Which type of fuel oil is known for having the highest heating value in BTU per gallon?

The type of fuel oil known for having the highest heating value in BTU per gallon is #6 fuel oil. This fuel, also referred to as heavy fuel oil or bunker oil, has a higher density compared to other lighter fuel oils. It is primarily used in large industrial boilers and ships due to its energy content and efficiency.

In practical terms, the higher heating value of #6 fuel oil allows for more energy to be extracted from each gallon, making it a cost-effective choice in applications where large amounts of fuel are burned to produce heat. This is particularly advantageous in marine and industrial settings where efficiency and fuel economy are critical.

In comparison, lighter fuel oils such as #2, #4, and #1 have lower heating values. For instance, #2 fuel oil is commonly used for residential heating and has a lower energy content than #6, making it less efficient for large-scale applications. Meanwhile, #4 and #1 fuel oils serve specific purposes but cannot match the energy density offered by #6 fuel oil, which is why #6 is widely preferred in high-demand situations demanding maximum energy yield.