Agave: Not Just for Tequila Anymore

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Agave, the plant used to make tequila, could someday be filling gas tanks, instead of just getting party-goers tanked on margaritas.

Instead of using the plant to produce firewater, the same fermentation and distillation process could be used to produce ethanol for firing the engines of automobiles, according to research published in a special agave edition of the journal Global Change Biology Bioenergy.

Fans of tequila and mescal could still have their drink of choice, while the leftover plant material could be used to create earth-friendly energy, according to Ana Valenzuela of the University of Guadalajara. The leftovers from the tequila making process could be burned to produce energy or used to make cellulosic ethanol. Other varieties of agave, grown for fiber, could be even better sources of biomass.

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What’s more, agave might even benefit from higher atmospheric carbon dioxide levels and increasing temperatures, according to researchers at the Colegio de Postgraduados en Ciencias Agricolas (Postgraduate College of Agricultural Science) in Texcoco, Mexico and the University of California. Agave can use higher levels of carbon dioxide in the air than many other plants, and it has adaptation to living in the desert.

Agave uses a metabolic technique that greatly reduces water loss. The plant uses a process called crassulacean acid metabolism (CAM). In CAM, a plant stores carbon dioxide absorbed at night, then uses it during photosynthesis in the daytime.

By inhaling carbon dioxide only at night, agave can keep the opening on their leaves, called stomata, closed during the heat of the day. That saves a tremendous amount of water compared to crops like corn, a C4 plant.

The CAM process is also what allows agave to use higher levels of CO2 than crops like wheat, barley, and potatoes, which are known as C3 plants.

Agave could reduce the food vs. fuel debate as well. Agave grows in areas where corn would wither and sugar cane would shrivel. It’s adapted to nutrient-poor, arid lands, so growing agave doesn’t compete with food and fiber crops. Though the price of agave ethanol fuel will probably never compete with tequila, there is currently an excess of agave production in Mexico that could be used as energy crops, according to Hector Nunez and his colleagues at the University of Illinois at Urbana-Champaign.

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Growing perennial grasses, like switchgrass, on marginal land has received attention lately, but even grasses require lots of water compared to agave, according to research cited by Global Change Biology Bioenergy editors.

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The researchers note that there are still not many studies on the use of agave as a biofuel source, and that more economic and agricultural analysis is needed. But it sounds like people in the drier regions of the world may someday be raising a toast to the agave for more than its tequila.

IMAGE 1: A margarita (Wikimedia Commons)

IMAGE 2: Blue Agave growing in Tequila, Mexico (Wikimedia Commons)

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