The US Energy Department’s National Renewable Energy Laboratory (NREL) is working with Ecopetrol, the largest oil company in Colombia, to process the residue from sugar cane and palm oil harvesting into fuel ethanol for blending with gasoline.
The Cooperative Research and Development Agreement (CRADA) between NREL and Ecopetrol aims to optimize the conversion process for bagasse (the material left over after the sugars are removed from the sugar cane) and to analyze the economic case for commercial production of biofuel from these materials. The CRADA will also include some limited study on palm rachis—the material left over after palm oil production.
The $2.3-million 18-month project is being funded by Ecopetrol, which turned to NREL for its expertise on conversion of biomass, its compositional analysis and techno-economic analysis capabilities, and NREL’s unique facilities. NREL has a pilot plant at its Golden, Colo., campus that has conversion capabilities from lab scale to pilot scale, processing up to one ton per day of biomass—everything from corn stover to switchgrass and poplar trees.
Colombia has an abundance of biomass in the form of sugar cane. The rainfall patterns in the region near the Pacific Coast where the sugar is grown for the biofuels industry allows the crop to be harvested all year round, but there’s not much room for expansion.
Sugar cane also is grown farther east, but because of incessant rain from April to August, it can only be harvested eight months a year. The plant spoils quickly if the sugars aren’t squeezed out. But the bagasse can be stacked and stored for a long time after the juice is removed and washed out of the green grass stalk.
That bagasse currently is burned to produce steam that drives turbines for electricity, but Ecopetrol is hoping to get more value out of it than that.
The hope is that commercial conversion facilities and employees can be kept busy all year round by processing the bagasse during the rainy season when it’s too wet to get to the fields and harvest the sugar cane. It’s more challenging to break down the cellulose in the bagasse than the sugar-rich juice, but if the conversion process is successful, the bagasse can be processed into a biofuel.
Rick Elander, Biochemical Conversion Manager at NREL’s National Bioenergy Center, notes that Ecopetrol already has in place a commercial facility for converting sugarcane juice into fuel-grade ethanol. The fermentation and distillation equipment at that facility could also be used to hydrolyze the bagasse and ferment the resulting sugar into additional ethanol, increasing the output of the facility and enabling year-round operations. It would only have to add the pretreatment process and tweak the “knobs and dials” to optimize the operation, Elander said.