Monday, March 28, 2011

Planning the Future of Energy with Rare Earths

Millions of jobs, less dependence on foreign energy suppliers, lower energy prices in the long-term, etc. These are just some of the buzz phrases that environmentalists and ‘Climate Hawks’ use to push for the development of trace emission energy sources over dirtier fossil fuels and even nuclear power. Unfortunately very few of these individuals/groups even consider the material resources that will be required to construct a new trace emission infrastructure of significant size. Until an honest and objective discussion and strategy is conceived for addressing the infrastructure demands it is irresponsible for individuals to push a trace emission environment in a specific direction.

The buzz phrase in the manufacturing industry with respects to the elements that comprise the most important aspects of what most individuals envision in a trace emission environment (wind turbines, solar panels, electrical batteries, etc.) is rare earths. The primary reason rare earths are important in these industries is their strong permanent magnetism. For example neodymium magnets are an alloy of neodymium, iron and boron that forms a tetragonal crystal structure with the molecular formula Nd2Fe14B.1 The chief advantage of these magnets is their energy product of approximately 440 kJ/m3, almost ten times that of ceramic ferrite magnets, which reduces the total size and weight demand on the magnets.2

The two problems surrounding rare earths are first that while the term ‘rare’ is somewhat misleading (most rare earths are more abundant than silver and gold in the Earth’s crust), most deposits are spread so thin that harvesting them is not economically attractive thus their commercial availability is significantly reduced versus their actual availability. Second, the presence of radioactive thorium can spoil some deposits.3 Compounding these problems are that while researchers are working hard to produce viable alternatives, no rare earth alternatives have been discovered which maintain the efficiency and effectiveness of its counterpart. Magnets are especially tricky for no alternatives currently exist which allow for miniaturization with similar energy yields and those energy yields are quite important for maintaining a reasonable size, weight and cost in devices like hybrid/EV engines and wind turbines.

Due to the critical importance of rare earths it is vital to determine consumption patterns with regards to how the new trace emission infrastructure will emerge. One way the importance of these rare earths in the future infrastructure can be seen is in the construction of wind turbines. One rare earth that is important in creating the most reliable and efficient wind generators for a turbine and has caught some attention is neodymium.

First, a source of supply needs to be determined. Based on recent Chinese statements it is unlikely that it will continue to export large quantities of rare earths after 2012, despite this limitation being an incredibly foolish strategy, thus other supplies, especially domestic, must take the bulk of the supply responsibility. Domestic supplies are important because if foreign supplies are tapped, environmentalists need to stop boasting ‘less reliance on foreign suppliers’ as an advantage to the generation of a trace emission energy infrastructure.

Contrary to some popular belief, China does not have 97% of the known economically viable rare earth deposits (only about 37%), but the 97% number relates to production rates. Therefore, in the short-term if China does stop exporting large quantities of rare earths it will take an unknown period of time before the necessary operations are available in other countries including the United States to compensate for those losses. The biggest problems for domestic production are not the mining operations themselves, but processing/purifying operations because almost all quantities of rare earths are not pure and actually permitting the mines themselves; basically the purification and the paperwork both which take copious amounts of time and money.

For example currently there is only one fully established rare earth mine in the United States, the Mountain Pass mine now owned by Molycorp, which closed in the 1990s due to economic concerns. The known reserves in Mountain Pass have been estimated at approximately 20 million tons with about 8.9% of those reserves being rare earths and about 11.1% of those rare earths being bastnaesite and monazite, which yield neodymium.4,5 Assume that 95% of this 11.1% is recoverable neodymium from bastnaesite and 5% is non-recoverable neodymium from thorium containing monazite. Assume that 100% of the neodymium reserves in Mountain Pass still exist and that all of the neodymium in Mountain Pass will be used in generators for wind turbines. Note these assumptions will probably not hold true, but for the sake of a best-case scenario analysis it makes sense. Therefore, of the 20 million tons of reserves in Mountain Pass about 187,701 tons of neodymium should be available.

Most trace infrastructure plans cite a significant dependence on wind power. So for this argument assume that the United States builds an additional 350 GW of wind nameplate capacity over the next 20 years (2011-2031). Note that nameplate capacity is the maximum generation potential for a wind turbine. Thus, a 1 MW wind turbine can generate at most 1 MW of power at any given time if the wind is blowing above a particular speed. Optimization of performance for these wind turbines demands the use of neodymium. The reason neodymium is required for a turbine is the use of a permanent magnet over gearboxes. Replacing gearboxes is preferable to ensure low maintenance and high reliability both in total operation time and during operation. Due to its inherent properties neodymium is the most effective material to use in the construction of these permanent magnets. It is possible to construct wind turbines that do not use neodymium, but it is difficult to have confidence that those turbines will provide a steady stream of power when conditions permit.

Earlier on it had been reported by Jack Lifton, Co-founder and Director of Technology Metals, that 1 ton of neodymium is required per 1 MW of nameplate capacity.6 However, that number has been misinterpreted for the 1 ton is in reference to neodymium-iron-magnet alloy not neodymium alone. The general consensus for the amount of required neodymium ranges between 200 – 300 kg per 1 MW of nameplate capacity or 441 – 661 pounds (0.22 – 0.33 tons).7-9 Therefore, for 350 GW of additional capacity these turbines will require 77,000 –115,500 tons of neodymium. So the largest known supply of neodymium for the United States covers 100% of a hypothesized, yet reasonable capacity of future wind power desired by a number of environmentalists with anywhere from a 62.5% to 143% additional overlap.

While the maximum reserves appear to be available, a secondary issue apart from the total neodymium demand is the yearly demand versus associated production. Assuming a linear average, construction of wind turbines over the 20-year period would result in the addition of 17.5 GW of nameplate capacity per year. This rate of construction demands a neodymium production rate of 3,850 – 5,775 tons per year. Due to the closing of Mountain Pass until just recently and lack of processing facilities, no reasonable person would suggest that the United States will be able to develop this amount of yield for a significant period of time (at least 5 years maybe) without shipping raw materials to a country like China that already had the processing capacity.

Another issue also exists apart from the rare earth issue, the fact that constructing this infrastructure will take enormous amounts of conventional resources. For example returning to the wind turbine discussion above, a 1.5 MW wind turbine typically requires approximately 29 tons of steel.10 Due to a lack of available information and the evolution of wind turbines in nameplate capacity assume only a 40% increase in steel requirement is needed for a 100% increase in nameplate capacity (40.6 tons for 3 MW). Constructing 350 GW of additional capacity would require 116,667 new 3 MW wind turbines, which would require 4,736,680 tons of steel.

On its face it appears that this value is not significant relative to global production values of over 1.35 billion tons of steel per year12 (2007 value is used to account for the loss during the global recession) and a U.S. annual production value of 98.1 million an additional 4.7 million should not be an issue. However, looking at the issue of steel is not as simple as solely comparing anticipated additional production to existing production. Recalling that because this steel requirement is an addition to the steel demand, it is important to ask about how this addition adds stress to the supply chain.

For example there are two possible scenarios that appropriately describe the situation. First, there is a gap between present production and maximum production, i.e. the resources are available to produce more steel, but the economic demand is not present. Second, there is not a significant gap between present production and maximum production; the resources to increase global steel production are not readily available. In the first scenario additional steel demand from new wind turbines can be absorbed in an economic way by the production stream, but in the second scenario it cannot. So it is important to confirm which scenario is valid before coming to the conclusion that the additional required steel will not be a concern.

Furthermore there are three important considerations to make regarding these numbers. First, taking the conservative assumption that U.S. electricity use only increases 10% in the next 20 years to approximately 4.57 billion MW-hr12 (once again 2007 data used to account for the recession) the deployment of an additional 350 GW of wind nameplate capacity will be able to replace, at a maximum, 27.6% of that theorized used electricity. Second, environmentalists are interested in using hybrids and electrical vehicles (EV) to replace transportation emissions. Unfortunately neodymium is a critical component in the operating engine requiring 1-2kg per car.13 Assume that 1 million hybrids/EVs are built per year over the next 20 years (20 million or about 12.5% of the existing vehicle fleet assuming no increase, which is a horrible assumption) would demand an additional 22,000 – 44,000 tons of neodymium total and 1,100 to 2,200 tons per year. Third and most importantly these numbers are for nameplate capacities and not real world wind generation values. Assuming an optimistic 35% operating capacity, an additional 1.085 million tons and 11.6 million tons of neodymium and steel respectively would be required to guarantee attaining an average for the original nameplate values. Clearly the steel value is still workable, but the neodymium requirement is not within domestic boarders or even global supply. These numbers also could include the 8% molybdenum that is typically doped into high-quality steel [total estimated requirement = 324,800 tons (for original estimate) to 928,000 tons (for nameplate average estimate)].

Tie these material requirements with the real potential of reduced wind speeds due to temperature equalization between Northern and Central latitudes along with the significant reduction in high-quality locations to collect wind power and it becomes difficult to envision the legitimacy of the large role that some environmentalists anticipate wind power playing in the future trace emission energy infrastructure. Until wind proponents can overcome these legitimate concerns regarding neodymium absolute resource limitation with regards to average capacity factors and yearly production demands it is difficult to take their arguments about wind power being an important part of a future energy infrastructure seriously.

The point of this post is not to conduct a full analysis of all of the potential limitations of rare earth supplies relative to demand, but instead bring this near-future production shortage and potential long-term optimized production shortage to the attention of those that argue that a future trace emission energy infrastructure should consist largely of wind and solar power. Also understand that cost relative to supply of neodymium is not the chief concern, but accessible supply itself and processing that supply. Recall that rare earth concentrations are not highly concentrated despite their frequent occurrence in the crust, thus when the major deposits run out new mines will have to be constructed for very insignificant concentrations which would highly dissuade many companies from even attempting extraction.

Note that this post did not address the element with the most critical crunch if massive wind scale up proceeds: dysprosium. Estimates range from 3-12% of the permanent magnets in wind turbines (the same which use neodymium) consist of dysprosium.14 Thus using the same example from above, 1 MW of nameplate capacity would require 60 to 240 lb of dysprosium and 350 GW would require 10,500 to 42,000 tons. On its face that range does not seem bad, until it is acknowledged that there may not be that much dysprosium economically available on the face of the Earth. For example less than 1,500 tons of dysprosium is produced globally (99%+ by China); that number is not influenced by a lack of demand and resources are heavily on the decline.

There are some high hopes for potential dysprosium deposits in Ucore’s Bokan Mountain Mine, but no hard numbers have yet to be complied. Even if significant deposits are uncovered, it will take years before production numbers reach what they need to be. Perhaps Paul Emile Lecoq de Boisbaudran saw the future when naming dysprosium after the Greek term for ‘hard to get’. Even if the production issues regarding neodymium are successfully worked out (remember this analysis only looked at estimated wind generation for the U.S. not global or no other elements like EVs), for wind power proponents it very well may come down to choosing either hybrid/electrical vehicles or wind power not both due to a lack of dysprosium.

Although not discussed serious concerns still exist for the construction of large-scale solar power instillations and PV panels especially concerning gallium and indium deposits. However, while wind power has serious questions that its proponents choose to ignore, solar power has some hope to overcome its rare earth problems. Potential viable efficiency increases lie both in exploration of the hot electron and quantum dots. Also preliminary lab tests have demonstrated effective solar cells using more common elements like copper, zinc, tin, sulfur, and selenium.15 However, these cells have not been tested in the field yet, so unforeseen problems could arise.

Overall it is important that those individuals who so feverously demand rapid deployment to a wind and solar energy infrastructure explain in specific detail how the massive required scale-up is going to avoid resource shortfall. In short if one believes that building a bridge over a 100 ft wide chasm is the best solution, that individual better check to confirm that existing resources will allow for the construction of a 100 ft bridge, not merely a 73 ft bridge. Otherwise it may be more beneficial for resources, effort, time and money to be devoted to other trace emission energy technologies over those that will fall short.

1. Drak, M. and Dobrzanski, L. "Corrosion of Nd-Fe-B Permanent Magnets." Journal of Achievements in Materials and Manufacturing Engineering. 2007. 20. 239:

2. Herbst, J. F. "Neodymium-Iron-Boron Permanent Magnets." Journal of Magnetism and Magnetic Materials. 1991. 100. 57:

3. Haxel, G, Hedrick, J, Orris, G. "Rare Earth Elements-Critical Resources for High Technology." U.S. Geological Survey Fact Sheet 087-02. Nov 02. 20.

4. David Jessey Geological Sciences.

5. Mountain Pass rare earth mine. Wikipedia.

6. "Rare Metals Investment News Updates, Today's Edition." Gerson Lehrman Group. May 7, 2009.

7. "The Effect Of Chinese Domestic Growth On Neodymium And Dysprosium Supply." Technology Metals Research. Mar 13, 2011.

8. 2nd Comment

9. "Why rare earth metals matter." Mineweb. May 18, 2009.

10. Pomeroy Wind Farm.

11. List of countries by steel production. Wikipedia.

12. “Electric Power Industry 2007: Year in Review.” Table ES1. Summary Statistics for the United States, 1996 through 2007. Energy Information Administration. May 2008.

13. Luft, Gal, Korin, Anne. Turning Oil Into Salt: Energy Independence Through Fuel Choice. 2009. ISBN: 1-4392-4847-8.

14. "The Fight over Rare Earths." Technology Metals Research. Nov 10, 2010.

15. "IBM Develops Higher-Efficiency Solar Cells Using Non-Rare Materials." Popsci.
Feb 2, 2010.

1 comment:

  1. "Although not discussed serious concerns still exist for the construction of large-scale solar power instillations and PV panels especially concerning gallium and indium deposits. However, while wind power has serious questions that its proponents choose to ignore, solar power has some hope to overcome its rare earth problems."

    I wonder what kind of different universe the author lives in in which silicon-based PV cells - the most common type of PV cells! - require rare earth elements.