Environmental outcomes of the US Renewable Fuel Standard.
Environmental outcomes of the US Renewable Fuel Standard.
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DOI：
10.1073/pnas.2101084119
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发表时间：
2022-03-01
影响因子：
11.1
通讯作者：
Gibbs HK
中科院分区：
文献类型：
--
作者：
Lark TJ;Hendricks NP;Smith A;Pates N;Spawn-Lee SA;Bougie M;Booth EG;Kucharik CJ;Gibbs HK
生物燃料被包括在许多减少人为温室气体排放和限制全球变暖程度的拟议战略中。美国可再生燃料标准是世界上最大的现有生物燃料计划，然而，尽管它很突出，但对该计划的环境结果的经验评估有限。即使不考虑可能的国际土地利用效应，我们发现美国玉米乙醇的生产也未能达到政策本身的温室气体排放目标，并对水质、用于保护的土地面积和其他生态系统过程产生了负面影响。我们的研究结果表明，要实现生物燃料生产和使用的预期环境效益，仍然需要在技术和政策方面取得重大进展。《可再生燃料标准》（RFS）规定了生物燃料在美国的使用，从而指导了全球近一半的生物燃料生产，但这项关键的气候和环境法规的结果仍不明朗。在这里，我们结合了计量经济学分析、土地利用观察和生物物理模型来估计可再生燃料系统在总体上和在美国个别农田规模上的实际影响。我们发现，RFS使玉米价格提高了30%，其他作物价格提高了20%，这反过来又使美国玉米种植面积增加了2.8 Mha(8.7%)，总耕地面积增加了2.1 Mha(2.4%)，政策颁布后的几年（2008年至2016年）。这些变化使全国每年的化肥使用量增加了3%至8%，水质降解剂增加了3%至5%，并造成了足够多的国内土地利用变化排放，使得在可再生燃料标准下生产的玉米乙醇的碳强度不低于汽油，可能至少高出24%。决策者在考虑可再生能源政策的未来以及玉米乙醇等燃料实现气候缓解目标的潜力时，必须权衡这些权衡，同时考虑生物燃料的好处。
Biofuels are included in many proposed strategies to reduce anthropogenic greenhouse gas emissions and limit the magnitude of global warming. The US Renewable Fuel Standard is the world’s largest existing biofuel program, yet despite its prominence, there has been limited empirical assessment of the program’s environmental outcomes. Even without considering likely international land use effects, we find that the production of corn-based ethanol in the United States has failed to meet the policy’s own greenhouse gas emissions targets and negatively affected water quality, the area of land used for conservation, and other ecosystem processes. Our findings suggest that profound advances in technology and policy are still needed to achieve the intended environmental benefits of biofuel production and use. The Renewable Fuel Standard (RFS) specifies the use of biofuels in the United States and thereby guides nearly half of all global biofuel production, yet outcomes of this keystone climate and environmental regulation remain unclear. Here we combine econometric analyses, land use observations, and biophysical models to estimate the realized effects of the RFS in aggregate and down to the scale of individual agricultural fields across the United States. We find that the RFS increased corn prices by 30% and the prices of other crops by 20%, which, in turn, expanded US corn cultivation by 2.8 Mha (8.7%) and total cropland by 2.1 Mha (2.4%) in the years following policy enactment (2008 to 2016). These changes increased annual nationwide fertilizer use by 3 to 8%, increased water quality degradants by 3 to 5%, and caused enough domestic land use change emissions such that the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher. These tradeoffs must be weighed alongside the benefits of biofuels as decision-makers consider the future of renewable energy policies and the potential for fuels like corn ethanol to meet climate mitigation goals.
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DOI：
10.1073/pnas.2013637118
发表时间：
2021-05-18
影响因子：
11.1
作者：
Domingo NGG;Balasubramanian S;Thakrar SK;Clark MA;Adams PJ;Marshall JD;Muller NZ;Pandis SN;Polasky S;Robinson AL;Tessum CW;Tilman D;Tschofen P;Hill JD
通讯作者：
Hill JD
影响因子：
16.6
作者：
Beaulieu, Jake J.;DelSontro, Tonya;Downing, John A.
通讯作者：
Downing, John A.
影响因子：
11.4
作者：
Ferin, Kelsie M.;Chen, Luoye;VanLoocke, Andy
通讯作者：
VanLoocke, Andy
DOI：
10.1073/pnas.0708300105
发表时间：
2008-03-18
影响因子：
11.1
作者：
Donner, Simon D.;Kucharik, Christopher J.
通讯作者：
Kucharik, Christopher J.
影响因子：
56.9
作者：
Fargione, Joseph;Hill, Jason;Hawthorne, Peter
通讯作者：
Hawthorne, Peter