Narrator: Listen to part of a lecture in an environmental science class.
Professor: So, we've been talking about renewable energy sources. Today, I want to focus on a specific challenge with solar power: its intermittency. The sun doesn't always shine, right? At night, or on cloudy days, solar panels produce less electricity. This creates a problem for grid stability, because supply must match demand in real time.
One solution is energy storage, like large-scale batteries. But batteries are expensive and have limited lifespans. Another approach is to overbuild solar capacity and then curtail—or waste—excess energy during peak production times. That seems inefficient.
A more innovative idea involves using solar power to produce hydrogen fuel through electrolysis. When there's surplus solar energy, we can split water into hydrogen and oxygen. The hydrogen can be stored and later used in fuel cells to generate electricity when solar power is unavailable. This effectively turns solar energy into a storable, transportable fuel.
However, there are challenges, such as the efficiency of electrolysis and the infrastructure needed for hydrogen storage and transport. But it's a promising avenue for solving the intermittency problem.
❓ Câu hỏi What is the main challenge with solar power that the professor discusses?
A. A. The high cost of solar panels
B. B. The intermittency of sunlight
C. C. The lack of government support
D. D. The environmental impact of manufacturing panels
✅ Đáp án đúng
B. The intermittency of sunlight
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word