COMPARING POTENTIAL IMPACTS OF LEAKS OF DIESEL, BIODIESEL, AND RENEWABLE DIESEL TO GROUNDWATER

Renewable diesel is a biofuel, which can be used as an alterative to diesel fuel, and it is considered a “drop-in fuel”; meaning it can be used in engines without modification. Currently, renewable diesel is available in limited quantities in North America. Renewable diesel is produced from various bio-feedstocks using different processes. This results in a variety of fuels described as “renewable diesel", where different feedstocks and different processes result in different chemical blends. There is limited information available on the potential fate and transport of these fuels should they leak and/or spill into the groundwater, especially in the scenario of a leak from a pipeline or underground from a storage tank.

In this study we conducted experiments to simulate leaks of renewable diesel from a pipeline into a simulated groundwater flow system, comparing leakage behaviour with similar spills of biodiesel and petroleum diesel. Three fuels were characterized pre-spill, and 900 mL of each fuel (biodiesel, petroleum diesel and renewable diesel) was injected into the upstream area of each tank to simulate a leak. Water flowed through the four tanks continuously with effluent discharging downstream. Experiments lasted several months, with water samples collected for analysis.

The renewable diesel used in these experiments contained benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations 2.4x greater than petroleum diesel, and 6.2x higher concentrations of parent polyaromatic hydrocarbons. By contrast, biodiesel contained no measurable BTEX or parent polyaromatic hydrocarbons, however, did contain alkylated polyaromatic hydrocarbons. Effluent from renewable diesel tanks contained BTEX concentrations up to 3.9x of those from the petroleum diesel tank effluent. Microtox analysis of renewable diesel tank effluent indicated that water had become moderately to highly toxic when dissolved organic contaminants (e.g. BTEX) were elevated. Preliminary results suggest that these fuels demonstrate different chemical and spill behaviours compared to petroleum diesel, leading to new knowledge for spill response and recovery.