LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 6A: TOOLS AND DATABASES 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
486
Cradle to gate life cycle inventory and impact assessment of
glyphosate
Evan Griffing 1,* , Kiyotada Hayashi 2 , Michael Overcash 1
1 Environmental Clarity LLC, Montgomery Village, MD, USA
2 National Agriculture and Food Research Organization, 3-1-1 Kannondai, Tsukuba, Ibaraki, 305-8666 Japan
* Corresponding author. E-mail: egriffing@environmentalclarity.com
ABSTRACT
Glyphosate is the active ingredient in the popular broad-spectrum herbicide Roundup. The cradle to gate life cycle inventory of
glyphosate was modelled with the design-based method. Industrial literature, patents, and input from agricultural chemists were used
to select a representative chemistry and develop detailed models of each manufacturing process in the supply chain. The results were
analysed using an energy analysis, and the global warming potential was calculated. The cumulative energy demand of 181 MJ
HHV/kg glyphosate is compared to other life cycle inventory results. Process efficiencies and energy hot spots in the supply chain
are described.
Keywords: life cycle inventory, herbicide, pesticide, design-based
1. Introduction
Agricultural production requires application of large numbers of herbicides and pesticides. Total herbicide
use in the United States (US) in 2006 was 226,000 metric tonnes. Of this, 37% was glyphosate, a broad
spectrum herbicide marketed by Monsanto as Roundup (USEPA, 2011). As of 2006, US use of herbicides as
a percentage of global use was 40% by market price and 25% by mass. Glyphosate was developed as an agricultural
product in the 1970s. Patent protection in the US expired in 2000. As of 1998, non-Monsanto
producers represented 40,000 tonnes / yr capacity (Woodburn, 2000). By 2009, capacity in China had grown
to 655,000 tonnes/yr (R & M, 2011). Global Industry Analysts predicts glyphosate production to reach 1.35
million metric tonnes by 2017.
Commercial glyphosate formulations are typically salts, which are more soluble in water. Common salts
are isopropylammonium, monoammonium, diammonium, and potassium (Green, S. and Pohanish, 2007;
BCPC, 2010). In this article, we present results for glyphosate as a solid. In addition, select results for the
potassium salt of glyphosate are given as an example of a commercial formulation.
Commercial production routes were summarized by Bryant (2003). The Monsanto routes and Chinese
chloracetic acid route described by Bryant all go through iminodiacetic acid (IDA) and phosphonomethyl
iminodiacetic acid (PMIDA). The primary production route for IDA in world production, which is used in
the new Monsanto route, involves diethylamine.
In the chloroacetic acid route given by Bryant, chloroacetic acid is reacted with hydrazine (NH2NH2) to
form an intermediate that is converted to IDA. In another variation, chloroacetic acid can be reacted with
ammonia to produce glycine, which is a starting material in a route specified by Unger (1996). Although the
glycine route has not been used commercially outside of China (Bryant, 2003), it appears to be the favoured
route in China (Yin, 2011).
Other life cycle inventory data on glyphosate production are available from Ecoinvent. The current version
2.2 (2010) shows production from the glycine route (Sutter, 2010) starting with acetic anhydride, formaldehyde,
ammonia, sodium hydroxide, chlorine, and phosphorus trichloride. Earlier versions were based
on data from Green and were given only in cradle to gate form. Results from this study are compared to the
ecoinvent data.
2. Methods
Industrial literature, patents, and input from agricultural chemists were used to select a representative
production route. Several routes for glyphosate were provided by Unger (1996) and Bryant (2003). The
newer Monsanto route was selected as representative.
To provide complete transparency, production of each chemical was divided into gate-to-gate (gtg) processes
that include a small number of primary chemical reactions. Each gtg was modelled using standard
process engineering methods as outlined by Overcash (1995 and Jimenez, et. al. (2000). Reports were generated
on a gate-to-gate level and include (1) all necessary chemistries, with reaction and overall process
yields, (2) process descriptions and literature reviews, (3) detailed process flow diagrams including all material
flows into and out of the process and process temperatures and pressures, (4) mass flow tables (5) energy
flows at the unit process level.