Elkem is among the world's cleanest metal manufacturers, but we still emit around 1.6 million tonnes of carbon per year. Production of silicon and ferrosilicon takes place in electric arc furnaces where quartz, which consists of silicon and oxygen, is mixed with carbon at a high temperature. This creates a chemical reaction process that releases the oxygen from the quartz to produce pure silicon, but also CO2. Due to prohibitive costs, but also challenges related to sustainability of biocarbon, Elkem mainly uses fossil coal as reduction material.
By replacing fossil coal with charcoal produced from sustainable biomass, the production processes could become carbon neutral. Studies have shown that charcoal (and woodchips) can perform even better in the chemical reaction than fossil coal and at the same time reduce our carbon footprint.
In 2015, Elkem initiated a research programme called Carbon Neutral Metal Production (CNMP). The concept of CNMP is to produce charcoal in the same production facility as ferrosilicon or silicon production, connecting this to an energy recovery unit to produce electricity from the excess heat. In an optimal situation with 100% biocarbon use and optimal energy recovery, such a plant would become both CO2 and energy neutral, delivering enough electricity to run the electric arc furnaces. The concept would thus integrate the forest industry with metal production, producing new, circular value chains.
The initial R&D project of the CNMP programme was funded by the Research Council of Norway and concluded that with existing furnace technology, we can reduce energy consumption by over 50 per cent with considerable reduction of fossil CO2 emissions.
However, the project also showed that the economic margins and risk are significantly dependent on the performance of the pyrolysis technology, both in terms of quality, commercial viability and energy yield. Our conclusion was that to ensure successful realisation of carbon neutral metal production further research is needed. Therefore, several project have been initiated to improve process integration, process performance and charcoal quality.
Two of the projects are research projects co-funded by the Norwegian Research Council (awarded approximately 25 mill NOK in 2017-2018).
- PyrOpt will look into pyrolysis of wood optimized for production of energy and tailor-made biochar for silicon production. The project is a collaboration with SINTEF and Papir & Fiberinstituttet. This project will look at resource-effective production of high quality charcoal. Elkem’s long-term goal is that charcoal will replace fossil coal in the production of speciality silicon as well as standard silicon and ferrosilicon production.
- SiNoCO2 is a project looking into silicon production with no CO2 emissions through the closing of silicon and ferrosilicon furnaces. If successful, closed furnaces would emit CO instead of CO2, enabling further industrial use of the off gas. Closing the furnaces could also be a step towards developing processes prepared for carbon capture. The project is conducted in collaboration with SINTEF and NTNU.
However, Elkem is committed to reduce our climate footprint even faster. Therefore, we are working on a project to start pilot testing industrial scale production of fit-for-purpose charcoal based on commercially available technology. Such production would not be able to replace all fossil carbon, due to the quality of the charcoal, but would take us a significant step on the way towards our 2030 target of 40%. The main barriers are commercial viability and availability of sustainable biomass at competitive prices.
The project, called Norwegian Wood, has explored the possibilities for building a pilot plant in Norway based on Norwegian biomass. The main barriers so far have been commercial. To become commercially viable, a pyrolysis plant would need to sell the significant amounts of heat, in the form of steam, to other industrial actors. In addition, long-term contracts for wood at predictable prices would have to be available for biocarbon to be a competitive raw material for Elkem.
So far, promising research has come out of the CNMP programme, strengthening our resolve and belief that the CNMP concept will secure our license to operate and provide products that are essential in the low carbon society.