By Cliff Rice
Electric vehicles are only a small part of the world vehicle market, but this is expected to change. While there are several competing battery chemistries which are likely to be used in this emerging market, many of them contain significant amounts of nickel. This is a problem, and to understand why it is a problem, we need to understand the basics of where nickel comes from. It gets a bit complicated.
Nickel is mined from two types of deposits — sulphide and laterite. Sulphide nickel occurs in hard rock that has formed from crystallization of magma with the proper conditions and chemistry. Laterite nickel is a product of the weathering of ultrabasic bedrock under proper conditions of rainfall, drainage, temperature, and slope in the tropics.
Nearly all nickel currently used in batteries comes from sulphide nickel. This is because batteries require nickel of high purity, which is usually obtained from sulphide nickel. Also, sulphide nickel can be mined, smelted, and refined with less environmental impact than laterite nickel. So, when Mr. Musk or other electric vehicle manufacturers indicate they want nickel which is efficient and environmentally friendly, they mean sulphide-sourced “clean” nickel.
The problem part of the “dirty nickel problem” is that sulphide nickel sources are limited. Most known locations with sulphide nickel are already being mined and cannot be readily expanded. Some of these mines are on the surface, but many are subsurface mines, sometimes with the nickel ore being brought up from thousands of feet below ground. Greatly increasing the output from such mines is problematic. Furthermore, recent discoveries of new locations with sulphide nickel have been small and finding them has been costly. So, we should not expect new discoveries to have much effect on sulphide nickel ore supplies.
This leaves us with laterite nickel, the dirty part of the “dirty nickel problem.” Laterite nickel is not just dirty, it is simultaneously dirty in four different ways. First, because laterite nickel ore has lower and variable concentrations of nickel, it takes a lot of energy to smelt it — in fact, many times as much as smelting sulphide ore. This energy is almost exclusively provided by burning coal. Typically, it takes 25 to 30 tons of coal to produce a single ton of nickel. When all the CO2 emissions are counted, smelting and refining laterite nickel releases nearly 90 tons of CO2 for every ton of nickel produced. That means an average electric vehicle with a 50 kg battery, 4 tons of CO2 were released during its production. Depending on the type of power used to charge that battery, that means one would have to drive that car for 4 years to break even on the CO2 footprint based on the manufacture of the battery alone.
Instead of smelting, laterite nickel can also be handled by a lovely-sounding process called high-pressure acid leaching (HPAL). The CO2 produced by HPAL is about one third that of laterite smelting, but still several times as much as even the more carbon-intensive variants of sulphide processing. Not only that, but HPAL produces large amounts of waste — unstable and hazardous tailings, acid slurry, and magnesium sulphate effluent. The difficulty in storing these products in areas of high rainfall (as laterite nickel producing regions are) and earthquake-prone locations has led to the proposal that they should be discharged into the deep sea. This is not an environmentally friendly option. For all these reasons, HPAL is the second way laterite nickel is dirty.
The third way laterite nickel is dirty is through the destruction of tropical rainforest — and not just any rainforest. Because of accidents of climate and geology, laterite nickel deposits are most extensive in Indonesia and the Philippines. These two countries account for 75% of laterite-nickel production. They are also considered biodiversity hotspots in that they are exceptional in the number and uniqueness of species that occur there. Therefore, effective conservation of their biological resources is a high priority.
Because laterite nickel deposits are widespread, low grade, and shallow, strip mining is the only realistic method of obtaining this ore. The first step in strip mining is, naturally, to remove everything growing on the surface. I estimated that over 40% of the nickel mines on the island of Sulawesi in Indonesia stripped intact rainforest to get to the nickel ore. Recent assessments by the United Nations and others have highlighted the accelerating rate of species loss on our planet. Strip-mining for laterite nickel is a threat to efforts to arrest and reverse these trends.
Importantly, due to the geochemistry involved, laterite nickel deposits often form along ridges and hilltops. A moment’s thought is all it takes to predict what will happen when heavy tropical rain falls on ridges and hilltops from which all vegetation has been removed. The rains will wash away any loose dirt, sand, or grit that has been exposed. Indonesia and the Philippines are island nations, and none of the islands with laterite nickel are very large. As a result, sediment washed off of nickel mines is, in short order, carried out to sea. In the tropics, “out to sea” means onto coral reefs. This is the fourth way laterite nickel is dirty nickel. Coral reefs around the world are already in crisis due to rising temperatures, pollution, and exploitation. Sediment settling out of discharge from streams and rivers severely exacerbates these issues. Coral reefs are the rainforests of the sea, and are also important in supporting local livelihoods through fishing and tourism.
So, an environmentally conscious person looking to minimize their personal impact and still meet their transportation needs might view sulphide nickel mining as a kind of necessary evil — necessary for the battery component of an electric vehicle. Laterite nickel, however, can only be viewed as a net loss environmentally and an ugly one at that. Certainly, electric vehicle manufactures cannot live up to their professed good intentions of using “environmentally friendly” nickel if that nickel comes from laterite deposits.
The rub is that electric vehicle manufactures may avoid laterite nickel and still be the cause of increased ecological damage due to increases in laterite nickel mining. The reason for this is that, as I mentioned earlier, there is little room for growth in cleaner sulphide nickel production. The total amount of nickel mined and utilized has to increase if large amounts of nickel are going to be used in electric vehicle batteries. This increase must, by and large, come from increased laterite nickel mining with all its dirty problems.
About the Author: Cliff Rice is an Affiliate Assistant Professor in the School of Environmental and Forest Sciences at the University of Washington and has had a lifelong interest in biological conservation around the world.