By Anupum Pant
Sun is an huge fusion reactor. Every second it produces enough energy that could power the US for 9 million years. But from the perspective of people living on earth, most of it radiates into the space and gets ‘wasted’. Still by using even the part of energy that is received by us, a solar death ray that melts steel can be built.
Earth is only a fraction of the size of sun. In comparison, sun is so mind-boggling-ly big that I bet you can’t manually scroll this page from Sun, all the way to earth (and this is a heavily scaled down version of our Solar System). In short, earth is so small that it receives a microscopic fraction of the energy radiated out by the sun.
Technically: The total flux received by earth is about 343 Watt per meter squared. On the way to earth’s surface, 30% of this gets scattered by the atmosphere and 19% of it is absorbed by the clouds. So, out of 343, only 51 percent reaches the surface. Which is calculated to be about 175 Watt per meter squared. Which is a very small part of the energy that sun gives out. [Source]
And yet, sunlight received by earth has by far has the highest theoretical potential of the earth’s renewable energy sources.
Harnessing this energy
For humans, it is possible to directly harness this energy broadly in two ways – heat or electricity (photoelectric effect). We are interested in only the heat part here. To demonstrate the kind of heat that can be generated by focusing 2 meter square worth of this energy to a single point, watch how this equipment can melt steel in seconds (The melting point of steel is around 1500 degree centigrade).
Making at home
Building something similar at home is fairly easy as far as the concept is concerned. But the process can be very tedious. I found three interesting ways in which this can be done at home.
1. Using a satellite dish: A satellite dish is parabolic and is designed to focus signal to a single point. Instead of signal, you could use it to focus light (sun rays). To use an old dish for making a solar death ray, all you’ll have to do is stick 5,800 tiny pieces of mirrors on its surface, like Eric Jacqmain did. – [Source]
2. Use a projection TV: A projection TV has a huge Fresnel lens in front of it. It is kind of a convex lens that is flat. If you can find an old projection TV, you could use the screen to make a solar death ray like Grant Thompson did.
3. Using water: Another creative way could be to use water. By combining the power of gravity and stretching plastic, you could turn clear water into a parabolic lens like this [Video]. Although I don’t think something like this could be efficient enough to melt steel. It could still be used as an outdoor machine to cook breakfast.
EDIT: Why isn’t there a comments section?
First I forgot to add this and remembered only when a reader pointed it out. I promised in my yesterday’s post, that i’d tell you the reason behind a missing comments section on this blog. Here it goes…
I use a theme built by Leo Babauta (see FAQ) and am a fan of his teachings. It [the theme] has an inbuilt comment section but Leo doesn’t use comments on his blog. For me to not use it too, there are 3 reasons:
- I’m a fan of Leo Babauta and try to emulate his ways in my life. (not perfectly)
- I want to create a pure reading experience for the reader (now ads, which hinder the pure reading experience, are for experiment only). People who really like to interact usually mail me. And it is a much more enriching experience.
- Unlike every other blogger, comments have a great effect on me. This in turn affects my ability to write. For instance, comments which appreciate, seem flattering to me. As a result, I become complacent. If they are critical, I get concerned about my writing abilities. There are hardly any neutral comments. I’d like to focus my energy on writing than arguing on the internet.
I do have plans to include it in the future. It is just that I’m not sure when I’ll do it. Probably when I change my theme, I’ll do that.