From Carbon To Metals: the Renewable Energy Transition

The Paris Climate Agreement, which was ratified by 174 countries and the European Union in 2016, aims to keep global warming “well below” 2 degrees Celsius this century and ideally not more than 1.5 degrees Celsius. Achieving this challenging target is dependent to an unknown degree on factors outside government control. However, the countries that have ratified the agreement agree that reducing the emissions to the levels agreed in the Paris Agreement will mean largely abandoning fossil fuels as energy sources, replacing them with lower-carbon alternative energy sources such as wind, solar, hydroelectric and nuclear power.  

In practical terms, this means pivoting away from petroleum products and natural gas towards electricity. Replacing the internal combustion engine with electric propulsion will be key to achieving the emissions targets in the Paris Agreement. Improving fuel efficiency of vehicles, appliances and business equipment is also crucial, since reducing the world’s demand for energy is as important as decarbonising energy sources. 

Low-carbon technologies are considerably more metal-intensive than fossil fuel-based technologies. For example, an electric car typically contains 80kg of copper, four times as much as a petroleum-fuelled car. Both wind and solar power plants contain more copper than fossil fuels: a typical solar plant contains about 5kg of copper per kilowatt, as against 2kg per kilowatt for a coal-fired power station. This is driving a new boom in metals extraction and processing. 

• solar (photovoltaic) power 

• wind power 

• batteries and other forms of energy storage

Although solar panels themselves are made of silicon, supporting structures are constructed of steel and aluminium, while copper is extensively used for wiring. Together with indium, gallium and selenium, copper is also a component of thin films (CIGS) used to block ultra-violet transmission.

The mining company Rio Tinto estimates that an extra 7-10 million tonnes of copper will be needed to meet demand for solar power out to 2030. However, this depends on what type of solar technology eventually dominates. The World Bank says that many estimates assume that the majority of future solar photovoltaic (PV) installations will be of the crystalline silicon variety. However, if CIGS installations make up a larger proportion, then demand not only for copper but for the rare metals involved in CIGS technology will rise.

Wind turbines require largeamounts of steel. One 2.0 megawatt geared turbine contains approximately 296 tonnes of steel. So meeting climate change targets potentially requires large numbers of wind turbines. However, the generating capacity of wind turbines is rising fast: GE’s Haliade-X 13 megawatt turbine has been approved for use in the UK’s Dogger Bank offshore wind farm, the largest in the world. And in February 2021, Vestas announced a 15 megawatt offshore turbine. As turbines become more powerful, the number needed will fall and hence the wind industry’s appetite for steel will diminish. 

Demand for other metals depends on the type of wind turbine that is adopted. There are broadly two types of wind turbine: geared turbines, that use gears to convert the relatively low rotation speed of the turbine to a much higher speed for the generator; and direct-drive turbines, which use a low-speed generator. Both geared and direct drive turbines use copper wiring in the generator, but most direct drive turbines also have permanent magnets that use rare metals.

If the majority of future installations are of the geared variety, there will be increased demand for copper but rare metals demand will be limited. However, the proportion of direct drive turbines is steadily increasing, rising from around 18.2% in 2011 to nearly 30% by 2020.

Improvements in battery technology are essential if electric propulsion is to replace internal combustion engines. So far, five countries have agreed to phase out the internal combustion engine entirely by 2025-40, while ten others have set targets for electric car sales. Most major vehicle manufacturers are already making all-electric vehicles or are planning to do so. Manufacturers of short-haul aircraft are also moving towards electric power supply.

Battery life is improving, but charging times are still long, making long-distance journeys impractical. Currently, this renders electric vehicles problematic for the haulage industry. However, electric vehicles are proliferating for light business and domestic use. In 2016, there were only 2 million electric vehicles on the road. The International Energy Agency (IEA) says that there could be 220 million by 2030.

Improving battery capacity and performance sufficiently for electric vehicles entirely to replace fossil fuel-powered vehicles will require considerable investment in battery technology. At present lithium-ion is the principal technology used in rechargeable batteries. The World Bank estimates that meeting the Paris Climate Change Agreement targets will raise demand for lithium and other battery metals by over 1000%.

However, lithium-ion batteries are far from clean technology. In addition to lithium, they typically use cobalt and nickel. The extraction processes for all three of these metals have serious environmental consequences. However, anticipated demand for these metals exceeds existing reserves; unless alternatives are found, there will have to be a substantial increase in mining. For cobalt, that would have to include discovery and exploitation of additional deposits. Scarcity amid growing demand is already driving up the prices of all three metals significantly.

Lithium production needs to double over the next 20 years to meet current projected demand. Lithium is abundant, but its production is currently concentrated in a few companies operating in South America and Australia. Supply bottlenecks could drive up its price, significantly raising the cost of electric vehicles and inhibiting their take-up worldwide. The United States has also expressed concern that market concentration could mean dependence on foreign sources for lithium. Lithium mining has unpleasant environmental and social effects: WIRED magazine reports that lithium production in water-scarce areas has devastating consequences for agriculture, while the chemicals used in the extraction process pollute waterways many miles from the site.  

Nickel deposits are widespread, including on the ocean floor. But extracting them releases sulphur dioxide, which acidifies rain and causes respiratory problems in humans. There are other environmental consequences too, notably clouds of toxic dust containing heavy metal traces. In 2017, the Philippines shut down 17 mines due to environmental concerns. More recently, scientists have expressed concern about the effect of deep-sea metals extraction on the delicate ocean floor ecosystem.

Perhaps the most problematic of the three metals is cobalt. Cobalt is not only expensive, it is extremely bad for corporate PR. Nearly two-thirds of known deposits are in the Democratic Republic of Congo, an extremely poor, war-torn state in central Africa with an unstable and ineffective government. Cobalt mining in the DRC relies heavily on cheap human labour, including children. The magazine WIRED called it “The BloodDiamond of Batteries,” a reference to the notorious mining of diamonds to fund violent conflicts.

The race is on to replace lithium, cobalt and nickel in batteries. Potential alternatives include metals such as manganese and iron, though these have not as yet proved as efficient as cobalt. Researchers at Honda have developed a fluoride-ion battery that can work at low enough temperatures to be suitable for electric vehicles. Other promising areas of development include replacing lithium with sodium, which can be obtained from seawater. Some researchers are looking towards non-metallic solutions such as polymers.

A more radical solution to energy storage for electric vehicles could be hydrogen fuel cells. These harvest the energy generated when hydrogen and oxygen are forcibly combined. They use small quantities of the rare precious metal platinum as a catalyst. Platinum is currently used in catalytic converters that reduce emissions from internal combustion engines (ICEs), which will become obsolete as ICEs are phased out; falling platinum use in catalytic converters should naturally offset rising demand for use in hydrogen fuel cells. Thus, although hydrogen fuel cell technology increases demand for platinum, arising from fuel cell technology is not expected to put pressure on global supplies. There is also a potential substitute for platinum in the form of the rare earth metal palladium, and research is proceeding into cheaper substitutes such as a mixture of iron, nitrogen and carbon. 

The environmental implications of rising demand for metals

The methods currently used to extract and process metals already contribute significantly to global warming and pollution. Primary production of aluminium and copper generates considerable quantities of greenhouse gases and carbon dioxide, while steel production still relies on coke, a form of coal. Production of nickel, cobalt and lithium, as well as the so-called “rare earth” metals, damages air quality, water, soil and ecosystems. Rising demand for metals due to the adoption of low-carbon technologies could perversely increase emissions and worsen environmental damage.

Mining companies are under pressure to respond to environmental concerns, for example by reducing their own reliance on fossil fuels. Global mining group Rio Tinto says that 68% of the energy it uses in primary production activities already comes from hydroelectric, solar and wind plants. The question is whether the pace of pivoting from carbon to metals will give miners sufficient time to develop clean extractive technologies.

Rising demand for base metals from low-carbon technologies and renewables also threatens to create supply bottlenecks for other industries. To prevent market disruption and keep supply flowing smoothly, the mining and metals production industries need to plan and invest for increased capacity.

For rare metals, rising demand poses market problems. Often, rare metals are a byproduct of a base metal process: for example, indium, germanium, bismuth and tellurium are byproducts of zinc smelting. Unless alternative ways of extracting rare metals are developed, meeting demand for rare metals could result in over-production of associated base metals, resulting in market gluts and storage problems.

Mines and production plants are themselves exposed to climate change. For example, many mines are in remote and inhospitable areas, making them vulnerable to extreme weather events. To prevent supply disruptions, supply chains need to be made resilient to such events, perhaps by developing multiple chains to avoid dependence on a single source.

Recycling

Recycling could offer a long-term solution to some of the environmental problems caused by the mining and processing of metals needed for renewable energy generation and storage. However, the road to full recycling is a rocky one. 

Recycling rates for base metals such as steel and aluminium already reach 90-100%, and emissions from metal recycling processes are much lower than from primary production. However, as recyclable metal typically has a long working life, it could be decades before recycling becomes the primary means of supplying base metals for new installations. 

Transitioning from a carbon-intensive to a metals-intensive economy is driving sharp increases in demand for many metals. This is creating profit opportunities for companies in every part of the supply chain. Investing in renewable energy sources, zero-emission technologies and energy-efficient processes can help companies to increase production capacity while limiting environmental damage.

Of course, demand projections don’t take account of technological innovations that are themselves driven by the cost and environmental consequences of rising demand for metals. As adoption of renewables and rechargeables gathers pace, the search for cheaper and less environmentally damaging alternatives to existing technologies is likely to intensify. Thus, in a few years’ time, demand projections may look very different. 

However, the earth has only a finite supply of metals. If demand for metals is to be sustainable in the longer term, mining and manufacturing will have to give way to recycling and reprocessing, particularly for rarer metals. And that implies a less intensive use of metals. 

If the economy of the future is to be truly green, it won’t be enough simply to replace carbon with metals and other minerals. Energy use must fall sufficiently for mining of new metals to end and renewable energy generation to sustain itself entirely on recycling and reuse of metals and other minerals. The green economy must be a circular one.