Submitted to: Global Change Biology Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2010
Publication Date: 8/1/2010
Citation: VanLoocke, A., Bernacchi, C.J., Twine, T.E. 2010. The Impacts of Miscanthus X gianteus Production on the Midwestern U.S. Hydrologic Cycle. Global Change Biology Bioenergy. 2:180-191. Interpretive Summary: There is an increasing need to use renewable energy to reduce our greenhouse gas emissions and dependence on fossil fuels. While currently a large amount of renewable energy comes from converting corn into ethanol, a growing body of research indicates that it may not be beneficial or even possible for corn ethanol alone to meet our energy needs. Highly productive plants chosen specifically for their ability to produce plant material that can be converted into ethanol have a greater potential to meet our energy needs. One of these plants could be Miscanthus x. Giganteus (Miscanthus). Miscanthus is anticipated to have minimal environmental impacts; however Miscanthus has been shown to use more water than current crops, so it is uncertain how planting large amounts of Miscanthus could affect the water cycle. One way to improve our understanding is to use a computer model to simulate the growth of plants. A new biofuels model was developed to represent the growth and management of Miscanthus within an existing model called Agro-IBIS. This model was used to simulate various amounts of Miscanthus production for the Midwestern U.S. to evaluate the impacts on the regional water cycle. According to our model simulations, when Miscanthus was grown on 10% of the land and distributed evenly over the entire region there was little to no change in the hydrologic cycle. When Miscanthus was grown on 25% or more of the land, there were changes in the water cycle because of an increase in water usage and a decrease in water drainage into and through the soil. These changes varied seasonally and were largest outside of the Corn Belt region. This shows that the impacts of producing Miscanthus on the water cycle will depend on the location and the level of production.
Technical Abstract: The need for renewable energy to offset fossil fuel dependence and greenhouse gas emissions is increasing, with the majority of U.S. renewable energy production focused currently on replacing gasoline with corn ethanol. A growing body of research indicates that it may not be beneficial or even possible for corn ethanol alone to meet demands for renewable energy. Highly productive feedstocks coupled with cellulosic ethanol production technology have greater potential to create a renewable and sustainable alternative to fossil fuels. One candidate feedstock, Miscanthus x. Giganteus (Miscanthus), is anticipated to have minimal environmental impacts, however uncertainty associated with large-scale implementation should be addressed regarding particularly the hydrologic cycle. A biofuels algorithm was developed for the Agro-IBIS terrestrial ecosystem model that represents the growth and management of Miscanthus. This algorithm was used to simulate various scenarios of Miscanthus production for the Midwestern U.S. to evaluate the impacts on the regional hydrologic cycle. Simulated fraction cover of 10% distributed evenly over the entire region indicate little to no change in the hydrologic cycle. However increasing fraction cover to 25% or greater is shown to increase evapotranspiration (ET) and decrease drainage. These changes vary seasonally and are largest outside of the Corn Belt and suggest that hydrologic impacts of Miscanthus production are dependent on location and fraction cover.