powersolar energywindturbine
I tried looking it up but there's no answer for this. This is mainly concerning nuclear power plants or natural gas plants, where they would have other buildings attached on site to operate the plants.
When they run the plants does it go to the grid and then back to the facilities? Or are the building circuits directly powered by the plant electricity, then the remaining electricity goes to the grid?
I also assume wind farms and solar PV farms don't have this concern, but I could be wrong.
A resistor will reach a thermal equilibrium when the dissipated energy equals the energy drained to the environment. To drain heat to the environment the resistor's temperature has to be higher than the environment's; the higher the temperature difference the more heat will flow. So the resistor can dissipate more power at low environment temperatures. Rated power may be specified at 25°C and derate at higher temperatures. These thick film chip resistors derate only from 70°C, as the following graph shows:
So a 100mW 0603 can still dissipate these 100mW at 70°C, but shouldn't dissipate more than 50mW at 100°C environment temperature.
The datasheet doesn't give suggestions towards copper layout (land patterns and trace widths) which will influence conducted heat. (Convection will be low for SMDs, and radiation almost zero; the temperature is too low for that.) It may be tempting to have lots of copper connecting to a pad, but make sure that this doesn't cause trouble in soldering.
To do these calculations, it's easiest to work in terms of power instead of current. For example, if your camera is averaging 250mA at 5V, then that is 5V x 0.25A = 1.25W. If you are running it for 24 hours, then that's 1.25W x 24h = 30 Watt-hours ("Wh") per day.
For comparison, your 40 Amp-hour ("Ah") battery, at 12V nominal, has 12V x 40Ah = 480 Wh of capacity.
With no other considerations, this would mean that the camera (by itself) would operate for 480Wh / (30Wh/day) = 16 days on the battery. Of course, there are many other considerations, including the inefficiency of converting your 12V to 5V...
Please look at this answer I made for a different application. It details the considerations and calculations for a battery powered system with possible solar input.
Good luck!
Best Answer
When a power station is up and running the power it generates can be used to power its internal operation.
However, many power stations do not have the ability to bring themselves back into service after a major outage. (referred to as a "Black Start").
It may not be worth the capital expenditure to provide adequate backup power (that would only be used very occasionally) to perform start-up; instead, they would use power from the power grid relying on other power stations in the same region. At least one would have to have the ability to bootstrap itself.
Wikkipedia - Power Station Black Start
Hydropower Plants as Black Start Resources