Hot air required for conveyor oven

Dear Engineers,

My name is Humza Afaf and I have recently started a new business in Pakistan. Due to energy crisis in my country, I am unable to get a natural gas connection for my conveyorized oven. I am involved in the business of making recycled polyester non-woven batting/wadding sheets which are used as in bed-covers, quilts, tents etc as a thermal batting. Along side other machinery there is an 3 pass oven (measurements being 20feet length, 13 feet width and 12 feet height) which requires hot air to dry my product once sprayed with water diluted glue adhesive.

The conventional method of heating the oven requires direct firing of a gas burner in a firing chamber and an ID fan sucks the hot air and flue and throws it in the oven. I am unable to get natural gas and alternatives being oil burners and propane burners have a very high operating cost. Kindly suggest a suitable alternative. According to my research wood and coal are the closest alternative with regards to the operating cost but they both leave smoke and residue which is harmful for my end product since it can not tolerate discolouring. Required temperature in the oven is around 250 Degrees C.

Thanks.