Turning Weeds Into Ethanol – Why Not?
by Lauren D. Quinn, Elise C. Scott, A. Bryan Endres, Tom Voigt, Jody M. Endres (University of Illinois/FarmDocDaily)
Media coverage of the controversy surrounding the use of certain non-native feedstocks for bioenergy is as pervasive as invasiveness itself. Plants such as giant reed (Arundo donax) and elephant grass (Pennisetum purpureum) are known to be weedy or invasive in natural habitats; the concern lies in their ability to spread propagules into natural habitats outside intended areas. So are bioenergy crops on the path to being the next kudzu (Pueraria montana)? The US Environmental Protection Agency (EPA) recently put in place growing restrictions and management plans to minimize the potential for escape when planting giant reed and elephant grass (Federal Register 2013, Scott et al. 2013).
The bad reputation and accompanying safeguards that require onerous record-keeping, monitoring, and reporting may dissuade farmers from planting feedstocks with invasive potential. But what if, on the flip side, bioenergy can serve as a motivator to remove existing weeds in farms, forests or even natural areas? That is, could ecologically damaging invaders be converted into cash crops that contribute valuable biomass to ethanol supply chains? Several authors already have proposed gasification or combustion (Jakubowski et al. 2010, Nielsen et al. 2011, Nackley et al. 2013) of existing stands of kudzu (Zaleski 2008, Sage et al. 2009); woody invaders like Russian olive (Elaeagnus angustifolia) and saltcedar (Tamarix spp.), and wetland invaders such as common reed (Phalaris arundinacea).
To date, however, the literature has not addressed whether this could actually be feasible from an economic, ecological or practical sense in the ethanol context. Sustainability standards such as the CSBP (2013) have entertained the notion that standards should reward producer actions to clear invaders for bioenergy purposes. In a recent study (Quinn et al. 2013), we examine existing barriers that could preclude commercial use of weedy and invasive biomass as a source of ethanol.
An Overarching Philosophical Dilemma
Biorefineries require a consistent and abundant source of biomass to operate profitably. Landowners and conservationists, on the other hand, primarily seek to eradicate invaders permanently from the landscape to restore ecological balance and eliminate economic losses. While weeds and invasive plants likely will reemerge even after aggressive control measures, their numbers will not be at the level required to meet consistent feedstock needs of a biorefinery. READ MORE Download study