Reducing the negative human-health impacts of bioenergy crop emissions through region-specific crop selection

Environ. Res. Lett. 10 (2015) 054004 doi:10.1088/1748-9326/10/5/054004 LETTER OPEN ACCESS Reducing the negative human-health impacts of bioenergy crop emissions through region-speciﬁc crop selection RECEIVED 17 December 2014 REVISED 16 March 2015 William C Porter 1,4 , Todd N Rosenstiel 1 , Alex Guenther 2 , Jean-Francois Lamarque 3 and Kelley Barsanti 1 ACCEPTED FOR PUBLICATION 31 March 2015 PUBLISHED 6 May 2015 Portland State University, Portland, OR 97201, USA Paciﬁc Northwest National Laboratory, Richland, WA 99354, USA National Center for Atmospheric Research, Boulder, CO 80305, USA Current address: Massachusetts Institute of Technology, Cambridge, MA 02139, USA. E-mail: wporter@mit.edu Keywords: bioenergy, air quality, climate change Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Supplementary material for this article is available online Abstract An expected global increase in bioenergy-crop cultivation as an alternative to fossil fuels will have consequences on both global climate and local air quality through changes in biogenic emissions of volatile organic compounds (VOCs). While greenhouse gas emissions may be reduced through the substitution of next-generation bioenergy crops such as eucalyptus, giant reed, and switchgrass for fossil fuels, the choice of species has important ramiﬁcations for human health, potentially reducing the beneﬁts of conversion due to increases in ozone (O 3 ) and ﬁne particulate matter (PM 2.5 ) levels as a result of large changes in biogenic emissions. Using the Community Earth System Model we simulate the conversion of marginal and underutilized croplands worldwide to bioenergy crops under varying future anthropogenic emissions scenarios. A conservative global replacement using high VOC- emitting crop proﬁles leads to modeled population-weighted O 3 increases of 5–27 ppb in India, 1–9 ppb in China, and 1–6 ppb in the United States, with peak PM 2.5 increases of up to 2 μg m −3 . We present a metric for the regional evaluation of candidate bioenergy crops, as well as results for the application of this metric to four representative emissions proﬁles using four replacement scales (10–100% maximum estimated available land). Finally, we assess the total health and climate impacts of biogenic emissions, ﬁnding that the negative consequences of using high-emitting crops could exceed 50% of the positive beneﬁts of reduced fossil fuel emissions in value. 1. Introduction As bioenergy crops continue to replace both existing agricultural crops and natural landscapes, the choice of crop species will become increasingly important given their likely impacts on air quality and climate. The use of crops such as poplar, eucalyptus, and switchgrass as bioenergy feedstocks has increased globally over the past decade, and while ongoing adoption trends are highly dependent on both eco- nomic outcomes and policy decisions, signiﬁcant increases are expected to continue (Energy Informa- tion Administration 2013). The large scale land-use changes associated with bioenergy production will have consequences on many aspects of environmental and human health, including food supply, watershed cleanliness, soil quality, and ecological diversity (e.g. © 2015 IOP Publishing Ltd Service 2007, Dominguez-Faus et al 2009, Ditomaso et al 2010, Pedroli et al 2013). In some cases, the environmental costs associated with bioenergy pro- duction and consumption have been estimated to outweigh the beneﬁts of reduced fossil fuel combus- tion completely (Hill et al 2009, Tessum et al 2014). In addition to these concerns, many of the most popular candidates for bioenergy crop feedstocks are high- emitters of isoprene, monoterpenes, and other bio- genic volatile organic compounds (BVOCs), precur- sors of surface-level ozone (O 3 ) and ﬁne particulate matter (PM 2.5 ). Recent observational and modeling studies of existing bioenergy crop plantations have highlighted the importance of examining ambient chemical and climatological conditions, along with crop emission proﬁles, when assessing the potential for large-scale cultivation to effect negative air quality