Journal of Energy Bioscience 2024, Vol.15, No.3, 208-220 http://bioscipublisher.com/index.php/jeb 213 shocks are positive (Dutta et al., 2018). Furthermore, the literature on the impacts of biofuels on agricultural commodity prices shows a wide range of estimates, with some studies indicating that a one billion gallon expansion of the US corn ethanol mandate could lead to a 3%-4% increase in corn prices (Condon et al., 2015). This price volatility poses challenges for the economic stability of ethanol production. 5.3 Subsidies and government policies impacting ethanol production Government policies and subsidies have played a significant role in the growth of the corn ethanol industry. Policies such as the Volumetric Ethanol Excise Tax Credit (VEETC) and the Renewable Fuel Standard (RFS) mandate have been instrumental in promoting ethanol production. These policies have not only supported the expansion of ethanol production but have also contributed to reducing gasoline prices at the pump by up to 10% (Janda et al., 2022). Additionally, supportive biofuel policies have led to a significant increase in corn ethanol production in the USA, from 1.6 to 15 billion gallons between 2000 and 2019, contributing to a reduction in greenhouse gas emissions (Lee et al., 2021). 5.4 Economic feasibility and scalability The economic feasibility and scalability of corn ethanol production are influenced by several factors, including facility size, feedstock costs, and technological advancements. Larger facilities benefit from economies of scale, resulting in lower production costs and higher economic viability (Ro et al., 2019). Techno-economic analyses of integrated biorefineries suggest that the production of hydrocarbon fuels and chemicals from corn ethanol can be economically competitive with conventional ethanol production, especially when considering the higher market value of hydrocarbon products (Wang et al., 2018). However, the scalability of these technologies requires further improvements in process yields, sustainable feedstock development, and catalytic reaction efficiencies (Tao et al., 2017). Overall, while the economic feasibility of corn ethanol production is promising, it is contingent on continued technological advancements and supportive government policies. 6 Environmental Impact and Sustainability 6.1 Greenhouse gas emissions and carbon footprint Corn ethanol production has been a significant focus of biofuel policies aimed at reducing greenhouse gas (GHG) emissions. However, the environmental outcomes have been mixed. Studies indicate that while corn ethanol can reduce GHG emissions compared to gasoline, the reductions are often modest and sometimes negligible. For instance, the U.S. Renewable Fuel Standard (RFS) has not met its GHG emissions targets, with some analyses suggesting that the life-cycle GHG emissions of corn ethanol may be comparable to or even exceed those of gasoline (Hill, 2022; Lark et al., 2022). Conversely, other studies have shown that improvements in agricultural practices and ethanol production technologies have led to a decrease in the carbon intensity (CI) of corn ethanol over time, achieving a 23% reduction in CI from 2005 to 2019 (Lee et al., 2021). Additionally, double-cropping systems in Brazil have demonstrated significant GHG reductions when maize is grown as a second crop with soybeans (Moreira et al., 2020). 6.2 Land use and impact on biodiversity The expansion of corn ethanol production has significant implications for land use and biodiversity. Increased corn cultivation often leads to the conversion of conservation lands and other ecosystems into agricultural use, which can reduce plant and animal biodiversity and disrupt ecosystem services (Hoekman and Broch, 2018). The intensification of corn farming, driven by biofuel policies, has also been linked to soil erosion, nutrient runoff, and other adverse environmental impacts (Hill, 2022). Moreover, the removal of corn stover for biofuel production can decrease soil organic carbon (SOC) levels, further exacerbating land degradation (Qin et al., 2018). However, strategies such as cover cropping and manure application can mitigate some of these negative effects by enhancing SOC and reducing overall GHG emissions (Qin et al., 2018). 6.3 Water usage and management Water usage in corn ethanol production is another critical environmental concern. The increased frequency of corn cultivation and the removal of stover can lead to a decrease in soil water content and water yield, impacting local
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