role of substitution in mitigating the supply pressure of rare earths in electric road transport applications

SUSMAT-00036; No of Pages 11 Sustainable Materials and Technologies xxx (2017) xxx–xxx Contents lists available at ScienceDirect Sustainable Materials and Technologies journal homepage: www.elsevier.com/locate/susmat F O Claudiu C Pavel a,⁎, Christian Thiel b, Stefanie Degreif c, Darina Blagoeva a, Matthias Buchert c, Doris Schüler c, Evangelos Tzimas a a a r t i c l e 10 11 12 13 14 19 18 17 16 15 36 37 38 39 40 41 Article history: Received September 2016 Received in revised form December 2016 Accepted 19 January 2017 Available online xxxx b c Energy, Transport and Climate Directorate, Joint Research Centre, European Commission, Westerduinweg 3, 1755 LE Petten, The Netherlands Energy, Transport and Climate Directorate, Joint Research Centre, European Commission, Enrico Fermi 2749, I - 21027 Ispra, (VA), Italy Oeko-Institut e.V., Rheinstrasse 95, 64295 Darmstadt, Germany i n f o R O 3Q1 a b s t r a c t P Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications The development of new high-efficiency magnets and/or electric traction motors using a limited amount of critical rare earths or none at all is crucial for the large-scale deployment of electric vehicles (EVs) and related applications, such as hybrid electric vehicles (HEVs) and e-bikes For these applications, we estimated the short-term demand for high-performing NdFeB magnets and their constituent rare earths: neodymium, praseodymium and dysprosium In 2020, EV, HEV and e-bike applications combined could require double the amount used in 2015 To meet the global deployment target of 7.2 million EVs sales in 2020 proposed by the International Energy Agency, the demand for NdFeB in the EV sector might increase by up to 14 times in only years (2015– 2020) Due to concerns about the security of supply of rare earths some manufacturers have decided to develop and adopt alternative solutions By assessing up-to-date available component substitutes, we show that the permanent magnet synchronous-traction motor (PSM) remains the technology of choice, especially for hybrid vehicles (HEV and PHEV) Better material efficiency and a larger adoption of motors free of rare earths have the potential to reduce the pressure on rare earths supply for use in electric road transport applications However even if such substitution measures are successfully implemented, the demand growth for rare earths in the EV sector is expected to increase significantly by 2020 and beyond © 2017 Joint Research Centre, European Commission Published by Elsevier B.V This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) D E C T E Keywords: Critical materials Rare earths Electric vehicles Substitution Permanent magnet R 35 45 43 42 Introduction Sources and approach Estimation of permanent magnets demand in traction motors used in electric road transport applications 3.1 Applications of permanent magnets in electric traction motors 3.2 Estimation of NdFeB magnet demand in electric vehicle types BEV and PHEV 3.3 Market momentum of hybrid vehicles and estimation of NdFeB magnet demand in HEV applications 3.4 Estimation of NdFeB magnet demand in e-bikes 3.5 Supply issues for rare earths and their demand for electric road transport applications (H&EVs and e-bikes) Substitution opportunities of rare earths in electric traction motors 4.1 Rare earths substitution in NdFeB magnets and improved material efficiency 4.2 Reducing the amount of NdFeB magnet in electric traction motor: dematerialisation 4.3 Component substitution for PSM traction motors in EVs and HEVs Impact of substitution on short-term demand for critical rare earths – Nd, Pr and Dy – in H&EV and e-bike applications Conclusions Acknowledgements References N C O 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 Contents U 47 46 R 44 0 0 0 0 0 0 0 0 64 ⁎ Corresponding author E-mail address: claudiu.pavel@ec.europa.eu (C.C Pavel) http://dx.doi.org/10.1016/j.susmat.2017.01.003 2214-9937/© 2017 Joint Research Centre, European Commission Published by Elsevier B.V This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/) Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 C 181 The research was carried out during 2015–2016 based on information collected from a wide variety of sources, including academic articles, relevant documents and reports on critical raw materials, industry publications, etc Although an exhaustive survey on the most recent industrial developments is difficult to carry out because of the high level of confidentiality in automotive industries research, this paper integrates the best available information with additional information gathered from interviews with material scientists, technical experts from industry and academics Over ten interviews have been conducted with European automakers (e.g Daimler, BMW, etc.) and research project consortium (e.g MotorBrain, CRM_Innonet, etc.) inquiring about their concerns on rare earths supply and feasibility of substitution of 182 F Sources and approach O 81 82 E 79 80 R 77 78 R 75 76 O 73 74 C 71 72 N 70 U 68 69 R O Countries gathered at the 2015 Paris Climate Conference (COP21) agreed to increase their efforts to limit climate change Transport is a growing sector that contributes almost one-quarter of current global energy-related GHG emissions More than half of this is related to road passenger transport [1,2] For example, in Europe, transport accounts for more than 30% of final energy consumption and the European Commission is already taking actions to decarbonise the transport sector [3] Limiting global temperature increases to below °C requires sustainable transportation solutions Electromobility for various transport modes coupled with a low-carbon power system is seen as a promising sustainable solution Electrified road transport is not a new concept, but it is only recently that electric vehicles (EVs) have gained relevant mass-market sales through third-generation technology Several factors push up the electromobility trend, such as the increasing volatility of oil prices, air quality concerns, climate change agreements, more stringent emission standards and market momentum for EVs At the end of 2015, the global EV stock accounted for over 1.26 million units and global EV sales in 2015 amounted to over 550,000 cars [4] Although the number of electric vehicles on the road is still very low when compared to the total number of passenger cars worldwide (0.1%), the shift towards electrified powertrains is becoming more apparent For instance, in 2015 the share of passenger EVs exceeded 1% of new market sales in Norway, the Netherlands, Sweden, Denmark, France, China and the UK [4] Several countries have set up ambitious sales and/or stock targets regarding vehicle electrification as guidance for creating national roadmaps and for gathering support from policymakers Among various uptake scenarios, the International Energy Agency (IEA) and the Electric Vehicles Initiative (EVI), a multi-government policy forum composed today of 16 members, presented an aggregated global deployment target of 7.2 million in annual sales of EVs and 24 million in EVs stock by 2020 [5] This is an important milestone in meeting the global deployment target of 100 million EVs by 2030 as announced at COP21 in the Paris declaration on electromobility and climate change and call for action [4] An even more ambitious target (140 million EVs by 2030) is presented by IEA under the °C scenario [4] For instance in Europe the combined targets aim to reach up to 8–9 million EVs on the road by 2020, but specific targets and timelines are subject to negotiation with the EU's member states [6] It is important to consider here the impact of availability of material resources and their secure supply on the future deployment pathway of EVs in view of the overall concerns about the supply of certain materials in the global transition to a sustainable energy future [7–10] In previous studies conducted by the European Commission's Joint Research Centre (JRC) we showed that several low-carbon energy technologies could be at risk because of potential bottlenecks in the supply chains of certain metals [11–13] Among these technologies, electric vehicles are of particular concern due to the dependence on critical rare earths used in NdFeB permanent magnets (PM), which are essential for producing light, compact and high efficiency traction motors Such magnets contain neodymium (Nd), praseodymium (Pr) and dysprosium (Dy) rare earths in their composition Dysprosium is used as an additive to improve the magnet coercivity at high temperatures [14] In recent years, traditional asynchronous motors have been continuously replaced by more efficient devices containing permanent magnets, e.g high efficient PM synchronous-traction motors (PSM) in EVs, HEVs and e-bikes [15] Due to the high energy density of NdFeB, this magnet is also increasingly used in high-tech applications and energy-related devices such as generators in wind turbines [16,17] Consequently, it is expected that the global demand for Nd, Pr and Dy elements will increase in the coming years as the market in these sectors will most likely increase [16,18–20] A series of events, such as imposing export restrictions on rare earth elements (REEs) by the near-monopolist China, caused the supply crisis 130 131 P 66 67 from 2010 to 2011 that drove up prices by between and times in less than a year [21–24] As a result, the costs of products containing rare earths increased Although prices for rare earths have declined since 2013, concerns regarding the supply of rare earths continue among industry and governments as another supply crisis remains a distinct possibility [16,18] These supply concerns are also due to the current reorganisation of rare earth market as well as introduction by the Chinese government of various measures to limit REE production, driven by environmental, social and resources preservation aspects Based on specific risk assessments, rare earths are in general evaluated as ‘critical materials’ [25–30] Different mitigation strategies such as the development of new mines and recycling are being considered, but both are seen as unrealistic to be implemented in the short-term From one side many barriers prevent a fast and sustainable primary production and on the other side large volumes of secondary rare earthbased products are not expected to enter soon into the recycling circuit [24,31,32] In the midst of this is the substitution A complete and direct (one-by-one) replacement of all critical materials by other more readily available or less critical without decreasing product performance, raise the price or both, is very limited [33] However, the substitution of rare earths and other critical materials appears to be a feasible solution, especially in cases where the substitution takes place at the product, component or technology level rather than the element level [34–36] According to Smith and Eggert [36], material substitution has ‘multifaceted’ dimensions and the authors identify five types of substitution in the case of NdFeB magnet: element-for element, technology-forelement, grade-for-grade, magnet-for magnet and system-for-system substitution The literature seems to agree on the fact that substitution represents an essential component of the strategy towards a sustainable use of scarce resources or environmentally problematic materials [37–40] Comprehensive information about the substitution of rare earths in permanent magnets and the impact of this approach on reducing reliance on rare earths in relation to the widespread adoption of electric vehicles is limited in the literature The state-of-the-art of some rare earths-free propulsion motors was addressed in several reviews [15,41,42] Here we intend to complement the literature by assessing the current technological status of these components and offer an outlook on further developments We are focusing on the most promising electric propulsion motor concepts that could be applicable at a large scale within a short period in electric road transport applications (i.e electric vehicles, HEVs and e-bikes) In this paper we first estimate the demand for permanent magnets for reaching the global deployment targets for electric vehicles in 2020 and describe its link to material resources availability The competition for PM-based traction motors from other applications, in particular HEVs and e-bikes, is also evaluated Then we analyse in-depth the possible substitutes for rare earths-based traction motors and assess their ability to enter into serial production in the short-term (2020) Finally, we evaluate the impact of substitution on reducing the demand for rare earths in electric traction motors under different scenarios D Introduction T 65 E Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 183 184 185 186 187 188 189 190 191 192 193 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 222 3.1 Applications of permanent magnets in electric traction motors 223 224 Today, the NdFeB alloy is a high power magnet with the largest sales share in the permanent magnets market [43] Based on their high energy density NdFeB magnets are widely used in the automotive industry either for electric traction motors or for non-traction electric components such as audio speakers, transmission, electric power steering, electronic sensors, etc [17] Since the magnet content is estimated as negligible in non-traction components [44], in this paper we take into account only electric traction motors There is a large diversity of electric propulsion systems available today In general electric vehicles refer to the passenger cars that have an electric motor as the primary source of propulsion using electrical energy from the grid stored in rechargeable batteries [6,45] The EV group comprises: battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), range-extended electric vehicles (REEVs) and plugin electric vehicles (PHEVs) Hybrid electric vehicles (HEVs) are not part of EV category since the electric motor represents a secondary propulsion source in combination with an internal combustion engine (ICE) In this paper we will refer to the electric vehicle types BEV and PHEV as well as HEV as these three classes are the most common variants and they may make use of NdFeB magnet [46] Currently most HEVs and EVs (abbreviated as H&EV) use synchronous motors with NdFeB permanent magnets It is estimated that by 2025 between 90 and 100% of H&EVs sales will be based on this technology [47] Overall several reasons explain the common use of rare earth-based PSM in H&EVs [41,48,49]: 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 C E R 231 232 R 229 230 N C O 227 228 • The very strong magnetic field of integrated NdFeB magnets allows a light and compact motor design; • PSMs have a high efficiency since no external power system is needed to induce a magnetic field in the rotor The magnetic field is provided by permanent magnet whereas other motor concepts require electricity to generate this electric field; • PSMs supply high torque and can be more easily controlled 258 259 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 3.3 Market momentum of hybrid vehicles and estimation of NdFeB magnet 282 demand in HEV applications 283 The number of new H&EVs models significantly increased from 12 to 60 in the period 2010–2014 (Fig 2) In 2014 hybrid types HEV and PHEV constituted 65% of the new electric models launched The high market momentum of HEV, and more recently PHEV, reflect consumer preference for no compromises in range compared to BEV, combined with lower fuel consumption compared to conventional ICE vehicles The evolution of H&EV penetration rates of these models is very sensitive to several factors, such as the price of oil, the cost and efficiency of the battery-pack, regulations, government support, infrastructure, customer preferences, etc An additional factor that could potentially influence the future adoption of electric and hybrid vehicles derives from the availability of rare earths and downstream products (e.g NdFeB magnet) It is estimated that all HEV and PHEV commercialised U 225 226 T 221 Estimation of permanent magnets demand in traction motors used in electric road transport applications Based on the current technology, a PSM for an electric vehicle needs between and kg NdFeB depending on motor power, car size, model, etc [44,47] If all of the EVs (BEV and PHEV) sold worldwide in 2015 (about 550,000 passenger cars) had been produced with NdFeB magnets, then up to 1100 tonnes of NdFeB would have been required This amount represents just over 1% of the global production of NdFeB magnets, which was estimated to range between 79,000 tonnes [51] and about 80,000 tonnes [52] in 2015 To meet the global deployment target of 7.2 million EV sales in 2020 [5], the number of EVs produced would need to grow progressively on average by approximately 67% compound annual growth rate (CAGR) from 2015 until 2020 Assuming that all 7.2 million EVs will use PSM motors, these would require between 7200 and 14,400 tonnes of NdFeB magnets in 2020 This translates to a significant increase in the annual demand for NdFeB magnets in EVs by up to 14 times in only years (Fig 1) Today China dominates the production of NdFeB magnets by 85– 90%, the rest being produced in Japan (10%) and in other countries from Europe, the USA, etc [52] Their manufacture appears to continue to move to China where access to REEs remains cheapest and most secure [18] F 203 204 O 201 202 256 255 257 3.2 Estimation of NdFeB magnet demand in electric vehicle types BEV and 260 PHEV 261 R O 200 P 198 199 D 196 197 E-bikes represent an additional application for NdFeB-based PSM because of their ability to offer low weight and compact size Significant growth rates for e-bikes were registered in the recent years, with almost all production and demand concentrated in China [50] permanent magnet or rare earths in electric traction motors In most of the cases the experts asked to remain anonymous The demand for rare earths in these applications was estimated using the average amount of permanent magnets in different types of electric powertrains and based on the elemental composition of NdFeB magnets The deployment targets for EVs are those presented by the International Energy Agency (IEA) Other scenarios were used as complementary information and are referenced throughout the paper Our demand projections for permanent magnets and rare earths represent a baseline necessary to carry out a more in-depth substitution analysis From our analysis and interviews with experts it is clear that magnet producers and automotive industries have looked at different types of substitution, some of them being more prevalent than others Four main approaches to reduce the demand for rare earths are evaluated in this paper: improving material usage through a better material efficiency, dematerialization (using less NdFeB magnet), direct substitution of rare earths in magnet (element-for-element substitution) and adoption of rare earth-free traction motors (defined as component substitution) The impact of substitution on decreasing the demand for rare earths in three electric transport sectors – EVs, HEVs and e-bikes – was calculated based on assumed scenarios While the potential of improving material efficiency is estimated according with industry experts, adoption rate of rare earth-free motors and dematerialisation are more arbitrarily chosen in order to highlight in impact of component substitution on decreasing the future demand for rare earths E 194 195 Fig Evolution of global annual sales of electric vehicles (BEV and PHEV) since 2010 [4] and 2020 deployment target [5] Estimation of NdFeB demand is based on the assumption that all EVs use NdFeB-PSM technology The error bar represents the standard error calculated based on the minimum and maximum amount of NdFeB magnet used in a PSM Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 284 285 286 287 288 289 290 291 292 293 294 295 296 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx 3.4 Estimation of NdFeB magnet demand in e-bikes 321 E-bikes integrate a small electric motor and rechargeable batteries to assist the rider in pedalling In general, they are classified as bicycles given their ability to be pedalled, distinguishing them from electric scooters and motorcycles Most e-bikes use PSMs with an NdFeB magnet, either as hub motors (integrated in the front or rear wheel) or as mid-drive motors (near the bottom bracket) The amount of NdFeB magnet in an e-bike is estimated to range from 60 g to 350 g [58] Since the NdFeB magnet has to cope with temperatures of up to 100 °C, it needs a low share of dysprosium to withstand demagnetisation According to experts, the loading of dysprosium in NdFeB magnet for e-bikes application is around 1% Dy, much lower compared to 4% found by Hoenderdaal et al [59] for two-wheel vehicles, which include along e-bikes also electric scooters and electric motorcycles [59] This difference might be also somewhat a result of manufacturer efforts to improve efficiency in materials use Later in this analysis we take into account a conservative loading of 1% Dy in NdFeB magnet for e-bikes The global e-bike sales are much higher than current sales of H&EV It is indicated that about 40 million e-bikes were sold globally in 2013, with China being the biggest market, followed by Europe, Japan and the USA (Fig 4) [50] Due to a high saturation of ownership a slower growth was registered in the e-bike sector during the period 2013–2015 [50,52] But the global e-bike market is expected to increase further at a CAGR of over 4% until 2019 [60] Based on these data, we estimate that around 50 million e-bikes will be sold in 2020 On the assumption that the e-bikes sold in 2015 is similar to that in 2013 and all e-bikes have used an NdFeB-based PSM, circa 2400–14,000 tonnes of NdFeB would have been required in 2015 The maximum amount represents more than 17% of current global NdFeB production and is approximatively 13 times higher than the quantity requested for EVs in the same year In 2020 the demand for NdFeB in the e-bikes sector is expected to increase up to 17,500 tonnes using current technology When adding the NdFeB amounts used in the three sectors – EVs, HEVs and e-bikes – the total annual demand for NdFeB magnet in 2015 could range from about 4000 tonnes in the lower bound case and up to 16,900 tonnes in the upper bound case The upper and lower bound cases indicate the maximum and minimum masses of NdFeB magnet needed in an e-bike motor The maximum amount of NdFeB requested for these three sectors represents about 21% of the current global production More importantly, the NdFeB demand for these electric road transport applications could increase very rapidly in the next years, driven by EV deployment targets (Fig 5) To meet the global deployment target of 7.2 million in 2020, the NdFeB demand is estimated to increase by around 1200% between 2015 and 2020 For HEV and e-bikes this increase is much less compared to EV, for instance by 50% and 25%, respectively 322 323 313 314 315 316 317 318 319 320 R O P D T C 311 312 E 309 310 R 307 308 R 305 306 O 303 304 C 301 302 N 299 300 today use PSM [41,47], thus competing with BEV and other technologies for the same materials The compact size and high performance of PSM makes it the favoured technology for hybrid cars because manufacturers have to cope with space restrictions due to the need to integrate two drive trains into the car (the electric engine and the combustion engine) According to Navigant Research, approximately 2.1 million HEVs were sold globally in 2015 [53], mostly in Japan, followed by the USA and Europe [54,55] Global annual HEVs sales are expected to increase, reaching 2.8 million in 2020 under a conservative scenario [53] or over 3.5 million in a more optimistic one [52] Further in our analysis we take into account the average of 3.15 million HEVs sales in 2020 An HEV propulsion motor needs less PM material than an EV motor, circa 42% of the EV-motor magnet weight [56] This translates to a range of 0.42–0.84 kg magnet per HEV Under this assumption up to 1800 tonnes NdFeB have been used to produce 2.1 million HEVs in 2015, representing a small fraction (2.3%) of current global production (Fig 3) The market trends indicate that HEV models will still remain the dominant electric powertrain in the near future [57] Based on our projections, the demand for NdFeB in the global HEV market is not expected to see very significant growth levels in the short-term Up to 2650 tonnes of NdFeB would be required for the 3.15 million HEV, about 1.5 times more compared to 2015 U 297 298 E Fig Estimation of new electric vehicles and HEVs models released since 2010 [6] O F Fig Evolution of global annual HEV sales, 2020 forecast [53–55] and estimation of the NdFeB demand for HEV The error bar represents the standard error calculated based on the minimum and maximum amount of NdFeB magnet used in a PSM Fig Estimated e-bikes sales by country in 2013 in million units [50] Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx O F operating times and generate significant amounts of heat, NdFeB is less suitable due to its reduced coercivity In fact, at temperatures above 80–120 °C, the coercivity of NdFeB declines significantly Both dysprosium and terbium can be used as a dopant to enhance the coercive force of an NdFeB magnet and enable it to perform stably at higher temperatures Currently, dysprosium is the most convenient dopant because of its low price compared to terbium The dysprosium loading in an NdFeB magnet for electric vehicle can vary between 3.7 and 8.7% [59,63], and the resulting compound demonstrates an increased coercivity between 100 and 200 °C For practical reasons however the content of dysprosium in NdFeB magnet used in electric vehicle motor is kept high, up to 7.7% [59] According to experts the actual Dy share in NdFeB magnet for an electric traction motor in EV is around 7.5% Taking into account the fraction of rare earths in magnet composition (i.e 30% Nd/Pr (Nd:Pr = 4:1) and 7.5% Dy in H&EVs (or 1% Dy in e-bikes)) and NdFeB demand projected in the previous sections, about 920–4050 tonnes Nd, 230–1010 tonnes Pr and 130–355 tonnes Dy would have been required to satisfy the HEVs, EVs and e-bikes market in 2015 In terms of demand/production share, the three sectors combined accounted for up to 19% Nd, 16% Pr and 25% Dy of each individual rare earth produced in 2014 The overall supply of rare earths is forecasted to increase by a factor of 1.38 from 2014 to 2020 [52] Assuming that the share of neodymium, praseodymium and dysprosium remains the same with respect to the overall REE supply in 2014, then the global annual supply for these three elements will reach approximatively 29,100 tonnes Nd, 8725 tonnes praseodymium and 1940 tonnes Dy in 2020 If the composition of NdFeB will remain constant, the demand for rare earths in 2020 in these three sectors will increase to a range of 2770–8290 tonnes Nd, 690–2075 tonnes Pr and 670–1450 tonnes Dy The maximum demand/supply share in 2020 is projected to be about 28% for Nd, 24% for Pr and 75% for Dy It becomes evident that the highest pressure in terms of material supply is expected for dysprosium In particular, up to 56% of the estimated annual Dy supply in 2020 (today it is around 6%) would be needed to meet the deployment targets for electric vehicles in 2020 This share is estimated at about 12% for Nd and Pr Despite the fact that the production of rare earths and downstream products will increase in the future, however the issue about REE supply and price stability could re-emerge, thus posing a potential bottleneck to the deployment targets for electric vehicles for 2020 and beyond Opening a new primary production of rare earths is unrealistic in a short time (about 8–10 years elapse between the discovery of rare earths deposits and production at the mine) Mining and refining of REE are associated with serious environmental problems, such as soil and water contamination, human health, air pollution, etc The environmental impact might also affect a sustainable production and stable supply chain of rare earths Moreover, large volumes of secondary rare earths production are not expected in the short term to influence the demand/supply balance since many end-of-life products containing NdFeB magnet will enter the recycling circuit after many years [59] The spike in prices for rare earths during 2011–2012 and the perceived risk associated with their supply and environmental pressure have already led to investments in NdFeB-free motors and the adoption of alternatives Such technologies can either use PM with a reduced level of rare earths or replace the entire NdFeB-based component with other types of drive system, such as an asynchronous motor Alternative electric traction motors that not require rare earths-based magnets have already been developed for serial production by several companies The main reason for developing REE-free motors was security of supply concerns rather than the price volatility of rare earths [52] In the next section we evaluate the substitution paths for NdFeB-based synchronous motors used in electric powertrains and analyse their current technology status 379 396 397 The global growth rate of NdFeB consumption for high-tech applications (e.g hard disk drives) and other energy-related devices (e.g wind turbines) is likely to increase in the near future [52], thus competing with NdFeB and its constituent rare earths for electric road transport applications These trends highlight that the REE supply issue must remain high on the agenda of security of supply policies despite recent positive developments such as the lifting China's export bans and decreasing rare earth prices Other factors to be considered are that the rare earths market is still small and dominated by Chinese production and Chinese demand Thus it may become again susceptible to price fluctuation In 2014 the global annual production of rare earths (in metal form) was estimated to be around 21,000 tonnes Nd, 6300 tonnes Pr and 1400 tonnes Dy [61] The NdFeB magnet is the major application for all three rare earths [61] The composition of NdFeB magnet is presented in Table For applications with a shorter operating period (e.g in speakers, computer devices, etc.) the NdFeB permanent magnet is ideal However, for applications like electric traction motors, which have longer t1:1 t1:2 Table Typical composition of sintered NdFeB for applications at room temperature [62] 388 389 390 391 392 393 394 395 C E R 386 387 R 384 385 N C O 382 383 U 380 381 t1:3 Chemical element Percentage by weight t1:4 t1:5 t1:6 t1:7 t1:8 t1:9 Neodymium (Nd) and/or praseodymium (Pr) Iron (Fe) Boron (B) Aluminium (Al) Niobium (Nb) Dysprosium (Dy)⁎ and/or terbium (Tb) 29–32 64.2–68.5 1.0–1.2 0.2–0.4 0.5–1 0.8–1.2 t1:10 t1:11 P 3.5 Supply issues for rare earths and their demand for electric road transport applications (H&EVs and e-bikes) D 377 378 373 374 T 375 376 In 2020, about 11,500–34,500 tonnes NdFeB magnet might be requested globally for the electric road transport applications In the upper bound case the NdFeB amount corresponds to a share of over 43% of the current global NdFeB supply When taking into account the forecasted production of NdFeB magnet in 2020, such as 118,000 tonnes [52], this share decreases to about 30%, but still a very significant fraction of the supply 371 372 E 370 R O Fig Estimation of global annual demand for NdFeB magnet in EV, HEV and e-bike applications in 2015 and 2020 and the percentage increase assuming that all traction motors are based on NdFeB-PSM technology Bars correspond to average values The error bar represents the standard error calculated based on the minimum and maximum amount of NdFeB magnet used in PSM for each application ⁎ The Dy content could be increased up to 9% to allow the magnet to operate at high temperatures, i.e up to 200 °C Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 At the moment there is no alternative magnet with similar properties to NdFeB or an approach that would enable the full substitution of rare earths with less critical raw materials at large Such solutions may still not be available in the near future Currently, research focuses mostly on reducing the rare earth content through two main approaches: (i) increasing material efficiency in magnet production (e.g grain boundary diffusion processes), thus obtaining NdFeB magnets with less rare earth content but with similar performance; (ii) optimising the motor design, enabling high technical performance while using less NdFeB magnet Details about improving material efficiency and rare earths substitution in permanent magnets were already described by our group in the context of NdFeB application in wind turbines [64] In summary, current research indicates a possible reduction of the amount of Nd and Pr needed to produce NdFeB For example, Lacal-Arántegui estimates a rise in material efficiency for neodymium and praseodymium of up to 29% from 2015 to 2030 in a permanent magnet of equal magnetic strength and cost [65] As result of research developments, Daimler indicates that the Dy content in permanent magnets in PHEV and HEV vehicles could significantly drop from 7.5–9% to approximately 5% in 2020 and afterwards to 2.5% [66] Terbium can replace dysprosium without losing performance, but due to its higher price and a supply criticality issue it is not considered a convenient substitute 4.2 Reducing the amount of NdFeB magnet in electric traction motor: dematerialisation 505 4.3 Component substitution for PSM traction motors in EVs and HEVs 506 507 Currently, most electric vehicles use PSMs with NdFeB magnets These can be affixed to the rotor's surface (surface magnets) or they can be located in pockets within the rotor (buried magnets) The stator carries windings connected to the power supply to produce a rotating magnetic field The torque results from the interaction between these different magnetic fields Alternatives to NdFeB-PSM exist in serial production for several BEV models For example, the Tesla S, Mercedes B-Class and Renault Twizy have an asynchronous machine (ASM) and the Renault Zoe and Renault Kangoo use an electrically excited synchronous machine (EESM) However, since hybrid vehicles have stricter requirements for a compact size and temperature stability, the use of PSM motors is the preferred option chosen by most manufacturers of HEV and PHEV The ASM and EESM technologies are technically available and have good performance, but they are not applied in serial HEV and PHEV production because of their lower power density and higher weight compared to PSM 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 R R O C 501 502 N 499 500 U 497 498 E 503 504 From the motor design side, high torque densities can be obtained in optimised PSMs by designing new electrical machines while simultaneously using less NdFeB magnets [67] BMW developed a hybrid motor using fewer magnetic materials embedded into salient rotor structures This led to a reduction of the rare earths content (30% to 50% less) in the BMW i3 model compared to other PSM designs [42] Since these motors provide both magnet and reluctance torques, they are also called ‘permanent magnet-assisted reluctance motors’ or just ‘hybrid motors’ [68] The hybrid motor is similar to the EU co-funded MotorBrain project concept for PSM, which uses ferrite for creating reluctance torque [69] 496 F 469 470 T 468 C 467 O 4.1 Rare earths substitution in NdFeB magnets and improved material efficiency R O 466 Synchronous machines and ASM operate on different physical principles In ASM, the torque is obtained by electromagnetic induction from the magnetic field of the stator winding The AC Power is supplied to the motor stator Whereas a synchronous motor rotor turns at the same rate as the stator field, an asynchronous motor rotor rotates at a slower speed than the stator The induction motor stator magnetic field therefore constantly changes relative to the rotor This induces an opposing current in the rotor Thus, currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field The torque is a result of these different magnet fields The ASM is also called “induction motor” as it bases on the principal of induction Externally excited EESMs only differ from PSMs in their rotor design The PSM uses a permanent magnet in the rotor, whereas the EESM does not use any magnets Electrical current from the battery magnetizes the copper windings in the EESM rotor to create an electrical magnet Other rare earths-free alternative motors are available and some are in the prototype stage with a high potential for the future serial production of EVs and HEVs Promising alternatives such as ASM with high revolution per minute (rpm) and PSM with low-cost magnets (e.g ferrite materials) have the potential to enter into the market for EVs and HEVs Another substitute for PSM might be the switched reluctance motor (SRM) if R&D can successfully solve significant technical obstacles such as inverter incompatibility for other engines and high noise due to very small sound-emitting air gaps The current status, major advantages and disadvantages of the most promising motor concepts as well as an outlook to 2020 are given in Table A crucial point in developing an electric vehicle is the improvement of overall vehicle efficiency to allow longer operational ranges This means that the efficiency of powertrain designs and their embedded motors is a major issue for vehicle manufacturers Therefore, alternative motor types have to compete with highly efficient PSMs The comparison shown in Table indicates that there is not an optimum substitute for PSM that can satisfy all traction conditions while also fulfilling technical and commercial requirements For instance, compared to PSM, the ASM is less efficient in urban conditions, but more efficient on motorways with high speed This characteristic is a strong advantage for PSM and EESM types, making them more suitable for urban applications Other characteristics of the main technologies - PSM, ASM and EESM are shown in Table The industry aims at a higher driving range for EVs, which also require a high efficiency at high speed Other motor types such as the switched reluctance machine (SRM) and transverse flux machine (TFM) are in early stage of development and further research is necessary prior to serial production The experts interviewed within this study believe that different electric motor concepts will contribute to the future H&EV market This observation is confirmed by a survey conducted by Hornick [80] Manufacturers will favour a motor type that best meets the specific needs of the vehicle at reasonable cost-effectiveness The ferrite magnet-based motor and switched reluctance motor are potential candidates as these technologies may offer the lowest cost in car manufacture compared to the relative high cost of NdFeB magnet-based PSM [42] Since technical requirements vary with vehicle type and its area of application, a variety of electric traction motors with specific performance characteristics is needed for the development of efficient and competitive H&EVs The development time of a new electric motor for H&EVs highly depends on economic conditions Based on the MotorBrain project, which developed a new motor prototype in three years [69], we could estimate that about years are needed from the conceptual stage until serial production The time could significantly decrease if electric motor design has merely to be adapted from other similar applications Given the variety of prototypes available today, it is expected that a rare earth-free motor can be produced within a short time P Substitution opportunities of rare earths in electric traction motors D 464 465 E Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 N Table Overview of main component substitutes for PSM in EVs and HEVs, and comparison to current state-of-the art PSM C t2:3 Motor type t2:4 Permanent synchronous motor (PSM) 0.56 kg REEs per EV motor⁎ (less in HEV and e-bikes) t2:5 Asynchronous motor (ASM) Rare earths free Used in some serial BEV (e.g Tesla S, Mercedes B class, Renault Twizy) and PHEV t2:6 t2:7 Externally excited synchronous motor (EESM) Rare earths free Used in few serial BEV (e.g Renault Zoe) and PHEV Also available for HEV t2:8 ASM with high rpm Rare earths free Serial production announced t2:9 PSM with low-cost magnets Rare earths free Prototypes using ferrite or AlNiCo magnets t2:10 Switched reluctance motor (SRM) Rare earths free First prototype t2:11 Transversal flux motor (TFM) Rare earths free Early R&D stage t2:12 t2:13 t2:14 Hybrid motor (e.g combine synchronous reluctance principle with permanent excitation) 0.37 kg⁎⁎ REEs or less per motor Used in the BEV BMW i3 and PHEV BMW t2:15 t2:16 Rare earths content Current status Major advantages Major disadvantages Outlook 2020 Ref Used in all serial HEV and in most serial PHEV and BEV • High efficiency at low and medium speeds • Compact size/high power density • Wide dissemination • Low production costs • Robustness • High reliability • High efficiency at high speed • High efficiency in all speed ranges • Dependency on rare-earth supply and their price variation • Lower efficiency at high speed Maintains a key role in EV and HEV as long as the price of rare earths not increase significantly [41,48,49] • Lower efficiency than PSM in urban conditions • Lower power density than PSM, requiring more package space and weight • Higher copper demand than PSM • Lower power density than PSM • More package space needed • Complex structure resulting in high manufacturing costs • No experience in serial production yet Maintains serial application in some EV and in mild hybrids, partly as improved ASM with high rpm [70,71] Remains an efficient alternative to PSM, but application in HEV is unlikely [42,72] Offers high potential for serial production in BEV, HEV and PHEV due to high efficiency and good cost effectiveness [42,73] O R R E C T E • Potential for high energy and material efficiency • Potential for low production costs • Potential for good overall performance • Robust construction • Potential for cheap engine production D • No experience in serial production P • High noise level • Requirement for a specific inverter, which is not compatible to production lines of power electronics for other engines • Potential for high power • Low technology readiness level density and efficiency • Similar performance as • Remaining rare earth demand PSM with less rare earths R O Offers good potential for serial production [68,74–76] due to high technical performance and reasonable cost effectiveness Needs further R&D to achieve highly [41,77] efficient and silent engines suitable for serial production Might offer high power density and high efficiency, but needs more intense R&D Applied in serial BMW i3 and BMW PHEV production with high potential for further vehicle types and models O [78,79] C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 t2:1 t2:2 U [68,69] F ⁎ The rare earths content in PSM takes into consideration the range of 1–2 kg permanent magnet per EV traction motor and the following chemical composition of NdFeB: 30% Nd/Pr (Nd:Pr = 4:1) and 7.5% Dy ⁎⁎ Value relates to kg NdFeB magnet per traction motor with the same chemical composition as above Table Comparison of principal characteristics of PSM, ASM and EESM [78] t3:3 595 596 597 598 599 600 601 602 603 604 605 606 607 + + O + + + + ++ very good performance; + good performance; O low performance Impact of substitution on short-term demand for critical rare earths – Nd, Pr and Dy – in H&EV and e-bike applications t4:1 t4:2 Table Possible substitution scenarios for rare earths in PSM used in H&EV and e-bikes 618 619 620 621 t4:3 E R R O 616 617 C 614 615 N 612 613 U 610 611 C 622 Future developments in material efficiency, motor design and component substitution may make the challenge associated with rare earths supply and environmental issue less daunting There are expected improvements in terms of efficiency in rare earths usage for production of NdFeB magnets Although the full substitution of rare earths will probably not take place over the coming years, experts consider that the share of Nd and Pr in NdFeB composition may decrease down to 26.5% Nd/Pr from 30% by 2020 Furthermore, a significant drop from 7.5% down to approximatively 5% of the Dy content in NdFeB magnets looks to be feasible for PHEVs and HEVs An optimised PSM design could lead to the use of much less NdFeB magnets (i.e as in the case of the hybrid design used in BMW's i3 motor) Moreover, some manufacturers may continue with or switch to rare earths-free motors for BEVs There are also pilot concepts of REEs-free motors for hybrid vehicles (PHEV and HEV) with a high potential for commercialisation Due to the large number of parameters and the high uncertainty of future technological and economic developments, the precise future 608 609 Substitution scenario - 2020 t4:4 t4:5 t4:6 t4:7 t4:8 t4:9 t4:10 t4:11 t4:12 t4:13 t4:14 t4:15 F There are no alternatives to PSM for e-bikes available on a large production scale Since the current, low rare earth prices give no incentive to manufacturers to develop rare earth-free motors for e-bikes, it seems that industry does not look for alternative solutions that might be accompanied by efficiency losses or higher e-bike weight This assumption is confirmed by industry experts Several European manufacturers, e.g Bosch, Brose Antriebstechnik, Derby Cycle located in Germany and Accell Group from the Netherlands, supply high-quality e-bikes to customers who demand high energy efficiency and light powertrains Consequently, the competitiveness of these manufacturers highly relies on the production of premium products Future shortages or high prices of rare earths might be tackled by the fast development of alternative motor systems This is evident in e-bike motors that have mostly been derived from automotive applications like electric power steering or windshield wiper motors O 593 594 EESM + + + ++ + ++ + R O 591 592 ASM ++ ++ ++ + ++ + + P 589 590 PSM D t3:11 Construction space Weight Cooling Production costs Power density Reliability Noise T t3:4 t3:5 t3:6 t3:7 t3:8 t3:9 t3:10 penetration rate of substitutions remains unclear Current low prices and a sufficient supply of rare earths give no strong incentive to switch to rare earth-free motors, unless they become more cost and performance-effective In this context, experts see a high potential for the newly developed ASM with high rpm, which has high efficiency and could also achieve low production costs Based on possible technological developments and inputs received from experts, in this paper we have analysed different substitution scenarios along three main parameters: materials efficiency, dematerialisation (less NdFeB content) and component substitution (replacement of PSM by other rare earth-free technology) We grouped them in case scenarios: (i) substitution case A, takes into account an increase in material efficiency; (ii) substitution case B, considers the material efficiency of case A and 30% of component substitution, (iii) substitution case C, on top of the material efficiency of case A it assumes 50% component substitution, and (iv) substitution case D adds dematerialization (i.e 40% less NdFeB magnet on top of case C Table gives an overview on the assumptions of the four substitution scenarios and compares them to the reference scenario, which exhibits no substitution and features the same NdFeB demand as shown in Fig The results obtained from this analysis are presented in Fig The impact of substitution is revealed through the four different scenarios A, B, C and D The results show that substitution has the potential to reduce the short-term global demand for rare earths in the H&EV and e-bikes sectors Compared to the 2020 reference case a decreasing demand by 12% for Nd and Pr can be achieved by improving material efficiency (substitution case A) This reduction can be more significant (from 38% up to 56%) if an adoption of alternative components complement the material efficiency (e.g 30% or 50% of PSM technology are replaced by rare earth-free electric traction motors as evidenced in substitution case B and C, respectively) If the decrease of NdFeB amount (through dematerialisation) will also take place, the reduction in Nd and Pr demand can reach about 73% (substitution case D) In case of Dy a substantial demand reduction (up to 33%) in H&EVs can be reached just by improving material efficiency, such as by decreasing the Dy loading in the magnet from 7.5% to 5% A decreasing of Dy loading below 5% in NdFeB used in electric traction motors for serial production of electric and hybrid vehicles will likely not take place before 2020 Material efficiency has no impact on e-bikes, which already use a very small loading (1% Dy) Moreover, if 30% of the rare earths' components is replaced, the demand for Dy in electric vehicles could be reduced by half (substitution case C) with respect to the 2020 reference case, decreasing further by 80% in case of substitution case D While already in the case of substitution case B the demand for rare earths in 2020 might decrease below the 2015 level in HEV and e-bikes, however even in the most ambitious substitution scenario (D) the growth rate for Nd, Pr and Dy consumption in electric vehicle sector is expected to increase over the next years in order to meet the E t3:1 t3:2 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx Base year - 2015 Reference case (no substitution) Substitution case A (material efficiency) Substitution case B (material efficiency + low component substitution) Substitution case C (material efficiency + high component substitution) Substitution case D (material efficiency + high component substitution + dematerialisation) Material efficiency Nd/Pr loading⁎ in PM (%) Dy loading⁎⁎ in PM (H&EVs) (%) 30 30 26.5 26.5 26.5 26.5 7.5 7.5 5 5 Dematerialisation Component substitution (%) 0 0 Reduction of NdFeB amount by 40%⁎⁎⁎ 0 30 50 50 ⁎ Nd and Pr are found in ratio 4:1 ⁎⁎ Dy loading in e-bikes is considered 1% in all cases ⁎⁎⁎ 40% magnet reduction leads to 0.6–1.5 kg NdFeB/electric car and 36–210 g NdFeB/e-bike Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx 680 Despite the benefits of climate change mitigation and from potential fuel savings, several barriers could hinder the widespread adoption of electric vehicles Among them is the potential supply disruption of critical rare earths for NdFeB magnet-based electric traction motors In 2015, the global EV sector consumed around 1% of the total market for NdFeB magnets Driven by efforts to foster EVs adoption and meet ambitious deployment targets of EVs in 2020, the demand for NdFeB could rapidly and significantly increase over the next few years HEVs and e-bikes further compete with EVs for NdFeB-based PSM We estimate that the H&EV and e-bike sectors combined would require over two times more NdFeB magnets in 2020 compared to 2015 (between 11,500–34,500 tonnes NdFeB), representing up to 30% of expected global NdFeB supply in 2020 Moreover the market for rare earths-based permanent magnets will likely grow for other applications, e.g high-tech and energy-devices The overall rising demand for NdFeB magnets could have important implications on the supply chain for rare earth, which may also lead to price fluctuation Dy poses the highest supply risk as up to 75% of its 2020 supply may be required to meet the global electric road transport applications The potential supply risks associated with rare earths for electric road transport applications cannot be easily mitigated as there are no effective substitutes for the rare earths used in permanent magnets However higher material efficiency, dematerialisation and adoption of alternative components, e.g rare earths-free electric traction motors, can attenuate the future increasing demand for rare earths Adoption of different substitution paths should take place in parallel as it does not appear that one substitution method prevails over the others Under the most optimistic substitution scenario, which implies adoption of different types of substitution, the global demand in 2020 for H&EV applications could be drastically reduced by 75% for Nd and Pr, and 80% for Dy versus a reference without substitution in the same year But even if such optimistic scenario was to be successfully implemented, the global annual demand for rare earths in electric traction motors in electric vehicle applications is expected to grow significantly up to 2020 This calls for an integrated ‘security-of-supply’ policy that need to consider various strategies along secure access, recycling and substitution For Europe and other countries/regions that lack domestic supplies, substitution may be an effective short-term solution This paper reveals that a number of high potential options for PMS exist and they could be rapidly brought to commercialisation, should prices for rare earths increase However more R&D investments are needed to further develop these solutions and to search for even better alternatives 681 682 Acknowledgements 724 U N C O R R E C T E D P R O O F Conclusions Fig Estimation of global annual demand for Nd, Pr and Dy in 2015 and 2020 in electric traction motors for H&EVs and e-bikes under different substitution scenarios Bars correspond to average values The error bar represents the standard error calculated based on the minimum and maximum amount of NdFeB magnet used in PSM for each application 672 673 674 675 676 677 678 679 deployment targets set for 2020 This demand is estimated to be at least times more in case of the substitution case D, compared to over 13% in the reference scenario without any substitution The growing demand for rare earths indicates a need for further actions to ensure a secure supply and development of suitable alternatives for rare earths-based PM traction motors This will allow Europe and other countries to accomplish the overall goals of cutting CO2 emissions and reducing the transport sector's dependence on oil 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 This work is part of a research project funded by the European 725 Q2 Commission The authors are thankful to various experts from the 726 automotive industry for providing their valuable inputs 727 References [1] International Energy Agency Report, World Energy Outlook, 2015 [2] United Nations Framework Convention on Climate Change, Paris declaration on electro-mobility and climate change & call to action, http://newsroom.unfccc.int/ media/521376/paris-electro-mobility-declaration.pdf2015 (accessed 11.05.16) [3] European Commission, Energy Union Package — A Framework Strategy for a Resilient Energy Union With a Forwards-looking Climate Change Policy, COM(2015)80 Final(Brussels) 2015 [4] International Energy Agency, Global EV Outlook 2016, Beyond one million electric cars, http://www.iea.org/publications/freepublications/publication/Global_EV_Outlook_2016.pdf2016 (accessed 02.06.16) [5] International Energy Agency, Global EV Outlook, Understanding the electric vehicle landscape to 2020, https://www.iea.org/publications/freepublications/publication/ GlobalEVOutlook_2013.pdf2013 (accessed 11.05.16) [6] Amsterdam Round Tables and McKinsey & Company, EVolution: Electric vehicles in Europe – Gearing up for a new phase? https://www.google.nl/url?sa=t&rct=j&q= &esrc=s&source=web&cd=1&ved= Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 [12] [13] [14] [15] [16] [17] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] E R [23] R [22] O [21] C [20] N [19] C T [18] F [11] O [10] R O [9] P [8] [38] R.U Ayres, On the practical limits to substitution, Ecol Econ 61 (2007) 115–128 [39] E Nakamura, K Sato, Managing the scarcity of chemical elements, Nat Mater 10 (2011) 158–161 [40] D Powell, Sparing the rare earths: potential shortages of useful metals inspire scientists to seek alternatives for magnet technologies, Sci News 180 (2011) 18–21 [41] L Kumar, S Jain, Electric propulsion system for electric vehicular technology: a review, Renew Sust Energ Rev 29 (2014) 924–940 [42] J.D Widmer, R Martin, M Kimiabeigi, Electric vehicle traction motors without rare earth magnets, Sustain Mater Technol (2015) 7–13 [43] O Gutfleisch, M.A Willard, E Brück, C.H Chen, S.G Sankar, J.P Liu, Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient, Adv Mater 23 (2011) 821–842 [44] J Speirs, Y Houari, M Contestabile, R Gross, B Gross, Materials availability: potential constrains to future low-carbon economy Working paper II: batteries, magnets and materials, UKERC/WP/TPA/2013/003, http://www.ukerc.ac.uk/asset/ F21105AE%2D78A7%2D4E9C%2D88C752A2149C8B54/2013 (accessed 13.05.16) [45] C Thiel, J Krause, P Dilara, Electric vehicles in the EU from 2010 to 2014 — is full scale commercialisation near?, Joint Research Centre — science and policy report, https://setis.ec.europa.eu/sites/default/files/reports/Electric_vehicles_in_the_EU pdf2015 (accessed 23.05.16) [46] Fraunhofer IAO, Strukturstudie BWe mobil 2011, http://wiki.iao.fraunhofer.de/images/studien/strukturstudie-bwe-mobil-2011.pdf2011 (accessed 23.05.16) [47] CRM_Innonet, Substitution of Critical raw Materials, Deliverable Report D5.3 Final Roadmap Report, 2015 [48] J Paulsen, Developing concepts in e-motor technology, online publication on resource centre for 3rd international conference advanced E-motor technology, Frankfurt (Germany), http://www.e-motor-conference.com/media/1000786/ 35833.pdf2015 (accessed 13.05.16) [49] P Els, Perfecting the electric vehicle drive motor, online publication on resource centre for 3rd international conference advanced E-motor technology, Frankfurt (Germany), http://www.e-motor-conference.com/media/1000786/35836.pdf2015 (accessed 13.05.16) [50] INSG insight, The global e-bike market, http://www.insg.org/%5Cdocs%5CINSG_Insight_23_Global_Ebike_Market.pdf2014 (accessed 25.05.16) [51] W.T Benecki, The permanent magnet market — 2015 Presentation at the conference magnetics Orlando, Florida, http://www.waltbenecki.com/uploads/Magnetics_2013_Benecki_Presentation.pdf2013 (accessed 20.05.16) [52] Roskill Information Services, Rare Earths: Market Outlook to 2020, 15th ed., 2015 [53] S Shepard, L Jerram, Electric vehicle market forecasts, global forecasts for light duty hybrid, plug-in hybrid, and battery electric vehicles sales and vehicles in use: 2015–2024, Navigant researchPublished 4Q 2015 https://www.navigantresearch com/wp-assets/brochures/MD-EVMF-15-Executive-Summary.pdf2015 (accessed 28.06.16) [54] International Energy Agency, Hybrid & electric vehicles-implementing agreement (IA-HEV) Hybrid and electric vehicles — the electric drive commutes, http:// www.ieahev.org/assets/1/7/2016_IA-HEV_BOOK_web_%281%29.pdf2015 (accessed 28.06.16) [55] Y Zhou, E-drive vehicle sales analyses, http://energy.gov/sites/prod/files/2015/07/ f24/van011_Zhou_2015_p.pdf2015 (accessed 23.05.16) [56] M Buchert, et al., Ressourceneffizienz und ressourcenpolitische Aspekte des Systems Elektromobilität Arbeitspaket des Forschungsvorhabens OPTUM: Optimierung der Umweltentlastungspotenziale von Elektrofahrzeugen, OekoInstitut e.V., Daimer AG, TU Clausthal, Umicore, http://www.oeko.de/oekodoc/ 1334/2011-449-de.pdf2011 (accessed 23.05.16) [57] The Boston Consulting Group, Powering autos to 2020 The era of the electric cars? https://www.bcg.com/documents/file80920.pdf2011 (accessed 23.05.16) [58] EU FP7 Marie-Curie Initial Training Network (EREAN), E-bikes and rare earths, http://erean.eu/wordpress/e-bikes-and-rare-earths/2015 (accessed 02.12.2016) [59] S Hoenderdaal, L.T Espinosa, F Marscheider-Weidemann, W Graus, Can a dysprosium shortage threaten green energy technologies? Energy 49 (2013) 344–355 [60] PRNewswire, Global E-bike market 2015–2019, http://www.prnewswire.com/ news-releases/global-e-bike-market-2015-2019-300018143.html2015 (accessed 26.05.16) [61] European Commission, Report on critical raw materials for the EU Critical raw materials profiles, http://ec.europa.eu/DocsRoom/documents/11911/attachments/1/ translations/en/renditions/native2014 (accessed 20.05.16) [62] E-Magnets UK, How neodymium magnets are made, http://www.ndfeb-info.com/ neodymium_magnets_made.aspx (accessed 05.12.16) [63] K Binnemans, P.T Jones, B Blanpain, T van Gerven, Y Yang, A Walton, M Buchert, Recycling of rare earths: a critical review, J Clean Prod 51 (2013) 1–22 [64] C.C Pavel, R Lacal-Arántegui, A Marmier, E Tzimas, D Schüler, M Buchert, D Blagoeva, Role of rare earths in permanent magnets and review of substitution opportunities in wind turbines, Manuscript submitted for publication to Renew Sustain Energy Rev (2016) (MS Ref No RSER-D-16-01647) [65] R Lacal-Arántegui, Materials use in electricity generators in wind turbines — stateof-the-art and future specification, J Clean Prod 87 (2015) 275–283 [66] K Ruland, Daimler AG, Personal Communication, 2015 [67] J Widmer, EV eMotors without rare earth materials Newcastle University, http:// cdn.awsripple.com/www.criticalrawmaterials.eu/uploads/14-05-07-J-WidmerCRM-Workshop-Rare-Earth-FINAL.pdf2014 (accessed 24.05.16) [68] Green Car Congress press release, BMW's hybrid motor design seeks to deliver high efficiency and power density with lower rare earth use, http://www greencarcongress.com/2013/08/bmw-20130812.html2013 (accessed 24.05.16) [69] MotorBrain press release, Compact and efficient electromotor without rare earth metals The “MotorBrain” research team presents the first prototype at the Hannover Messe 2014, http://www.motorbrain.eu/2014 (accessed 24.05.16) [70] E-mobil BW, Fraunhofer institute for industrial engineering (IAO): structure study BWe mobile 2011: Baden-Württemberg on the way to electromobility, http:// www.e-mobilbw.de/files/e-mobil/content/DE/Service/Publikationen/e-papers/e_ mobil_structure_study_en/files/mobile/index.html#12011 (accessed 24.05.16) D [7] 0ahUKEwj1lPjmiNLMAhUBJpoKHVYKCCAQFggdMAA&url=http%3A%2F%2Fwww mckinsey.com%2F~%2Fmedia%2FMcKinsey%2520Offices%2FNetherlands%2FLatest% 2520thinking%2FPDFs%2FElectric-Vehicle-Report-EN_AS%2520FINAL.ashx&usg= AFQjCNHD4p87eDheWXdnekdbp2Un1A7XiA&sig2=w0r_9lE64QRlyoSfLNA3Q&cad=rja2014 (accessed 11.05.16) California Institute of Technology, Resnick institute report Critical materials for sustainable energy applications, http://resnick.caltech.edu/docs/R_Critical.pdf2011 (accessed 12.05.16) World Wide Fund – WWF, Critical materials for the transition to a sustainable energy future, http://www.ecofys.com/files/files/wwf-ecofys-2014-critical-materials-report pdf2014 (accessed 12.05.16D:\Programs\SPS\WMS2016\repos\LC85\smt00036\12 05.16) UK Energy Research Centre, Materials availability for low-carbon technologies: an assessment of the evidence, http://www.ukerc.ac.uk/asset/34D2BFC5%2D9C0D% 2D4C07%2DBA6CD6D15BDE549A/2014 (accessed 12.05.16) M.L Bustamante, B Hubler, G Gaustad, C.W Babbitt, Life cycle assessment of jointly produced solar energy materials: challenges and best practices, Sol Energy Mater Sol Cells 156 (2016) 11–26 R.L Moss, E Tzimas, H Kara, P Willis, J Kooroshy, Critical metals in strategic energy technologies — assessing rare metals as supply-chain bottlenecks in low-carbon energy technologies, European Commission, Joint Research Centre, http://bookshop.europa.eu/en/critical-metals-in-strategic-energy-technologiespbLDNA24884/downloads/LD-NA-24884-EN-N/LDNA24884ENN_002.pdf? FileName=LDNA24884ENN_002.pdf&SKU=LDNA24884ENN_ PDF&CatalogueNumber=LD-NA-24884-EN-N2011 (accessed 12.05.16) R.L Moss, E Tzimas, H Kara, P Willis, J Kooroshy, The potential risks from metals bottlenecks to the deployment of strategic energy technologies, Energ Policy 55 (2013) 556–564 R.L Moss, E Tzimas, P Willis, J Arendorf, L Tercero Espinoza, Critical metals in the path towards the decarbonisation of the EU energy sector — assessing rare metals as supply-chain bottlenecks in low-carbon energy technologies, European Commission, Joint Research Centre, https://setis.ec.europa.eu/sites/default/files/reports/ JRC-report-Critical-Metals-Energy-Sector.pdf2013 (accessed 12.05.16) Y Zhang, T Ma, X Liu, P Liu, J Jin, J Zou, M Yan, Coercivity enhancement of Nd-Fe-B sintered magnets with intragranular adding (Pr, Dy, Cu)-Hx powders, J Magn Magn Mater 399 (2016) 159–163 J.-R Riba, C López-Torres, L Romeral, A Garcia, Rare-earth-free propulsion motors for electric vehicles: a technology review, Renew Sust Energ Rev 57 (2016) 367–379 K.S Stegen, Heavy rare earths, permanent magnets, and renewable energies: an imminent crisis, Energ Policy 79 (2015) 1–8 J Lucas, P Lucas, T Le Mercier, A Rollat, W Davenport, Permanent Magnets Based on Rare Earths: Fundamentals, in Rare Earths — Science, Technology, Production and Use, Elsevier B.V, 2015 213–230 European Rare Earths Competency Network (ERECON), Strengthening of the European rare earths supply chain — challenges and policy options, http://ec.europa.eu/DocsRoom/documents/10882/attachments/1/translations/en/renditions/native2015 (accessed 12.05.16) E Alonso, A.M Sherman, T.J Wallington, M.P Everson, F.R Field, R Roth, R.E Kirchain, Evaluating rare earth element availability: a case with revolutionary demand from clean technologies, Environ Sci Technol 46 (2012) 3406–3414 K Nansai, K Nakajima, S Kagawa, Y Kondo, S Suh, Y Shigetomi, Y Oshita, Global flow of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum, Environ Sci Technol 48 (2014) 1391–1400 M.A De Boer, K Lammertsma, Scarcity of rare earths elements, ChemSusChem (2013) 2045–2055 L Baldi, M Peri, D Vandone, Clean energy industries and rare earth materials: economic and financial issues, Energ Policy 66 (2014) 53–61 A Golev, M Scott, P.D Erskine, S.H Ali, G.R Ballantyne, Rare earths supply chain: current status, constraints and opportunities, Resour Policy 41 (2014) 52–59 K Habib, H Wenzel, Exploring rare earths supply constraints for the emerging clean energy technologies and the role of recycling, J Clean Prod 84 (2014) 348–359 S Massari, M Ruberti, Rare earth elements as critical raw materials: focus on international markets and future strategies, Resour Policy 38 (2013) 36–43 B Achzet, C Helbig, How to evaluate raw material supply risk — an overview, Resour Policy 38 (2013) 435–447 S Glöser, L.T Espinoza, C Gandenberger, M Faulstich, Raw material criticality in the context of classical risk assessment, Resour Policy 44 (2015) 35–46 European Commission, Report on critical raw materials for the EU, http://ec.europa eu/DocsRoom/documents/10010/attachments/1/translations/en/renditions/native2014 (accessed 12.05.16) US Department of Energy, Critical materials strategy, http://energy.gov/sites/prod/ files/DOE_CMS2011_FINAL_Full.pdf2011 (accessed 12.05.16) M Goe, G Gaustad, Identifying critical materials for photovoltaic in the US: a multimetric approach, Appl Energy 123 (2014) 387–396 J.H Rademaker, R Kleijn, Y Yang, Recycling as a strategy against rare earth element criticality: a systemic evaluation of the potential yield of NdFeB magnet recycling, Environ Sci Technol 47 (2013) 10129–10136 L.T Peiró, G.V Méndez, R.U Ayres, Material flow analysis of scares metals: sources, functions, end-uses and aspects for future supply, Environ Sci Technol 47 (2013) 2939–2947 T.E Graedel, E.M Harper, N.T Nassar, B.K Reck, On the materials basis of modern society, PNAS 112 (2015) 6295–6300 N.T Nassar, Limitation to elemental substitution as exemplified by the platinumgroup metals, Green Chem 17 (2015) 2226–2235 C.C Pavel, A Marmier, E Tzimas, T Schleicher, D Schüler, M Buchert, D Blagoeva, Critical raw materials in lighting applications: substitution opportunities and implication on their demand, Phys Status Solidi A 216 (2016) 2937–2946 B.J Smith, R.G Eggert, Multifaced material substitution: the case of NdFeB magnets, 2010–2015, JOM (2016) 1964–1971 T.E Graedel, Material substitution: a resource supply perspective, Resour Conserv Recycl 34 (2002) 107–115 U 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx E 10 Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 C.C Pavel et al / Sustainable Materials and Technologies xxx (2017) xxx–xxx [76] Yaskawa Electric Corporation news release, Development of an EV motor without a neodymium magnet, https://www.yaskawa-global.com/newsrelease/product/ 42462013 (accessed 24.05.16) [77] Green Car Congress press release, Ricardo develops prototype next-generation 85 kW switched reluctance EV motor; no rare earth elements, http://www greencarcongress.com/2015/02/20150223-ricardo.html2015 (accessed 25.05.16) [78] J Stoll, wbk Institute of Production Science at Karlsruhe Institute of Technology, Production of Electric Motors, Seminar at e-Mobil BW, 2013 [79] VENUS FP7 EU project, http://www.venusmotorproject.eu/index.php/project2015 (accessed 25.05.16) [80] W Hornick, E-motor survey results, online publication on resource centre for 2rd international conference advanced E-motor technology, Frankfurt, http://www.automotive-iq.com/alternative-powertrains/articles/e-motor-survey-results/2014 (accessed 25.05.16) N C O R R E C T E D P R O O F [71] W Hackmann, Comparison of the performance capabilities and impacts on production of different e-traction motors: synchronous machine, PM machine, induction machine and reluctance machine, in: H Schäfer (Ed.), Elektrische Antriebstechnologie für Hybrid- und Elektrofahrzeuge, Haus der Technik – Fachbuchreihe, Essen, 2013 [72] Continental Corporation, Axle Drive System, Fact sheet, http://www.conti-engineering.com/www/download/engineering_services_de_en/themes/hybrid_electric_vehicle/download/fact_sheet_axle_drive_en.pdf2015 (accessed 24.05.16) [73] Speed 2E project, Innovatives super-Hochdrehzahl-Mehrgang-Konzept für den elektrifizierten automobile, http://www.speed2e.de/index.html2015 (accessed 24.05.16) [74] W Kakihara, M Takemoto, S Ogasawara, Rotor Structure in 50 kW Spoke-type Interior Permanent Magnet Synchronous Motor With Ferrite Permanent Magnets for Automotive Applications, Proceeding of 2013 IEEE Energy Conversion Congress and Exposition, 2013 606–613 [75] J Lay, J Lutz, A Gilbert, Unique lanthanide-free motor construction UQM technologies, Inc, http://energy.gov/sites/prod/files/2014/07/f17/ape044_lutz_2014_o pdf2014 (accessed 24.05.16) U 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 11 Please cite this article as: C.C Pavel, et al., Role of substitution in mitigating the supply pressure of rare earths in electric road transport applications, (2017), http://dx.doi.org/10.1016/j.susmat.2017.01.003 945 946 947 948 949 950 951 952 953 954