With the increasing depletion of minerals and fossil fuels, new energy alternatives are required

Energy and mining have always been intimately related. On the one hand, mining is required to access certain

primary sources of energy – such as coal, oil shale, tar sands and uranium. On the other hand, energy is required

for the mining and processing of minerals. Pre-industrial mining relied on human labour for extraction, and biomass

energy – chiefly wood – for metals processing, such as the smelting of copper and later iron ores.

In the industrial era, the exploitation of fossil fuels together with technology in the form of machinery and

transportation infrastructure massively increased the scope and scale of both open-cast and underground mining

operations.

The ongoing depletion of finite fossil fuels – and/or restrictions on carbon emissions to mitigate climate change –

raises important questions. Will limits be encountered on mining production and mineral processing in the coming

decades? Or can renewable energy sources be used to maintain mining on anything like the present scale?

If not, what are the implications for our complex, high-tech industrial society that has become heavily reliant on

processed metals
and minerals?

Growing demand for minerals

Humans continue to find new uses for minerals – at least 36 precious, base and rare-earth metals (REMs) are mined

commercially.

In volume terms, iron completely dominates production with more than 80% of the global total (see Figure 1). Most

of the iron is converted into steel and used for construction of buildings and infrastructure such as transport

systems (railways, trains, cars, ships, planes, etc.) and energy systems (e.g. pipelines, drilling rigs, wind

turbines).

Copper is used extensively as a conductor for electricity and communications, as well as for plumbing pipes.

The main use of gold is for jewellery, although it also serves as a store of value or hedge against monetary

inflation.

Platinum is used chiefly in automobile catalytic converters, but also in hydrogen fuel cells and other specialist

industrial applications, as well as for jewellery.

REMs – so called because they seldom occur in concentrated ores and consequently are mined in only a few geographic

locations – are used in a wide variety of high-tech products.

Examples include many electronic gadgets such as cellular phones, flat-screen televisions and computers. Other

important uses include glass polishing, miniature magnets, fluorescent lamps and components of hybrid cars.

Other scarce metals include indium and gallium, both used in liquid crystal displays.

Over the past decade, the demand for many minerals and metals has been growing prodigiously in China, India and

other emerging economies that are rapidly industrialising (see Figure 2). But will the supply of minerals be able

to keep pace with this surge in demand?

Mineral depletion

Although all minerals are technically finite resources, their scarcity or abundance in the Earth’s crust varies

greatly, as does their concentration in usable ores.

Recently, the vigorous debate over mineral depletion that emerged in the 1970s has ignited once again. The

conventional view – as espoused by most economists – is that when the price of a particular mineral rises, it will

stimulate further exploration and development of new mines, and make production from lower grade ores economically

feasible.

Hence, physical limits are in general not seen as a problem.

However, an alternative perspective – mainly held by certain geologists and Earth scientists – is that physical

limits on supply will be encountered sooner or later for many minerals.

This is because over time, the prospecting success rate typically declines and the highest quality ore grades

usually are exploited earlier on, making it progressively more difficult and expensive to extract the desired

minerals.

Put simply, miners have to dig deeper underground, in more remote areas of the world, and process more rock to

extract useful minerals.

By way of example, Figure 3 shows the downward trend in gold ore grade for a group of major gold-producing nations.

As a result of these factors, according to this view, mineral production follows a roughly bell-shaped curve, as

with oil – i.e. a “Hubbert curve”.

Using data from the United States Geological Survey, Italian scientists Ugo Bardi and Marco Pagani (2007, “Peak

Minerals”) found clear evidence that production of 11 of 57 minerals had peaked already, and concluded that the

Hubbert model is likely valid for the global production of minerals.

For instance, a logistical Hubbert model for selenium – an important metal used in the semiconductor industry –

showed a peak in 1994 despite continued demand growth since then (Figure 4).

According to Bardi and Pagani, the peak and decline results from the gradual but cumulative increase in production

costs as the quality of the resource base declines with depletion. In other words, it is caused by a combination of

geological and economic forces.

Energy for mining

Ultimately, as Professor Bardi (2008, “The Ultimate Mining Machine”) states, “Energy is the physical entity that

defines what you can extract and what you can’t”.

Mining is a multi-stage process and each stage is a highly energy-intensive enterprise.

The first phase – extraction of ores – is heavily reliant on diesel fuel to operate machinery such as trucks,

shovels and cranes (all typically huge in scale), as well as electricity to power drills, operate mine shaft lifts

and run air conditioners.

According to the United States Department of Energy, diesel accounts for about a third of the energy consumed by

the US mining industry. Electric lifts and conveyor belts and/or trucks are then used to move
the materials.

The next phase, beneficiation, requires more energy to separate the minerals from the ores, leaving behind large

quantities of tailings or “gangue”. Many minerals, including copper, aluminium and iron, are smelted and refined

using coking coal or electric
arc furnaces.

Bardi states that “in general, the energy required for extracting something from an ore is inversely proportional

to the ore grade,” so energy use typically grows over time as ore grades decline.

The manufacture of steel from iron ore is particularly hungry for energy. According to Bardi, annual world steel

production utilises approximately 5% of the world’s total energy supply.

China is the world’s leading producer of steel and the largest consumer of coking coal. In 2008 the country

accounted for around 38% of world steel production (World Steel Association) and 43% of global coal consumption

(“BP Statistical Review of World Energy”).

Although aluminium oxides are mined often from ores with high concentrations, large quantities of electricity are

used by aluminium smelters at the refining stage – a typical smelter may require over 1 000 megawatts of power.

Overall, Bardi estimates that as much as 10% of the world’s energy is used by the mining and metal-producing

industries.

Fossil fuel depletion and peak minerals

Meanwhile fossil fuels, which provide at least 80% of the world’s primary energy, are being depleted at a

significant rate.

There appears to be an emerging consensus that global production of conventional oil will most likely peak and

begin an irreversible decline within about a decade. Some experts contend that the peak was passed in 2008. Even

the International Energy Agency, which until recently assumed there would be no supply constraints before 2030, is

now saying oil could peak by 2020.

Natural gas and coal production will reach their peak rates of production at a later stage than oil, but possibly

within a couple of decades nevertheless.

Just as important, if not more so, the energy return on energy invested (EROEI) for fossil fuels continues to

decline as the easier-to-access deposits are depleted and the frontier for new discoveries is pushed into further

extremes.

This means that increasing amounts of energy are required to extract and process fossil fuels, leaving less and

less energy available for other uses, including the mining and processing of minerals.

Moreover, there is a feedback effect between energy and mining: as fossil fuels become more expensive, so too will

steel and other processed metals, which in turn will raise the cost of infrastructure required to extract,

transport and process raw fossil fuels (e.g. drilling rigs, pipelines and refineries).

Bardi argues that fossil fuel depletion will likely become a limiting factor for mineral production, in effect

giving rise to “peak minerals” before natural depletion of the minerals does.

Can alternative energy do the job?

But can non-fossil energy sources not be used to mine and process metals? It turns out that all the alternatives

have limitations, partly because of their complex dependencies on minerals and fossil fuels.

In the case of nuclear power, the uranium feedstock first has to be mined and enriched – both very energy-intensive

processes. The net energy return for nuclear energy is low and does not provide liquid fuels.

All renewable energy technologies – including solar photovoltaic cells, wind turbines, hydroelectric plants, wave

farms and geothermal plants – rely for their manufacture on metals, particularly coal- hungry steel.

Other constraining factors include low EROEI ratios relative to fossil fuels; lower transportability and energy

density compared to oil; and intermittency in the case of wind and solar power.

Current energy storage technologies – which are critical for future renewable energy systems – rely on scarce

minerals that have to be mined and processed.

The key examples are lithium – which is used presently in the most efficient batteries – and platinum, which is

required for hydrogen fuel cells.

Renewable liquid fuels – biodiesel and ethanol – compete for arable land and water with food production. Biomass

can be used to generate heat energy, but at lower temperatures than coking coal.

Finally, to the extent that renewable and nuclear energy will be able to substitute for fossil fuels in mining,

they will have to compete with other demand sectors such as transport, electricity generation, and industrial and

residential consumption.

Costs and competition

Because energy is such an important input into the production of minerals, the prices of minerals are linked

closely to energy prices. When energy costs rise, marginal mines may become uneconomic and the capital costs of

developing new mines grow and may become prohibitive.

André Diederen (2009, “Minerals scarcity: A call for managed austerity and the elements of hope”) points out

another vicious cycle: mineral depletion and increasing scarcity will raise the costs of extracting fossil fuels

and alternative energy sources – which in turn will make mining and mineral processing more expensive.

Competition for increasingly scarce minerals is set also to intensify, with possible geopolitical ramifications.

According to the US Geological Survey, China accounts for approximately 95% of the world’s production of REMs (see

Figure 5). Over the past decade, the Chinese have imposed restrictions on the export of a wide range of these

scarce metals, considering them to be of national strategic importance.

However, the recent discovery of a large REM deposit in Greenland could break the Chinese monopoly.

Some other strategic minerals also have a highly restricted distribution. For example, around 50% of the world’s

known lithium deposits occur in Bolivia. And South Africa is home to almost 90% of the world’s platinum group metal

ores and accounts for around 60% of global production.

Mitigation options

If indeed the depletion of fossil fuels constrained future minerals production, and alternative energy sources

could not adequately fill the gap, what other mitigation options could be employed?

One possibility is to substitute for scarce metals, either with more abundant metals or with other materials.

However, many substitutes still require energy. For example, replacing copper with plastic for piping may be less

economically feasible after the oil peak drives up oil prices.

And as Bardi points out, even though it is technically feasible to substitute aluminium for copper as an electrical

conductor, from an energy perspective this does not make sense, since production of aluminium is more energy

intensive.

Any future substitutes for today’s minerals and metals should be more energy efficient, not less. A good example is

fibre optic cables that replace copper cables. However, such fibre optic cables use an REM erbium, of which

supplies are limited.

Some REMs, such as europium – used in liquid crystal displays – have no known substitutes.

Technologies that allow ‘dematerialisation’, such as wireless communications systems, hold the best promise.

Nanotechnology optimists hope that carbon nanotubes will one day be a cost-effective substitute for steel.

To the extent that efficient substitutes cannot be developed for scarce metals and minerals, the next obvious

solution is recycling.

In fact, this strategy is employed already to a significant extent: according to Bardi, “the average level of

recycling for most common metals remains of the order of 50%.”

Although the recycling of metals uses less energy than the full mining cycle – because the extraction and

beneficiation stages are cut out – it still requires substantial energy inputs, and the process is always less than

100% efficient.

A key issue for the efficiency of recycling is dispersal: in general, the wider the material is dispersed, the more

energy will be required to collect it and transport it to a recycling plant.

For example, much of the platinum used in automobile catalytic converters is dispersed onto roads through exhaust

emissions, making recovery very difficult and costly.

Bardi points out that the ‘mining’ of metals from landfills is possible, but complicated by the mixed nature of

waste and its toxicity.

A more energy-efficient strategy than recycling is reuse, which extends the lifespan of products made from metals

through deliberate design for durability as well
as repair.

In some cases, mineral products can be reused with minimal energy inputs. A prime example is gold, of which stock

does not diminish significantly over time, but rather accumulates with new production.

To be implemented widely, however, a reuse strategy would require a change in the way that firms typically operate

in the industrial growth economy: planning for obsolescence, replacements and upgrades must give way to building

products to last.

The cheapest strategy to deal with possible mineral scarcity would be to reduce consumption, although clearly this

would have implications for lifestyles and perhaps for the technological complexity of
human societies.

Reuse, recycling and reduced consumption of mineral products would have the additional benefit of curtailing the

negative environmental effects of mining and processing, which can include land degradation, water contamination,

the release of toxic chemicals, air pollution, and greenhouse gas emissions.

South Africa: a case in point

South Africa, as a country generously endowed with both energy and mineral deposits, provides an interesting

example of the energy-minerals nexus and the depletion conundrum.

The mining industry has been pivotal to the economy since the discoveries of diamonds and gold in the latter half

of the 19th century.

Gradually, cheap labour was augmented and substituted with capital machinery powered by fossil fuels – including

domestically produced coal.

For decades, South Africa was the world’s top gold producer, but annual gold production peaked in 1970 and has been

falling ever since (see Figure 6).

With several of the deepest gold mines in the world – some over three kilometres deep – the local mining industry

has faced the typical scenario of declining ore concentrations together with rising energy requirements and

production costs.

The energy-hungry nature of mining came to a head during the electricity supply crisis of 2008, when the national

utility Eskom was forced to ration power. Mines and smelters, which consume a significant portion of the country’s

electricity supply, had to cut back on production so that the national grid could be stabilised.

The ongoing decline of gold production also raises questions about the sustainability of uranium production, which

historically has been linked closely to gold mining – illustrating another mining-energy feed-
back loop.

Down the track, peak oil could have a debilitating impact on the mining industry by raising costs of diesel fuel

and transport, including the haulage of coal to power stations.

Summing up: another sustainability challenge

Mining and minerals processing are highly energy-intensive activities that currently rely overwhelmingly on fossil

fuels. However, fossil fuels are depleting and their net energy return is declining over time at a steepening rate.

Renewable energy has major limitations in respect of the energy requirements of mining and processing of minerals,

particularly in terms of liquid fuels but also with regard to heat energy.

At the same time, many mineral deposits are becoming more difficult and expensive to access, as high grade ores

diminish with depletion. This progressively raises the energy requirements for mining.

At the very least, this combination of forces over time will drive up the economic costs of mining and processed

minerals significantly. Potentially, the production of a wide range of mineral products could peak and decline

within the coming years and decades.

In order to be more sustainable, the future supply of many metals will have to be met increasingly from recycling

and particularly reuse.

In addition, technological innovations will be required which create substitutes for scarce and energy-intensive

minerals.

In short, the links between energy and mining force yet another rethink about the sustainability of our present

industrial society.

References

Bardi, U. (2008) “The Universal Mining Machine”, http://europe.theoildrum.com/node/3451

Bardi, U. & M. Pagani (2007) “Peak Minerals”, http://europe.theoildrum.com/node/3086

BP (2009) “Statistical Review of World Energy 2009”, www.bp.com

Diederen, A. (2009) “Minerals scarcity: A call for managed austerity and the elements of hope”,

http://europe.theoildrum.com/node/5239

Haxel, G., Hedrick, J. & Orris, J. (2006) Rare earth elements critical resources for high technology. Reston (VA):

United States Geological Survey. USGS Fact Sheet: 08702. http://pubs.usgs.gov/fs/2002/fs087-02/

International Monetary Fund (2009) “World Economic Outlook 2009”, www.imf.org

Laherrère, J. (2009) “Peak Gold”, http://europe.theoildrum.com/node/5989

Mudd, G. (2009) “Gold Mining and Sustainability: A Critical Reflection”, Encyclopaedia of Earth

http://www.eoearth.org/article/Gold_mining_and_sustainability%3A_A_critical_reflection

World Steel Association (2009) http://www.steelonthenet.com/ISSB/Review-02-09.pdf

Jeremy Wakeford