Assessment: Sources of Energy and Environmental Impacts

Which of the following is classified as a secondary energy source?

Find the energy released by burning 3 kg of coal with a calorific value of 28 MJ/kg.

A city's energy demand is 300 MW, growing at 6% per year. Find its demand after 8 years.

A wind turbine has blade radius 15 m, air density 1.2 kg/m³, and wind speed 12 m/s. Find the power available, in kilowatts.

How many kg of natural gas (calorific value 50 MJ/kg) must be burned to release 400 MJ of energy?

A factory burns 2000 kg of natural gas with an emission factor of 2.75 kg CO2/kg. Find the total CO2 released, in tonnes.

Why are wind farms often built offshore or on hilltops rather than in sheltered valleys?

A power plant switches from coal to natural gas, which has a lower emission factor per unit of energy produced. What is the direct effect on CO2 emissions for the same energy output?

A country's energy demand grows at 4% per year. Approximately how many years will it take for demand to double?

A wind turbine generates 100 kW at a wind speed of 8 m/s. Using P∝v³, estimate its power output at 12 m/s (same turbine, same air density).