“Renewable” Energy: Solar Photovoltaics and Stochasticity
Summary: When it comes to using energy available on Earth, solar is clearly the way to go. Apart from a few dark episodes in our deep past when our tiny ancestors huddled around deep-sea volcanic vents during long ages when the oceans were frozen over, solar power has been the energy story of life and has provided the great bulk of human exosomatic energy use. When you start a campfire with old wood, eat oatmeal from your field, or make rabbit stew, you’re manipulating solar energy. As we have seen, baseload power generated by burning fossils is solar energy that was sequestered long ages ago. We have been indirectly tapping solar flows from the get-go, so directly tapping solar flows makes good intuitive sense. And now, using fossil energy, we have created several mechanisms that can do that. The simplest are mirrors... if you reflect the sun from mirrors onto a small spot, you can generate very high irradiance at that spot, creating high temperatures that can be used to drive power turbines. Such systems can also “store” the heat in materials as molten salt, thereby evening out the solar power to something that is more like baseload. Of course, this works best in areas where there is intense sun and few clouds, such as deserts, and most humans do not live in deserts.
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