Closing the Loop on Biofuel Production

Biofuels offer an opportunity to make the most of existing resources through an integrated industry, using waste streams as inputs and maximizing the value of biological resources. Capitalizing on these opportunities requires diversifying our efforts.

Feedstocks for the wide range of biofuels in Canada include trees, grasses, agricultural crops and residues, animal wastes and municipal solid waste. Through bioconversion and biorefining processes, these feedstocks can variously be converted to ethanol, biodiesel and many other products. The processes are wide-ranging, including enzymatic fermentation, gas/liquid fermentation, acid hydrolysis/fermentation, gasification, combustion and co-firing.

Agriculture and Agri-Food Canada estimates that by harvesting residuals of cereals, grains, corns, forest wastes and other biomass -- essentially collecting the straw and stubble -- 6.5 billion litres of ethanol a year could be produced without shifting away from existing food crops and forest products.

Photo Credit: Helen Corbett

Additionally, new closed-loop approaches are enhancing the efficiency of producing ethanol and other biofuels.  In a closed-loop model conventional energy inputs are replaced by energy produced from what would otherwise be biomass waste streams, and using the wastes from energy production as fertilizer for further biomass production.  For example, closed-loop ethanol production replaces natural gas use with methane created on site to produce the heat required for boilers in the ethanol process.

Here’s how it works.  The methane is created in an anaerobic digester, which processes cattle manure and cellulosic matter from local corn production.  At the same time, the distillers’ grains (spent corn or wheat from ethanol brewing) that would typically be disposed of or dried at great expense before being marketed, can be fed to cattle on site with little to no energy-intensive processing.  Meanwhile, the leftover slurry from the methane digester is used to produce a rich fertilizer for corn production. Finally, the manure produced by the cattle at the nearby feedlot is fed back into the anaerobic digesters, completing the closed loop and replenishing soil health at the same time.

The efficiencies of closed-loop production are promising.  For example, an E3 biofuel closed-loop facility in Mead, Nebraska boasts its fossil-fuel consumption is 20 times more efficient than traditional ethanol production.

Mark Stumborg from the Applied Science and Technology section of Agriculture and Agri-Food Canada in Swift Current looks at closing the loop on biofuel production, including use of the residuals from existing agriculture and forestry as the most immediate opportunity for next generation feedstocks.

“Closing the loop means bringing nutrients back to the land by rotations including forage crops that bring nitrogen and nutrients back into the soil, and by the application of animal manures from operations using distillers grains. This promotes healthy soils, which are going to ensure the health of the food system.” says Stumborg.  “When we consider straw from cereal production, we’re taking the lowest economically valued material in agriculture and bringing it into production, adding value for producers and consumers.  Including cattle and anaerobic digestion in a combined feedstock biofuel production system will help close the nutrient loop and reduce energy costs.”

Researchers are also looking at the ability of marginal agricultural lands to produce biofuels crops. One feedstock crop that promises to overcome hurdles such as poor soils, salinity and cooler temperatures is triticale, a hardy, productive wheat-rye hybrid. Indeed, the Alberta Agriculture Research Institute (AARI) looks to biorefining of triticale as a key strategic research and development priority.

AARI Executive Director Stan Blade sees the benefits of biorefining as another viable approach (similar to creating closed-loop systems) for maximizing triticale’s potential for creating ethanol and other bioproducts, bringing value to farmers and consumers. “Biofuels are a complement to food production, not a threat,” he says.

The Canadian Triticale Biorefinery Initiative is an Alberta-driven project that aims to treat triticale production much like oil refining and its spinoff products. A triticale biorefinery would have multiple product streams, including fuels like ethanol as well as advanced materials and chemicals.

Unlike biomass residuals in closed-loop production, biorefining triticale is still on the horizon. But Blade and Stumborg agree we need to take a multi-pronged approach.

“We need to explore a lot of avenues,” says Blade.  “Think of the Internet 15 years ago and where it is now. No one knew what was going to take off. We need to back multiple initiatives to catch the opportunities both ethanol and future technologies offer.”

“We have a window of opportunity to get these production systems off the ground, but we need to support a strong strategy that aids both established and future technology,” says Stumborg. “In the past, governments have put funds towards biofuels sporadically.  We need long term commitment of developmental funding to realize the potential of biofuels and an integrated biomass industry offering fuel alternatives.”