Clear Science!

A current (simplified) view of the electrical grid shows that the demand for electricity and the amount of electricity generated must essentially match. This is done by ramping power plants up and down as people change how much electricity they want.

Solar power and wind power are not easy to regulate. But we want to be able to make them a large part of the grid, since they’re green. One way to do this is add electrical storage to the grid, which is like being able to put electricity in a box and save it for later. During periods of low demand you fill up the storage and then use it during high demand. A charged battery is an example of “stored” electricity.

We’re going to address the question of why making energy generation more environmentally sustainable is an important but difficult problem. Take solar power. One very big problem with solar power one may not realize is that it is intermittent and unpredictable.

Of course you know the sun shines in the daytime and goes down at night. If you plot power generated versus time of day, this will produce a smooth parabola (arc or rainbow shape). When clouds go over, however, it causes sudden dips. Your solar array might even shut off. 

We are going to talk about energy for a while. Humanity uses energy a few ways. Sometimes we make electricity first and then power things with that. Other times we burn fuel directly to power an engine or a heater. But let’s step back and ask: where does energy come from in the first place?

Shown above are several primary generation methods for making electricity. What’s actually happening is that we are taking energy from somewhere else and converting it to a more useful form.

Fossil fuels like coal or oil have energy stored in the chemical bonds inside them. When we use fossil fuels, we are claiming that energy. Nuclear generation is similar, but it’s from the atomic bonds within the nuclei of the fuel materials.

If a material is high in a gravitational field it also has energy, and that is what we’re claiming with hydroelectric generation. Water up high is being lowered, and we get the energy liberated by lowering it. Wind generation claims the kinetic energy from blowing wind. Solar generation claims the radiation energy emitted by the sun.