Activity Overview: The Sun is the ultimate source of energy for almost all processes on Earth, from weather and climate to fossil fuels to the energy students need to get out of bed or run around the track. The only non-solar energy sources are the moon, which provides the forces for tidal energy, and uranium, which provides the raw material for nuclear energy. This activity relies on deep questions and critical thought to trace the ultimate source of energy on Earth to the sun.
Start with those primary energy sources that are obviously solar; photovoltaic panels convert light from the sun into electrical energy. Similarly, concentrated solar power facilities concentrate the sun's heat for industrial processes or thermoelectric energy production.
Lead students from light and heat in the traditional sense of industrial energy production to the more abstract concept of climate and weather, recalling your class's progress through weather and climate science. The sun causes the difference in surface temperature that cause winds, which in turn can generate electricity if harnessed appropriately. Further, the sun's energy powers the global water cycle, which lifts water from it's stores on Earth's surface to condense in the atmosphere and then fall elsewhere, where it can be retained in a reservoir and leveraged for generating hydroelectric power.
Take a step further from precipitation, and consider the sun's role in photosynthesis. The sun provides the energy required to grow all biomass, and therefore also for fossil fuels. Ancient algae and other organisms converted energy from the same sun into their energy to live, and after they died, that energy became oil and natural gas through thousands of years of compression and other forces.
Time: 20 minutes
Write each of the forms of primary energy on the board or project them on the overhead projector. Use structured questions to determine as a class which sources gain their ultimate source of energy from the sun.
Hydroelectric: "What moved water so high that it might have a strong potential energy before flowing through a dam?"
Wind: "Winds are caused by grand scale disparity in surface temperatures. What causes these differences?"
Biomass: "From where do plants receive the energy they need to live and grow?"
Tidal: "What causes the tides?" - This one is answered by the moon.
Fossil Fuels: "What is the ancient raw material for fossil fuels and what living organisms do these most resemble?"
The Bradbury Science Museum operated by Los Alamos National Laboratory produced a short one-page regarding the source of nuclear material when they made a statement generalizing that all energy came from the sun.
The introduction for this activity was adapted in part from the Renewable Energy section from Resourcefulness: An Introduction to the Energy-Water Nexus.