I completely forgot about inserts reuired to make the rocket fuel, thanks.BlakeMW wrote:I've been thinking about rocket fuel in boilers. You lose 10% of the fuel value by converting solid fuel to rocket fuel but otoh you can use productivity modules and with 4x Prod3 module in assembler 3 you get 26% more fuel value - a gross profit of 45MJ of electricity. The net profit is trickier, I think the minimum cost to perform the conversion (fully utilized alternating rows assembler/beacon) is about 15MJ leaving a net profit of 30MJ. Of course, if supplementing with solar power the electricity expense can be further discounted.
Rocket Fuel also saves energy on inserts (for all inserter types, not only burner inserter) but actually increases total factory inserts because the 10 solid fuel had to the inserted into the chemical plant to make the rocket fuel - you're not saving energy on inserts, only changing where those inserts happening and causing more inserts.
But the last part, did you account for the inserters used to make rocket fuel will not be burner inserters but stack inserters or fast ones? The number of inserts isn't the only thing that determines how much inserter energy is used since different inserters use different amounts of power. The inserters that are working often are more energy efficient/movement and the ones moving the rocket fuel into boilers have no drain.
Also if inserter energy used goes up from making rocket fuel it doesn't matter that much with how much extra is gained by productivity modules. Burners are still the energy efficient alternative at your boilers with rocket fuel now, so maybe people will stop using electric ones for the tiny energy usage advantage electric ones have for coal. Using electric ones is just a big risk and hassle.
But getting rid of overdraw killing your power plant completely requires burner mining drills, burner inserters at coal train stations for un/loading cargo wagons, no bot transport of fuel. For oil it's not possible to get rid of your electric dependence. The most important part is inserters to boilers though since it requires a pretty short overdraw to activate the death spiral. You should also also use burner inserters from your buffer storage at the power plant to belts. If you place stack inserters higher up on the belt then the burners will idle until the stack inserter lose power, so they will only activate in an emergency anyways.
But ultimately inserters are not a big power drain for your factory anyways.