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Renewable energy's uneasy relationship with the deep sea mining industry

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Building the Clean Energy Revolution

One of the best ways to understand the nature of the energy transition is as a shift from a resource driven model of energy production to a manufacturing driven model.

It’s a useful description, because it demonstrates why – over the long haul – renewables are destined to win in the battle between competing energy sources. Manufactured products become progressively cheaper over time, and solar panels, wind turbines, and batteries are no different in this respect.

Cost declines are partly due to greater economies of scale, and partly because the more of a product we produce, the better we get at doing so. And once a solar panel or a wind turbine has been manufactured, it continues to generate energy at very little additional cost for over two decades.

An industry that relies solely on the extraction and consumption of a finite pool of resources, like the fossil fuels industry, simply won’t be able to keep up. That’s good news for the climate.

Of course, manufacturing also needs a strong resource base to sustain it. This is particularly true of clean energy technologies, which rely on some of the world’s rarest and most valuable raw materials to manufacture.

As scientists discover new energy efficient semiconductors, new ultra-light composites for wind turbines, and new ways of improving battery performance, access to valuable resources is likely to become more, rather than less important for the renewable energy industry.

Take into consideration this recent breakthrough made by researchers at the University of Surrey, which may make comparatively inexpensive perovskite solar cells competitive in performance terms with the crystalline silicon solar cells that currently dominate the market.

Or this new supercapacitor polymer, which could cut electric car charging times down to a matter of minutes. They’re neat ideas, and without access to valuable natural resources, they’ll remain nothing but that.

If we’re going to bring off the transition to a low carbon future, we’re going to need these materials, and we’re going to need them in ever greater quantities. So where are they going to come from?

Declining Reserves

Presently, around 90% of the world’s production of rare earth minerals takes place in China. It’s a market the country has had cornered since the early 1990’s.

This has given China immense sway over the development of the renewable energy industry and over other high-tech forms of manufacturing. The geopolitical implications in a world dependent on renewables to meet the majority of its energy needs are obvious.

If that concerns you, the good news is that by then we may not need to worry about a repeat of Chinese embargoes of rare earths. China’s stocks are depleting quickly.

According to a whitepaper released by the Chinese government in 2012, the country’s reserves are likely to last only another 20 years, based on current patterns of consumption. The richest seams have already been mined, which means that the remaining reserves will be more expensive to extract.

So the question remains – where are the resources needed to bring about the energy transition going to come from?

Mining the Ocean Floor

One option is the floor of the ocean. The concept of deep sea mining (DSM for short) has been gathering momentum since at least the 1960’s, but only recently have economics of deep sea resource extraction turned in the industry’s favour.

Nautilus Minerals’ Solwara 1 Project, which will begin production in Papua New Guinea’s territorial waters in 2019, will be the world’s first ever commercial deep sea mine. Grants for 13 other projects have been issued by the International Seabed Authority, with six more in prospect.

It’s still tentative going - but the rewards could be huge. Just this April, researchers in Japan discovered a massive trove of rare earth elements near the island of Minamitori. The researchers estimate that the 2500km region they studied could hold up to 16 million tonnes of precious elements. That’s enough to supply the world on what they describe as a “semi-infinite basis”.

A year before the Minamitori find, British scientists investigating a 3000m seamount in the vicinity of the Canary Islands made their own discovery. Crust samples from the seamount contained quantities of tellurium in concentrations 50,000 greater than desposits found on land. In total, the seamount was estimated to contain 2670 tonnes of the substance.

The find was significant because tellurium is one of the key ingredients in the manufacture of cadmium telluride solar cells. These “thin film” solar cells can be manufactured quickly, present significant cost advantages over crystalline silicon solar cells, and are rapidly increasing in efficiency too. Demand for tellurium over the last few years has been driven by large scale production of CdTe cells by American PV manufacturer First Solar.

Tellurium is also integral to the manufacture of blu-ray discs, memory chips, fibre optic cables and electric blasting caps.

Tellurium Crystal for Solar Panels

Tellurium, an extremely rare metal used in the manufacture of cadmium telluride solar cells

Besides rare earth metals, the ocean floor also contains huge quantities of other valuable metals. The Economist reports that the seabed may contain gold reserves worth as much as $150 trillion. By comparison, the combined GDP of every nation on earth last year was a piffling $79.87 trillion. Reserves of copper, silver and cobalt on the sea floor are also copious.

Resources on this scale could literally transform the global economy. They could do so not only by providing the raw materials needed to engineer the low carbon revolution, but by opening resource extraction out to new players. The winners from a deep sea mining boom won’t be those lucky enough to benefit from a strong domestic resource base. They’ll those with the technology and gumption needed to grasp the opportunity.

But deep sea mining could also have potentially disastrous consequences for some of the planet’s least documented and most vulnerable ecosystems – and even for its climate. We’ll explore these effects in greater depth in due course.

Before we get to the drawbacks, let’s run through some of the supplementary arguments advanced in favour of deep sea mining.

The Advantages of DSM

DSM avoids many of the problems associated with mining on land

It’s no secret that the conventional mining industry has its problems. These include:

  • Child labour and exploitation of workers - Amnesty International warns that many of the largest cobalt consuming companies are not doing enough to prevent the practice of child labour among their suppliers, including Microsoft, Renault, and Huawei. The conflict stricken Democratic Republic of the Congo is currently the world’s largest supplier of the metal, which is a crucial component in the manufacture of the lithium ion batteries used in EV’s, laptops and smartphones. The DRC, where child labour and unsafe working conditions are rife, is on track to achieve a 73% share of the cobalt market by 2023. The World Ocean Review estimates that the Pacific Ocean’s Prime Crust Zone – a cobalt rich region of seabed approximately the size of Europe – may contain as much as 7.5 billion tonnes of the substance.
  • Deforestation and destruction of land-based ecosystems: It is well understood that conventional mining operations are a significant cause of deforestation. But a 2017 study by researchers at the University of Vermont suggests that we may be underestimating their contribution. The study found that mining was directly responsible for 10% of deforestation in the Amazon basin over the decade from 2005-2015. This was much higher than previous estimates, because 90% of these mining activities were undertaken without mining leases granted by the Brazilian government.
  • Tailings and soil/freshwater contamination: Tailings refer to the waste materials from mining operations, after the valuable ore has been extracted. Hundreds of million tonnes of toxic slurry are produced by the mining industry every year, and disposing of it can be both costly and technically challenging. Ironically, some land-based mining operations employ the practice of Deep Sea Tailing Disposal – in which mining waste is deposited on the ocean floor via pipeline. As rare earth metals are often toxic, the pollution from mining the resources needed for renewable energy technologies can be particularly harmful. Mining in China’s rare earths hotspot, Ganzhou province, has led to unsafe drinking water, soil contamination and failed harvests. Chinese officials estimate there are 190 million tonnes of mining waste in Ganzhou province alone.

As we shall see shortly, deep sea mining has its own ill effects. But the critical point is this. Assuming equal levels of demand in a world which embraces DSM and a world which doesn’t, choosing the latter option will concentrate the burden of meeting the world’s resource needs on the 29% of the earth’s surface not covered by water. This is the same 29% that we live on, that meets the majority of our food needs, and that sustains what remain of our great terrestrial wildernesses.

DSM operations shouldn’t be tarred with a single brush

Just as there are different approaches to conventional mining, each with different impacts on the surrounding environment, so the impacts of deep sea mining will depend on the methods used.

Some of the most sought-after deposits are in the form of polymetallic nodules – potato sized concretions of iron and manganese hydrates found in their highest concentrations at depths of between 4000m and 6000m. In the most promising locations, such nodules can cover up to 70% of the sea floor.

Proponents of DSM argue that the environmental impact of mining for polymetallic nodules would not be severe. As they are visible without the need for digging, the DSM industry claims that they can be “harvested” or “plucked” by remote controlled equipment, with minimal disturbance to sea life.

Another sought after resource comes in the form of polymetallic massive sulphides, huge deposits of metallic ore generally found in volcanically active areas, in close proximity to hydrothermal vents (basically the underwater equivalent of geysers). Hydrothermal vents warm the surrounding ocean, leading to unique and as yet little understood communities of marine life.

But the industry claims that only inactive vents are likely to be targeted by mining operations, as high water temperatures and low PH levels around active vents would damage mining equipment.

A much greater impact is anticipated as a result of mining for cobalt-rich crusts. These crusts occur in a thin layer (approximately 25cm thick) over a broader area of sea floor, usually around seamounts, submerged ridges and plateaus. The International Seabed Authority estimates that as much as 1.7% of the ocean floor may be covered in cobalt-rich crusts.

DSM can solve the offshore sector’s sunk costs problem

The offshore oil and gas sector has floundered ever since 2008’s precipitous drop in oil prices slashed investment.

Recent months have seen a modest uptick in interest in developing new offshore projects, as concerns about interruptions in supply from Iran and Venezuela have caused oil prices to recover some lost ground.

But it is generally considered that oil prices will need to breech $100 a barrel – and will need to show positive indications of remaining at that level for some time to come – before the offshore sector can hope to see something approaching a full recovery.

Deep sea mining could provide an alternative source of profits. Many of the skills needed for deep sea mining operations have already been developed and perfected by the offshore energy industry. The vessels required are also pretty similar.

If you’re not a member of the offshore energy industry, and you’re wondering why you should consider this good news, here’s why: it can help sidestep the sunk costs problem. A real obstacle to the energy transition is resistance due to money already invested in forms of training, infrastructure and equipment that cease to be useful after a switch to renewable technologies.

If deep sea mining can replace lost profits from the extraction of offshore oil and gas, it will go some way to countering the problem.

If you want to learn more about the offshore sector’s involvement in deep sea mining, join the KNect365 Energy team at Offshore Vessel Connect Global.

Those are the arguments in favour of DSM. Now let’s take a look at the side of the argument that the deep sea mining industry would rather you didn’t hear.

The Dangers of DSM

DSM could destroy precious habitats little known to science

Here are a few interesting facts about hydrothermal vents you may not be aware of.

Because they occur at depths to which sunlight can’t penetrate, the lifeforms in hydrothermal vent zones cannot gain energy from photosynthesis.

Instead, they rely on a process called chemosynthesis, in which specially adapted bacteria feed off of minerals spewing through the vents from the earth’s crust. These bacteria are the foundation of a unique food chain, which includes a range of strange aquatic fauna including tube worms, clams, octopi, and many species new to science.

In some vent zones, known as cold seeps (because water temperatures are generally lower than other zones, which makes them more amenable to DSM), the water contains high concentrations of methane. In these zones, different strains of bacteria convert the methane into sulphides, and from there into organic materials. Remember that part about the methane, because we’ll be returning to it.

Hydrothermal vent zones are estimated to contain densities of marine life 10,000 to 100,000 greater than the surrounding sea floor. Such estimates are necessarily imprecise, because scientists don’t really know that much about the deep ocean.

For instance, they don’t yet understand how organisms specifically adapted to survive in hydrothermal vent zones are able to travel between them. But scientists know they must be able to propagate, as similar species can be found in widely dispersed locations across the ocean floor.

They also disagree about how resilient the communities around hydrothermal vent zones actually are. One school of thought has it that these communities must be able to recover quickly from destructive events – after all, they occur in volcanically active areas, so such events must be common.

But others believe that deep sea mining operations could cause the extinction of species and permanent alterations to the way marine communities function. Multiple mining operations taking place in the same region would make a permanent impact much more probable.

The mid-term impact may be even more severe. A recent paper assessing the body of evidence on deep sea mining’s environmental effects, published in the Harvard Environmental Law Review, “found little to no recovery of mined locations, even years after… experimental operations concluded.”

As a side note, another thing scientists have trouble agreeing about is the origin of life. One theory, known as the iron-sulphur world hypothesis, has it that the energy released by primordial hydrothermal vents may have provided the impetus needed to kickstart life on earth. Which is food for thought.

Evidently, much remains to be discovered about the marine biome of the deep sea before a complete picture can be gained of how mining may impact it. Take polymetallic nodules – the valuable “potato sized concretions of iron and manganese hydrates” found over much of the sea floor. The deep sea mining industry believes that extracting them would be minimally invasive, and thus minimally harmful.Polymetallic Nodules Deep Sea Mining

Polymetallic nodules on the floor of the deep ocean

But researchers have only recently come to understand that these deposits themselves play a role in regulating marine environments. More than half the species in the mineral rich Clarion-Clipperton Zone may be biologically dependent on polymetallic nodules, researchers from the ABYSSLINE deep sea exploration project have discovered. That could make the ecological consequences of removing them devastating.

DSM could have damaging effects on the wider marine environment

Another claim made by the Deep Sea Mining industry is that the effects of responsible DSM operations are highly localised. Because valuable metals can be found in higher concentrations on the sea floor, the industry says, a much smaller area needs to be mined – which reduces the environmental impact. It’s an argument that doesn’t hold up to much scrutiny.

Take the Solwara 1 Project. The location in which Nautilus Minerals have chosen to mine features copper grades of approximately 7%, which compare with an average of 0.6% for land based mines. That means copper in that particular stretch of seabed is 1166% more concentrated than on land. Parts of the Solwara 1 mining site also contain gold grades of 20 g/tonne, compared with an average of 6 g/tonne on land.

Those are impressive numbers – and they’re one of the reasons why mining at a depth of 1600m can still be profitable. Nautilus Minerals say the proposed extraction area is approximately 0.1km² in size, which equates to 0.00003% of seabed area of the Bismarck Sea (where the mining operation will take place).

That sounds like good news. Unfortunately, when it comes to mining the ocean floor, the size of the extraction area is only one part of the story.

What also needs to be appreciated are the effects of plumes – clouds of sediment kicked up by mining equipment and dispersed over the surrounding area, with potentially dire implications for marine life.

Plumes are released in a number of ways. Digging equipment is a major contributor. But so are the tank-style treads DSM vehicles use to navigate the sea bed, and the risers designed to convey hundreds of tonnes of ore up to vessels on the surface.

The last of these is particularly worrying, because risers release particles higher up the water column. This means they can interfere with life in shallower waters (such as the fish we eat), and become dispersed over a larger area.

DSM plumes have a range of impacts on the marine biome. The release of toxic particles (including trace amounts of the very minerals miners are attempting to extract) is one concern. Another is that sediment released higher in the water column can inhibit light penetration, and cover lifeforms on the sea floor when it eventually settles.

Accurate impact assessments are tricky because anticipating plume behaviour is complicated science. For a start, the size of the particles released alters their behaviour – larger particles in suspension tend to sink to the bottom over time, but particles small enough to be dissolved can be carried much further away from the extraction area.

Another thing to take into account is turbulence, and the strength and direction of ocean currents. Deep sea currents tend to be slower but more unpredictable than currents in the upper reaches of the ocean. To gain even an approximate picture of plume dispersal, detailed three-dimensional models factoring in depth of discharge, probable particle size, and the interaction of currents are required.

As yet, no full scale commercial DSM project has begun, which means that understanding of plume behaviour is further hampered by a scarcity of available data. But tests at the Solwara 1 site have found sediment layers of 500mm within a 1km radius of experimental mining activities. This compares to an estimated rate of sediment accumulation for abyssal and seamount habitats of a few millimetres every millennium.

DSM could interrupt processes vital to the regulation of our climate

Do you remember what we said about the bacteria found in hydrothermal vents zones being able to convert methane into organic materials? Here’s why that’s important.

You probably already know that methane is one of the most potent Greenhouse Gases in our atmosphere. Over a hundred-year period, each tonne of methane released is somewhere between twenty-eight and thirty-six times more impactful than an equivalent quantity of carbon dioxide. Over a shorter timescale, it’s even more impactful than that.

Disrupting the delicate ecological balance of methane rich hydrothermal vent zones could interrupt the microbial processes that convert methane into organic materials. It is estimated that over 90% of the methane released by hydrothermal vents is sequestered by the microorganisms that thrive in these regions. Allowing this methane to make its way into the atmosphere would not bode well for the climate.

Microorganisms in the deep ocean also play a vital role in sequestering carbon dioxide. Much like trees and terrestrial plants, phytoplankton in the upper reaches of the ocean consume CO2 from the earth’s atmosphere. When the phytoplankton dies, quantities of organic carbon sink into the deeper ocean. As these organic remnants decay they release CO2, which dissolves into the surrounding water.

In a process known as carbon fixation, microorganisms in hydrothermal vent zones prevent this CO2 from returning to the atmosphere by converting it back into the complex organic molecules which form the basis of the vent zone’s food chain. Marine organisms account for more than half of the 258 billion tonnes of carbon fixed annually on earth. Once again, the consequences of this carbon making its way into the atmosphere would be disastrous.


Given the arguments laid out both for and against deep sea mining, should we support it or oppose it?

It’s a tough call to make. On the one hand, DSM might be indispensable to the technological revolution climate advocates believe is our best hope for preventing irreversible planetary warming. On the other, it could open up a new front in the war waged against life on our planet, and even exacerbate the warming processes clean energy technologies are supposed to mitigate.

At present, we understand so little about deep sea environments that it’s very difficult to assess just how damaging deep sea mining could be on a macroscopic scale. Which is both an argument for or against DSM, depending on your appetite for risk.

To say that more research is needed is to state the obvious. It is also to place ourselves in danger the kind of evidentiary paralysis that prevents policy makers and the wider public from coming to a decision until – for better or for worse – a decision is made for them. We already know how that plays out.

When the Solwara 1 operation goes ahead next year, it will provide a test case for deep sea mining’s commercial feasibility and environmental impact. We should watch the operation closely. And once the effects are apparent, we should ask ourselves: was it worth it?

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