Maria Bolevich for the DSM Observer
Last April, DeepGreen published a first of its kind life cycle analysis comparing the environmental, social, and economic impacts of land-based ores and deep-ocean polymetallic nodules. “Billions of tons of metal will be taken from the planet between now and 2050 to enable the clean energy transition,” says Gerard Barron, CEO of DeepGreen. “We need to understand the environmental and social cost of this extraction and do everything we can to compress it. [Life cycle assessment] helps compare the impacts of the alternatives.”
Life Cycle Assessment (LCA) is among the most successful methods to gauge the environmental impacts associated with a product from creation to disposal. Life cycle assessment has broadened to include life cycle costing and social LCA, within the life cycle sustainability assessment framework.
Deepak Rajagopal, a professor at the UCLA Institute of the Environment and Sustainability, explains that LCA is valuable for individual mining contractors to identify where much of the cost and emissions arise in deep-sea mining and how this compares to alternatives at each step in the production chain and it can help civil society understand the overall costs and emissions compared to the long-term potential of the mining activity. “LCA is very useful at early stages of a new technology,” says Rajagopal, “but extrapolating LCAs to infer anything about long-run or large-scale impact is very challenging. It is best used to identify hot-spots or vulnerabilities in the supply chain and try to alter the design or supply chain before things solidify too much.”
Kwame Awuah-Offei, a professor of mining engineering at Missouri University of Science and Technology, argues that LCA is usually a more valuable tool to governments and policymakers, rather than industry. “LCA is good at predicting potential impacts of providing a particular product or service. So it is limited in the sense that it doesn’t provide actual impacts,” says Awuah-Offei. “[For example] if I’m interested in the climate change impacts of providing batteries for electric vehicles, an LCA will help me predict the greenhouse gas emissions along the entire supply change. But those [greenhouse gas] emissions do not reflect the actual emissions at any particular mine or refinery in the supply chain. They could differ. Another important limitation is that it tends to minimize local impacts in favor of more global impacts. [For example], land use impacts are often big for mining/extraction but because along the supply chain there are different land uses and pressures, it is difficult to aggregate them into a single measure of land use.”
The results of the DeepGreen life cycle assessment showed that nodules place 94% less stored carbon at risk, produce 100% less solid waste, result in 94% less land use, and put 93% less wildlife at risk. But Barron emphasizes that the LCA is not an argument for or against deep-sea mining. “It says nothing about [deep-sea mining] as a category, just gives us insight about what is possible if battery metals are produced from [Clarion-Clipperton Fracture Zone] nodules using a [DeepGreen]-type collection system and metallurgical flow sheet, it tells us nothing about mining [seafloor massive sulphides] or cobalt crusts – new analyses are required to understand LCA impacts there.”
Barron adds that they have high confidence in their assessment of most environmental, social, and governance impacts with the exception of impacts on marine biodiversity and ecosystem function, an area of focus for DeepGreen at the moment. “We know the sediment in the abyssal plain stores 15x less carbon than on average on land and there are no known mechanisms for this carbon to be released into the atmosphere from 4 km depth”, says Barron. “That’s on the subsea environment side. We have also made a lot of progress on characterizing and modeling the impacts of the collection system, e.g., we expect to entrain only 5 cm of subsea sediment and redeposit over 90% of this sediment back at the seafloor, we expect most of this sediment to resettle within hours-to-days within 10s-1,000 of meters from origin.”
According to Ehsan Vahidi, an assistant professor at the University of Nevada, if we include social impacts as well as environmental impacts deep-sea mining of nodules could reduce waste, tailings, and dust generation in critical mineral production and substantially reduce freshwater use. “This method can diminish incidents associated with traditional mining such as open-pit and underground mining methods. Thus, human fatalities as well as injuries can be decreased.” says Vahidi, who goes on to explain that an LCA will incorporate a number of assumptions and uncertainties. “In order to utilize LCA as a decision-making tool in the deep-sea mining method, uncertainties originated from lack of robust database must be handled properly by statistical methods.”
According to Awuah-Offei, LCA is good for answering certain specific questions for decision making but not all. “If the cobalt is mined in the DRC,” explains Awuah Offei, “refined in China and then made into a battery in Japan, how do you aggregate 1 hectare of land disturbance in all three locations? The impact and nature of land degradation depends on the land uses before mining/industrial activity and the extent of the impact. But this will differ for the mine in DRC, the refinery in China and the factory in Japan. So it is easier for LCA studies to just focus on things like greenhouse gases that we can simply add up because a ton of CO2 emitted in DRC, China and Japan have the same impact on the climate. But that doesn’t mean the local impacts are any less meaningful.” Awuah-Offei continues, “If I’m interested in the question of sourcing lithium from salt brines in South America vs hard rock mining, then LCA can be a good tool because it helps me compare the two different supply chains. But if I’m interested in the specific impacts of mining in the Atacama Desert then LCA may not be that useful.”
For Kris Van Nijen, managing director of GSR, LCAs are a way to benchmark their impacts and effects compared with alternative sources of primary mining. “LCAs help us to decide which potential sources have the least impact on our planet, LCAs help us understand where we need to focus our efforts along the mining and processing chain. The LCAs help in seeing the merits of different options in terms of environmental effects and in making an informed decision on different technologies and methodologies. Looking at the problem of metal supply holistically, LCAs let us uncover Best Available Techniques to achieve a circular economy.”
Van Nijen adds that the benefit of LCAs is that they demonstrate the impact of different options and help them decide where they should focus efforts. “On carbon emissions we can be confident about making robust comparisons between sea and land. However, for biodiversity it is more challenging because there is limited data about land-based mining’s impact on, for example, microfauna and meiofauna. Nevertheless, with respect to megafauna and mammals there is more data available. It is important not to have an asymmetric debate where data is compared with the absence of data.Finally, biodiversity is just a number – a number doesn’t provide information about the ‘value’ or ecosystem services the organisms that make up that biodiversity provide.”explains Van Nijen.
Roderick Eggert, Viola Vestal Coulter Foundation Chair in Mineral Economics at Colorado School of Mines, says that deep-sea mining could be a significant source of supply for some metals – but not for the foreseeable future. According to Eggert the technologies for recovering deep-sea minerals need to be demonstrated at commercial scales of operation without significantly damaging the often fragile deep-sea environment and competitive with conventional land-based mining. “As human living standards improve,” says Eggert, “we expect demand for many if not most materials to grow… Even if we increase the extent to which products or materials are recycled, mining will be necessary.”
“So often we see results of studies being presented in isolation,” concludes Van Nijen. “We often read that the impact of [deep-sea mining] may be ‘destructive’, ‘disastrous’, ‘catastrophic’ or ‘harmful’, but none of these adjectives mean much if not put into context of the impacts the alternative solutions would bring.” Van Nijen believes LCAs could help bring seemingly opposed stakeholder groups together. “Today, we see the different stakeholders hunker down in their positions. There are groups that think [deep-sea mining] can never be considered and there are groups that think [deep-sea mining] can provide a better solution. We have to realize that both positions come at a cost for society.”
Featured Image: C-LCA by Julienpoullot from Wikimedia Commons.