Today in our environmental science lecture, we're discussing renewable energy sources. While solar power is popular, wind energy has become increasingly efficient. However, the key challenge isn't generating electricity, but storing it. Batteries are expensive and lose charge over time. One innovative solution is using excess wind energy to pump water uphill, then releasing it through turbines when demand peaks. This method, called pumped-storage hydroelectricity, already accounts for over 90% of global energy storage. It's reliable, though it requires specific geography. So, despite advances in battery technology, this old technique remains dominant.