The Energy Policy Act of 2005 (EPAct, P.L. 109-58 ) established a renewable fuel standard (RFS), requiring the use of biofuels (such as ethanol) in the nation's fuel supply. The Energy Independence and Security Act of 2007 (EISA, P.L. 110-140 ) significantly expanded this mandate. The RFS mandate has been a major impetus to the development of U.S. biofuels industries, especially the ethanol industry. As a result, ethanol production capacity and the demand for corn as a biofuel feedstock have grown dramatically over the past few years. In 2005, the United States produced 3.9 billion gallons of ethanol, requiring roughly 1.4 billion bushels of corn; in 2007, those numbers had increased to 6.5 billion gallons and 2.3 billion bushels. In 2007, roughly one-quarter of the U.S. corn crop was directed to ethanol production. In 2013, production had increased to roughly 14 billion gallons using approximately 5 billion bushels of corn or roughly 40% of the 2013 crop. Increasing demand for corn for biofuels, the rise in energy prices, and other supply concerns in international grain markets led to rapid increases in corn and other grain prices in 2008. These higher grain prices raised concerns globally over food prices and availability. Because of these concerns, as well as the capacity for the U.S. industry to meet the growing RFS mandates, there is continuing interest among some policy makers to amend or eliminate the RFS. Under the provisions of EPAct and EISA, the administrator of the Environmental Protection Agency (EPA) has the authority to waive the RFS requirements in whole or in part, in response to a petition by a state or a fuel provider, or on her own motion. In April 2008, Texas Governor Rick Perry sent a letter to EPA Administrator Stephen Johnson petitioning for a 50% waiver from the RFS requirements. In his letter, Governor Perry stated that he initiated the petition because of the negative effect of the requirements on the Texas economy and on global food prices. In August 2008, EPA denied the waiver request because the agency found that the effects of the RFS on food, feed, and fuel prices was minimal, and thus the economic effects of the RFS "could not be categorized as severe." In August 2012, Arkansas Governor Mike Beebe and North Carolina Governor Beverly Eaves Perdue submitted petition letters to EPA requesting full or partial waivers of the 2012 and 2013 RFS mandates. Governors of several other states joined that petition. The governors cited the effects of the 2012 drought, further compounded by the increased grain demand from the RFS, as leading to severe economic harm to their states, especially their livestock producers. However, EPA denied these petitions for similar reasons as in 2008. Another factor that could lead the EPA Administrator to waive certain parts of the RFS is the "blend wall." The vast majority of the RFS is met using ethanol blended into gasoline at the 10% level (E10). However, there is a limit to the amount of ethanol that can be blended into gasoline at this level, and other options for supplying ethanol (e.g., higher-level ethanol blends such as E15 and E85) are currently constrained because of infrastructure and other impediments. In prior years this had not been a problem because the volume of biofuels needed to meet the RFS mandate was below the maximum amount of ethanol that could be supplied as E10; but stakeholders were especially concerned about the possibility of facing this "blend wall" in either 2013 or 2014. In November 2013 EPA proposed using its general authority to lower the RFS mandates in cases of "inadequate supply." EPA proposed an overall mandate of 15.21 billion gallons for 2014, instead of the 18.15 billion gallons of biofuels scheduled for 2014 in EISA, and below the 2013 mandate of 16.55 billion gallons. Within the overall RFS there are sub-mandates for the use of cellulosic biofuels, biomass-based diesel fuels, and other advanced biofuels. However, questions have been raised over whether there is enough feedstock supply and production capacity to meet some of these carveouts, especially the cellulosic biofuel carveout. EPA waived most of the 2010 cellulosic biofuel carveout—EISA set the mandate at 100 million gallons but EPA only required 6.5 million gallons, more than 90% less than scheduled by EISA. EPA cited a lack of then-current and expected production capacity, driven largely by delays in production plans and a lack of investment in commercial-scale refineries. Similarly, EPA finalized cellulosic biofuel mandates of 6.0 million and 10.45 million gallons for 2011 and 2012, respectively—97% and 98% lower than the amounts scheduled in EISA. Because of a lack of commercial cellulosic biofuel production capacity—only about 20,000 gallons were registered in 2012—gasoline and diesel fuel producers challenged the lowered mandates in court. In January 2013, the U.S. Court of Appeals for the D.C. Circuit vacated the 2012 cellulosic mandate and remanded the rule back to EPA. EPA subsequently set the 2012 level at zero and has proposed doing the same for 2011. For 2013, EPA finalized a cellulosic mandate of 6.0 million gallons (instead of 1 billion gallons), and this lowered mandate is also subject to a court challenge, and EPA granted petitions from two oil industry groups to reconsider the 2013 rule. For 2014, EPA has proposed a cellulosic mandate of between 8 million and 30 million gallons, instead of 1.75 billion gallons scheduled in the statute. The RFS requires the use of 16.55 billion gallons of renewable fuel in transportation fuels in 2013—corn ethanol is limited to 13.8 billion gallons of the 2013 mandate. The RFS is scheduled to increase to 36 billion gallons by 2022 with an increasing share coming from "advanced biofuels"—biofuels produced from feedstocks other than corn starch—including cellulosic biofuel and bio-based diesel substitutes. As has been the case in previous years, in 2013 the vast majority of the mandate was met with U.S. corn ethanol (and a smaller amount of biodiesel, as well as sugarcane ethanol from Brazil). For 2014, the overall mandate is scheduled to increase to 18.15 billion gallons, with up to 14.4 billion gallons coming from corn ethanol and 3.75 billion gallons coming from advanced biofuels, and 1.75 billion gallons of the advanced biofuel mandate coming from cellulosic biofuels. In November 2013, EPA proposed lowering all three of the mandates, to 15.21 billion gallons, 13.0 billion gallons, 2.20 billion gallons, and roughly 17 million gallons, respectively. By 2015 corn ethanol's share of the RFS is effectively capped at 15 billion gallons per year. The EISA amendments to the RFS specifically mandate the use of cellulosic biofuel (16 billion gallons by 2022) and biomass-based diesel fuel (at least 1.0 billion gallons annually by 2012). However, some advanced biofuels, especially cellulosic fuels, have been slow to develop and fuel production lags EISA's mandated schedule. As amended by EISA, Section 211(o)(7) of the Clean Air Act gives the EPA administrator the authority to waive, in whole or in part, the total volume of renewable fuel mandated by the RFS if, in her determination, there is inadequate domestic supply to meet the mandate, or if "implementation of the requirement would severely harm the economy or environment of a State, a region, or the United States." Further, under certain conditions, the EPA administrator may waive (in whole or in part) the specific carve-outs for cellulosic biofuel and biomass-based diesel fuel. On the petition of a state or a fuel provider, or at her own discretion, the administrator may waive the overall RFS requirement for a given year. If a waiver is granted, any adjustment applies to total national requirement. Regardless of who initiates the waiver petition, all fuel suppliers' quotas would be reduced by a similar percentage. As the law is written, EPA may not waive the requirement for an individual state or supplier within a state, but must reduce the entire national mandate. To grant the waiver, the EPA administrator must determine, in consultation with the Secretaries of Agriculture and Energy, that one of two conditions has been met: there is inadequate domestic renewable fuel supply; or implementation of the requirement would severely harm the economy or environment of a state, a region, or the United States. However, it is unclear how EPA will interpret these criteria. In its May 1, 2007, final rule for 2007 onward, EPA explicitly stated that it would not establish more specific criteria for the waiver: While EPA realizes that the criteria provided by the statute are quite general, the rationales of severe environmental or economic harm or inadequate domestic supply are sufficient for a basic framework upon which a petition can be built and evaluated. Each situation in which a waiver may be requested will be unique, and promulgating a list of more specific criteria in the abstract may be counter-productive. Within 90 days of receipt of the waiver petition, EPA must act to approve or disapprove the petition, after public notice and opportunity for comment. If EPA does grant a waiver, the waiver expires after one year, but may be extended by the EPA administrator in consultation with the Secretaries of Agriculture and Energy. In November 2012, EPA denied waiver petitions from the governors of Arkansas, North Carolina, and several other states.