Critical elements – the hidden price of innovation
Recent high tech innovation has helped to bring a wide variety of new products to the market, but there is a victim. The elements. Although seemingly abundant, some critical and important elements are running low, with recent reports by the American Chemical Society, US Department of the Interior and the EU highlighting their decline and future supply risks. One which is clear is lithium, essential in high performance batteries and a key part in the electric vehicle revolution. But what other elements are at risk and how can they influence our lives? Here we cover some critical elements which may surprise you, and potential avenues to prevent their decline!
Helium – Now this may seem surprising, as it is the second most abundant element in the universe (after hydrogen), but this small and extremely boring element is running low. Unlike other elements, helium can be lost from the planet, with its light nature allowing it to exit the earth’s atmosphere. Its gaseous form is the only way we can find it naturally, with deposits in natural gas fields in the USA as the main source. The concerns of helium do fluctuate, with it dropping off the EUs critical list in 2020, but it has recently entered the list again, with rising demand driving this change.
Why is it important? It is likely you have encountered helium in balloons at children’s parties, able to transform people’s voices, but it does serve other very important applications. Helium is essential in cryogenics (extremely cold conditions), being used heavily by hospitals owing to the low temperature of its liquid form, important to operate MRI machines which require cooling of their magnets. Also, its inert nature makes it a perfect carrier gas in chromatography, preventing unwanted side reactions taking place. Its inert nature additionally means it has been used in the welding of air sensitive metals acting as a shielding gas, protecting the metal.
Solutions – Depending on the application a variety of alternative gasses can be used, with argon, nitrogen and hydrogen all having potential. Recently Sion-Technologies has produced a system using hydrogen instead of helium in gas chromatography, but the highly reactive nature of hydrogen puts some people off. For welding applications argon is often employed as a replacement for helium. The biggest problem arises with the cryogenics, with nothing else able to achieve the chilly conditions helium offers in its liquid form. Recycling is one avenue, with closed loop systems helping to recover lost helium and reuse. Alternatively, Siemens recently unveiled a new MRI design which uses less helium, reducing usage without impacting equipment performance, with its adoption ongoing at medical sites.
Phosphorus – Of the elements presented here, phosphorus is not considered an immediate threat, but at potential future risk. However, due to phosphorus being essential for life it is an element we should certainly keep an eye on, particularly with its rising demand. It is found in the soil, but the most useful reserves are as phosphate rocks, mined in several locations globally. Processing of this crude rock can generate fertilizers or other products.
Why is it important? The biggest use of phosphorus is as fertilizers, accounting for over 80% of its usage. It is essential for life, a key component of DNA and RNA, alongside being essential in biological processes, so everything on earth should be cautious around phosphorus use! And, although not explicitly a victim of technological innovation, population growth and increased demand for food are driving its decline. Further, currently 80% of phosphates applied to the soil are lost. Being trapped in the soil or ending up washed away in waste water, where they have additional environmental problems.
Solutions – Unlike the other mentioned elements, there is not a direct elemental replacement for phosphorus in fertilizers, instead strategies to mitigate waste or recover phosphates are essential. Recovery of phosphates from waste water is being developed by a range of companies. ViviMag®, is an innovative technology developed in Europe involving magnetic separation to recover iron phosphate from sewage, with up-scaling ongoing. Other groups are producing slow releasing fertilizers, allowing improved and directed phosphate application over time, with hydrogels being employed academically. Improved phosphorus uptake in soil is the approach undertaken by American start-up Phospholutions. Here phosphates are trapped in their highly porous additive, preventing it being washed away, with controlled release of the phosphates for plant use, allowing 50% phosphate reduction.
Indium – Sitting at element number 49, indium is an extremely useful and soft metal, produced commercially as a byproduct of zinc refining. Unfortunately, as it is a byproduct, no dedicated indium mines exist (yet), with supply limited to several companies. It is widely adopted within the electronics industry and with this increased demand there is a worry it may run out, although, it did recently drop off the EUs critical element list, it is still classed as a threatened element.
Why is it important? Indium is an essential transparent electrode, being used in most display applications including liquid crystal displays, organic light emitting diodes and light emitting diodes. It is not used in its elemental form, but is combined with tin and oxygen, forming indium tin oxide (ITO). ITO’s conductive nature and transparency make it ideal for these display applications. An estimated 50% of indium is used within display applications.
Solutions – ITO replacements have been studied for several years. Silver nanowires are an attractive alternative, being studied academically, with commercialisation observed by several companies including C3Nano, however, it is utilizing another scarce element. The wonder material graphene has also emerged as a potential replacement, with a recent academic paper showing it being used as a direct replacement for ITO in an Organic light emitting diode, but commercial realisation is still far away, despite the big push from Paragraf a graphene company operating out of the UK.
Rhodium – An essential element which you likely needed to get to work today, rhodium is the rarest, non-radioactive element in the earth’s crust. Owing to its limited availability, it is no wonder rhodium enters the list of endangered elements. It is primarily extracted as a byproduct of copper and nickel mining and refining. As it is so rare and hard to extract, 1/3rd of all rhodium is produced through recycling of existing products.
Why is it important? Rhodium is primarily used within automobiles in catalytic converters, accounting for over 80% of its use. It is used alongside palladium and platinum in the classic three-way catalytic converter design. The combination of these three metals, breaks down toxic chemicals, with rhodium specifically attacking NOx, reducing it to harmless nitrogen. It is also used generally in chemical catalysis, being widely adopted in organic synthesis, notable examples include the production of acetic acid and hydrogenation reactions.
Solutions – The recycling and reuse of rhodium is an active area of research, with 1/3rd of rhodium on the market from recycled sources. Recent research has looked into extending the lifespan of rhodium in catalytic converters, with researchers exploring the degradation pathways of rhodium catalysts, in an attempt to improve their design. Alternative research has investigated the use of perovskite materials instead, where they can reduce NOx effectively and competitively compared to rhodium, although their adoption industrially has not been seen yet, with rhodium still essential. There has been a recent drive to replacing rhodium and other noble metals in organic catalysis with metal free alternatives like our old friend graphene, although this is still early stage.
Hafnium – A rare and often overlooked element, hafnium, is considered extremely vulnerable. Although its position in the periodic table and properties were predicted early, it took a long time for hafnium to be discovered, trapped alongside its close neighbour zirconium. This close relationship with zirconium is still how it is extracted, being a byproduct of zirconium mineral mining, with every piece of zirconium mineral containing a small percentage of hafnium (2 – 5%), limiting hafnium supply. Due to its high demand and limited sourcing hafnium joins the list of endangered elements.
Why is it important? Hafnium has several important areas where it is used. The first is a rather niche area, nuclear reactors. Here hafnium acts as a good absorber of neutrons and hence is used in control rods in nuclear reactors. Its biggest market, accounting for over 60% of its demand, is within super alloys for the aerospace industry where hafnium is combined with other elements like nickel and tantalum. Here it is used in jet turbines and rocket engines providing heat and physical resistance. Although, normally doped at no more than 10%, the size of the market and the limited extraction have resulted in hafnium being overused.
Solutions – Beyond recycling, people are exploring new sites and extraction for hafnium production. This ensures new sources can be used to produce hafnium, however, this does not reduce its use, just improves supply. Alternatively, there are some discussions surrounding replacing hafnium with other elements. Previous work has shown rhenium alloys perform similarly in super alloys with a recent report suggesting a push to these old alloys is coming soon, while simply using zirconium within existing alloys could be another avenue to explore. In nuclear control rods, zirconium cannot be used as a drop in replacement, with alternative materials like silver-cadmium-indium rods being adopted.
Here we have looked at a few of the endangered elements with a range of uses. Although their decline is often thought as overinflated, it is an area we should all think about. The majority of our reported alternative strategies are still early stage, with improvements expected as their supply decreases. Other strategies, including recovery and recycling, are all essential approaches we should undertake alongside these to ensure we don’t see an extinct element in the future!