Ramping up the production of corn ethanol to meet the targets set by the new US Renewable Fuel Standard (RFS) will worsen pollution in the Gulf of Mexico, increasing the “Dead Zone”—a growing hypoxic region in the Northern Gulf of Mexico (NGOM)—that kills fish and aquatic life, according to a Canadian-American research team.
Simon Donner of the University of British Columbia and Chris Kucharik of the University of Wisconsin quantified the effect of projected biofuel production on the problem of nutrient pollution in a waterway. Their findings are published in the Early Edition of the Proceedings of the National Journal of Sciences.
The researchers looked at the estimated land and fertilizer required to meet proposed corn-based ethanol production goals. The US Energy Independence and Security Act of 2007 (EISA) mandates, among its many components, an aggressive ramp-up in the use of renewable fuels, culminating in a 36 billion gallon RFS by 2022. Of that, corn ethanol production is capped at 15 billion gallons per year starting in 2015; the remainder is expected to be provided by “advanced biofuels”, the majority of which are cellulosic biofuels. (Earlier post.)
The corn-ethanol goal represents more than three times than triple the production in 2006.
Nitrogen and phosphorus from agricultural fertilizer have been found to promote excess growth of algae in water bodies—a problem that’s common across North America and in many areas of the world. In some cases, decomposition of algae consumes much of the oxygen in the water. Fertilizer applied to cornfields in the central US—including states such as Illinois, Iowa, Nebraska and Wisconsin—is the primary source of nitrogen pollution in the Mississippi River system, which drains into the Gulf of Mexico.
Each summer, the export of nitrogen creates a large “Dead Zone” in the Gulf of Mexico, a region of oxygen-deprived waters that are unable to support aquatic life. Marine species either die or flee the hypoxic zone, so the spread of hypoxia reduces the available habitat for marine species which are important for the ecosystem as well as commercial and recreational fishing in the Gulf. In recent years, it has reached more than 20,000 km2 in size, which is equivalent to the area of New Jersey.
Donner and Kucharik’s findings suggest that if the US were to meet its proposed ethanol production goals, nitrogen loading by the Mississippi and Atchafalaya Rivers to the Gulf of Mexico would increase by 10-34%. Generating 15 billion gallons of corn-based ethanol by the year 2022 will increase the odds that annual dissolved inorganic nitrogen (DIN) export exceeds the target set for reducing hypoxia in the Gulf of Mexico to >95%. To arrive at these figures, Donner and Kucharik combined the agricultural land use scenarios with models of terrestrial and aquatic nitrogen cycling.
The nitrogen levels in the Mississippi will be more than twice the recommendation for the Gulf. It will overwhelm all the suggested mitigation options. This rush to expand corn production is a disaster for the Gulf of Mexico. The US energy policy will make it virtually impossible to solve the problem of the Dead Zone.—Simon Donner
The results of the study call into question the assumption that enough land exists to fulfill current feed crop demand and expand corn and other crop production for ethanol. The study concludes that increasing ethanol production from US croplands without endangering water quality and aquatic ecosystems will require a substantial reduction in meat consumption.
In October 2007, draft report from the Science Advisory Board (SAB) to the US Environmental Protection Agency (EPA) suggested that changes to the current structure of economic incentives favoring corn-based ethanol may be necessary to prevent a dramatic increase in nutrient loadings in the Mississippi and Atchafalaya River Basin (MARB) that would lead to an expansion of the annual Dead Zone. (Earlier post.)
In October 2007, the US National Oceanic and Atmospheric Administration (NOAA) awarded first-year funding of $284,000 to researchers at the University of Texas at Austin Marine Science Institute (UTMSI) as part of a three-year $781,000 project to develop a better understanding of how nutrient pollution from the Mississippi River affects the Dead Zone in the Gulf of Mexico. (Earlier post.)
Simon D. Donner and Christopher J. Kucharik. Corn-based ethanol production compromises goal of reducing nitrogen export by the Mississippi River. Proc. Natl. Acad. Sci. USA, Published online on March 10, 2008, 10.1073/pnas.0708300105