Low emissions of regulated pollutants. Propane water heaters offer substantial air-quality benefits by reducing emissions of oxides of nitrogen (NOx), carbon monoxide (CO), sulfur dioxide and carbon dioxide, the main “greenhouse” gas. Compared to a typical electric water heater with a 0.93 energy efficiency factor, a propane water heater with a 0.58 energy efficiency factor reduces NOx emissions by approximately 90 percent, CO emissions by approximately 70 percent, sulfur dioxide by 99 percent and carbon dioxide by approximately 60 percent. These air pollution reduction estimates represent the difference between emissions from power plants utilizing a typical fuel mix and emissions expected from the combustion of propane in a properly adjusted water heater in good condition, as listed in U.S. Environmental Protection Agency publications on air pollution.
Low greenhouse-gas emissions. Used for space heating and water heating, propane’s total fuel-cycle emissions of urban air pollutants and greenhouse gases are second-lowest after natural gas, according to DeLucchi (1999). Electricity has total fuel-cycle emissions two to four times higher than those for natural gas or LPG, according to this analysis.
Off Road Engines
Clean enough to use indoors. LPG forklifts can reduce emissions of indoor and urban air pollutants, especially emissions of particulate matter compared to diesel and carbon monoxide compared to gasoline. “Overall, the urban air-quality benefits of LPG are similar to the benefits of CNG (generally considered the cleanest of the fossil-fuel alternatives.)” (Delucchi, 1999).
Low air toxics. Propane cuts emissions of toxins and carcinogens like benzene and toluene by up to 96 percent, compared to gasoline, according to studies by Southwest Research Institute.
Ground- and surface-water safe. Propane is nontoxic; spills vaporize rather than soaking into soil or water.
Low greenhouse-gas emissions. Propane has the best greenhouse-gas emissions performance of any fossil transportation fuel when emissions from the complete fuel cycle of production, distribution and combustion are considered. Propane offers substantial greenhouse benefits compared to gasoline in light-duty vehicles and diesel fuel in heavy-duty vehicles.
An analysis by M. A. DeLucchi for Argonne National Laboratory concluded that the LPG fuel cycle produces the least amount of greenhouse gases of all the fossil fuel cycles, including that of diesel fuel. The study concluded that “Liquefied petroleum gas, consisting of 95% propane and 5% butane, offers a 20-25% reduction in emissions of greenhouse gas from LDVs [light-duty vehicles] (compared with gasoline). Moreover, the use of LPG in HDVs [heavy-duty vehicles] would actually decrease greenhouse gas emissions (compared with diesel fuel). The combined HDV-plus-LDV effect of an LPG policy would be a better-than-15% reduction in fuel cycle emissions of greenhouse gases.”