How SAFFiRE process works
Processing corn stover: The corn stover used in the SAFFiRE process is a valuable resource that is largely left to decompose in the fields after the corn harvest each year. Corn stover is collected by custom harvesters or by local farmers and processed through a proprietary Deacetylation and Mechanical Refining (DMR) technology developed by NREL called “DMR pretreatment.”
Produce ultra-low CI ethanol: Once the corn stover is pretreated, we use existing, proven technology to hydrolyze, ferment, and separate it into renewable ethanol with a projected Carbon Intensity (CI) of zero.
Upgrade the ethanol to sustainable aviation fuel: Alcohol-to-jet technology is utilized to upgrade the ethanol into fully certified sustainable aviation fuel that will be used by the airline industry.
NREL has repeatedly demonstrated DMR pretreatment at pilot scale; DMR uses standard, off-the-shelf equipment used in the pulp and paper industry
All other unit operations to produce SAF from corn stover are commercial; we use commercially available enzymes and yeast
The Alcohol-to-Jet process is commercial and has received ASTM D4054 approval for its SAF
SAFFiRE is unique and has exclusive rights to the technology to produce SAF using corn stover
Pretreatment is the Most Critical Step in the Process
When converting biomass to ethanol, the pretreatment step is the most critical process step as it impacts the success or failure of the enzymatic hydrolysis and fermentation steps that follow pretreatment. Pretreatment is, therefore the key step in producing ethanol from corn stover; previous attempts to make ethanol from corn stover failed due, in part, to issues related to dilute acid pretreatment.
NREL’s patent pending alkaline DMR pretreatment avoids the operational and capex challenges of dilute acid pretreatment by virtue of the following:
DMR operates at low temperatures (<100°C) and atmospheric pressure, reducing capex and eliminating biomass feeding issues such as plugging and sever erosion of biomass feeding equipment
DMR is an alkaline pretreatment (high pH), eliminating corrosion issues associated with dilute acid pretreatment; DMR pretreatment does not require expensive metal alloys
DMR’s low temperatures do not produce fermentation inhibitors such as furfural and hydroxymethyl furfural (HMF)
Acetic acid, ash, and lignin are removed during deacetylation, improving enzymatic hydrolysis and fermentation performance
DMR’s low temperatures and deacetylation preserve valuable lignin properties, making lignin sequestration by incorporation into construction material, asphalt, adhesives and other materials possible
DMR does not create lignin fouling, improving reliability and downstream operations
SAFFiRE will utilize NREL’s patent-pending DMR pretreatment, thus avoiding the issues created by dilute acid pretreatment and other high temperature and high pressure pretreatment processes. NREL has demonstrated very high sugar yields at very low enzyme loading with the DMR pretreatment process. DMR pretreatment is the key to low-cost, high-yield, and very low-Carbon Intensity ethanol production from corn stover.