Insider Brief:
- Graphite is rapidly increasing in demand, and is a vital component of battery anodes for electric vehicles. Mining has not kept up with demand.
- Synthetic graphite is a high-emitting process. A new study identifies the portions of the process which emit the most carbon.
- Adoption of renewable energy and green hydrogen can cut emissions substantially, the study finds.
Graphite is quickly rising in stature as a ‘critical mineral,’ given how important it is for manufacturing, steelmaking, nuclear reactors, and anodes for electric vehicle batteries.
Currently, China produces 78% of global graphite, according to the U.S. Geographical Survey (USGS). Graphite is also produced by Mozambique, Madagascar, and Brazil. In 2024, an estimated 1.6 million tons of the mineral was produced worldwide – well short of the demand, estimated to be between 3.7 and 3.8 million tonnes worldwide.
Demand not yet met by mining
This demand is only going to grow, as industries, and particularly EVs, increase in production. North American demand for graphite anode material will grow 300% in the next five years, with global demand increasing by 189% in the same period, according to the North American Graphite Alliance.
To meet this demand, lots of new graphite mines in the U.S. and Canada have recently sprung up – but are not yet in production; he Lac des Iles graphite mine in Quebec is the only graphite mine currently producing in North America.
Synthetically produced graphite is one way that manufacturers are closing the gap in the availability of naturally mined graphite. According to Natural Resources Canada, synthetic graphite accounted for 67% of total graphite consumption, with the bulk of this demand originating from Asia.
New study identifies methods to decarbonize synthetic graphite
In a new study recently published in ACS Sustainable Chemistry & Engineering, scientists identified a method to substantially decarbonize the synthetic graphite creation process.
The authors – led by Shaojun Zhang at Tsinghua University and Xin He at the Aramco Research Center in Detroit – found that synthetic graphite currently accounts for 82% of the current global battery anode supply. Synthetic graphite is preferred over natural graphite for its higher capacity to extend battery cycle life and fast-charging capabilities of lithium-ion batteries.
Primary feedstock materials for synthetic graphite include calcined petroleum coke and coal tar pitch, as well as oil-based needle coke and ethylene tar pitch. Previous calculations of the carbon footprint of synthetic graphite production had not incorporated these two feedstocks, the study said.
“These new feedstocks, driven by the surging demand of high-performance synthetic graphite, have substantially transformed the entire supply chain,” the authors wrote.
Some production stages more polluting than others
By studying 12 operational plants and 22 upcoming plants in China, with a combined production capacity of 2.5 million tonnes per year, the authors identified which parts of the synthetic graphite process generated the most carbon emissions, based on the different types of feedstock.
The process for synthetic graphite production includes six stages: drying and multistage grinding of feedstocks in the pretreatment phase; four separate thermal treatment phases, including coating and granulation, precarbonization, graphitization, and carbonization; and the separation of final synthetic graphite from byproducts such as crude graphite.
Several of the feedstocks have high carbon footprints. Carbon footprint levels for uncalcined cokes, such as petroleum coke, coal-based needle coke, and oil-based needle coke, generate 0.34, 1.2, and 2.1 tonnes of CO2 per tonne of product, respectively.
Calcinating particular feedstocks – a necessary process to prepare these feedstocks – increase carbon footprints between 30% and 50%, when applied to petroleum coke, coal-based needle coke, and oil-based needle coke.
The authors proposed a threshold carbon footprint level of 0.9 tonnes of carbon dioxide per tonne of synthetic graphite to distinguish between low-end and high-end feedstocks.
Decarbonization approaches to consider
The report authors find potential for decarbonizing the synthetic graphite process in using green electricity and green hydrogen in needle coke production.
Of all the processes required to create synthetic graphite, graphitization generated the most carbon, followed by pretreatment, and carbonization. Carbon generated during the carbonization phase largely originate from electricity consumption.
Synthetic graphite production plants are separated into four categories: entry-level, reinforced entry-level, premium, and reinforced premium. Of these, the entry-level group has the lowest carbon footprint, while the reinforced entry-level group has a 20% higher carbon footprint due to increased energy consumption.
Premium group plants have similar levels of carbon footprint to reinforced entry-level plants, while reinforced premium plants have a 30% increase in terms of carbon footprint, due to increased electricity use and auxiliary material inputs and graphitized coke outputs.
By substituting 20% of insourced and outsourced energy with renewable energy, synthetic graphite plants can decrease their carbon footprint by 16%, the authors found, and they suggest plants construct their own rooftop solar panels and pursue purchases of renewable energy to meet this goal.
The carbon footprint of plants can also be reduced to 5.3 tCO2/t if green hydrogen is used to produce oil-based needle coke and other feedstocks. Employing a combination of clean electricity and green hydrogen can reduce the carbon footprint of synthetic graphite using oil-based needle coke from 23 to 25%.
By pursuing these two decarbonization pathways, synthetic graphite producers can reduce the carbon footprint of their reinforced entry-level plants by 42%, and their premium plants by 35%, due to its lower electricity consumption and use of needle coke.
If plants were to replace 50% to 80% of energy with renewably sourced energy, the authors calculated plants could reduce their carbon footprint by 55% to 70%.
It may become necessary from some plants to move to regions which offer more renewable energy in their grids to meet these decarbonization goals, the authors concede.
They also point to likelier higher prices for decarbonized synthetic graphite production, due to renewables and also the high cost of green hydrogen.
However, given the four-fold increase graphite anode demand expected by 2030, and continued demand by governments on carbon reduction, graphite anode producers may have little choice but to opt for these decarbonization measures.
