The use of biofuels, particularly ethanol derived from corn, has been championed as a sustainable alternative to fossil fuels. Proponents argue that biofuels offer three major benefits. First, they reduce greenhouse gas emissions because the carbon dioxide released during combustion is roughly equal to the amount absorbed by the plants during growth, creating a near-carbon-neutral cycle. Second, biofuels enhance energy security by decreasing reliance on imported oil, as they can be produced domestically from agricultural crops. Third, they stimulate rural economies by creating new markets for farmers and generating jobs in processing and distribution. These advantages have led many governments to mandate blending ethanol into gasoline, with the expectation that biofuels will play a key role in transitioning to a low-carbon future.
🎧 听力讲座
🎯 模拟考试环境：先点「播放讲座」听完内容，再作答。听力原文默认隐藏。
However, the lecture challenges each of these claims. Regarding emissions, the professor explains that when land-use changes are considered—such as converting forests or grasslands to cornfields—the released soil carbon and lost carbon sequestration capacity far outweigh any savings from biofuel combustion. In fact, some studies show that corn ethanol can produce more lifecycle emissions than gasoline. On energy security, the professor points out that biofuel production is highly energy-intensive, requiring significant fossil fuel inputs for fertilizers, farm machinery, and processing. Thus, for every unit of energy gained, nearly as much—or more—fossil energy is consumed, meaning biofuels do not truly reduce oil dependence. Finally, the economic benefit to rural areas is questionable. Government subsidies that support ethanol production often inflate corn prices, which hurts small farmers who cannot compete with large agribusinesses, and the jobs created are largely temporary and dependent on continued subsidies. The professor concludes that the purported advantages of biofuels are overstated and that they are not a viable solution to climate change or energy independence.
📝 Writing Prompt Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
