Title: Almond hulls as a biofuels feedstock: Variations in carbohydrates by variety and location in California Authors
Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2014
Publication Date: February 2, 2014
Citation: Offeman, R.D., Holtman, K.M., Covello, K.M., Orts, W.J. 2014. Almond hulls as a biofuels feedstock: Variations in carbohydrates by variety and location in California. Biomass and Bioenergy. 54:109-114. Interpretive Summary: Due to their high content of simple sugars, almond hulls have potential as a biofuels feedstock. About 80% of the world’s supply of almonds is produced in the state of California, generating about 1.65 million tons of hulls annually. But how the sugar's content of the hulls varies between almond varieties and growing locations is not well known. This paper reports the results of a two-year survey of the sugars and sugar alcohol's content of almond hulls in California. Fermentable sugars ranged from 25 to 33 % of the dry weight of the hulls, with the Nonpareil variety (~39% of total production) having the highest level. The amount of ethanol that theoretically could be produced ranged from 31 to 42 gal/ton hulls.
Technical Abstract: Hulls of the almond (Prunus Amygdalus) have a high content of fermentable sugars (glucose, fructose, sucrose), and are a potential feedstock for biofuels and other uses. Six almond varieties across seven counties in the state of California were studied to assess the amount and variability of sugars and sugar alcohols in the hulls. Implications for industrial processing to ethanol are considered.