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Journal of Sustainable Metallurgy
ISSN 2199-3823
J. Sustain. Metall.
DOI 10.1007/s40831-017-0118-4
Sustainability of Permanent Rare Earth
Magnet Motors in (H)EV Industry
Gwendolyn Bailey, Nabeel Mancheri &
Karel Van Acker
1 23
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REVIEW ARTICLE
Sustainability of Permanent Rare Earth Magnet Motors in (H)EV
Industry
Gwendolyn Bailey
1
•Nabeel Mancheri
2
•Karel Van Acker
1
ÓThe Minerals, Metals & Materials Society (TMS) 2017
Abstract It is clear that hybrid/electric vehicles [(H)EVs]
are only as green as the materials and energy that they use.
According to MIT, the production and processing of rare
earth elements (REEs) found in (H)EVs come with their
own hefty environmental price tag (K. Bourzac, ‘‘The
Rare-Earth Crisis,’’ MIT Technol. Rev., 114(3):58–63,
2011). These damages include radioactive wastewater
leaks and ‘slash-and-burn processes’ required to manu-
facture and separate REEs. Some life cycle assessment
(LCA) studies found that the carbon advantage of an
electric vehicle over an internal combustion engine vehicle
is small considering the production/manufacturing and
end-of-life stages (C.-W. Yap, ‘‘China Ends Rare-Earth
Minerals Export Quotas,’’ Wall Street Journal, updated 5
Jan. 2015; D.S. Abraham, ‘‘The War Over the Periodic
Table,’’ Bloomberg View, 23 Oct. 2015). However, sus-
tainability is not only about environmental impacts, but
also concerns other sustainable development principles
such as economic viability and social well-being. Perma-
nent magnet (PM) rare earth motors are most widely used
in the (H)EV industry, but the price volatility of REEs does
not make them an economically sustainable option. The
research involving the potential social impacts of the
extraction and use of rare earths for the automobile
industry is examined. This review addresses the technical
aspects of PM motors and how it contributes to or with-
draws from the sustainability of (H)EVs. This paper
undertakes a review of the literature and the present situ-
ation of sustainability of REEs in the electric vehicle
industry. Furthermore, this paper highlights the areas of
sustainability research considered by academic and indus-
trial representatives to be essential for cleaning up the
clean technology. The intention is not to declare rare earth
PM motors sustainable, but to analyze their contribution to
sustainability in terms of technical, social, environmental,
and economic aspects. Ultimately, the potential opportu-
nities toward a more sustainable rare earth PM motor are
revealed.
Introduction
Rare earths have been used in the car industry for over
20 years, but they have not been of considerable interest
until recently. In 2010, the world woke up to discover that
China, the largest producer and holder of REE reserves,
had slashed the REE export quota by 40%, tightening the
belt another notch on their already heady monopoly [2–4].
During this time of panic, and amid the headlines such as
the ‘War Over the Periodic Table’ and ‘EU stockpiles rare
earths,’ the focus was given to the criticality of REE supply
[5,6]. Automobile industries reacted by scrambling for
different solutions to avoid relying on rare earth exports by
China. For example, Honda started extracting rare earth
metals from used nickel metal hydride batteries [7]. Some
electric vehicle applications have chosen to forgo magnets
in their design by using an induction motor (IM), which
will be discussed in the technical section. While there are
many magnets throughout the hybrid and electric vehicle
The contributing editor for this article was S. Kitamura.
&Gwendolyn Bailey
gwendolyn.bailey@kuleuven.be
1
Department of Materials Engineering, KU Leuven, Leuven,
Belgium
2
Institute of Environmental Sciences, Leiden University,
Leiden, The Netherlands
123
J. Sustain. Metall.
DOI 10.1007/s40831-017-0118-4
Author's personal copy
[(H)EV], the NdFeB permanent magnets (PMs) found
inside the motor/generator, specifically those inside the
rotor, are the focus for this paper.
It has been suggested that the shift toward electric and
hybrid vehicles could make EV traction motors the main
application for REE by 2050. Hybrid cars are currently
dominating the automotive hybrid and electric market [8].
Permanent rare earth magnets are critical to many sus-
tainable technologies; however, motors for use in small
automotive and industrial applications remain the most
important group in terms of absolute neodymium–iron–
boron, or NdFeB, volumes [8]. Among different types of
PMs, NdFeB has the highest energy density available and
presently dominates the market in terms of value.
Figure 1shows that the largest applications of PMs are
in motors and generators such as engine components, bat-
tery components, moving car parts, and other integral
systems [10]. There are around 40 magnets in motors and
actuators, and 20 sensors in a typical car. REE magnets
provide the best solution for many automotive applications
and considered to be the top technology choice for the
electric vehicle industry.
The global automotive industry is on a gradual trans-
formative path as most of the original equipment manu-
facturers, or OEMs, are introducing new models of (H)EVs
in the market. Thus far, the most successful (H)EVs have
REE motors, including a majority of newly introduced
models like Nissan Leaf, except Tesla, which does not use
any REEs in its motor. Other companies are choosing to
recycle REEs from end-of-life vehicles. Several years ago,
Toyota, Honda, and Mitsubishi announced their campaign
to start recycling rare earths; however, the status of their
recycling activities is not advertised [7,11].
Global trend on vehicle sales shows that smaller, highly
fuel-efficient vehicles’ sales are on the rise. Consumers
who are more environmentally conscious than before no
longer demand conventional large vehicles, and all major
car manufacturers are adapting to this trend by introducing
new (H)EVs to the existing brands [12]. For example, in
the case of Toyota, more than one-fifth of all new vehicles
sold by the manufacturer in the EU were hybrid electric in
2013 [13]. A report by the International Council on Clean
Transportation Europe calculates that in Japan about 20%
of all new car sales in 2013 were hybrids, and in the US the
share of hybrid electric passenger cars was around 6% [13].
If the trend continues, then (H)EVs with dual-functionality
engines will become dominant, replacing conventional
internal combustion engines, which would possibly
increase the demand for certain REEs [14]. Not only
businesses but also governments have recognized the
increasingly important role that (H)EVs are playing in
modern society. Recently, the Netherlands have set a leg-
islation in place with the goal of increasing electric vehicle
sales, ultimately pushing for all vehicles on roads to be
electric by 2030 [13].
Introducing new models of HEV and EVs is part of the
global automotive industry’s efforts to reduce CO
2
emis-
sions along with other measures such as thermal efficiency
improvement in internal combustion, transmission, and
weight reduction. Figure 2demonstrates that there will be a
35% improvement in CO
2
reduction from the sales of
(H)EVs by 2025 and this would certainly increase the
demand for certain REEs. Last year at the United Nations
COP21 Climate Change conference, the European Auto-
motive Manufacturers Association (ACEA) explained in
their position paper that ‘‘a more ‘comprehensive’
Fig. 1 Rare earth magnets by
application. Reproduce this
figure obtained by
Constantinides [9]
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approach is necessary to address all the aspects of use
phase of a vehicle’’ [16]. However, the use phase is not the
only aspect of electric vehicles which need attention, and
focusing exclusively on utilization is no longer sufficient.
The book-ends of the rare earth PM motor process—
manufacturing and end-of-life phases—must also be
counted. The sociopolitical–economic and environmental
aspects of the manufacturing of EVs and especially their
PM motors need decoding. This can be done by performing
an analysis on the sustainability of PM motors. To our
knowledge, no sustainability assessment has been proposed
for PM motors. Sustainability assessment can be defined as
the process of identifying, predicting, and evaluating the
potential impacts of initiatives and alternatives [17]. The
possibility to assess products and processes is particularly
important for a sector as inertial as that of the automobile
industry. Since the ‘‘greenness’’ of the (H)EV has been
called into question [18], we researched whether the use of
the PM motor could contribute to tarnishing of the (H)EV
image, or polish it. Thus, in order to discern whether the
(H)EV industry is making its proper contribution to sus-
tainability, we have presented a review of the literature and
analysis of the state of play of sustainability of permanent
rare earth magnet motors in the (H)EV industry.
Technical Background
Sources vary on the share of REEs used to make PM
motors, but a combination of extensive literature research
and modeling indicates that 21–36% of the world’s REE
production is used to make PM motors [10,19]. The weight
of a NdFeB magnet in a single EV motor is around 1 kg
[20]. Neodymium, a light rare earth (LREE), is the leading
element in the NdFeB magnets with iron used as a transi-
tion metal. REEs are the 15 elements which are found at
the bottom of the periodic table and sometimes includes
yttrium and scandium. The term rare is a misnomer and
they are only rare in their chemical composition [8]. Since
REEs all occur together, they are difficult to separate [21].
The weight percentage of total rare earths in NdFeB
magnets is approximately 31%, which includes a certain
amount of dysprosium depending on the application [21].
For higher temperature applications, and particularly in the
direct drive wind turbines, neodymium is partially substi-
tuted with dysprosium, a heavy rare earth (HREE), well
beyond 5% by weight. NdFeB magnets with a higher ratio
of dysprosium are widely used in the motors and generators
of (H)EVs for their combustion engine-electric motor dual
functionality. (H)EVs benefit from greater amounts of
dysprosium to reduce the size of their large motor assem-
bly. Dysprosium is used in order to increase the intrinsic
coercive force of the material (Hci) or to increase the
resistance to demagnetization as the engine environment
requires NdFeB with higher temperature grades [10].
Methodology
The literature relating to permanent rare earth magnet
motors was extensively reviewed from both academic and
industry standpoints. Due to the lack of literature on the
sustainability of REEs in the EV industry, we concentrated
Fig. 2 2025 Sources of
improvement in CO
2
reduction
and real fuel economy. Source:
[15]
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on examining the literature covering four associated cate-
gories: environmental, social, economic, and technical
aspects of REE PM motors in the (H)EV supply chain. This
methodology was appropriated for the author’s use from
the framework put forth in a conference paper by B.C.
McLellan [22]. The first three of these categories, the three
Ps—people, profit, and planet—follow the widely
acknowledged triple bottom line approach. However, one
element not included in a typical sustainability report is the
technical aspect. We argue that this should be included
because if a product or system presents challenges because
of its state of technology, then it is less durable, ergo less
sustainable. It is known that the main issue preventing
(H)EVs from making a proper contribution to sustainability
is associated with technical feasibility in the field of
recycling. It is less known how the technology of the motor
itself contributes to sustainability. Thus, we acknowledge
the literature focusing on the technical aspects of perma-
nent rare earth magnet in (H)EV motors versus other types
of motors used in EVs as well as the recycling methods.
Results: Environmental, Social, Economic,
and Technical
The results of the review are organized below under their
respective thematic heading.
Environmental
The following discussion explores the aspects of envi-
ronmental sustainability within the value chain—from
production, use, end-of-life of the rare earth PM motors.
The source of materials and energy matter in the envi-
ronmental footprint of EVs. With regard to materials in
the EV motor production phase, there are no published
data on exact locations of resources and their compositions
due to company’s change to confidentiality. But what we
do know is that 75% of the materials are still largely
coming from primary, virgin sources [23]. The bill of
materials for the PM motor consists mostly of stainless
steel, but the magnet embedded within the rotor is made
up of rare earths which usually are co-mined with iron
ores. The RE industry as a whole is highly reliant on finite
stocks of bastnasite ores (a rare earth fluorocarbonate (Ce,
La)(CO
3
)F) and monazite ores (a rare earth phosphate (Ce,
La, Y Th) PO
4
), which is made up of a majority of Chi-
nese feedstock [24,25]. These geological reserves exist
around the world, that is, not solely in China. The LREEs
are more abundant and concentrated than HREEs [24].
Lee and Wen [26] suggest that more energy goes into
extracting and Weng [27] processing the HREEs than the
LREEs.
Mining
For the production stage, a Chinese article explains that
there are indeed heavy metals which are emitted into
groundwater during the mining process (namely cadmium
and lead), and this increased heavy metal concentration can
have effects on aquatic eco-toxicity levels [28]. There can
be large amounts of toxic waste [29] and radioactive waste
associated with the production of REEs [30]. This is a
potential environmental health and safety concern. In fact,
many assume that a major reason why REE production has
been monopolized by China is because of the lackadaisical
or worse, unenforced environmental regulation [31,32].
The costs for scrubbers and other depolluting infrastruc-
tures, which are mandated in many Western countries,
drive up the price of the product, which makes it difficult
for the Western RE market to compete.
The HREEs, in particular, are extracted in an environ-
mentally troubling way. They are extracted by a leaching
process, which is sometimes referred to as ‘slash and burn’
[33]. The details of this process are not published, but a
simple explanation of a general REE extraction process is
as follows: Chinese mining companies flood the ground
with toxic chemicals and then drain it [33]. The REEs get
collected in the drained liquid and then the Chinese add
other organic chemicals into these ponds to precipitate out
the REEs [26]. Once the REEs are precipitated, the mining
company leaves behind the ruined earth and tailings ponds.
However, the Chinese are now cracking down on this
[34,35].
The processes associated with the extraction stage of
REEs are mining, mineral beneficiation, roasting, and
leaching which are represented in Fig. 3. These processes
involve significant environmental costs for energy and
solvents and effluent, radioactive material and hazardous
waste handling. A simplified flowsheet of the NdFeB
magnet production route from mining and extraction to
processing is shown in the figure. The energy intensity is
marked by the corresponding thickness of the arrows. From
the flowsheet, it is easy to conclude that the making of PM
magnet is energy and material intensive.
Use Phase
The following discussion focuses on the sustainability of
(H)EV motors in the use phase. While (H)EVs tend to have
the image of a very low environmental footprint for their
use phase, they are, in fact, only as green as the energy
used to power them [37,38]. A Union of Concerned Sci-
entist report, which takes into account the full life cycle
assessment (LCA) of a Nissan Leaf EV, demonstrates that
in areas where the electric utility relies on natural gas,
nuclear, hydropower, or renewable sources to power its
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generators, the potential for electric cars and plug-in
hybrids to reduce carbon dioxide emissions is great [38].
However, where (H)EVs are plugged into generators
powered by burning a high percentage of coal, electric cars
may not be even as good as the latest gasoline models, or
even hybrids. LCA, which is a methodology used to
measure environmental impacts throughout each stage of a
product or systems life cycle, sometimes makes conclu-
sions which may not be so evident, such as EVs may not be
more environmentally friendly than their competing fuel-
efficient internal combustion engine vehicles. Of course,
one of the downfalls of LCA studies is that they do not give
regionalized results, and they rarely address the impact of
regional energy grid mixes. While many parts of Western
civilization are still powered by coal-burning plants, elec-
tricity technology is moving toward employing cleaner
energies such as natural gas, nuclear, hydroelectric, wind,
or solar facilities. ‘‘To prevent the worst consequences of
global warming,’’ the report concludes, ‘‘the automotive
industry must deliver viable alternatives to the oil-fueled
internal-combustion engine’’ [38].
We have examined the use phase of the typical PM
motor, but as one may know one must evaluate all phases
of a product and compare it with similar products before
determining its contribution to sustainability. There are
different types of these EV motors and we will briefly
review which type presents the more sustainable option.
Considering the negative environmental impact of PM
making, there are some who wonder whether an electric
motor can be constructed without the environmental
drawbacks of the REE-based PMs [20]. IM contain no
permanent magnetic materials, instead they operate by
inducing electric currents in conductors in the motor’s
rotor, and these currents in turn give rise to a magnetic field
in the rotor, producing torque. However, IM take all their
energy from the supply since they have no magnets pro-
ducing energy.
IM incur losses in their rotor conductors, which can
result in total rotor losses two to three times higher than
that in a PM-based motor. This implies that IM efficiency
is lower than PM motor. For instance, at 6000 rotations per
minute, in [39] the IM motor has been shown to have an
Fig. 3 Diagram of a simplified material flow analysis of NdFeB magnets. Data from [36]
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efficiency of 83% and the PM to have an efficiency of 91%.
More examples of alternative motors for (H)EVs include
wound rotor motors, switched, and synchronous reluctance
motors. However, these are not often favored because these
motors have variation in reluctance and can have unwanted
vibration and noise. Moreover, the efficiencies of these
motors are somewhere between IM and PM motor [40]. It
is important to note for the PM-assisted synchronous
reluctance motor, the power factor is greater than IM. In
fact, one can employ ferrite magnets instead of rare earth
PMs in this motor and still have an improved efficiency
over IM. This proves that the presence of magnet improves
power factor as well as efficiency. Despite this clear
advantage, rare earth PM motors and IM are still the two
most common commercially available (H)EV motors.
End-of-Life
Recycling technologies for PMs simply are not advanced
enough to be considered economically viable or even
sustainable. Current recycling of the PMs is very minimal
and practices exist only with return of minor amounts of
scrap material to the alloy manufacturing plant [41]. Effort
to recycle the end-of-life products containing NdFeB yields
a small return, and their physical extraction is difficult as
these magnets are brittle intermetallics, which are deeply
embedded and sometimes glued onto other products.
Despite these challenges, development of new magnet
technologies and new cost effective and innovative recy-
cling technologies are being pursued [42,43,44]. But most
of the time, recycling efforts for these PM motors are not
viewed as worth the cost. And even liberating and recy-
cling some of these PMs via pyrometallurgical or
hydrometallurgical techniques could emit harmful gases or
sludge. Contrary to a popular belief, recycling could even
be seen as harmful to the environment in this case.
The potential environmental impact of recycling NdFeB
magnets has been reviewed in several recent studies
[21,45,46]. Benjamin Sprecher’s life cycle study looks at
the complete energy and environmental impacts of pro-
ducing a kilogram of the rare earth metal neodymium for
magnets by recycling computer hard drives versus mining
the same amount of virgin material [47]. In the case con-
sidered, recycling had a human toxicity score more than
80% lower than mining and used almost 60% less energy
[47]. A more recent LCA study verifies that virgin NdFeB
is worse in terms of environmental impacts than its recy-
cled counterpart [45]. However, there is as yet insufficient
data available to apply these studies directly to the (H)EV
industry. Even conventional RE processing environmental
impacts are far from clear; needless to say, the recycling
methods and other new technologies require significant
research to be deemed as viable solutions.
General LCA Study Results
To introduce the idea that clean technologies and their
components and recycling strategies may not be as sus-
tainable as they seem, we provide a general overview of
some of the results of various LCA studies of PMs and
(H)EV motors. In terms of the life cycle production of
REEs, one LCA concluded that mining and beneficiation
have much lower energy and material consumption com-
pared to other downstream stages—separation of rare earth
oxides and reduction of REEs [48,49]. However, others
conclude that it is the mining and production process which
is the most environmentally impactful [45,47,49,29]. To
examine EVs as a whole, Troy R. Hawkins’ article titled,
‘‘Comparative Environmental Life Cycle Assessment of
Conventional and Electric Vehicles,’’ concludes that it is
the production phase which exhibits the higher environ-
mental burden [50]. Hawkins writes that the EV production
phase is more environmentally intensive than that of
ICEVs for all environmental impact categories with the
exception of terrestrial acidification potential [50]. The
study concludes that the supply chains involved in the
production of electric powertrains and traction batteries
add significantly to the environmental impacts of vehicle
production.
Social
Socio-environmental issues have been raised in terms of
rare earths used in (H)EV motors. Conditions for workers
in these rare earth mining and processing facilities are not
fit to cope with many health and safety measures required
for the refining of this type of metals. Continue to source
neodymium and other rare earth elements from China to
avoid sometimes burdensome environmental regulation
regarding toxic and radioactive by products [38]. All REEs
cause organ damage if inhaled or ingested; some must be
handled with extreme care to avoid poisoning or combus-
tion [51,52]. Rim et al [53] state that the whole process
poses a great risk to miners and residents of mining towns
who inhale higher amounts of radioactive dust.
Thorium, like any radioactive element, has its own
societal implications. The fact is that in legal and regulated
mining operations, the uncontrolled exposure to radioactive
airborne dust is unlikely. Many mining operations already
have in place safety precaution measures which effectively
prevent or inhibit gamma radiation exposure via inhalation.
But there are some REE mining companies operating in
China that are not legal [54] and therefore could be guilty
of submitting workers to gamma radiation exposure. The
main concern is the inhalation of radionuclides in the
thorium decay series. In the situations where radionuclide
activity concentrations in the materials being handled are
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low; however, only in the case of bastna
¨site (less than
0.02% thorium concentration), ‘‘it is important to recognize
that the silica content of the airborne dust is likely to be of
greater concern for occupational health than the radionu-
clide content’’ [30]. Particularly because the physical
extraction and separation steps contain much more
amounts of airborne metals and mineral dust.
The exposure to the general public may be more serious
than those exposed in the workplace. In Malaysia, for
example, several plants reported a range of 0.3 and
7.3 mBq/m
3
in activity concentration of thorium. The
elevated gamma dose rates were recorded in public areas
near mineral processing plants with mineral stockpiles
[55]. The highest dose rates were recorded at one of the
mineral piles in an area where large amounts of monazite
had been deposited on the roadside at up to 2.67 lGy/h.
This was 13 times the mean environmental radiation level
of Malaysia [55]. The potential radiation exposure to
Malaysians has created understandably a social resistance
to REE mining [32]. This situation, along with the devel-
opment of Lynas Advanced Materials plant in Kuantan,
Malaysia led to even more ‘‘claims of environmental and
social injustice.’’
The samarium cobalt magnet, also has a reputation for
being in conflict with social welfare. Samarium cobalt was
widely utilized in high-performance motors in the 1970s
until civil unrest in the Democratic Republic of Congo
(DRC) in 1978. Surprisingly, it was not the REE that was
the bone of contention, but the cobalt. This disrupted the
supply of cobalt and the price of cobalt increased 6.5 times
over base price [56]. The cobalt price volatility today is not
as dire, but still many companies still are hesitant to invest
in or purchase cobalt, partly due to the new Dodd Frank
legislation and the upcoming European Parliament pro-
posal which is a requirement for US and European com-
panies to certify that their products are ‘‘conflict free’’ with
regard to the DRC [57,58] and other conflict zones.
Another more recent example of one country using its
monopoly power as leverage in an economic war is China’s
dispute with Japan over a fishing boat near the Senkaku
Islands. During this time, China blocked rare earth ship-
ments to Japan, for 3 weeks, which resulted in wide socio
economic ramifications [59].
Social aspect of PM sustainability is also related to the
illegal mining of HREEs in southern China, which used to
be largely done by artisanal miners in the region. Most of
the global supply of HREEs (e.g., dysprosium) originates
from the ‘‘ion adsorption clay’’ ores of southern China.
Since the HREEs are considered more strategically valu-
able, significant efforts have been made by Beijing to crack
down on unbridled illegal mining in the region. Media
reports have often attributed China’s low rare earth cost to
poor environmental standards. Fearing irreversible
pollution and the waste of resources caused by the rampant
mining by the small rural mines, the central government in
1991 declared that ionic absorption clays in southern China
would be kept under the protection of the state, and their
mining, refining, and processing would be controlled by the
central government. This policy, however, has never been
effective. It was estimated that in 2012, illegal production
of rare earths amounted to more than 40,000 tons [60]:
Particularly in the case of middle and HREEs mined in
southern provinces, it was estimated that 70% of the
resources came from illegal mines (Fig. 4).
The social issues of the production of REEs for PM
motors have been addressed above, but the consequences
of the use and recycling of this motor within the (H)EV
industry have yet to be illuminated. It is certainly true that
the automobile industry does not have the reputation for
developing sustainability. In fact, they have been accused
for years as being one of the major contributors to global
climate change [13]. In this report, road transport was cited
as responsible for 16% of CO
2
emissions. However, with
the onset of (H)EV market, the industry is contributing to a
greener economy, which is a positive social consequence.
Despite their associated positive social good, EVs are not a
mass market, less than 1% of the automobile industry
consists of EVs. But within the market, the main reason,
aside from fuel cost savings, why people choose to buy
EVs is because they wish to protect the environment and
our health and well-being [61]. A EU government docu-
ment states people perceive EVs as something healthy for
the environment [62]. Social perceptions of the risk of
using critical metals and dirty electricity thus need to be
balanced against broader priorities toward sustainable
development. As recycling and reuse technologies improve
for EVs, there is less likely to be social resistance toward
the PM rare earth motor, and may even become known as a
green and economic product.
Economic
Currently, the main challenge in PM sustainability comes
from the economic aspects, namely the price volatility of
rare earth materials. The graph below evokes the EU crit-
icality index [63], but with a focus on clean energy instead
of pure economic importance to the EU. This graph
demonstrates the criticality of elements such as neody-
mium and dysprosium, large amounts of which are used in
the PMs of the (H)EV, in contrast to the relatively low risk
for the batteries of (H)EVs which contain nickel. A dis-
cussion on the economic importance and price volatility of
REE PMs follows.
Risk related to mineral procurement is a major issue for
the automotive companies due to excessive oligopolies and
an increase in resource nationalism [64]. The
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stable procurement of mineral resources required for pro-
duction activities has become an important issue for man-
agement at the resource-using companies in developed
countries as they are totally dependent on countries like
China to meet their mineral demand. Therefore, the sus-
tainable supply of these metals has a significant influence
on the development of alternate energy and efficient
automotive systems.
Due to this risk of obtaining critical materials, magnet
manufacturers are also seeking to reduce the rare earth
content of magnets while maintaining or increasing their
performance. An example is Hitachi Metals who have
developed magnets which reduce dysprosium content when
compared to conventional NdFeB materials, reportedly
without a reduction in their high temperature coercitivity
[65]. According to Oliver Gutfleisch, for (H)EV motors,
dysprosium partially substitutes neodymium in order to
increase the coercitivity to a sufficient level [65]. The
disadvantages of this are the reduction in the energy den-
sity and the exorbitant price of dysprosium [65]. While
substituting REEs for other materials or even removing
them completely could be seen as a possible sustainable
solution, the development of a new type of motor or
magnetic material may increase mining of new materials
which in turn could increase environmental impacts [66]
(Fig. 5).
Unlike the conventional metals, rare earths are not tra-
ded at the exchange. As a result, pricing is highly obscure,
and there is no way for either of the producers or con-
sumers to hedge prices. Rare earth prices are also very
affected by Chinese domestic policies as the country
controls more than 90% of global supply. For example, the
tightening supply policies of China caused the sharpest
increase in neodymium price, which quintupled from 15
dollars in 2009 to 230 dollar per kilogram in 2011. The
heavier rare earths (e.g., dysprosium, terbium, and euro-
pium) are more expensive, and historically prices have
risen steadily for these elements since 2003 due to China’s
rising domestic demand and escalating export controls.
However, LREEs, such as lanthanum and cerium, recorded
relatively modest increases of 7 and 23% during these peak
periods. Tiny quantities of dysprosium can make magnets
in electric motors lighter by 90%. According to a United
States Energy Department report, dysprosium has become
the most important element in clean energy technology [4].
Fig. 4 Japan’s RE dependence on China (in %). Source: Author’s calculations based on the UN Comtrade (2016). https://comtrade.un.org/data/
Fig. 5 Rare earth criticality and importance to clean energy. Source:
[4]
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Currently, 1 kg of dysprosium oxide costs around 200 USD
per kilogram and 1 kg of neodymium oxide around costs
40 USD.
Rare earths fall under the classic definition of structural
scarcity, meaning that unequal access to natural resources
in a given society makes them scarce for large segments of
the population [67]. Dysprosium is one of the most rare of
the rare earths because it is not found in high concentra-
tions and is found together with other rare earths [68]. The
supply of dysprosium is elastic, and it will not be balanced
with the production of other REEs. That is, mining for
LREEs will not affect the dysprosium supply. For now, it is
impossible to increase the production of dysprosium and at
the same time maintain economic viability [4].
While the long-term price of the LREEs remains open
for debate, the Chinese production quota, the region-based
ad-valorem tax system, and consolidation of the industry
will probably continue to tighten the supply of HREEs,
such as terbium and dysprosium, keeping the prices high
for these elements. The price of dysprosium oxide, used not
only in hybrid vehicles but also in lasers and nuclear
reactors, is projected to rise to above USD 500 in the next
few years. The consolidation of RE industry and China’s
clampdown on illegal mining will have a considerable
impact on prices in longer terms.
The widest usage of rare earths is in PM sector, which
consumes about 25–35% of total rare earths supply by
quantity and more than 50% in terms of value [10]. The
current applications of rare earths are divided among
phosphors, ceramics, glass, and metals, with PMs repre-
senting just 23% of the volume of 130,000 tons of rare
earth oxides. The most important economic application is
overwhelmingly that of PMs at 38%.
If REE production faces a mountain of economic
problems, then these problems look like molehills in
comparison to the economic challenges posed by REE
recycling. The following will review some of the recycling
bottlenecks and reveal their economic and technological
unfeasibility. In the automotive sector, there are no end-of-
life recovery or recycling efforts in place to recover the
PMs, as it is considered economically unfeasible. The
problem is that many of the differing parts and components
in the motor have different chemical and physical com-
positions making it difficult to recycle and reprocess.
According to a source around 70 or 80% of the hybrid
vehicles existing are produced by Toyota Motor (Personal
communication, April 24, 2016). In terms of recycling, the
big difference between the EVs and the (H)EVs (Personal
communication, April 8 2016) is the size of the battery and
the number of motors. The Nissan Leaf, for example, is an
EV so it has one motor, but a Toyota Prius hybrid has two
motors. One cannot make the assumption that, because
hybrid has two motors and electric has one, the hybrid uses
more PMs than electric, as some hybrid vehicles function
almost exactly like an EV using just one motor and some
function using three motors. Not only it is technologically
difficult to figure out how to remove the motor/magnets for
recovery in an economic way, but it is even more difficult
to know if there is enough feedstock to recycle. And if
there is enough how much is needed to make recycling
investments ‘‘worth it.’’ However, our knowledgeable
source or expert, ‘‘frankly speaking, nobody knows the
answer of how many vehicles will be enough (to make
recycling feasible)’’ (Personal communication, April 24,
2016).
Despite the rather nascent commercial success of
(H)EVs, there has been quite an evolution of demand.
Based on certain assumptions, a study by Fulton et al. 2013
found that the combined share of all types of hybrid
vehicles may reach over 75% market share in 2050, and
even by 2035 they reach about 45% of global light-duty
vehicles’ sales [69]. In such a scenario, this would certainly
increase the demand for certain rare earths and whether the
demand could be met from the existing mines sustainably
is a relevant question to ask now. With the absence of
efficient reuse and recycling or the development of tech-
nologies which use lower amounts of dysprosium and
neodymium, following a path consistent with stabilization
of atmospheric CO at 450 ppm might lead to an increase of
approximately 700 and 2600% in the use of these two
elements, respectively, over the next 25 years if their pre-
sent needs in automotive and other applications are repre-
sentative of the future needs [68].
The price evaluation of neodymium and dysprosium is
discussed in the following: When the prices of neodymium
and dysprosium spiked in 2010 and 2011, manufacturers
and users worked quickly to reduce or eliminate their need
for these elements in their products. In some cases, the use
of the REEs was reduced or eliminated temporarily,
through technological or material substitutions, but in
many cases the reduction and elimination have been made
semi-permanent. The industry also witnessed a dramatic
reduction in demand and major importers like Japan and
the US cut short their imports. Prices collapsed almost
more quickly than they had risen. Unable to cope with the
low prices and escalating cost, Molycorp, the major non-
Chinese producer suspended its operations in August 2015.
Prices are now almost at the same level as in the period of
2009.
There have been efforts made to move away from the
Chinese monopoly and boost supplies of rare earths for
automakers [70]. In Japan, there have been efforts to make
EVs free of rare earths [71] and the government of Japan
has announced that they hope to start the production of
REEs from deep sea deposits in 2018 [72]. However, not
all the efforts the Japanese have made have contributed
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positively to the reducing of the economic strain on REEs.
The Japanese perpetuated an event called panic buying
which occurs when companies increase their stockpiles
dramatically which in turn increases prices. This economic
phenomenon which occurs within the context of rare earth
PM motors is the raising of prices due to perceived threats
and was explored extensively in [73]. During the 2010 REE
crisis, some Japanese companies forced their suppliers to
increase their stockpiles of rare earths at the very moment
the prices were highest and the materials were hardest to
obtain [73]. Moreover, the enormous price jumps in 2012
(Figs. 6,7) are thought to be caused by speculators [73].
The (H)EV industry could not afford to rely on rare earths
due to these economic uncertainties (Fig. 8).
Another economic anomaly in reference to REEs is
called the balance problem [74,75]. Simply put, there is
an abundance of certain REEs in the mixed RE ores, and
a serious lack of others and the ones which are not
abundant in nature are those which are the most in
demand. The ideal economic balance would be that the
supply and demand of REEs were equal. However, within
(H)EVs, there is a greater need for HREEs such as dys-
prosium, for example, than lighter REEs such as cerium.
The balance problem implies perhaps the EV industry
should help to find new ways to use all types of REEs.
However, the adoption of a substitute may lead to com-
petitive situations for the material’s original use: For
example, if one substituted terbium in place of dyspro-
sium in (H)EV PMs, it could have a boomerang effect in
the availability and price of terbium which is used in LED
lighting [76].
Technical
Geopolitical- or economy-related developments often bring
technological change in the market. Global PM industry
has a long history of technological developments. Over the
last 50 years or so, PMs have evolved through four gen-
erations of technologies. Figure 9shows the evolution of
these magnets [14]. Aluminum nickel cobalt (AlNiCo)
magnets have been replaced by hard ferrites. These in turn
have been replaced by the superior samarium cobalt
(SmCo) rare earth magnets. In response to the perceived
shortfall of cobalt due to conflict in the Congo and Cold
War politics surrounding Soviet Union (another leading
cobalt producer of that time), companies in the US and
Japan developed the NdFeB magnets in late 1970s. This
magnet has been currently the dominant technology ever
since.
The performance of the motor largely depends on the
quality of the magnets used. The high-performance motors
use rare earth magnets containing NdFeB, which offers by
far the highest energy density for EVs [23]. A partial
substitution of neodymium by dysprosium enables the use
of these PMs even at higher temperatures, which is espe-
cially important for use in electric motors. However,
instead of adding dysprosium, which is an expensive and a
critical HREE, one could easily substitute the NdFeB
magnet with SmCo. Replacing the rare earth PMs with
ferrite magnets or AlNiCo is not really possible due to the
enhanced risk of demagnetization.
At present, there are only two main types of motors used
in EVs—the IM and the PM. PM motors are more widely
Fig. 6 Rare earth oxide prices—LREEs (USD per kilogram)
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used in automotive companies such as Toyota, Nissan, and
BMW. The IM is used by EV manufacturers like Tesla.
There are many specifications for a PM motor such as
being able to operate under relatively high temperatures,
and a high BHmax and flux output. The PM motor has high
torque and high power density, and therefore, like PMs
over ferrite magnets, PMs can perform at the same level
while utilizing less space. The PM motor could be viewed
as more efficient than even the Tesla IM in that the PM
motor saves energy required for cooling due to less heat
loss in the motor. The lower weight of the PM motor, by
40%, results in saving on fuel [77].
The PM motor presents some obvious advantages over
the IM in these aspects. But the IM has some compelling
advantages, too. The biggest advantage might be that it
does not contain any rare earth PMs. The second is that the
cost of Tesla IM motor is quite low compared to a Nissan
Leaf PM motor. According to the International Copper
Association, a PM motor costs an estimated $260–$590
and an IM motor costs around $200 [77]. Lastly, PM motor
has a complex control strategy and needs more mainte-
nance than IM. Overall, the design of IMs is simpler than
PM motors and thus costs less and their recycling is
potentially easier [78].
While the Tesla IM seems to garner a ‘green’ image, the
contribution of its motor to sustainability is not so clear.
Because the PM motor can power a car with less material
(and weighing 40% less), one could argue that the PM
motor has a smaller emission load as well. More evidence
for the sustainability and efficiency of PM motor can be
seen in its magnetic flux. The current (energy) in any motor
can be divided into two types: magnetizing current (flux)
and the current producing torque [39]. In IM, both the
currents (flux) come from the supply, meaning the battery.
In PM motors, the magnets provide magnetization in the
motor and hence the motor needs less current than IM to
produce the same torque which means less copper losses
(Personal communication, December 11, 2016) [79]. PM
motors are undoubtedly more efficient than the IM given
the same size of the motor [77]. Nevertheless, it cannot be
claimed that the Nissan Leaf’s PM motor is more sus-
tainable than Tesla’s IM motor, because the efficiency of
the motor can vary with speed, size, and power output. All
in all, an IM, which is the same size as a PM motor, will
always have a lower efficiency compared with PM motors.
In the previous sections, the challenges with regard to
economic viability and environmental and social aspects of
introducing REE-based motors have been discussed. It is
clear that the way forward also implies many technological
challenges. Dismantling these motors from (H)EVs in an
automatic or systemized manner is currently not possible.
Although there has been some research into developing
dismantling features in LCD TVs and laptops [80–81],
Fig. 7 Rare earth oxide prices—HREEs (USD per kilogram). Metal Pages (2016). Argus Media private limited London.http://www.metal-
pages.com/metalprices/rareearths/
Fig. 8 Automotive technology evolution. Source: [69]
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none have been developed for (H)EVs. Moreover, the
placement of the motor and the position of the rare earth
magnets inside are not convenient for removal. To give
more detail on why these motors have magnets not
designed for easy removal, we turn again to our expert
source explains that if we try to generate a large amount of
torque by using a small, lightweight motor, then we have to
increase the number of rpm (rotations per minute) and
transform it to torque. However, if we try to increase the
rpm of motor, then this causes the motor to have a lot of a
vibration. Therefore, one must use a strong material to fix
the magnet inside the motor. Thus, the increased rpm and
the material make it difficult to remove the magnet from
the motor (Personal communication, April 24, 2016). And
to make matters worse, the placement of these magnets is
different in almost every vehicle model, no matter if they
share the same brand, make, and model.
Automotive industries seem to be actively working on
researching and developing dismantling and recycling
techniques and incorporating them in vehicle designs.
Toyota established the Automobile Recycle Technical
Center within Toyota Metal Co., Ltd. in 2001 in order to
look at ‘‘dismantling technologies for the magnets used in
devices such as hybrid vehicle drive motors which use
neodymium and dysprosium’’ [82]. Toyota is taking a two-
fold approach that many car companies are following: (1)
use less rare earths when possible and (2) procure rare
earths from recycled motors or urban mines. Unfortunately,
to date, it has been proven that there is no constructive
method for recycling the rare earths in these powerful
magnets.
One of the most reliable recycling method for REE
PMs was developed by the University of Birmingham in
[83]. It was a major breakthrough because it allowed one
to apply hydrogen to a used PM from a motor which
turned into a rare earth oxide powder in a matter of
minutes [83]. The issue here is that the quality diminishes
each time the material is decrepitated. The nickel coating,
which covers the magnet in a Ni–Cu–Ni layer, is often
the cause of the recycling barrier. Because of these
technical bottlenecks, there are still no commercial recy-
cling processes available. The hydrogen decrepitation
process is one of the most feasible recycling techniques to
date in terms of environmental and economic cost,
because it allows one to use as little energy and chemicals
as possible to recover the neodymium and let the
hydrogen do the hard work (data from Dr. Vicky Mann’s
presentation ‘‘Magnetic Materials Group (MMG) Recy-
cling of Rare Earth (NdFeB) Magnets‘‘, within the
NMP2-SE-2012-310240 REMENANCE project) [84].
However, this is only ‘‘one step in the process’’ suppliers
are not using it because it is not economically interesting
at this moment to turn the resulting rare earth powder into
an alloy for direct reuse (Personal communication, Mika
Zakotnik, April 2016). Also, the powder needs to be
handled in an inert protective atmosphere due to its high
Fig. 9 Evolution of permanent magnets and their strengths. Source: [9,14]
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reactivity with oxygen (Personal communication, Enrique
Herrariz, April, 2016).
Discussion
The techniques for determining whether PM motors are
sustainable or not are not precise. However, this type of
assessment (like many sustainability assessments) of PM
motors sheds light on a shadowy aspect of the (H)EV
industry. Unfortunately, many of the industry-sponsored
studies and publications contain data which are sensitive
and sometimes confidential and therefore only viewable in
a highly aggregated format. This is another reason why it is
important to carry out a sustainability assessment of a small
component of (H)EVs of such a large (automotive)
industry. Performing environmental impact assessments
which are released to the public is one way to increase
accountability and social aspects. If there was an associa-
tion or open line of communication between the auto
industry and the PM manufacturers, then the opportunities
for increasing knowledge share and sustainable measures
would increase. Currently, there is no global association
existing to facilitate exchange between the manufacturers,
post-processors, and recyclers of these motors. By focusing
on the aspect of (H)EV motor production and manufac-
turing, and not just use phase, which is what the auto
industry tends to focus on, it is possible to communicate, in
a concise manner, the gains (and losses) in the sustainable
development of a rare earth PM motor.
The authors venture to explain different methods on how
to bypass the sustainability constraints of PM motors. The
sociopolitical decisions made by the rare earth and HEV
industry so far do not reflect the upmost sustainable values.
For example, the decision for the rest of the world to sit on
the sidelines while China took over was convenient for a
short period but proved near-sighted and has evidently
become less and less durable as time passes. Furthermore,
the (H)EV industry continues to source these magnets for
their motors, letting China take the ’’environmental‘‘ hit. If
the West decides again to take up the large-scale mining
and pre-processing of these magnets, then sustainable
actions could be implemented more easily, but always at a
cost. Sustainability recognizes that both extremely high and
extremely low costs are not lasting and are inherently
unsustainable.
Sustainability also recognizes the social and economic
need to mine and emit harmful substances, but in an
accountable and open manner. This is the concept of
responsible mining, and involves all the four pillars of
sustainability addressed in this review. Sustainability for
the PM motor supply chain would mean employing
advanced tecnological improvements advanced
technological improvements such as scrubbers for smelters
and environmental, health and safety monitoring system for
employees at all stages of manufacturing and dismantling,
all for a fair price. But the economics has not worked out
for Chinese producers to be able to do this. The sustainable
automotive and REE industries are intertwined and
dependent on each other. Thus, they must work together
and rely on each other to ensure a sustainable value chain.
The rare earth industry is needed to create an environ-
mentally friendly transportation sector, with neodymium
and other REEs needed in large quantities if the electric car
revolution will succeed in removing combustion engines
from the automotive industry. On the other hand, the
(H)EV industry needs to be held accountable for sourcing
their magnets responsibly.
Conclusions
These cross cutting pillars of sustainability—environmen-
tal, economic, social, and technical—have differing con-
clusions regarding the permanent rare earth magnet motor
in the (H)EV industry, which shows the need for the
automobile industry to come up with strict results (using
LCA, cost–benefit analysis, etc.). The conclusion of the
environmental assessment is that PMs are not sustainable
and are performing poorly in terms of overall ‘greenness.’
The conclusion of the economic assessment is that the
HREEs are the most costly part of a PM motor and more
effort should be done to source the LREEs. The social
assessment shows that PMs can induce geopolitical strife
and cause health problems for the communities where they
are extracted and processed. The technical assessment
states that technologies for producing PMs and recycling of
PM motors need to be developed in order for them to be
considered sustainable.
We recommend that the (H)EV industry take heed of
this sustainability assessment, but recognize that a sus-
tainability assessment can often have conflicting results.
For instance, if the sociopolitical assessment concludes a
need for material substitution in order to combat monop-
olies and criticality, then this approach is not necessarily a
sustainable solution for the environment. Alexander King
in a conference paper states this is because increased
mining may ’’increase environmental impacts and spread
them to new locations,‘‘ and the development of a new
magnetic material will threaten the research which is going
into putting a recycling solution in place [66]. The right
conclusion is clearly not to write off the concept of EVs or
PM motors for that matter. Rather, a good conclusion
might be to acknowledge the inherent attractiveness of the
EV target state while also acknowledging the innovative
opportunity to increase the knowledge of recycling
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processes for these rare earth motors. The intention of this
paper is meant to have sharply defined what needs to be
known in order to make the PM motor and its industry
practices more sustainable.
We conclude that the sustainability of these PM motors
will be largely dependent on the following aspects:
improved recovery and recycling methods of these magnets
from automobile sector, acceptable alternative propulsion
technologies, continued price stability and availability of
critical REEs, cost to produce (H)EVs, and improvement in
communication within the value chain. Other aspects
mentioned by King include ’’technology substitution at the
system level as opposed to the material level, that is, using
heat engines in place of electric motors, or a new type of
motor in place of permanent magnet motors. The future of
sustainable transportation hinges on the development of the
aforementioned approaches. The four pillar paradigm
examined in this paper reveals how a sustainable technol-
ogy has developed and currently subsists unsustainably.
Acknowledgements The research by Nabeel Mancheri was funded
by the European Commission’s Marie Curie Actions, Grant
No. 656998. The research by Gwendolyn Bailey was funded by the
European Union’s EU Framework Programme for Research and
Innovation Horizon 2020 under Grant Agreement No. 674973. The
research was supported by KU Leuven Departement Industriele
Ingienieurswetenchappen, Oude Markt 13,3000 Leuven (Faculty of
Engineering Technology). The authors would also like to recognize
and thank the following persons for their contribution toward the
technical section of this paper: Awais Ikram, Amit Jha, and Pranshu
Upadhayay.
References
1. Bourzac K (2011) The rare-earth crisis. MIT Technol Rev
114(3):58–63
2. Yap C-W (2015) China ends rare-earth minerals export quotas.
Wall Street Journal. Available at: https://www.wsj.com/articles/
china-ends-rare-earth-minerals-export-quotas-1420441285.
Accessed 5 March 2017
3. Han-Wei L, John M (2012) China’s Rare Earths Export Quotas:
Out of the China-Raw Materials Gate, But Past the WTO’s Finish
Line?. J Int Economic Law 15 (4): 971-1005. doi:10.1093/jiel/
jgs037
4. Bauer D, Diamond D, Li J, Sandalow D, Telleen P, Wanner B
(2011) U.S. Department of Energy, Advanced Research Projects
Agency, Energy Critical materials strategy. United States. doi:10.
2172/1000846
5. Abraham DS (2015) The war over the periodic table. Bloomberg
View. Available at: https://www.bloomberg.com/view/articles/
2015-10-23/the-war-over-the-periodic-table. Accessed 5 March
2017
6. Financial Times (2011) EU stockpiles rare earths as tensions with
China rise. [online]. Available at: http://business.financialpost.
com/investing/eu-stockpiles-rare-earths-as-tensions-with-china-
rise. Accessed 6 Feb 2017
7. Harman A (2012) Honda rare-earth recycling may avoid China
Export Flap. WardsAuto. http://wardsauto.com/industry/honda-
rare-earth-recycling-may-avoid-china-export-flap. Accessed 25
April 2016
8. Golev A, Scott M, Erskine PD, Ali SH, Ballantyne GR (2014)
Rare earths supply chains: current status, constraints and oppor-
tunities. Resour Policy 41:52–59. doi:10.1016/j.resourpol.2014.
03.004
9. Constantinides S (2016) Market Outlook for Ferrite, Rare Earth
and Other Permanent Magnets: 2015 to 2025. In: The magnetics
2016 meeting was held Jan. 21-22, 2016 in Jacksonville, FL.
10. Humphries M (2013) Rare earth elements: the global supply
chain. In: CRS Report for Congress. Congressional Research
Service. Washington, DC
11. Els F (2013) Honda’s starts recycling program to extract 80% of
rare earths from used hybrid batteries. Available from: http://
www.mining.com/hondas-starts-recycling-program-to-extract-
80-of-rare-earths-from-used-hybrid-batteries-43719/. Accessed 7
Nov 2016
12. Environmentally Friendly Vehicles (2012) Environmentally
friendly vehicles and the world forum for the harmonization of
vehicle regulations (WP. 29). Representatives of India and USA
13. Mock P (2015) European vehicle market statistics. Available
from: http://eupocketbook.theicct.org. Accessed 6 April 2016
14. Shaw S (2012) Permanent magnets: the demand for rare earths.
In: 8th international rare earths conference, Arnold Magnetic
Technologies, Hong Kong
15. Moore K (2015) Is the automobile industry driving away from
REE motors. In: North America rare earth conference, Las Vegas
16. Association EAM (2015) ACEA Position Paper: The COP21
climate change conference 2015, Brussels
17. Devuyst D (2000) Linking impact assessment and sustainable
development at the local level: the introduction of sustainability
assessment systems. Sustain Dev 8(2):67–78
18. Hickman L (2012) Are electric cars bad for the environment. The
Guardian. https://www.theguardian.com/environment/blog/2012/
oct/05/electric-cars-emissions-bad-environment. Accessed 25
April 2016
19. Kingsnorth D (2012) The rare earth industry: a delicate balancing
act. In: Technology metals summit, Toronto
20. Widmer JD, Martin R, Kimiabeigi M (2015) Electric vehicle
traction motors without rare earth magnets. Sustain Mater
Technol 3:7–13. doi:10.1016/j.susmat.2015.02.001
21. Schulze R, Buchert M (2016) Estimates of global REE recycling
potentials from NdFeB magnet material. Resour Conserv Recycl
113:12–27. doi:10.1016/j.resconrec.2016.05.004
22. McLellan BC et al (2016) Sustainability of the rare earths
industry. Procedia Environmental Sciences 20:280–287
23. Ford (2014) Ford sustainabilty report 13-14
24. Yang XJ, Lin A, Li X-L, Wu Y, Zhou W, Chen Z (2013) China’s
ion-adsorption rare earth resources, mining consequences and
preservation. Environ Dev 8:131–136. doi:10.1016/j.envdev.
2013.03.006
25. Li L, Yang X (2014) China’s rare earth ore deposits and benefici-
ation techniques. In: European Rare Earth Resource Conference.
26. Lee JCK, Wen Z (2016) Rare earths from mines to metals:
comparing environmental impacts from China’s main production
pathways. J Ind Ecol. doi:10.1111/jiec.12491
27. Weng, Z, Haque N, Mudd, GM, Jowitt SM (2016) Assessing the
energy requirements and global warming potential of the pro-
duction of rare earth elements. J Clean Prod 139:1282–1297
28. Wang Y, Wu P, Wang P, Chen N, Zhang Y, Ma X, Yue H, Peng S
(2014) The emission standard of rare industrial pollutant task
group. J Safe Environ. doi:10.13637/j.issn.1009.6094.2014.04.056
29. Koltun P, Tharumarajah A (2014) Life cycle impact of rare earth
elements. ISRN Metall 2014:907536. doi:10.1155/2014/907536
30. Agency IAE (2011) Radiation protection and norm residue
management in the production of rare earths from thorium con-
taining minerals, in safety report series. International Atomic
Energy Agency, Vienna
J. Sustain. Metall.
123
Author's personal copy
31. Kaiman J (2014) Rare earth mining in China: the bleak social and
environmental costs. The Guardian. Available at: https://www.
theguardian.com/sustainable-business/rare-earth-mining-china-
social-environmental-costs. Accessed 5 March 2017
32. Ali SH (2014) Social and environmental impact of the rare earth
industries. Sustainability 3:123–134. doi:10.3390/resources
3010123
33. British Broadcasting Company (2014) Elements. In: Rowlatt J
(ed) Rare earth elements (Ce, Nd, Dy, Er, etc). http://www.bbc.
co.uk/programmes/p02rnvf2. Accessed 31 August 2016
34. Qi Z (2011) Rare earths to be more tightly controlled. In: China
Daily Europe, Beijing. http://europe.chinadaily.com.cn/china/
2011-03/08/content_12133351.html. Accessed 25 April 2016
35. Juan D (2012) Green priority for rare earths. In: China Daily
Europe. http://europe.chinadaily.com.cn/business/2012-06/21/
content_15516454.htm. Accessed 25 April 2016
36. Sprecher B et al (2014) Life cycle inventory of the production of
rare earths and the subsequent production of NdFeB rare earth
permanent magnets. Environ Sci Technol 48(7):3951–3958.
doi:10.1021/es404596q
37. Stenquist P (2012) How green are electric cars? Depends on
where you plug in. The New York Times. http://www.nytimes.
com/2012/04/15/automobiles/how-green-are-electric-cars-depends-
on-where-you-plug-in.html. Accessed 11 November 2016
38. Don Anair AM (2012) State of charge: electric vehicles’ global
warming emissions and fuel-cost savings across the United
States. Union of Concerned Scientists, Cambridge
39. Pellegrino G, Vagati a, Boazzo B, Guglielmi P (2012) Compar-
ison of induction and PM synchronous motor drives for EV
application including design examples. IEEE Trans Ind Appl
48(6):2322–2332
40. Jha A (2010) Electric cars cannot cut CO
2
emissions on their
own, warn engineers. The Guardian. https://www.theguardian.
com/environment/2010/may/25/electric-cars-carbon-emissions.
Accessed 11 November 2016
41. Binnemans K, Jones PT, Blanpain B, Van Gerven T, Yang Y,
Buchert WM (2013) J Clean Prod 51:29–38. doi:10.1016/j.jcle
pro.2012.12.037
42. Dent PC (2012) Rare earth elements and permanent magnets
(invited). J Appl Phys 111(7):07A721. doi:10.1063/1.3676616
43. Recycling Permanent Magnets In One Go‘‘. Fraunhofer-Ge-
sellschaft. N.p., 2017. Web. 7 Feb. 2017. https://www.fraunhofer.
de/en/press/research-news/2015/september/recycling-permanent-
magnets-in-one-go.html. Accessed 11 November 2016
44. Magnetic idea: Rare-earth recycling.’’ Department of Energy
Pulse. Number 377.http://web.ornl.gov/info/news/pulse/no377/
story3.shtml. Accessed 11 November 2016
45. Jin H, Afiuny P, McIntyre T, Yih Y, Sutherland JW (2016)
Comparative life cycle assessment of NdFeB magnets: virgin
production versus magnet-to-magnet recycling. Proc CIRP
48:45–50
46. Sprecher B, Kleijn R, Kramer GJ (2014) Recycling potential of
neodymium: the case of computer hard disk drives. Environ Sci
Technol 48(16):9506–9513. doi:10.1021/es501572z
47. Sprecher B (2014) Life cycle inventory of the production of rare
earths and the subsequent production of NdFeB rare earth per-
manent magnets—supporting information. Environ Sci Technol
48(7):3951–3958. doi:10.1021/es404596q
48. Tharumarajah A, Koltun P (2011) Cradle to gate assessment of
environmental impact of rare earth metals. In: 7th Australian
conference on life cycle assessment. Australian Life Cycle
Assessment Society, Melbourne. https://publications.csiro.au/rpr/
pub?list=BRO&pid=csiro:EP124364&sb=RECENT&n=44&rpp
=50&page=81&tr=5035&dr=all&dc4.browseYear=2011.Acces-
sed 25 August 2016
49. Navarro J (2015) Environmental Evaluation of Rare Earth Ele-
ments: Processing, Products, and Pathways. https://search.pro
quest.com/docview/1729568731?accountid=17215. Accessed 16
November 2016
50. Hawkins TR et al (2013) Comparative environmental life cycle
assessment of conventional and electric vehicles. J Ind Ecol
17(1):53–64. doi:10.1111/j.1530-9290.2012.00532.x
51. Kemakta Konsult AB (2014) Geological Survey of Finland
Institute of Geology & Mineral Exploration Health and safety
issues in REE mining and processing An internal EURARE
guidance report. Available at: http://www.eurare.eu/docs/inter
nalGuidanceReport. Accessed 6 February 2017
52. Kiggins, RD (ed) (2015) The political economy of rare earth
elements: rising powers and technological change. Palgrave
Macmillan UK
53. Rim KT, Koo KH, Park, JS (2013) Toxicological evaluations of
rare earths and their health impacts to workers: a literature
review. Saf Health Work 4(1):12–26
54. Mancheri NA (2012) China’s white paper on rare earths. East Asia
Forum 2012. Available from: http://www.eastasiaforum.org/2012/
08/16/chinas-white-paper-on-rare-earths/. Accessed 23 Oct 2016
55. Omar M, Hassan A, Sulaiman I (2006) Radiation exposure during
travelling in Malaysia. Radiat Prot Dosimetry 121(4):456–460.
doi:10.1093/rpd/ncl060
56. Constantinides S (2016) Permanent magnets in a changing world
market. Magnetics Business & Technology, Arnold Magnetic
Techonolgies
57. European Parliament (2017) Conflict minerals: MEPs secure
mandatory due diligence for importers. Available at: http://www.
europarl.europa.eu/pdfs/news/expert/infopress/
20161122IPR52536/20161122IPR52536_en. Accessed 6 Febru-
ary 2017
58. China’s global quest for resources and implications for the United
States (2012). In: United States-China Economic and Security
Review Commission, Washington, DC. http://origin.www.uscc.
gov/sites/default/files/transcripts/1.26.12HearingTranscript.pdf.
Accessed 25 November 2016
59. Blakely CC, Joseph, Khaitan A, Sincer I, Williams R (2016) Rare
earth metals & China. Available from: \http://sites.fordschool.
umich.edu/china-policy/files/2012/09/Rare-Earth-Metals-China.
pdf[. Accessed 7 April 2016
60. Packey DJ, Kingsnorth D (2016) The impact of unregulated ionic
clay rare earth mining in China. Resour Policy 48:112–116.
doi:10.1016/j.resourpol.2016.03.003
61. Ultra Low Emission Vehicles (2015) Uptake of ultra low emis-
sion vehicles in the UK: a rapid evidence assessment for the
Department for Transport. https://www.gov.uk/government/pub
lications/ultra-low-emission-vehicles-evidence-reviewof-uptake-
in-the-uk. Accessed 20 July 2016
62. Science for Environment Policy: European Commission DG
Environment News Alert Service, edited by SCU, The University
of the West of England, Bristol.
63. European Commission (2011) Critical raw materials for the EU,
Report of the Ad-hoc Working Group on defining critical raw
materials
64. Mancheri NA, Marukawa T (2016) Rare earth elements: China
and Japan in industry, trade and value Chain. ISS Contemporary
Chinese Research
65. Gutfleisch O et al (2011) Magnetic materials and devices for the
21st century: stronger, lighter, and more energy efficient. Adv
Mater 23(7):821–842. doi:10.1002/adma.201002180
66. King AH (2016) When agendas align: critical materials and green
electronics. In: Electronics goes green 2016?International
Congress, Berlin. https://www.electronicsgoesgreen.ISBN978-3-
00-053763-9org6. Accessed 14 October 2016
J. Sustain. Metall.
123
Author's personal copy
67. Bingham Kennedy J (2001) Environmental scarcity and the
outbreak of conflict. Available from: http://www.prb.org/Pub
lications/Articles/2001/EnvironmentalScarcityandtheOut
breakofConflict.aspx. Accessed 7 Nov 2016
68. Alonso E, Sherman AM, Wallington TJ, Everson MP, Field FR,
Roth R, Kirchain RE (2012) Evaluating rare earth element
availability: a case with revolutionary demand from clean tech-
nologies. Environ Sci Technol 46(8):4684. doi:10.1021/es2035
18d
69. Fulton L, Lah O, Cuenot F (2013) Transport pathways for light
duty vehicles: towards a 2°scenario. Sustainability 5(5):1863–
1874. doi:10.3390/su5051863
70. Mancheri NA (2012) Chinese monopoly in rare earth elements:
supply-demand and industrial applications. China Report Nov
48:449–468
71. Phys Org (2010) Japan develops vehicle motor free of rare earths.
https://phys.org/news/2010-09-japan-vehicle-motor-free-rare.html.
Accessed 1 June 2016
72. Government of Japan (2013) Basic plan of ocean policy. Tokyo
73. Sprecher B et al (2015) Framework for resilience in material
supply chains, with a case study from the 2010 rare Earth crisis.
Environ Sci Technol 49(11):6740–6750. doi:10.1021/acs.est.
5b00206
74. Binnemans K, Jones PT, Van Acker K, Blanpain B, Mishra B,
Apelian D (2013) Rare-earth economics: the Balance Problem.
JOM 65:846–848. doi: 10.1007/s11837-013-0639-7
75. Binnemans K, Jones PT (2015) Rare Earths and the Balance
Problem. J Sustain Metall 1:29–38. doi:10.1007/s40831-014-
0005-1
76. Zepf V, Reller A, Rennie C, Ashfield M, Simmons J (2014)
Materials Critical to the Energy Industry. An Introduction, 2nd
edition. BP P.L.C., London. http://www.bp.com/content/dam/bp/
pdf/sustainability/group-reports/ESC_Materials_handbook_BP_
Apr2014.pdf. Accessed 25 April 2016
77. International Copper Association (2013) Performance/cost com-
parison of induction-motor & permanent-magnet-motor in a
hybrid electric car. http://www.coppermotor.com/wp-content/
uploads/2013/08/Techno-Frontier-2013-MBurwell-ICA-EV-Trac
tion-Motor-Comparison-v1.8-Eng1.pdf. Accessed 15 October
2016
78. Nanada G, Kar NC (2006) A survey and comparison of charac-
teristics of motor drive used in Electric Vehicles. In: Canadian
conference on electrical and computer engineering, Ottawa
79. Yildirim M, Polat M, Ku
¨ru
¨m H (2014) A survey on comparison
of electric motor types and drives used for electric vehicles. In:
16th international power electronics and motion control confer-
ence and exposition, Antaly
80. Peeters JR et al (2012) Active disassembly for the end-of-life
treatment of flat screen televisions: challenges and opportunities.
In: Matsumoto M et al (eds) Design for Innovative value towards
a sustainable society: proceedings of EcoDesign 2011: 7th
international symposium on environmentally conscious design
and inverse manufacturing. Springer, Dordrecht, pp 535–540
81. Peeters JR (2013) Effects of boundary conditions on the end-of-
life treatment of LCD TVs. CIRP Ann Manuf Technol
62(1):35–38
82. Vehicle Recycling (2014) Toyota Motors Corporation, Toyota
City, Aichi Prefecture, Japan. http://www.toyota-global.com/sus
tainability/report/vehicle_recycling/pdf/vr_all.pdf. Accessed 03
May 2016
83. Harris IR, Williams A, Walton A, Speight J (2014) Magnet
recycling. Google Patents. https://www.google.com/patents/
US8734714. Accessed 30 April 2016
84. Mann, V (2012) Recycling of Rare Earth (NdFeb) Magnets.
University of Birmingham. Presentation
J. Sustain. Metall.
123
Author's personal copy
