Limiting evaporative emissions
In the 1980s CARB conducted research to find out what contributes to greenhouse gases and smog in California. It found that OPE was a significant contributor, and CARB developed an evaporative emissions limit. Currently the limit is 1.5 g/m²/day. In 2000 the EPA studied greenhouse gases and smog and decided to make the CARB regulation cover the entire U.S. Recently the EPA has been tightening the regulations, and in the future CARB plans to further reduce allowable evaporative emissions to approximately .5g/m²/day—a 65% reduction from today. Also, China is looking to adopt a regulation similar to EPA’s in 2021.
Many OPE manufacturers are relying on the fluorination of polyethylene tanks to meet the current evaporative emissions requirements. This technology relies on hydrofluoric acid (HF), a toxic chemical, some of which invariably is released into the environment. Furthermore, this technology is adding complexity to the supply chain and is unable to meet upcoming regulatory limits that are more stringent than current regulations.
Standard HDPE emits 25 to 30 grams of hydrocarbons per square meter per day, more than 15 times the allowable limit. Fluorinating HDPE fuel tanks creates a thin surface treatment of ~0.2 microns thickness in a batch process, yielding an average barrier performance two times below the specification, however, variation in performance can be three times specification. Over time, this thin barrier on the tanks can erode during normal use of the equipment, such as surface abrasion or wear, thus becoming less effective, ultimately making it a risky choice for staying within compliance over the useful life of the tank.
Because OPE manufacturers are under pressure to meet EPA’s 2022 regulations, limiting evaporative emissions from fuel tanks has become an area of focus. CARB already amended its small off-road engine rules to increase stringency of procedures used to test evaporative emissions, and both CARB and EPA are testing and auditing products they purchase from retail stores. They are finding some products to be non-compliant.
Leading OPE manufacturers have begun to understand that the chemicals necessary for HDPE fluorinated tank production are harmful to the environment and people. Just as the consumer electronics industry has moved away from the use of bromine in their products, more and more players in the OPE market are looking for ways to reduce their exposure to fluorine in theirs.