Among four new California Low Carbon Fuel Standard (LCFS) fuel pathway applications is a used cooking oil (gutter oil) to renewable diesel (NExBTL) pathway from Neste Oil at its Singapore plant. (Boeing and COMAC are opening a demonstration facility in China to convert gutter oil to renewable aviation fuel. Earlier post.)
Neste Oil Singapore Pte Ltd. produces approximately 250 million gallons annually of drop-in renewable diesel (RD)—i.e., not biodiesel—using a hydrogenation process and multiple oil and fat feedstocks. Neste has also filed applications for renewable diesel pathways for California (all from its Singapore plant) using Southeast Asian rendered fish oil (earlier post); New Zealand tallow (earlier post); North American tallow (earlier post), and Australian tallow (earlier post). Of the five RD pathways proposed so far, the gutter oil pathway has the lowest carbon intensity.
Neste’s process also generates a propane-rich off-gas as a co-product. (The company is commercializing this as bio-propane at its Rotterdam refinery in Porvoo. (Earlier post.) The propane-rich off-gas is produced during the hydrotreatment process. The yield is not feedstock specific.
In Singapore, the high pressure portion of this off-gas (both high- and low-pressure gas is generated) is conveyed via a dedicated pipeline to a hydrogen plant located on Jurong Island. There it displaces natural gas that would otherwise have been consumed as both a process fuel and a feedstock at the steam-methane reformer. The hydrogen supplied by the Jurong Island plant is piped back to the Neste plant where it is used for hydrotreatment. The low-pressure propane-rich off-gas is sent to a natural gas steam boiler that provides process heat to the RD plant.
Neste Oil has calculated the carbon intensity (CI) of this pathway to be 16.21 gCO2e/MJ. This CI includes a 3.09 gCO2e/MJ credit for the natural gas displaced by the propane-rich off-gas from the RD plant. This proposed carbon intensity value includes transportation of the feedstock to the refinery, renewable diesel production, finished fuel transportation to California from Singapore, and vehicle tailpipe emissions.
|LCFS CI (gCO2e/MJ) of Neste Oil renewable diesel from different feedstocks|
|Gutter oil||NZ tallow||Australian tallow||NA tallow||SEA fish oil|
19.65 (w/ lower-energy rendering)
The baseline LCFS CI value for petroleum diesel fuel is 94.71 g CO2e/MJ. California Air Resources Board (ARB) staff recommends that Neste Oil’s application for this gutter oil pathway be approved.