Level 7: Storing energy

Energy and power · level 7 of 8 · rough age 15-16 (a guide for parents; anyone can start anywhere)

Sunlight comes by day and stops at night, and on Mars a dust storm can dim it for months. This level is about keeping energy for later: in batteries, in hydrogen, in spinning wheels and in raised weights. You compare them by energy per kilogram and by how much comes back out, then size a store to carry a base through a storm.

Lesson	You will be able to
Why store energy?	Size an energy store from the power needed and how long it must last
Batteries	Use \(E = QV\) with amp-hours and watt-hours, and explain why cold hurts a battery
Hydrogen	Follow energy from electrolysis to a fuel cell, and find the round-trip efficiency
Flywheels	Use \(E = \tfrac12 I\omega^2\) to find the energy in a spinning wheel
Pumped storage	Use \(mgh\) to size a store of raised water or weights, on Mars and on Earth
Through a dust storm	Size the store a solar base needs to get through a long dust storm

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