Firefighters battled all day on Saturday to extinguish a blaze at the recycling warehouse Hierros España in Huelva.
The origin of the fire is under investigation but appears to have been the result of spontaneous combustion caused by moisture and heat.
The warehouse contains around 5,000 tons of biomass residues. According to the company they are environmentally friendly, the main problem being the danger in a change of wind direction which would blow the smoke towards the city of Huelva.
No-one has been injured in the fire.