Fusion on the sun but not here on earth?

Question

why is it that fusion happens all the time on the sun but is very difficult and requires a huge amount of energy on the earth.

Fusion does happen on the sun all the time. and the reason that the son is hot is because of fusion. the reason that fusion works on the sun and not earth is because the Sun is enormous and has a huge gravitational force unlike the earth. Therefore the sun's gravity forces together isotopes that have opposing charges. On earth we use electro magnetic force. but it takes a huge amount of electricity just to make one little fusion.

P.S. A solar panel uses converts solar energy into electrical energy it has nothing to do with fusion.
whatsername needs to get his facts straight.

Answer 1

To make fusion happen, besides needing Hydrogen, you need three things:

Time
Temperature
Pressure

We, on Earth, don't have the temperature and pressure for fusion under normal Earth conditions. And when we use the fusion reactors we enough for a short period of time which means we don't get that big of a return. Additionally, it takes a lot of energy to get the right temperature and pressure.

(We do have Hydrogen bombs, but they aren't very useful for making useful energy).

The sun, in its center, has the temperature and pressure and it has the time for the reaction to take place. The fusion rate on the sun is actually low and slow because the temperatures and pressures aren't that great, but unlike earth, there is no containment problem, so the reaction can just run and run and run. The sun is suppose to last another 5 billion years burning Hydrogen at the rate it is now. :)

Answer 2

The answer is simply that fusion does not happen "all the time" in the sun. It is actually a very rare event!

The sun takes billions of years to burn through its fuel, a fusion reactor on earth, on the other hand, has to fuse a significant amount of nuclei in its volume in a rather short time. Therefor, the conditions created in a fusion reactor on earth require much, much hotter and far less dense plasmas. And since the plasma on earth has a rather small volume, the energy loss through the surface is enormous in comparison to a typical volume element in the sun's core.

Fusions is not that difficult to achieve on earth, either. Any thermonuclear device can do it. It's just not a very neat and useful process. The magnetic confinement devices, on the other hand, are bulky and expensive. They would work wonderfully and could probably be built rather cheaply per W output power, if we just could scale them up ten-fold (in linear dimensions) to minimize losses. But now you are talking about a reactor with 1000GW output... we don't need that much energy, especially not in one spot. And the cooling of something like that would be nearly impossible without enormous environmental impact.

Fusion is great... in the sun. Put a solar panel on your roof and you get all the fusion energy you want... for cheap (at least in comparison of what you will pay for the reactor made energy).

Answer 3

To answer your question, it requires a huge amount of energy IN the sun, but the sun can easily provide it. Earth is basically a cold rock compared to the sun, we get most of our energy from it.


Its just a matter of time before we can do it easily.
Think of nuclear power (fission), we first made a bomb, and now we have reactors to provide us with energy.
Think of sub-nuclear power (fusion), we made a bomb, its just a matter of time before we can controll it.

Here is the crux of the matter, the sun is so huge that it doesnt mind having hydrogen explode in it all the time, the gravity contains the energy, if the gravity stopprd containing the energy we would get a supernova.

Earth however is very very very VERY small compared to the sun, our gravity is so weak we defy it incredibly easily. This means fusion on earth cannot rely on gravity to vcontain it, and since we dont have a material strong enough to contain it artificialy we fail. Making H-bombs (fusion) is easy, we dont need to contain it, but its very destructive.

Answer 4

Fusion doesn't require a huge amount of energy to occur on the earth. The problem is that the reaction cannot be controlled like fission can.

Answer 5

It requires just as much activation energy on the Sun as it does on Earth. Difference is, that amount of energy is present in the deep hot sun. It is not present on the Earth.

Answer 6

I think its b/c of the diff in heat .. i mean the heat on the sun is really high .. therefore the fusion happens .. but the heat on earth isnt enough....