As we all know, energy cannot be used but only transformed from one form to another. So, we have the heat energy given off by beam weapons overloading. Why not convert the heat energy, into kinetic energy to turn a dynamo which can in turn transfer the kinetic energy back into electrical energy to power the jump drives, or to provide more power to other systems. (whether this is realistic/possible... perhaps someone could shed some light here)
This is going to be big but it should answer all questions on the "getting waste heat from turrets to generate energy"-problem:
Little introduction on myself: I'm currently studying system electronics and part of my education involved power plants and energy production.
There are several laws in physics which you have to take into account, here. What you're describing is actually already done in power plants of the 21st century.
1. Every system in physics strives to reach it's lowest energy state. It's the reason why elements form molecules. Sodium and chlorine form a bond where their outer electron shells are full which is a lower energy state for every atom. The surplus energy in this reaction is radiated as electromagnetic radiation.
2. Every system strives to maximum entropy. Meaning the temperature within a gas will even out over time. Maximum entropy means minimal energy density, a lower energy state and you need energy to "order" the gas and get an uneven energy distribution, again.
3. Energy does not simply "sit in your power grid". You have to store it in capacitors, or any other energy buffer of the 24st century. Storing energy is a lossy operation duo to the resistance of conductors and isolators.
4. Every energy conversion into useable energy (maybe electric power) is lossy. You will always get waste heat to deal with until maximum entropy is reached.
To extract energy (with any device known in the 21st century) you need displacement of energy or moving energy. Movement is generated with a temperature gradient, for example. But also with pressure differences. (A cold and a hot place, for example). The heat will move into your colder medium, hot gas and high pressure moves towards the colder, low pressure environments. A greater difference in energy potentials forces more energy to move, therefor you get more out of it. I don't have to say that it's not worth to try extracting energy from the heat dissipation of a human being. The differences in potential energy are to small.
So what can be used to exploit this:
- Beam weapons probably produce a vast amount of waste heat which can be used.
- Laser turrets are a nice source, as well.
- Any waste heat from high temperature reactors, but they usually already use their waste heat for power generation.
What can't be used:
- Computer equipment. (Which does not produce that much waste heat, sadly. And furthermore, it's more likely that quantum computers are used in the 24st century, which have to be cooled down to only a couple of kelvin. Meaning the gradient is to small for sufficient energy production.)
- Waste heat from life support and air conditioning. (These systems have to operate at their most efficient point. Also, they consume energy to cool or heat the environment for the crew. Extracting energy from this system would be the same as decreasing the energy you put into the system. This is the reason why your fridge or air conditioning does not produce energy from it's waste heat.)
- Waste heat from dynamos or energy conversion systems themselves. (This exhaust has already reached the state of maximum entropy and can not be used)
How would you do it:
It could be possible to use a cooling grid, which takes heat from all weapon hardpoints, cooling them and taking the heat to an additional power plant.
This power plant extracts energy from the surplus heat of your turrets and creates power for your ship. But wait! You need a temperature gradient to extract energy! This power plant would also have heat sinks, probably build into the ships hull to get rid of it's own used waste heat. After all, the coolant for your turrets has to be cooled down, again. 1. To create a heat gradient in order to extract energy in the first place. 2. To cool the turrets, again.
Every power plant has to get rid of entropy, or else it stops functioning.
Such a system would only prevent some of the energy wasted to heat actually become wasted completely. It's more likely a solution to make your ship more efficient in energy use, but there will still be waste heat.
This energy has to be stored within a buffer, as well and must be available for fast access. Capacitors in our real world heat up if they're under heavy load. (Lots of charging and discharging) the amount of energy used by weapon systems must be incredible high. This creates a 2nd source of waste heat which has to go somewhere.
Where are the limits of this system:
- heat dissipation through the ships hull. (This is not an easy task, since the only way to radiate heat away in space is actual radiation and not conduction, also external events like incoming warheads and heat from stars add to your heat balance)
- heat accumulation within the cooling cycle. (It's a cooling system, therefor this is a bad thing)
- Actual cooling power needed by your turrets. (They still have to be able to maintain fire)
What does this mean for beam overloads?
- It still happens when fire control is faced with a heavy battle.
- Every turret, even though cooled, has it's own problems with internal heat building up. The conduction of heat within a material is limited by it's chemical and physical properties
- The same amount of heat has to exit the ship, there's no difference. We generate energy from moving energy potentials not from heat itself.
What do I think of it:
Well, I think in the 24st century, space fairing warships are already doing this. We do it nowdays already. It does not change the fact that huge space ships with weapons which probably drain gigawatts of power each wouldn't have significant problems with their heat management. After all, it is much harder to radiate heat away in space. An environment, where no heat conduction to other materials touching the hull exists.
But I like the fact that someone actually thought of this possibility, since it would be quite an improvement for energy production.
Sadly, we don't know how much energy a subspace jump actually takes or how much beam weapons drain, but I would assume it's a lot!
I hope I could clear out some questions. I'm afraid I actually summoned new ones. ^^
