The global potential for Agave as a biofuel feedstock

Abstract

Large areas of the tropics and subtropics are too arid or degraded to support food crops, but Agave species may be suitable for biofuel production in these regions. We review the potential of Agave species as biofuel feedstocks in the context of ecophysiology, agronomy, and land availability for this genus globally. Reported dry biomass yields of Agave spp., when annualized, range from o1 to 34Mg ha À1 yr À1 without irrigation, depending on species and location. Some of the most productive species have not yet been evaluated at a commercial scale. Approximately 0.6 Mha of land previously used to grow Agave for coarse fibers have fallen out of production, largely as a result of competition with synthetic fibers. Theoretically, this crop area alone could provide 6.1 billion L of ethanol if Agave were reestablished as a bioenergy feedstock without causing indirect land use change. Almost one-fifth of the global land surface is semiarid, suggesting there may be large opportunities for expansion of Agave crops for feedstock, but more field trials are needed to determine tolerance boundaries for different Agave species.

Innovative Biological Solutions to Challenges in Sustainable Biofuels Production

“…Certain species have been reported to display annual above ground productivities that are comparable to those of the most wateruse efficient C3 or C4 crops but with only 20% of the water required for cultivation (Borland et al, 1999). Such characteristics have provoked interest in the potential of Agave as a sustainable source of bioenergy feedstock that will not compete with food and fodder production, whilst offering potential for carbon sequestration on marginal and degraded land (Davis et al, 2011). The desirable traits of high productivity and water conservation in Agave can be attributed to the operation of crassulacean acid metabolism (CAM), a specialized mode of photosynthetic CO 2 acquisition (Fig.…”

“…Besides having relatively low requirements for water and nutrients, species such as A. tequilana, A. mapisaga and A. salmiana can provide high yield and high quality biomass for biofuel production. The typically low rates of transpiration in Agave leaves obviate the requirement for a highly lignified xylem and so lignin contents are relatively low (3-15% by dry weight) whilst cellulose content is relatively high (up to 68%) (Davis et al, 2011). Agave biomass can be harvested year-round, producing up to 500 metric tons (green) of biomass per hectare annually (Austin, 2010a;Austin, 2010b).…”

How can land-use modelling tools inform bioenergy policies?

“…Plants that have high water-use efficiency and drought tolerance, like those that use a photosynthetic pathway known as Crassulacean acid metabolism (CAM), have recently been introduced for such scenarios [22,23]. Specifically for areas of Mexico, Africa and Australia where water is an extremely limiting resource for food and crop production, CAM plants like Agave may be a viable option to maximize efficient production without losing other land-based resources [24,25].…”

Homology Modeling and Functional Annotation of Heat Shock Protein (HSP) Gene from Agave Americana

“…Survival of agaves in such regions is often related to their fleshy massiveness, or succulence. The such water capability occurs on a cellular level and is also related to the photosynthetic pathway used by most of other related plant species, known as Crassulacean acid metabolism (CAM) [2]. Plants exhibiting CAM open their stomata and have a net uptake of CO 2 mainly at night, when the lower tissue temperature and higher ambient relative humidity lead to less water than daytime stomata opening.…”