ARB posts six new LCFS pathway applications for comment; new PFAD biodiesel approach
18 December 2013
The California Air Resources Board (ARB) staff has posted six new Low Carbon Fuel Standard (LCFS) pathway applications to the LCFS public comment web site: corn ethanol; molasses ethanol (from Brazil); palm fatty acid distillates (PFAD) to biodiesel; and landfill gas to LNG, L-CNG, and CNG.
The LCFS requires oil producers, importers and other fuel providers gradually to reduce, on a full-fuel lifecycle basis, the carbon intensity (CI) of their transportation fuel mix (measured in gCO2e/MJ) by from 0.25% in 2011 to 10% by 2020. (Earlier post.) The current batch of new applications covers quite a range of carbon intensity in the fuels: from 88.69 gCO2e/MJ for the corn ethanol, down to 10.64 gCO2e/MJ for biodiesel produced from PFAD—the first such pathway considered for the LCFS program. The baseline carbon intensity for gasoline in the LCFS lookup table is 99.18 gCO2e/MJ and 98.03 gCO2e/MJ for diesel.
According to the latest status report on the progress of the LCFS published in May, regulated parties in the LCFS continued to exceed the required reductions in carbon intensity specified by the standard.
The six new pathways are:
Heron Lake BioEnergy, LLC (HLBE) produces ethanol from corn at a dry mill plant in Heron Lake, Minnesota. Nameplate capacity is 50 million gallons per year of denatured ethanol. The plant was originally fueled by coal but was converted to natural gas in 2010.
The natural gas combustor is equipped with a Heat Recovery Steam Generator (HRSG) supplies steam to support ethanol production. Currently, the applicant reports that the majority of the DGS it produces is dry DGS. Some small amount of corn oil (about 3% of total co-product) is also produced.
HLBE calculated the carbon intensity (CI) of its corn ethanol pathway to be 88.69 gCO2e/MJ. An application filed for the pathway HLBE chose must must be evaluated against reference pathways from the LCFS Lookup table, and must achieve at least a five gram CO2e/MJ CI improvement over that pathway. The reference pathway for HLBE’s corn pathways is ETHC004 at 98.4gCO2e/MJ (Midwest dry mill, natural gas, dry DGS corn pathway, respectively). The HLBE corn ethanol pathway improves upon their reference pathway CI by more than the requisite five grams of CO2e/MJ.
Raizen Energia S.A. (Raizen) produces ethanol derived from sugarcane by-product molasses in the State of São Paulo, Brazil. Sugarcane is harvested on company-owned and partnership farms, and then transported to the Costa Pinto (COPI) sugar mill and ethanol distillery located in the City of Piracicaba. After the sugarcane has been crushed, the cane juice is filtered, treated with calcium hydroxide, decanted, and then sent to sugar production. A by-product of the sugar production process is molasses which is recycled into the sugar production process to recover additional sugar crystals. After recovery (by centrifuge) of the optimum amount of crystalline sugar from the molasses, the remainder of the molasses by-product stream is sent to the ethanol distillery for fermentation and distillation, resulting in the production of anhydrous ethanol.
Ethanol produced from fermentation of the molasses is transported by truck to the eastern port of Santos, and loaded onto ocean-going tankers for shipment to California. Ethanol transport and distribution modes in California are assumed to be identical to those used in the Brazilian sugarcane ethanol pathway.
When upstream and sugar production emissions are combined with ethanol production, addition of denaturant, transport, and distribution emissions, the total well-to-tank (WTT) life cycle GHG emissions for the Raizen COPI pathway are estimated to be 21.01 gCO2e/MJ fuel.
However, the Raizen COPI mill exports surplus co-generated electricity to the public grid. The resulting electricity cogeneration and surplus export credit, based on a displacement of Brazilian marginal electricity, is estimated to be 21.86 gCO2e/MJ of fuel produced. When applied to the WTT carbon intensity (CI) of ethanol, this credit results in a net WTT CI of – 0.85 gCO2e/MJ. When life cycle emissions due to land use change (LUC) are added to the WTT CI estimate, the final WTW CI for the Raizen COPI pathway is estimated to be 14.93 gCO2e/MJ of ethanol fuel produced.
Endicott Biofuels LLC will soon begin producing biodiesel (BD) from palm fatty acid distillates (PFAD) at its newly constructed plant in Port Arthur, Texas, with a capacity of 30 million gallons of BD annually. PFAD is a low-value byproduct of the palm oil production process.
Unlike the more common fatty-acid methyl ester process, which cannot tolerate high fatty acid concentrations, the patented Endicott Process employed at Sabine utilizes free fatty acids to produce BD via reactive distillation using the Davy process.
Because the Sabine Process desires free fatty acids, all natural fats or oils are accessible but those fats or oils that are waste in nature are preferred. The Sabine Process can also process glyceride oils by breaking them down into their free fatty acid components in a pre-treatment step.
(Sabine’s process also yields a high-BTU, renewable co-product known as pitch. Because it is similar to Number 6 heavy fuel oil in terms of heat content and viscosity, pitch can displace Number 6 fuel oil in the marketplace. Number 6 fuel oil is commonly used to fuel large ocean-going vessels. The co-product credit for pitch was calculated based on its ability to displace Number 6 fuel oil in such vessels.)
Sabine obtains PFAD from various palm oil refineries in Southeast Asia. This feedstock is transported 30 miles via heavy-duty truck from the refiner to the port for loading onto an ocean tanker. The ocean tanker then travels approximately 13,300 miles to the Port of Houston. From the Port of Houston, the feedstock is transferred to a barge and travels 102 miles to the Sabine plant in Port Arthur. The resulting BD is then transported approximately 1,600 miles by rail to California.
The pitch co-product from Sabine’s process yields a co-product credit of 18.04 gCO2e/MJ. This credit is partially offset by the CI associated with the PFAD feedstock. Sabine estimated that CI by equating it with the co-product credit that dry mill ethanol plants earn for selling DGS into the livestock feed market (where it displaces corn). That credit is 11.51 gCO2e/MJ. Combining this credit and feedstock CI with the GHG emissions from the fuel production, transport, and use phases of the fuel life cycle produces an overall pathway carbon intensity at 10.64 gCO2e/MJ.
Clean Energy has applied for three landfill-gas-to-biomethane fuel pathways. The landfill gas (LFG) for all three pathways is extracted from the McCommas landfill in Dallas, Texas. One pathway covers the liquefaction of the resulting biomethane at Clean Energy’s Boron, California liquefaction facility and the dispensing of the fuel as liquefied natural gas (LNG); one pathway covers the liquefaction of the resulting biomethane at Clean Energy’s Boron, California liquefaction facility and the subsequent vaporization and compression of the liquefied natural gas into compressed natural gas (CNG); and the final pathway covers the compression of the biomethane for dispensing at CNG fueling stations. All fueling stations covered by these pathways are located in California.
Clean Energy has calculated the CIs of its LNG, CNG, and L-CNG pathways to be 32.99, 28.42, and 35.11 gCO2e/MJ, respectively. Clean Energy’s LFG-to-LNG and LFG-to-CNG pathway CIs are higher than the corresponding California LFG-to-biomethane pathway CIs. California LFG-based LNG (LNG0076) has a CI of 15.56 gCO2e/MJ, while CNG from California LFG (CNG0037) comes in at 11.26 gCO2e/MJ.
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