Narrator: Listen to part of a lecture in an environmental science class. Professor: So, we've been talking about renewable energy sources, and today I want to focus on tidal power. Unlike solar or wind, tidal energy is predictable because it depends on the gravitational pull of the moon and the sun, which we can calculate with great accuracy. However, there are significant challenges. One major issue is the high cost of building tidal barrages—these are essentially dams across estuaries. They require massive concrete structures and turbines, and the initial investment is enormous. Also, environmental impacts are a concern. For instance, the barrage can disrupt the migration patterns of fish and alter the sediment flow, which affects local ecosystems. Some researchers are exploring smaller-scale tidal turbines that can be placed on the seabed without blocking an entire river mouth. These have less environmental impact, but they generate less electricity. So, while tidal power is reliable, we still need to weigh its benefits against the costs and ecological consequences. Any questions? Student: Yes, professor. You mentioned predictability. Is that a unique advantage compared to other renewables? Professor: Great point. Wind and solar can be intermittent, but tides are constant. This makes it easier to integrate into the grid. However, the high upfront costs remain a barrier. Now, let's move on to another example...
❓ 题目 What is the main challenge of tidal power discussed by the professor?
A. Intermittency of tidal energy generation
B. High construction costs and environmental impacts
