Before star I want to note this:
- 1 PW = 1,000 TW, 1 TW = 1,000 GW, 1 GW = 1,000 MW, 1 MW = 1,000 KW
- This can also be used with PJ, TJ, GJ, MJ and KJ.
- Also note that to convert Kelvin to Celsius you have to substract or sum 273.5.
- m^3 or m3 and m^2 or m2 are the same.
Solar panels could be very useful like a renewable source of power. It's a pity that solar power always have to be a secondary source power and you must to have batteries to store emergency power.
Comercial solar panels have efficiencies of 20% - 25%, investigation solar panel have 40% - 50%, and new theorical panels have reached 58%. You said that we can make our own physical laws so I think it won't be a problem have a 95% efficiency solar panel.
- If the ship is in Earth orbit it would produce an amount of 1,296.75 Wh/m^2 aproximately, knowing that you have 1 km^2 of surface >>> 1,29675 GW/h. In Mercury's orbit (closer to the sun) it would produce 8.66 GW/h.
Nuclear reactors could be a perfect soltion, they doesn't need light, they only need a little amount of uranium-235 to work, remember that uranium have 83.14 TJ/kg equal to 23.0944 GWh/Kg, 19 times the energy generated by one hour in the Earth's orbit with solar panels, in a setting were nuclear reactor have been mastered you could have an almost 100% efficiency and even use low enriched uranium, plutonium, etc. Also you could use remaints of fuel to make weapons...
Also, if you don't want to spend water in the nuclear reactor (remember that nuclear reactors heat water used to produce energy in a turbine) you can have a dozen of littles radioisotope thermoelectric generators (their use pellets of 238PuO2).
Who want fission power with uranium when you can simply fuse a drop of water!
Maybe your are not familiarized with the term so I will quote this:
Fusion reactions occur when two or more atomic nuclei come close enough for long enough that the strong nuclear force pulling them together exceeds the electrostatic force pushing them apart, fusing them into heavier nuclei. For nuclei lighter than iron-56, the reaction is exothermic, releasing energy. For nuclei heavier than iron-56, the reaction is endothermic, requiring an external source of energy. Hence, nuclei smaller than iron-56 are more likely to fuse while those heavier than iron-56 are more likely to break apart.
In this page there are a lot of different fusion reactor if you want to use them.
Fusion can be made with a lot of materials, water (H2), deuterium, tritium, helium, litium, etc. For example a large power station generating 1,500 megawatts of electricity would consume approximately 600g of tritium and 400g of deuterium each day.
- Fussing 1 kg of helium-4 (Alpha particules) could produce 16 TWh. See triple-alpha-process.
- Fussing 1 kg of deuterium could produce an amount of 2 PWh. See proton-proton chain
- Fussing 1 kg of deuterium and helium-3 could produce 362 PWh.
Solar Fusion Power
I have marked this in cursive because it's a compound energy generation system. This idea come from the Destiny, Do you know what I am talking about? If not put in your browser:
Stargate Universe: Destiny Recharge Power.
The idea of this system is to collect solar energy with a new way. This system is only suitable by armored or shielded ships (for the high temperature). The idea is come closer the ship to the Sun's Photosphere and steal a little part of Sun's gas.
The photosphere is compound of 74.9% Hydrogen and 23.8% Helium at 4,500 K and 6,000 K with a density of 2×10^−4 kg/m^3 (0,2 g/m^3), so each cubic metre of photosphere have 13,35 GWh only in Hydrogen.
If you use the material of a star to produce energy you can make a stellar nucleosynthesis like the CNO Sun cycle witch produce 177 TWh per kilograme of hydrogen (CNO means Carbon - Nitrogene - Oxigen but their are catalyst, hydrogen is the fuel). There are a lot of more reactions.
Basically is a ship who produce a very big magnetic field to capture hydrogen atoms of the space and produce nuclear fusion. Because there is only a little of hydrogen per m^3 of space this ship must to travel at a minimal speed of 1% ligh speed (I would put the link of this but I found this information 1 or 2 years ago). Maybe you could be interested in this answer.
Did you know that 1g of antimatter produce 180 PJ equivalent to 50 TWh when it touch 1g of matter?.
Well, It speak by itself. I don't know how to get an important amount of antimatter (neutron stars produce some thousand possitron per second) but for a sci-fi setting you could say that black hole produce antimatter.
Well, am tired of write so I will only write their names and a link. Their are taken of Stargate
I found this useful answer, basically you could have a room filled with radioactive diamonds. (How to make them).