What's up with propane?

This month, the most destructive fire in Colorado history was initially blamed on a propane storage tank struck by a vehicle. Authorities are now convinced an unattended fire pit, not the propane tank, was the culprit. Still, the Fourmile Canyon fire, which started on Labor Day and has destroyed at least 136 homes while burning across 6,200 acres, made me ponder the ball of fuel attached to my barbecue grill.

How safe and environmentally sound is propane, also known as liquefied petroleum gas? Burning propane, which is made during either petroleum refining or natural gas processing, emits greenhouse gases, but it is relatively safe and energy efficient.

Energy efficiency

Propane has a higher fuel density than most other alternative fuels, providing more heating or cooking per unit of fuel. Propane packs about 2,500 BTU (British Thermal Units) of energy per cubic foot, compared to 1,000 BTU per cubic foot of natural gas. Most gas appliances can be switched to run on more efficient propane with some minor adjustments.

On the other hand, gasoline is a more efficient transport fuel. A gallon of propane provides about 92,000 BTUs, and gallon of mid-grade gasoline provides 125,000 BTUs.

Toxicity

Propane’s lower energy density may be outweighed by cleaner emissions. The U.S. Department of Energy found an 80-percent decrease in particulates and a 20- to 40-percent reduction in carbon monoxide emissions when vehicles were converted from gasoline to propane. 

Moreover, the DOE tested a heavy-duty truck that was designed to run on propane. When compared to a traditional diesel truck, the propane vehicle emitted virtually zero particulates and reduced carbon monoxide emissions by more than 90 percent and total hydrocarbon emissions by more than 80 percent. The low emissions are a major reason propane is widely used in forklifts and other indoor-use vehicles.

Propane, unlike natural gas, is not considered a greenhouse gas when released directly into the atmosphere. Propane also is nontoxic, so it’s safer for soil or water than gasoline and some other fuels.

Propane is relatively efficient and green energy source despite being derived from fossil fuels. Proponents also say it is good for national security. The Propane Education and Research Council touts propane as a good step toward energy independence because 85 percent of U.S. propane is produced domestically.

Home safety

As with any combustible fuel, propane poses some dangers. If propane leaks or spills, it can ignite unexpectedly. Propane is heavier than air, so it may settle and pool in a basement or other low, enclosed area.

Dangerous carbon monoxide also may build up. Propane companies add a chemical odor to the naturally odorless and colorless fuel. Many distributors offer “scratch-and-sniff” patches to help users identify the smell. The liquid fuel also is very cold and can burn the skin.