Cogeneration, also known as ‘combined heat and power’ (CHP) or the combined cycle, is the simultaneous production of heat (usually in the form of hot water and/or steam) and power, utilising one primary fuel.
Primary fuels commonly used in cogeneration include natural gas, oil, diesel fuel, propane, coal, wood, wood-waste and biomass. These ‘primary’ fuels are used to make electricity, which is known as a ‘secondary’ fuel. The pulp mills use black liquor as primary fuel.
Cogeneration involves burning the black liquor at the recovery boiler, generating electrical and thermal power that is sold to the grid entirety.
Altri has been investing significantly over the past years in order to increase electrical efficiency. Currently the total renewable cogeneration power produced by the three mills is net positive, e.g. Altri is producing a surplus of electrical power that is fed into the national grid.
Currently Altri produces 365 GWh of electric power through cogeneration per year, broken down by mill as follows:
- Celbi 180 GWh
- Caima 100 GWh
- Celtejo 85 GWh