1. ts used to day, are hydropower, wind, and biomass truly renewable energy sources? Answer separately for each. 2. Hydroelectric dams can, surprisingly, result in signicant greenhouse gas emissions. What's the source of these emissions? 3. Why can't a wind turbine extract all of the winds kinetic energy? 4. Why is the power curve in Figure 10.13 so steep in the region below the rated speed? 5. Tailpipe emissions of VOCs are lower for ethanol than for gasoline, but overall VUC emissions are higher with ethanol fuels. Why? Er. What accounts for the difference between gross and net primary productivity? 1 By what factor must the wind speed increase in order forthe power carried in the wind to double