A Possible Negative Impact of Ethanol Production on Water Quality

The unintended energy impacts of increased nitrate contamination from biofuels production

Kelly M. Twomey, Ashlynn S. Stillwell  and Michael E. Webber.

Journal of Environmental Monitoring, 2010, 12:  218-224

The Energy Independence and Security Act of 2007 (US) promoted the cultivation of corn for cornstarch-based ethanol production, due to increased interests in biofuels worldwide. The concern for green house gas emissions, depletion of fossil fuels, and higher oil prices have led us to venture out into alternative ways to make biofuels, by using biomass and renewable sources.

Twomey et al. (2009) discuss how ethanol production from corn could have unintended adverse impacts on the environment (e.g. water quality) and lets us consider the further implications this could mean. In a nutshell, the production of ethanol requires more corn plantations, which would require more fertilizers, and this would introduce excess nitrate into both surface and groundwater, leading to increased energy requirements for water treatment. It appears that this is going in a circle and lets us reconsider if ethanol production is really any better than fossil fuels in reducing green-house gas emissions and energy efficiency. On the contrary, it seems to be introducing another harmful impact on the environment, which should be accounted for, before a plan is implemented.

The EPA allows the current maximum contaminant level of nitrate to be 10mg/L and if the level exceeds this, water treatments are required. The researchers calculate that when nitrate levels increase because of increased corn plantations, that 2100% increase in energy requirements will be needed for water treatment (based on previous treatments)! Currently, the Renewable Fuel Standard (RFS) is increasing the blending of renewable fuel into gasoline from 9 billion gallons in 2008 to 36 billion gallons by 2022. It’s also interesting to note that the majority of corn cultivation and ethanol production is located in the Corn Belt Region (MidWest), which is exactly where regions of high nitrogen input and high vulnerability are concentrated. Several analyses projected 10-37% increase in nitrogen loading into water nationally from 2017-2022, if corn production was to meet the quantity of cornstarch-based ethanol prescribed by EISA 2007.

In conclusion, the researchers admit that they’re the first to do this kind of analysis and that lack of enough data regarding the current state of nitrate contamination in the groundwater is hindering them from reaching any specific conclusion. But they do say that the projected nitrate increase in surface water of Mississippi-Atchafalaya River Basin is not likely to exceed the 10mg/L standard.

One Response to A Possible Negative Impact of Ethanol Production on Water Quality

  1. Jonathan says:

    The problem I have with ethanol is it is solely a political payoff to a small constituency, in addition to its effect on the environment (namely, the amount of water required to produce it). Your post brings another point to the forefront, the effect of planting the same crop over and over requiring prodigious amounts of fertilizer (eventually the ground could reach a “saturation point” where no amount of fertilizer would assist in growing a crop), not to mention the adverse effects of all that nitrate and whatnot in the soil leaching into the water table.

    Mainly, the political payoff part raises my ire. Plus, ethanol DOES NOT carry the same energy as gasoline. Let’s use our crude resources WHILE we develop alternatives that make sense. We’ve got plenty of crude, if we’d just go after it.


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