# Why can’t raw energy be stored or used but has to be transformed to heat or other forms and then be used for e.g. electricity?

530 views

They explained how a power plant works in the Chernobyl mini-series. One part that got me thinking is how they use the energy from the fission to heat up that generate the steam which in turn run the turbin and give electricity (Correct me if i’m wrong).

What I don’t understand is why can’t the raw energy from the fission directly be used instead of going the whole cycle? What kind of energy is released from the fission and why can’t it be stored in a battery or capacitor-like thing?

In: Physics

Because a fision doesn’t generates electricity. It generates energy (heat basically). You need to harness that energy into electricity. Turbines do that. Look in Wikipedia how a turbine generates electricity l. Then you just need something to move those turbines. That’s where vapor comes into play. Vapor is water heated by the energy generated in a nuclear reactor. That vapor moves the turbine that generate the electricity thus transforming nuclear power into electricity usable.

In general, heat is produced. In detail it’s flying tiny particles, but they are going to hit something except in a pretty hard vacuum, so in practice you’re talking about heat.

In general, we don’t want to make things hot by slamming radioactive particles into them. So, we turn that heat into electricity.

Energy isn’t real. It’s very similar to money and is used for accounting. Like for dropping something and measuring the value m x g x h of something dropping down by a height h you find that it equals to the final 1/2 x m x v^2. That’s all. It’s a conserved quantity sort of like money. You can trade 3 ferraris for a big house. You can trade an mgh for a 0.5mv^2 . But the ferrari is not money and the house is not money and the ferraris is not house. It’s just accounting.

In reality to get electricity you want a moving electric field. To get that you want a moving magnetic field. To move a magnetic field continuously you want it to rotate. To rotate something you want a reaction fluid to push it. To get the fluid to a high temperature and pressure to be able to push a turbine you need to heat a fluid. Fusion gives off lots of heat.

Energy doesn’t exist on its own – energy is only ever a property of physical systems. This is similar to mass – there isn’t any abstract ‘mass’ floating around, mass is a property of particular physical objects. This is part of why the mass-energy equivalence isn’t as weird as it initially sounds.

So, the energy isn’t liberated in some abstract sense, it is transformed from one place in the system (mass) to another place (kinetic energy of products). Sometimes we can use kinetic energy to produce electricity more directly, by having it drive a magnet through a coil, but since the decay kinetic energy is randomly distributed it necessarily has the form of heat, and we have to build a heat engine. Turbines are, though seemingly outdated, a very effective heat engine.

There is no such thing as “raw energy”. Energy has a number of forms it can exist in, but it cannot exist outside of these forms. Nuclear fission releases energy in the form of heat and electromagnetic radiation. This energy is used to heat water to run a turbine.

Heat energy is difficult to store, due to its tendency to conduct through any insulating media (and nuclear fission produces so much heat that it must be dissipated or the reactor will melt down). And electromagnetic radiation is pretty much impossible to store. So the best way to store that energy is to convert it into a form that can be stored, such as converting it into electrical energy and then storing it as chemical potential energy in a battery.

Atomic batteries do exist which use charged particles like positrons(anti-electron), beta (high energy electrons) or alpha radiation (helium nuclei) to create current, but they are very inefficient. Most of the energy from fission is heat, so that’s what we use.

Energy comes in many forms. Heat, radiation, chemical, kinetic, potential and electrical are all forms of energy. You can convert one to another, but there’s no such thing as pure energy.
Your understanding of how nuclear power works is correct. However moving heat a long way is expensive and inefficient. Moving electricity a long way can be efficient and cost effective. That’s why the heat is converted to electricity.

Fission works by splitting atoms. Uranium has very heavy atoms (lots of neutrons, subatomic particles). It takes a lot of energy to hold atoms together. The bigger they are, the less stable they are. It’s like a Jenga tower, where the taller it gets, the more likely it is to tip over. The atoms are made even more unstable by bombarding them with neutrons. The neutrons either bounce off or stick, causing it to become more massive and unstable.

This causes the atom to do one of a few things. The most desirable action being fission, or a splitting of the atom. When the atom splits, it releases the energy(gamma radiation mostly) that was required to hold such a massive atom together, plus some smaller atoms and neutrons. These neutrons are released with high speed and collide with other uranium atoms continuing this reaction.

Due to all this collision and energy release taking place, it generates heat from speeding up the surrounding particles. After all, heat is mostly just an increased speed of particles.

This heat is transferred into a fluid, typically water, which generates steam, which propels a turbine, which creates electricity.

TLDR: The atom explodes from being massive causing water to heat up which makes steam and generates electricity through turbines

the energy emission from fission is heat already.

The problem of turning heat into something usable like electricity is an engineering problem well studied by two centuries (thermodynamics), and their solution (steam engines) have already reached very high efficiency.

In other words: converting heat to stream, steam (and a source of cold water) to rotation, rotation to electricity has currently the highest efficiency of energy extraction.