Strategically important metals - Science and Technology Committee Contents


Written evidence submitted by University of Strathclyde and University of Oxford (SIM 04)

THE MINERALOGICAL LIMITATIONS OF LOW CARBON ENERGY:
RESEARCH TOWARDS A TRULY SUSTAINABLE ENERGY FUTURE

EXECUTIVE SUMMARY

Although the conclusions of the Club of Rome report "The Limits to Growth" have now been largely discredited, the introduction of new technologies to support renewable energy, such as fuel cells, batteries, PV etc will place strain on certain strategically important materials. One example is the provision of platinum group metals for fuel cells. We recommend the formation of a research cluster whose objectives will be to identify crucial gaps in materials supply and to propose new research directions, such as alternative materials or effective recycling that will make renewable energy truly sustainable. The UK is in a global competition for these resources and as things stand will not be able to proceed to a carbon free economy. These problems will not simply disappear and it is our recommendation that an academically based experts committee be formed to examine the reliance of clean energy technologies on strategically important minerals. It is fundamentally important to develop new research lines in this area.

INTRODUCTION

The arguments promoting the use of clean, renewable sources of energy such as wind, marine, solar and bio-derived to replace fossil fuel sources are so well known that it is hardly necessary to discuss them here. The environmental, economic and security arguments have sparked a global effort to develop energy supply chains based on these sources. Although the debate over whether nuclear energy is a sustainable energy still rages, for our purposes it is regarded as a low-carbon technology that will have an important part to play in reducing carbon emissions over the medium and long-term. Consequently, it is given an equal weighting here.

Given the fact that there is more than enough wind, marine, bio and solar energy to satisfy societal needs the question "Is renewable energy sustainable?" may seem paradoxical. However, as will be demonstrated here, current technological developments in renewable energy rely on mineral sources that are most definitely not sustainable: A complete reassessment needs to be made of the deployment of such technologies and indeed, the development of certain technologies may be completely abandoned.

All of this is set against an increasing global requirement for energy in all of the OECD, BRIC-bloc (Brazil, Russia, India, China) and developing countries.

Renewable energy sources have created new challenges but perhaps the hardest to deal with is their intermittent or unpredictable nature, or indeed, both. Perhaps the next greatest challenge is to provide energy for transport. The solution here is to develop efficient energy storage systems. For convenience, technologies of importance here are categorised as hydrogen or electron based. The hydrogen route consists of hydrogen production (such as electrolysis), storage and conversion (such as PEM fuel cells). The non-hydrogen route relies on devises such as batteries, supercapacitors, superconducting magnetic energy storage and flywheels.

Alongside this is the need to develop efficient methods for energy collection, distribution and conversion. Examples of energy collection are wind turbines, photovoltaic devices. New technologies for energy transmission include superconducting cables. High temperature fuel cell designs such as solid oxide and molten carbonate based devices are being developed for the efficient conversion of bio-derived power.

The above list is not exhaustive but represents some of the most heavily researched areas of renewable energy. Each of them relies to some a greater or lesser extent on increasingly scarce mineral resources. Their potential global deployment would therefore perturb current markets to a corresponding extent that needs to be analysed in considerable detail.

Before this, it is important to set a reasonable global context for future energy requirements. According to Energy Information Authority figures, annual global energy utilisation is about 500 Quadrillion Btu. Although energy consumption has fallen in the EU, China showed an increase of energy consumption of 7.7% in 2007 and globally energy consumption is likely to rise at an annual rate of 2-3%. The time frame considered here is fifty years; by which time other energy technologies (such a nuclear fusion, which also creates mineralogical problems which are considered here) may well dominate.

ESTIMATION OF MINERALS RESERVES

Much of the data used here is based on the United States Geological Survey (USGS) database1. The USGS make a clear distinction between the ideas of "Reserve" and Reserve Base". They also list the annual production rate for most minerals. From these two values a Reserve to Production (R/P) ratio can be calculated with the unit of years. R/P ratios are commonly used for fossil fuel reserves and give an estimation of the lifetime of reserves if used at a particular rate.

The USGS definition of Reserve is relatively straightforward and is defined as "A concentration of naturally occurring solid, liquid or gaseous material in or on the Earth's crust in such form and amount that economic extraction of a commodity is currently or potentially feasible". Whilst massively useful in itself this paper deals with technologies that will create new demands on mineral resources, a situation which will certainly distort commodities markets and require new minerals deposits to be developed. Consequently, the USGS Reserve Base figures are of more use here. Understandably, the definition is a little less clearly defined but is best illustrated by the following key phrase "The reserve base includes those resources that are currently economic (reserves), marginally economic (marginal reserves) and some of those reserves that are subeconomic (subeconomic reserves)". Therefore, if unprecedented demands were to be made on a particular mineral, this is a more conservative, and realistic figure. The USGS also give information about the current utilisation of different minerals, how much is recycled, possible alternative materials and a global distribution of resources.

As an example consider Boron, the base of a possible hydrogen storage material, Lithium Borohydride. The current global reserve (as B2O3) is estimated at 170 106 Tonnes whereas the Reserve Base is estimated at 410 106 Tonnes. The current rate of production of Boron (in all forms) is estimated at 4.3 106 Tonnes yr-1, although the figure for the USA is withheld for commercial reasons. The principal use of Boron is for glasses and ceramics (72%) for which there is no industrial substitute. A negligible amount of Boron is recycled.

The above illustrates a number of features to be discussed. Firstly, the (static) R/P ratio based on Reserves is less than 40 yr but the R/P ratio based on the Reserve Base is almost 100 yr. The fact that a negligible amount of Boron is recycled leads to the concept of "minerals entropy" in which relatively concentrated forms of Boron are eventually distributed globally leading to an almost irrecoverable loss. Clearly, unless Boron is recycled then it should not be regarded as a long-term sustainable resource.

The issue here however, goes well beyond these considerations and asks the question as to what would happen if Boron were to act on a large scale as a material for the storage of hydrogen. In fact, there is physically not enough boron in the world to satisfy the demand for large-scale hydrogen storage and it is questionable whether research in this subject is worthwhile from a commercial point of view. As will be seen, te situation is equally critical for a wide variety of raw materials.

Although the famous report from the Club of Rome "The Limits to Growth" (1972) is largely discredited, we feel that the issues raised will become a reality within the next forty years, unless research is taken into developing alternative forms of renewable generation, storage and conversion starting immediately. The research cluster proposed here will commence and coordinate this activity within the UK and in close cooperation with the country in which these issues will be even more important, China.

THE NEED TO DEVELOP NEW ENERGY TECHNOLOGIES

We have identified the technologies most at risk from the availability of strategic minerals and the following have agreed to participate in such a cluster:

  • Professor Peter Hall (Strathclyde) - energy storage.
  • Professor Peter Edwards FRS (Oxford) - hydrogen.
  • Professor Xiao Guo (UCL) -Chinese links, hydrogen and biofuel cells.
  • Professor George Smith FRS (Oxford) - nuclear fission and fusion materials.
  • Professor Professor Stuart J C Irvine (Glyndwr University, OpTIC Technium) - PV.
  • Professor Peter Bruce FRS (St Andrews) - Li batteries.
  • Professor Stephen Skinner (Imperial) - high temperature fuel cells.
  • Professor Keith Scott (Newcastle) - low temperature fuel cells.
  • Professor Nick Hanley (Stirling) - resource economics.

Each of the cluster members are well connected to the energy community in the UK and collectively the group has a track record of participation on governmental committees and supplying evidence to parliamentary committees. This is essential to our mission of influencing both future research directions and energy policy.

The main activities of the subject will be small meetings; national and international study visits and UK workshops. There will be differences in the activities of the subject groups to enable specific information to be gathered and assessed, for example to determine information about specific minerals directly from mining companies etc.

The subject groups will feed information into the cluster for biannual meetings. The main function of the cluster will be to produce two high profile reports. The first produced by the end of the fourth quarter will be a comprehensive overview on the supply problems of renewable energy to be published in a high impact journal such as Science. Additionally, the cluster will formulate and support joint research proposals to EPSRC and ESRC. The final high impact report will be a review of the progress made by the cluster in pointing the way to a truly sustainable energy future.

The main functions of the management team will be external communications, publicity, cluster meeting organisation and final report assembly. Since the work of the cluster is of long term consequence and will need monitoring beyond the scope of this call, the cluster have agreed to meet on a regular basis beyond three years and that this will be funded out of individual research contracts or by a further proposal to EPSRC, Royal Society etc of necessary.

WORK PROGRAMME

The work will be divided into two broad (overlapping) phases: problem identification and the development of radical, sustainable alternatives to current paradigms. In general terms, problem identification will consist of establishing the relationship between current developing technologies and the availability of strategic materials in terms of the likely global requirement. This is by no means a trivial task, requiring forward thinking and interactions with other consortium members, especially regarding the geochemical and economic aspects. One key objective of the first phase will be to write new research proposals to strengthen the applied geochemical and resource economic aspects of the consortium. The second phase is equally challenging and will develop new research directions to ameliorate or avoid the materials supply problems

  • (i)  Energy Storage (Peter Hall). Energy storage is also considered in the hydrogen and battery subject groups and this subject is mainly concerned with redox flow batteries and superconducting magnetic energy storage. These are two research groups that are under represented in the UK although superconducting technologies were mentioned in the recent MAT-UK report on transmission and distribution. Research needs to be conducted into the use and availability of a number of materials such as Yttrium, Strontium, Barium and Bismuth amongst others. As the class of high temperature superconductors increases annually, it is necessary to produce a summary report relating the scientific progress to metals availability. In the field of redox batteries large amounts of materials are needed to produce the large devices needed for storing grid energy. Therefore it is important to relate the different redox cycles eg vanadium, cerium and zinc based systems to materials availability and safety:
  • (ii)  Links with China (Xiao Guo) China's rapid and continued rise in economic and technological stances largely influences the global resource and climate issues. Close engagements with key scientists, funding bodies and policy makers in China are important to sustain a clean energy economy. While priorities may vary, close bilateral discussions and exchanges are beneficial to scientific and technological planning, resource management and long-term collaborations. In this aspect of the Cluster, we aim to foster UK-China interactions by the following strategies: 1) Organisation of bilateral forums on "Clean Energy and Resource Implications for Sustainable Low-Carbon Growth", with early involvement and co-sponsorships from National Natural Science Foundation of China and Chinese Academies of Sciences and Social Sciences, linking to the newly formed National Energy Bureau / Commission; 2) Establishing links with a multidisciplinary group of influential Chinese scientists in social, economic and natural sciences by exchange visits and focussed discussions, eg via the internet; 3) Identifying the overall challenges for resources and low-carbon energy technologies and specific areas for joint research projects with co-funding opportunities from funding agencies, eg joint projects from the Ministry of Science and Technology and EU Framework Seven.; and 4) Creating a sustainable UK-China network in "Sustainable low-carbon economy - tackling the Mineralogical Limitations and Challenges", which may be extended to other international links, as the Cluster expands over time.
  • (iii)  Nuclear (George Smith) The materials resource issues involved in nuclear power generation are highly complex, and there are many uncertainties involved in making forward projections. There are two main technologies to consider: nuclear fission and nuclear fusion. These involve rather different issues. Nuclear fission technology is relatively mature, and the main resource issue is the long-term availability of fuel materials. With the upsurge of global demand for new nuclear build, important questions arise about the future availability of adequate supplies of uranium minerals. In some countries (eg India), there is an upsurge of interest in alternative fuel cycles, for example based on thorium. Fuel reprocessing will become of increasing importance, and the use of fast reactors to "breed" additional fuel supplies will need to be re-visited. Elsewhere in the nuclear fission sector, there is increasing emphasis on safety, reliability and efficiency, extension of safe operating lifetimes, and reduction of the need for routine maintenance and inspection. New designs are emerging for high-temperature gas-cooled reactors, modular reactors, and hybrid electricity and hydrogen-generating reactor systems. It is too early to say whether these trends will put any real pressures on natural resources, but it will be necessary to keep the whole of this field under constant review. One example from current research will indicate the kind of issues that can arise. It is becoming clear that the stress corrosion cracking resistance of the stainless steels used in reactor primary cooling systems can be markedly improved by additions of certain platinum group metals (PGMs). Whilst this may improve the reliability and durability of nuclear plant, such a technology change would put additional pressure upon an already stretched PGM resource sector. In the case of nuclear fusion, the materials challenges are far from clear, because the field is still at an early stage of development, and the final selection of preferred materials for commercial-scale fusion energy power systems will not have to be made for one or perhaps two decades. However, some key issues can already be identified. One concerns the lithium blanket, used to breed tritium for use in the reactor. It seems likely that large-scale use of lithium in that application could put some strain on global resources for this material. Also, if superconducting magnet technology is employed, the sheer scale of the magnet engineering required could put pressure on the supply chain for the very high quality niobium alloys (or equivalents) that will be required. Finally, and perhaps most importantly of all, there is a pressing need to develop new alloys that can withstand unprecedented levels of heat and neutron irradiation without suffering rapid degradation of mechanical properties, or becoming excessively radioactive (and thereby generating a new range of waste storage and / or disposal issues). A broad spectrum of materials is under consideration, ranging from oxide-dispersion strengthened steels (involving rare earth additions), to exotic metals such as vanadium. In a number of cases, large-scale deployment of such materials could lead to severe shorter-term pressure on global production capacity, and perhaps ultimately to significant impact upon global resources.
  • (iv)  PV (Laurie Peter). Photovoltaic cells based on monocrystalline silicon will be replaced at least in part by cheaper thin film solar cells as the cost of PV power is driven downwards towards a level that can compete with power generation from fossil fuels. Several technologies are in the running - the most promising for the short term being based on cadmium telluride and copper indium diselenide as absorber materials. In the longer term concerns about the toxicity of cadmium and the rapidly increasing price of indium raise issues of sustainability. In an effort to address these concerns, Professor Peter's group in Bath is working on low cost dye-sensitized solar cells as well as on new sustainable inorganic absorber materials for thin film solar cells. Dye-sensitized solar cells can be fabricated using low cost titanium dioxide and small amounts of sensitizer dyes. This technology is already being used by G24i in a newly established plant in Wales, and the Bath group is collaborating with other UK research centres and Corus Coatings to develop dye cells on metal substrates for deployment in roofing areas. Work on inorganic thin film solar cells continues as part of the recently renewed PV21 SUPERGEN programme. Sustainability is a central platform of the renewal programme, and inorganic materials identified in Bath as potential candidates to replace materials such as copper indium (gallium) diselenide include the very promising compound copper zinc tin sulfide (CZTS), in which the costly indium and gallium are replaced by equal amounts of zinc and tin. CZTS cells with world-leading efficiencies have already been fabricated in collaboration with colleagues at Northumbria. Other materials that will be explored include copper bismuth sulfide, which has promising properties. The search for new materials will be underpinned by a detailed computational exploration of emerging and new materials using the UK Teraflop supercomputer (HPCx) at Daresbury
  • (v)  Batteries (Peter Bruce). There is expected to be a large and continuous increase in the demand for Li based batteries over the next twenty years for transport and grid applications. The dominant technology at present consists of a negative electrode formed from carbon (usually graphite), a positive electrode based on LiCoO2 and an organic electrolyte based LiPF6 dissolved in a mixture of alkylcarbonates as the electrolyte. Cobalt has been the dominant cathode material in rechargeable lithium batteries since their introduction. The mining of cobalt is economically viable in only a few locations worldwide and these are politically and economically unstable. In recent years the price of cobalt has increased almost tenfold with major implications for the lithium-ion battery industry. The limited availability of Co on the planet means that it is unviable to develop larger scale lithium batteries based on Co. Considering cost and abundance, Mn and Fe are the most attractive elements with which to form lithium transition oxides suitable as cathodes in future rechargeable lithium batteries. However even these metals have seen significant increases in cost and demand over recent years. For example, between 2006 and 2008 the demand for Fe ores increased by some 40% so even these materials, regarded presently as abundant and cheap, may not continue to be so in the new industrial landscape in which India and China are major players.1 Concerning the anode, already the performance limitations of graphite have resulted in the replacement of this material by metal alloys, such as the introduction recently by Sony of a metal alloy anode based on Sn and Co. In addition to the comments made about cobalt above, the supplies of Sn may be exhausted within 20 years. Again we see that even the new generation lithium battery technologies can only have a limited lifetime because of resource implications. Although there is no metallic lithium in a lithium-ion battery, lithium is a major component. There are widely different predictions concerning the planetary resources of lithium (lithium carbonate). A Recent report by R. K. Evans2 suggests that there are abundant lithium resources corresponding to 28.5 million tonnes of lithium, equivalent to sufficient lithium carbonate for 1,775 years of supply. In contrast, another report from Meridian International Research3 estimate around four million tonnes of which around two million tonnes of chemical grade lithium carbonate are likely to be available by 2015. These vastly different predictions demonstrate that it is crucial to undertake a rigorous examination of the resource implications for future lithium-ion technology. Such considerations drive towards the development of new lithium-ion battery materials from waste biomass or crops. This could have radical implications for the direction of research in the field, signalling a move away from inorganic materials to organic based cathodes and anodes. Given the critical nature of this technology in addressing global warming it is vital that a group of scientists, engineers and geoscientists, knowledgeable on lithium batteries, their materials requirements and mineral resources, examine the significance of raw materials and tension them against the drivers of cost and performance.
  • (vi)  High temperature fuel cells (Stephen Skinner) Solid oxide fuel cells (SOFCs) are a technology area that has been in development for many years and has now reached a point of maturity where viable large-scale commercialisation is imminent. Indeed in the UK, for example, utilities such as Centrica have entered partnerships with fuel cell developers to deploy 30,000 units over the next five years and in the US, it is anticipated that annual spending on fuel cells will reach $975 million by 2012, growing by 600% from current values. The high temperature SOFCs are based on the development of ceramic oxides (functional oxides) that overcome some of the concerns with low temperature fuel cells that rely on high Pt contents. However bulk oxide development and deployment of SOFCs raises concerns over the availability, and security of supply, of many of the materials currently considered as state-of-the-art. These include rare earth stabilised zirconia, and Gd-doped CeO2 amongst others. To address these concerns the group at Imperial College is investigating a number of approaches: development of new oxide and related materials with greater ionic conduction, implementation of nano-fabrication to reduce materials requirements and enhance properties, investigation of complementary technologies (eg proton conductors). Much of this work is performed in conjunction with the SUPERGEN fuel cell consortium, and is focussed on the durability of fuel cell components. These programmes are concerned with the long term viability of materials solutions and involve the interaction with materials simulation experts to identify potential new components. We are also actively involved in developing epitaxial thin film technology and deposited heterostructures with groups in Europe and the US. Further complementing our activities are linkages with groups in Beijing focusing on new technologies including BaCoO3 cathodes and SrTiO3 anodes.
  • (vii)  Hydrogen storage (Peter Edwards). Hydrogen storage is one of the most complex subjects in the area of renewable energy. A wide variety of systems have been evaluated for potential development and it is still not clear which system will come to dominate. As has been noted earlier, the sever limitation in supply of certain materials such as boron may exclude their future development and indeed an analysis of the availability of strategic materials will help clarify research directions in this area. The most promising systems are based around light metals such as Li and Mg but to be effective they need to be doped with a catalyst to reduce hydriding temperature or to improve kinetics. This can be either a transition metal or a Pt group metal. Therefore, one obvious research direction would be to relate the loading of these additional metals to their availability and to estimate their impact on global production rates and recycling.
  • (viii)  Low temperature fuel cells (Keith Scott). Fuel cells and electrolysers for hydrogen production are prime examples of technologies where resource availability will have a major impact. Notably combating the resource limitation of Pt. Achieved by researching alternative materials with alternative cell technology or operating conditions. The issues for both technologies are similar and can be tackled using similar strategies. For Hydrogen PEMFC technology there is interest in the application of alternative electrocatalysts to Pt such as Raney nickel (Ag may be suitable) and inter-cell connectors based on stainless steel, such as Ni. High temperature PEMFCs can increase conductivity and improve electrode kinetics, which can provide the opportunity for alternative electrocatalysts. Alternatives are based on palladium; but again resource limitation may exist. Research is also taking place to further reduce the PT content and alternatives based on non-precious metals such as W may be possible. For the cathodes, there is large interest in Pd and Au based catalysts but alternative non-precious metal catalysts should be investigated. In the field of electrolysers hydrogen production by water electrolysis is based on one of two technologies; alkaline electrolytes and solid polymer electrolytes (SPE). Currently the dominant (lower cost) route to hydrogen is alkaline electrolysis. The use of a solid polymer electrolyte (SPE) in water electrolysis enables hydrogen production from pure (demineralised) water and electricity. Proton exchange membrane (PEM) water electrolysis systems offer advantages over traditional technologies; greater energy efficiency, higher production rates (per unit electrode area), and more compact design. Like proton exchange membrane (PEM) fuel cells; catalysts used are based on precious metals: Pt for the cathode and a mixture of Ru; Ir; Ti (with possibly Sn; Pt) oxides for the anode. The anode catalyst cannot be supported on carbon as it oxidises at the potential for oxygen generation. Thus catalysts are unsupported typically deposited onto the membrane. Anode electrocatalyst connectors need to based on an inert metal such as Ti or Ta. Alkaline (hydroxide conducting) membrane electrolysers; combine the advantages of the PEM electrolyser and the alkaline electrolyte electrolyser. The application of alternative electrocatalysts to Pt such as raney nickel (is Ag sustainable). High temperature PEM electrolysers can increase conductivity and improve electrode kinetics which can provide the opportunity for alternative electrocatalysts.
  • (ix)  Resource economics (Nick Hanley). Mineralogical limits to renewable energy technologies pose interesting questions for economists in terms of market failure and institution design, and are an example of a supply-side constraint on a development path. Currently, knowledge is very limited on the extent to which market forces will smooth the transition towards a low-carbon economy, in the presence of government interventions such as tradeable carbon credits and green certificates for renewable electricity. Possible causes of market failure with respect to supply-side constraints include (i) public good aspects of R&D into alternative sources of inputs and alternative technologies (ii) information asymmetries (iii) externalities connected with the supply chain and (iv) private sector discount rates being higher than the social rate of discount. In addition, the distributional impacts of supply-side issues may lead the government to intervene in market adjustments on non-efficiency grounds. Three main activities are envisaged. The first is the organisation of an international workshop on the economics of renewable energy, focussing on supply-side factors and innovative policy solutions to problems identified. This will bring together economists from across Europe and the US with an interest in renewable energy, and will result in publication of a workshop proceedings. We will also seek to publish this collection as an edited book, for example the the Routledge series on "Explorations in Environmental Economics", for which NDH is the series editor. A smaller group of economists will then take the most promising ideas contained within the workshop proceedings, and work them up into a series of policy proposals, which can be analysed in a second workshop which will draw on non-economist members of the cluster and its stakeholder community. This will lead to the publication of a second report containing a finalised set of policy proposals from the cluster on the issue of instrument design and supply-side constraints to renewable energy development. This report will then be launched at a stakeholder conference to be held towards the end of the cluster's award period.

REFERENCES

1 United States Geological Survey, Mineral Commodity Summaries Report (2008)

2 R. K Evans, An Abundance of Lithium (2008)

3 The Trouble with Lithium 2, Meridian International Research, Les Legers, France (2008).

Professor Peter J. Hall
Department of Chemical and Process Engineering University of Strathclyde, Glasgow

Professor Peter P. Edwards
Department of Chemistry, University of Oxford, Oxford

16 December 2010



 
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