existence of resources is checked by calculating models for characterization through the life cycle inventory.
- Phase 4: The last step is the interpretation of the results by the present life cycle inventory and the estimation of the ecological impact for the LCA (10).
4 LCA based on the Bayan Obo mine, Inner Mongolia
Even though hard coal is no longer one of the main sources of demand growth in China, it still accounts for half of the world’s coal production and consumption. In addition, it can be noted that since 2013 the consumption of hard coal has been relieved by the diversification of the energy mix. In parts, this means less dependence on hard coal and increasing dependence on alternatives such as rare earths. Therefore, the transition to a decarbonized economy has already begun and renewable energies are becoming more and more important (12). A main goal of the latest Five Year Plan (Chinas Five Year Plans list main goals for every following five years to achieve an enhanced economy and overall development) is to evolve renewable energies as one of the main drivers for the energy consumption (2, 13). Nevertheless, there is currently a renewed increase in the construction of coal-fired power plants, which runs counter to the developments around a green economy and renewable alternatives. However, in the case of China in particular, one factor plays a decisive role: economic growth. This is also one of the main goals of the five-year plans, both now and in the past. There is a close link between economic growth and the satisfaction of China’s population in terms of a secure energy supply, secure jobs and salaries, the financing of pension funds and, quite simply, social welfare. The closure of coal-fired power plants means many kinds of consequences, such as job losses and dissatisfaction, due to lack of alternatives, faltering security of supply, regional further development, especially in coal-intensive regions. Reconciling these large gaps is not immediately achievable, but requires long-term planning and takes time (14).
While these developments in the coal industry are important to consider in detail, they are not intended to be the focus of this article. Rather, it is important to know this background and to put it in relation to the growing renewable energy generation sector. After all, this energy is supposed to be clean and “green” and thus a better substitute than coal, but is it?
In the meantime, it seems that the green image of renewable energies is crumbling, because the production processes resort to the use and extraction of rare earths in high quantities. These are rarely environmentally friendly, because they require a lot of material and produce large amounts of emissions for air and water. Solid waste with entire landfills created for this purpose also play a major role here. As the production of rare earths is expected to further increase, it is even more important to provide an assessment of the issue by means of LCA. Furthermore, this can help to possibly reduce the ecological footprint in the future, if these alternatives are to be used increasingly and permanently (14). Looking now at production using rare earths in China, large-scale production there has also drawn international attention to environmental impacts. In particular, emissions of heavy metals and radioactivity have caused major damage to groundwater and rivers, as well as to soil vegetation. Due to the long-term affection of this emissions in combination with factors considering the human health, e. g., through the constant inhalation of mining dust, lasting damages are caused to the ecology and to the human development (8, 15).
When considering China with regard to the use of rare earths, something stands out in particular: The city of Baotou and the Bayan Obo mine located there are mentioned repeatedly in sources and scientific analyses on this issue. Here, the negative effects seem to be particularly present and representative, forming a negative example to this rising trend. Therefore, the LCA is applicated to the Bayan Obo mine in Baotou to examine the consequences in more detail. For the following analysis of the processes of the rare earth extraction the results of Navarro and Zhao (2014) are used. They used the method of LCA to applicate them in the production process of rare earth elements (15).
The Bayan Obo mine is currently the biggest deposit for rare earths worldwide. “The reported total reserves are at least 1.5 bn t of iron (average grade 35 %), (and) at least 48 Mt of RE oxides (REO) (average grade 6 %)…” (16). The mine mainly contains bastnäsite and monazite as rare earth elements, which are processed there. However, the extraction of these elements is only the by-product of the main extraction of iron ore that takes place there. The ore, in turn, is extracted classically with the help of shovels and then transported by rail over the railroad line to Baotou. Here, the grinding and processing processes take place. According to research, the mining of the iron ore alone produces 11.9 kg of carbon dioxide per ton. Therefore, the emission of the by-products, i. e., the rare earths, can only be calculated by allocation. Furthermore, there are a total of six different ways of ore beneficiation in this mine. The most common method is the creation of the bastnäsite concentrate and the monazite concentrate by using the crude ore. First, the method of classification and magnetic separation helps to get to the non-magnetic tailings. Through the using of different additives, e. g., sodium carbonate, it is possible to then produce mixed bastnäsite and monazite REO, but also tailings. A last removal of oil or magnetic separation from the mixed oxides leads to the concentrate of bastnäsite and monazite (Figure 2) (15).
This is followed by the chemical treatment. One possibility of this treatment is to take the mixed high grade bastnäsite and monazite concentrate for a roasting with sulfuric acid. This leads to a split of releasing the scrubbed off gas into the air and creating a neutralization of the residue through leaching with water and adding magnesium oxide, as well as Iron (III) chloride. After the neutralization, there is still residue that also contains radioactivity to some extent. On the other hand there is the purified leachate, which is then used to determine the age of the rocks, but also to produce the rare earth carbonate through mainly filtration (Figure 3) (15).
With regard to LCA for these processes, in summary, a general organic chemical is often used. This serves as a surrogate and sometimes leads to large errors. Furthermore, in terms of allocation, both mass-based and turnover-based were used, with the aim of avoiding the problems that often arise from the various steps in the processing of rare earth elements. The standardization according to DIN standard 14040 provides here for an extension of the system for the allocations, but this cannot be implemented. Furthermore, both possibilities of allocation have insufficient requirements. In the case of the mass-based allocation, frequently existing metals are loaded to an increased degree. In the case of the revenue-based allocation, the unstable market for rare earth elements poses a problem, as prices fluctuate here, sometimes strongly, depending on which metal is in demand (15).
Other approaches exist that will go too far at this point and are very specific to the chemical processes. Therefore, with regard to LCA, it can be stated that the number of LCA studies to date is manageable. Furthermore, much of the data used relates to information that has been provided from China itself. It must therefore be taken into account that only little usable and reliable information is available. As a result, there is not only a lack of accuracy and completeness of the data, but also a lack of representativeness. Especially in the case of the clear impact of the manufacturing processes at the Bayan Obo Mine, further analysis should be conducted to be able to determine the LCA. Otherwise, this cannot contribute to an improved development for the future (15).
In terms of the announced climate neutrality in China, major shifts in the hard coal industry can be expected. Especially, the rising of renewable energies has just begun and is going to be the global future potential of a low carbon economy. Environmental protection is becoming an important part in the policy-making of nations, which led to the decision of climate neutrality in China. Furthermore, China recognized this growing importance and is already a global leader in producing renewable energy alternatives, like windmills or solar panels by using their large amount of rare earth reserves.
Recapping the results shown in this article in regard of environmental consequences leads to the fact that no matter if looking at renewable energies through producing with rare earths or using hard coal, it arises the question: What impact will this then have in the future, with the goal of a green economy and climate neutrality? With regard to the factor of sustainability, it can be said that even renewable energies cannot offer a miracle solution. Here, too, carbon dioxide is used for the production of regenerative uses or, according to the current state of knowledge, that rare earths are mostly non-recycable resources is a problem that needs to be solved when it comes to future uses of them. These not only produce carbon dioxide, but the environment also has to suffer from waste dumps, air pollution or contamination of water, which causes tremendous effects on the human health, too.
Nevertheless, the energy transition has already begun and it is the first step towards change and also towards the willingness to make big changes for a potential better future. However, this is not the solution that is often promised or presented to the outside world. It will take a few more decades before only this energy generation is used. It requires much more expertise in this production processes and an efficient LCA. In the case of China in particular, other factors such as economic growth and energy security are primarily in the foreground, whereby hard coal and the associated high carbon dioxide emissions will still play a major role for the environment and climatic effects in the coming years. The environmental impacts are long term not only affecting land, air and water, but also on the human development through induced diseases and inhibition of development. Lastly, the LCA is still highly underrepresented in this research field and needs more reliable data and calculations for improved policy decisions and strategic action in the future. This is the only way to avoid further negative consequences in the future and to advance prevention through appropriate planning.
References / Quellenverzeichnis
References / Quellenverzeichnis
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