A typical BF produces 1200 – 2000 Nm³ of furnace gas per ton of pig iron, containing 20–28% CO and 1–5% H₂. The energy content of this gas may equal to an energy export of around 5 GJ/t-pig iron, or approximately 30% of the gross energy consumption in BF. This energy content can be utilized by recovering, cleaning, and storing the BF gas and using it as a fuel or for the generation of electricity. The energy content of the gas varies but is usually low (between 2.7–4.0 MJ/Nm³ depending on CO concentration). Therefore, BF gas is often enriched by coke oven gas or natural gas prior to use.

In cases where the BF is fitted with a two bell charging system, approximately 1.5% of the BF gas is lost every time the furnace is charged. Most of this gas could be recovered by discharging the high pressure gas between the two bells into the low pressure side of the gas collection system just prior to opening the top bell for charging.