8.4 Solar, Wind and Hydropower

Notes

Renewable sources produce little pollution during operation and do not run out, but have trade-offs.

• Solar: photovoltaic (PV) cells turn sunlight directly into electricity; solar thermal concentrates heat. Passive solar designs use windows and thermal mass. Limits: works only in daylight, needs storage, and uses land and materials.
• Wind: turbines convert wind to electricity. Best on open plains, coasts, and offshore. Limits: intermittent, can kill birds and bats, noise, visual impact.
• Hydropower: moving water spins turbines. Provides reliable electricity but dams flood habitat, block fish migration, and change river flow.
• Intermittency is addressed with batteries, pumped storage, a wider grid, and mixing sources.
• Costs for solar and wind have fallen sharply over the past decade.
• Example: a solar panel produces little at night, so a battery or grid connection is needed.