Magrathea to produce first inherently carbon neutral primary metal
San Francisco, 15 January 2025 - Magrathea, a company developing innovative technology for the production of carbon neutral light metal from seawater, has shown quantitatively that its future product can be inherently carbon neutral using ISO-compliant prospective life cycle assessment (LCA).
To show that Magrathea’s process will be able to produce metal with net zero cradle-to-gate embodied CO2 emissions, the company partnered with Minviro, a globally recognized expert in metals and chemical production LCA. Minviro independently built an ISO 14040-14044/ISO-14067-compliant prospective LCA for an example set of engineering process data from Magrathea’s modeling work representing a future project configuration. The LCA showed that Magrathea’s process can be configured to produce metal with embodied CO2 emissions of around 0 kg CO2 eq./kg magnesium.
“Inherently carbon neutral primary structural metal was previously considered impossible,” said Alex Grant, CEO of Magrathea. “Customers representing a quarter of the entire world’s non-China magnesium market have signed LOIs and MOUs with us because they see how this future will improve their products and the world.” A summary of the results of the LCA as compared to alternative primary production processes for magnesium is shown below. The LCA was partly funded by the Department of Energy’s Vehicle Technologies Office.
Figure 1: Results of Minviro's Comparative Life Cycle Assessment for a Variety of Magnesium Products
This CO2 footprint is enabled by technology specifically designed to integrate clean, renewable intermittent energy and a carbon-sequestering magnesium oxide co-product. The magnitude of CO2 absorbed by the produced magnesium oxide can be the same or even more than the CO2 generated in the production of magnesium through Magrathea’s process. The company will conduct specific LCAs for future projects.
The exact embodied CO2 emissions of Magrathea’s future product depends on a variety of factors and it is possible for this number to be higher or lower. The purpose of this prospective LCA is to show what is possible. A panel of LCA and metallurgy experts reviewed the results to ensure accuracy and reliability of the methodology. Their suggestions were incorporated into the study. If you are interested in the full ISO-compliant LCA report, please reach out to media@magratheametals.com.
History of Magnesium Metal Life Cycle Assessment
The following section reviews past LCAs of primary production of magnesium metal and compares the results to those calculated in Magrathea’s assessment.
Several LCAs have been done on the primary production of magnesium metal over the last few decades. Motivated by increased emissions regulations, Norsk Hydro conducted one of the first primary magnesium production LCAs on its electrolytic process.[i] Norsk Hydro’s electrolytic processes were operated in Porsgrunn, Norway, and Bécancour, Quebec, Canada. The process used seawater, dolomite, and magnesite feedstocks to produce a dry magnesium chloride salt. The salt was then split using molten salt electrolysis into magnesium metal and chlorine. The study found the process had a global warming potential of 19 kg CO2 eq./kg magnesium metal.[ii]
In the early 2000s, society became increasingly concerned about industrial emissions, and several more LCAs were conducted. During this time, the Chinese Pidgeon process became the dominant form of primary magnesium production due to Chinese dumping on Western markets. It is a thermal process that leverages cheap or free heat from semi-coking ovens and cheap (sometimes forced) labor available in China to produce low-cost metal at the expense of environmental and social sustainability. In 2004, Ramakrishnan and Koltun conducted an LCA on the Chinese Pidgeon process and found it to have a carbon footprint of 42 kg CO2 eq./kg magnesium metal.[iii] They also considered uncertainty in their inventory analysis, resulting in a range of 37 kg CO2 eq./kg magnesium metal to 47 kg CO2 eq./kg magnesium metal. This study considered the sulfur used in the process to prevent oxidation but did not mention other cover gases.
In 2008, Cherubini et al. compared several thermal and electrolytic processes. The study assessed Australian electrolysis, an electrolytic process that uses a magnesite feedstock, recycling the chlorine gas produced to acidify ore. It also included the Bolzano process, a thermal process that is used today in Brazil, the Magnetherm process, a French thermal process, and the Chinese Pidgeon process. Similarly to Ramakrishnan and Koltun, the authors concluded that the Chinese Pidgeon process has a global warming potential of 42 kg CO2 eq./kg magnesium metal. Additionally, they found that the Australian electrolytic process had a global warming potential of 25 kg CO2 eq./kg magnesium metal, the Bolzano process had a global warming potential of 10 kg CO2 eq./kg magnesium metal, and the Magnetherm process had a global warming potential of 14 kg CO2 eq./kg magnesium metal.[iv] The study found that the Chinese Pidgeon process has a much greater impact than alternative thermal processes due to coal consumption. The cover gas for the electrolytic process and sulfur use in the thermal processes were considered, but the use of additional cover gas in the thermal processes was not discussed.
In 2008, the International Magnesium Association (IMA) conducted their first LCA focusing on the Chinese Pidgeon process. Several power alternatives were considered including coal, natural gas, producer gas, coke oven gas, and an integrated plant, all of which are predominant in China and rely on the coal industry. The study found the global warming potentials as follows: coal with 47 kg CO2 eq./kg magnesium metal, natural gas with 25 kg CO2 eq./kg magnesium metal, producer gas with 37 kg CO2 eq./kg magnesium metal, coke oven gas with 32 kg CO2 eq./kg magnesium metal, and an integrated plant with 29 kg CO2 eq./kg magnesium.[v]
A very similar study was conducted by Gao et al. in 2009. This study examined the Chinese Pidgeon process, comparing the impact variation due to differing power sources, specifically coal, producer gas, and coke oven gas. The results showed that coke oven gas had the lowest emissions at 34 kg CO2 eq./kg magnesium metal, followed by coal with 37 kg CO2 eq./kg magnesium metal, and producer gas with 42 kg CO2 eq./kg magnesium metal.[vi] Interestingly, the authors concluded that the Chinese Pidgeon process inherently drives emissions, and it is impossible to decarbonize it.
Du et al. performed a similar study in 2010, comparing three different cases of scenarios observed at Chinese Pidgeon plants. They determined an average embodied CO2 emission value of 27 kg CO2 eq./kg magnesium metal and a potential range of 18 kg CO2 eq./kg magnesium metal to 32 kg CO2 eq./kg magnesium metal.[vii] The values from this study are significantly lower than others. This seems to be driven by a lower quantity of coal in the inventory analysis.
In 2013, the IMA updated their LCA. They re-examined the Chinese Pidgeon process but eliminated the use of coal as an energy source, which is peculiar given the current energy mix in China and the nature of the Chinese Pidgeon process. Additionally, this study seems to reduce the embodied CO2 from ferrosilicon production with no explanation. The authors weight their results based on a proposed energy mix, resulting in an average embodied CO2 value of 26 kg CO2 eq./kg magnesium metal, much lower than their previous study.[viii] Additionally, they chose to omit cover gas. A portion of the study also considers coke oven gas and semi-coke oven gas as waste products with zero embodied CO2 emissions. However, this seems misrepresentative of the emissions occurring. Furthermore, the study investigated the emissions of Israeli electrolytic magnesium production, assuming a hydrofluorocarbon R135a cover gas, which suggested a global warming potential of 18 kg CO2 eq./kg magnesium metal. The authors also considered the offtake of potassium chloride and chlorine by-products, lowering the results to 14 kg CO2 eq./kg magnesium metal.
Another LCA of the Chinese Pidgeon process and an Australian electrolysis project was done by Morimoto et al. in 2020, comparing magnesium to aluminum. In this study, the authors consider how an updated energy mix, mainly increased renewable and nuclear power, may affect the Chinese Pidgeon process and the Australian electrolytic process. They found that the current Chinese Pidgeon process has embodied CO2 emissions of 26 kg CO2 eq./kg magnesium metal. A cleaner energy mix resulted in 23 kg CO2 eq./kg magnesium metal. The study also found that the Australian electrolysis project with clean energy could have delivered 9 kg CO2 eq./kg magnesium metal.[ix] The lack of consideration of coal most likely drives the low emissions for the Chinese Pidgeon process. This study demonstrated how a clean energy mix does not help decarbonize the Chinese Pidgeon process. The only known process technology for making magnesium metal that can truly be decarbonized is electrolytic.
In 2020, the IMA updated their study again from the 2013 analysis. This study reports a slightly higher global warming potential for the Chinese Pidgeon process of 28 kg CO2 eq./kg magnesium metal. The drivers of this are opaque as the use of coal is still omitted. Additionally, the study uses ash by-products in making cement and credits this against the carbon liability.[x] The author also re-analyzed the Israeli electrolytic process once more and came to the same result of 18 kg CO2 eq./kg magnesium metal. This study also assessed a Chinese electrolytic process, a Turkish version of the Chinese Pidgeon process, and the Bolzano process, with results of 9 kg CO2 eq./kg magnesium metal, 23 kg CO2 eq./kg magnesium metal, and 26 kg CO2 eq./kg magnesium metal, respectively.
Throughout literature, cover gas is commonly neglected, particularly when analyzing the Chinese Pidgeon process. Argonne National Laboratory conducted a study on cover gas in magnesium foundries, focusing on SF6, a widely used cover gas in magnesium foundries. They found that the Pidgeon process and standard electrolytic processes use 1.7g SF6/kg magnesium metal.[xi] The global warming potential of SF6 is incredibly high at 22,800 kg CO2 eq./kg SF6, so it is hypothesized that most studies neglect this because it would significantly inflate the global warming potential of magnesium when SF6 is used. Magrathea does not use SF6 as a cover gas.
Conclusions
Below are the main takeaways from the history of magnesium metal LCA:
Energy is the main driver of CO2 emissions for many magnesium metal production pathways.
Emissions in the Chinese Pidgeon process and other thermal reduction processes are impossible or almost impossible to eliminate as they are inherently part of the process.
Many studies neglect the use of coal in the Chinese Pidgeon process.
It is critical to include cover gas in LCA of magnesium production, especially when SF6 is used.
LCA offers a useful tool for guiding process and project development decision making to achieve low cost, low CO2 emissions, and making the magnesium metal that the world needs.
About Magrathea
Magrathea is a technology company based in California developing a new generation of electrolytic process for making carbon neutral metal from seawater and brines for the era of electrification and decarbonization. For media inquiries, please contact media@magratheametals.com.
About Minviro
Minviro is a leading provider of advanced life cycle assessment (LCA) services and software for the mining, energy, and materials industries. By delivering cutting-edge solutions, Minviro enables organizations to reduce their environmental impact, optimize resource use, and achieve sustainability goals through data-driven insights.
References
[i] Brown (2011). “Environmental Challenges for the Magnesium Industry”. Magnesium Technology 2011.
[ii] Albright and Haagensen (1997). “Life Cycle Inventory of Magnesium”. IMA Annual World Conference, Toronto, Canada.
[iii] Ramakrishnan and Koltun (2004). “Global warming impact of the magnesium produced in China using the Pidgeon process”. Resource Conservation and Recycling.
[iv] Cherubini et al. (2008). “LCA of magnesium production: Technological overview and worldwide estimation of environmental burdens”. Resource Conservation and Recycling.
[v] Ehrenberger et al. (2008). “Status and potentials of magnesium production in China: Life cycle analysis focusing on CO2 eq. emissions”. German Aerospace Center (DLR).
[vi] Gao et al. (2009). “Life cycle assessment of primary magnesium production using the Pidgeon process in China”. International Journal of Life Cycle Assessment.
[vii] Du et al. (2010). “Life cycle greenhouse gases, energy and cost assessment of automobiles using magnesium from Chinese Pidgeon process”. Journal of Cleaner Production.
[viii] Ehrenberger (2013). “Life Cycle Assessment of Magnesium Components in Vehicle Construction”. German Aerospace Center (DLR).
[ix] Morimoto et al. (2020). “Methodological Study of Evaluating Future Lightweight Vehicle Scenarios and CO2 Reduction Based on Life Cycle Assessment”. Journal of Sustainability.
[x] Ehrenberger (2020). “Carbon Footprint of Magnesium Production and its Use in Transport Applications”. German Aerospace Center (DLR).
[xi] Dai et al. (2016). “Update of Recycled Content and SF6 Emissions for Magnesium in the GREET® Model”. Argonne National Laboratory.
A PDF version of this announcement can be found here.