The most efficient method to reduce energy loss per produced ton of silicon is by making the production process more energy efficient. Even though Elkem has some of the most energy efficient smelting furnaces in the world, we are still working systematically on improvement through a dedicated R&D project called Si 2020 focusing on furnace design, process control and more efficient use of raw materials.
There are two main paths to energy recovery from our smelting process, both with their advantages and challenges.
The first method is to let the excess heat be used directly in the form of steam or hot water. Using steam or hot water is very efficient, but most of Elkem’s plants are located in remote locations with a low demand for heat from the local community or other industries.
The second method is to use the excess heat to produce electricity. This involves first converting it to high pressure / high temperature steam, and thereafter feeding it into a turbine and generator that generates the electricity. The advantage is that the electricity can be fed directly into the grid and transmitted to the customer’s location, but the disadvantage is that two thirds of the energy is lost.
Both methods are in use at Elkem today. Elkem Thamshavn generates around 160 GWh electircity per year. Elkem Bjølvefossen generates 50 GWh per year of electricity and is now investing to reach 80-85 GWh/year. Elkem's plant in Chicoutimi, Canada now has a capacity of supplying up to 220 GWh of steam per year to Rio Tinto's plant next door. This results in a recovery rate of 70-85 per cent of the supplied electrical energy for Elkem Chicoutimi. In addition all plants recover more than 200 GWh for external or internal district heating.
Through a high focus on energy efficiency Elkem Thamshavn and Elkem Chicoutimi have become the world's most energy efficient facilities within their niches. The potential for our other plants is also huge and a number of projects have been initiated to realise the potential.
Elkem is currently implementing systems for energy management in line with ISO 50001 at all plants. Through the process we see that even small measures, such as better insulation, engine control, light control, sealing leaks in compressed air systems, and controlling heating and cooling, could provide significant savings, even though each individual measure is relatively minor compared with the energy consumption of a furnace. Potential savings of 10 per cent of utility electricity (non-furnace related) have been identified. For the Norwegian plants, this entails 30 GWh a year in energy saved. This is equivalent to the electricity consumed by 2,000 homes.
Read more in Elkem’s Sustainability report.