Abstract  Legislation passed in 2007 by the U.S. Congress increased by about 1.3 billion bushels the net amount of corn required to be processed annually into ethanol for motor-fuel use. We estimate that corn prices were about 30% higher from 2006 to 2014 than they would have been without this demand increase. We develop a partially identified structural vector autoregression model. Our identification strategy is unique in the literature because it enables us to estimate the effects of transitory shocks, such as weather, separately from the effects of persistent shocks, such as the increased ethanol mandate. Moreover, by only partially identifying our model, we show how to generate robust conclusions without strong identifying assumptions.

Abstract  Farmers’ cropping decisions are a product of a complex mix of socio-economic, cultural, and natural environments in which factors operating at a number of different spatial scales affect how farmers ultimately decide to use their land in any given year or over a set of years. Some environmentalists are concerned that increased demand for corn driven by ethanol production is leading to conversion of non-cropland into corn production (which we label as “extensification”). Ethanol industry advocates counter that more than enough corn supply comes from crop switching to corn and increased yields (which we label as “intensification”). In this study, we determine whether either response to corn demand -- intensification or extensification -- is supported. This is determined through an analysis of land-use/land-cover (LULC) data that covers the state of Kansas and a measure of a corn demand shifter related to ethanol production -- distance to the closest ethanol plant -- between 2007 and 2009.

Abstract  Although the United States has pursued rapid development of corn ethanol as a matter of national biofuel policy, relatively little is known about this policy's widespread impacts on agricultural land conversion surrounding ethanol refineries. This knowledge gap impedes policy makers' ability to identify and mitigate potentially negative environmental impacts of ethanol production. We assessed changes to the landscape during initial implementation of the Renewable Fuel Standard v2 (RFS2) from 2008 to 2012 and found nearly 4.2 million acres of arable non-cropland converted to crops within 100 miles of refinery locations, including 3.6 million acres of converted grassland. Aggregated across all ethanol refineries, the rate of grassland conversion to cropland increased linearly with proximity to a refinery location. Despite this widespread conversion of the landscape, recent cropland expansion could have made only modest contributions to mandated increases in conventional biofuel capacity required by RFS2. Collectively, these findings demonstrate a shortcoming in the existing 'aggregate compliance' method for enforcing land protections in the RFS2 and suggest an alternative monitoring mechanism would be needed to appropriately capture the scale of observed land use changes.

Abstract  Seeds for the historic drought of 2012 were sown during the back-to-back La Niña episodes of 2010–11 and 2011–12. La Niña, a name given to anomalous cooling of the equatorial waters of the central and eastern Pacific Ocean, often correlates with drought development and expansion across the southern United States. Indeed, drought began to develop across the southern tier of the U.S. during the winter of 2010–11, and quickly intensified during the 2011 growing season. Effects of the 2011 drought were particularly severe in the south-central U.S.

Abstract  Expansion of ethanol production in the United States has raised concerns regarding its land- use change effects. However, little is known about the extent to which observed land use change in the United States can be attributed to ethanol plant proximity or is caused by changes in crop prices that may be partly induced by expansion in ethanol production. This study aims to examine the determinants of changes in corn acreage and aggregate crop acreage by simultaneously identifying the effects of establishment of ethanol plants serving as terminal markets for corn and the effects of changes in crop prices in the United States between 2003 and 2014. Our results show that corn acreage and total acreage are fairly inelastic with respect to both changes in ethanol capacity in the vicinity, as well as changes in crop prices. Our estimates of acreage elasticity with respect to corn ethanol production are smaller than those obtained by previous studies that disregard the price effect on crop acreage. We find that, ceteris paribus, the increase in ethanol capacity alone led to a modest 3% increase in corn acreage and less than a 1% increase in total crop acreage by 2012 when compared to 2008. The effect of corn price and aggregate crop price on acreage change from 2008 to 2012 was more than twice larger than that of effective ethanol production capacity over this period; but this price effect was largely reversed by the downturn in crop prices after 2012. This study shows that land- use change is not a static phenomenon and that it is important to examine how it evolves in response to various factors that may change over time.

Abstract  This report updates the findings of the first Report to Congress, published in 2011, with respect to environmental and resource conservation impacts, which together are intended to address the Section 204 statutory impacts since the passage of the EISA. This report reflects the current scientific understanding of the Section 204 impacts as presented in the published literature about biofuel use and production using data gathered through May 2017. Data on U.S. land use and the scientific literature through April 2017 were also reviewed. Greenhouse gas emission reductions that result from replacing biofuel with fossil fuel are not assessed in this report. This report does not make comparisons to estimated environmental impacts of other transportation fuels or energy sources.

Abstract  The Renewable Fuel Standard (RFS) sets annual mandates for renewable transportation fuels sold or introduced into commerce in the United States. The current RFS sets mandates through 2022. The Renewable Identifi cation Number (RIN) system was created by the U.S. Environmental Protection Agency to facilitate compliance with the RFS. A RIN is a 38-character numeric code that corresponds to a volume of renewable fuel produced in or imported into the United States. RINs remain with the renewable fuel through the distribution system and ownership changes. Once the renewable fuel is blended into a motor vehicle fuel, the RIN is no longer required to remain with the renewable fuel. Instead, the RIN may then be separated from the renewable fuel and used for RFS compliance, held for future compliance, or traded. The RFS mandates are prorated down to “obligated parties”—individual gasoline and diesel producers and/ or importers—based on their annual production and/or imports. Each year, obligated parties are required to meet their prorated share of the RFS mandates by accumulating RINs, either through fuel blending or by purchasing RINs from others. Understanding the RIN system and the prices for RINs when bought and sold can provide key insights into the impact of mandates on biofuel and feedstock markets. For 2011, conventional ethanol RIN prices have been low, implying low probability that the corresponding mandate has been binding and suggesting that other factors have contributed to expansion beyond the mandate. Conversely, biodiesel RIN prices have been high in 2011, implying a more binding biodiesel mandate with effects on soybean oil and other biodiesel feedstock markets.

Abstract  This paper examines the extent to which biofuel production has been driven over time by the U.S. Renewable Fuel Standard (RFS) and the extent to which it was driven by non-RFS policies and market forces. While the RFS has played a critical role in providing a secure environment to produce and use more biofuels, at least in the 2000s, it was not the only factor that encouraged the biofuel industry to grow. While the existing literature has successfully identified the key drivers of the growth in biofuels, it basically has failed to properly quantify the impacts and contributions of each of these drivers separately. This paper develops short- and long-run economic analyses, using Partial Equilibrium (PE) and Computable General Equilibrium (CGE) models, to differentiate the economic impacts of the RFS from other drivers that have helped biofuels to grow. Results show: 1) the bulk of the ethanol production prior to 2012 was driven by what was happening in the national and global markets for energy and agricultural commodities and by the federal and sometimes state incentives for biofuel production; 2) the medium-to long-run price impacts of biofuel production were not large; 3) due to biofuel production, regardless of the drivers, real crop prices have increased between 1.1 and 5.5% in 2004–11 with only one-tenth of the price increases were assigned to the RFS, 4) for 2011–16, the long-run price impacts of biofuels were less than the time period of 2004–11, as in the second period biofuel production increased at much slower rate; 5) biofuel production, regardless of the drivers, has increased the US annual farm incomes by $8.3 billion between 2004–11 with an extra additional annual income of $2.3 billion between 2011–2016; 6) the modeling practices provided in this paper assign 28% of the expansion in farm incomes of the period of 2004–2011 and 100% of the extra additional incomes of the period of 2011–16 to the RFS.

Abstract  Documentation exists for many chemicals that cause tastes and odors in water, however, water suppliers do not routinely monitor for these chemicals. Effective management of a taste-and-odor (T&O) problem in drinking water often requires good verbal description of the offending sensory experience. Experience demonstrates that obtaining verbal descriptions is challenging. To improve our understanding of communications, sensory science literature was reviewed to obtain descriptors for twenty-one chemicals acknowledged to cause T&O issues in drinking water. The review focused on pure chemicals above their odor threshold concentrations. Results reveal that descriptors follow four general categories. For select chemicals, strong consensus exists around a single or very few appropriate descriptors. Examples are "salty" for sodium and "chlorinous" for free chlorine. The next category has moderate agreement for several descriptors, with at least one major descriptor. For example the microbiological metabolite 2-methylisoborneol is most commonly described as "earthy/musty/moldy" but also "camphor, grass, and sweet". Some chemicals have weak agreement on their descriptors, but overall associate words with similar meaning. An example is the chemical toluene with descriptors of "solvent-like" words including "solvent", "gasoline", "paint-like", "cleaning fluid", and "etherish", but also "vinegar" and "sweet". The last chemical category possesses diverse descriptors with no consensus. For example, the oxylipin n-heptanal is described as "oily, fatty, chemical, musty/earthy/moldy, rancid, sweaty, grass, sickening, and stale". While descriptor diversity for select chemicals may not identify the cause of T&O, understanding that certain chemicals are perceived very differently aids in effective communications and eliminates confusion from expecting consumers or utility personnel to respond with consensus.

Abstract  U.S. ethanol production capacity increased more than threefold between 2002 and 2008. We study the effect of this growth on corn acreage. Connecting annual changes in county-level corn acreage to changes in ethanol plant capacities, we find a positive effect on planted corn. The building of a typical plant is estimated to increase corn in the county by over 500 acres and to increase acreage in surrounding counties up to almost 300 miles away. All ethanol plants are estimated to increase corn production by less than their annual requirements.

Abstract  Releases of greenhouse gases (GHG) from indirect land-use change triggered by crop-based biofuels hate taken center stage in the debate over the role of biofuels in climate policy and energy security. This article analyzes these releases for maize ethanol produced in the United States. Factoring market-mediated responses and by-product use into our analysis reduces cropland conversion by 72% from the land used for the ethanol feedstock. Consequently; the associated GHG release estimated in our framework is 800 grants of carbon dioxide per megajoule (MJ); 27 grants per MJ per year, over 30 years of ethanol production, or roughly a quarter of the only other published estimate of releases attributable to changes in indirect land use. Nonetheless, 800 grants are enough to cancel out the benefits that corn ethanol has on global warming, thereby limiting its potential contribution in the context of California's Low, Carbon Fuel Standard.