Biofuel - best use in steamboiler or combustion engine ?

[Jugg3rV]

I talked to a guy in the chat some days ago. He had a nice programm to calculate the output of a steam tank.

With this one i would like to know if it would be better to fuel a steam boiler with biofuel, or perhaps get 2 combustions running. So if you are interessted, we should do some math here

Right now it's a 4x4 firebox with a 3 block high tank, which feeds 3 normal steamengines. Those keep the logger, fermenter and stil running. The firebox is full of fuel, as are pipes and the stils tank.

 

[Busuwe]

One bucket of biofuel in a combustion engine lasts 40 000 ticks and produces 5MJ/tick for a total of 200 000 MJ
One bucket of biofuel in a 2x2 steam boiler two tanks high (low pressure, max heat) lasts ~11111 ticks and produces 16 MJ/tick (80 steam, 5 steam = 1 MJ) for a total of ~177 777 MJ.
Though, the bigger the boiler the more energy you get out of each bucket! (With longer warm up time as the trade off)
2x2, 3 tanks high you get 188 000 MJ out of one bucket.
3x3, 3 tanks high you get 241 000 MJ out of one bucket!
3x3, 4 tanks high you get 290 000 MJ out of one bucket!!!

Using high pressure tanks does not have any effect on the fuel efficiency in an already heated boiler. It uses up twice as much fuel and produces twice as much steam.
It does require more time to heat up and thus requires more fuel.
Last I heard the warm up time on the max sized high pressure boiler was around 6 hours. During that time you will on average use 4.5 times as much fuel as when it has reached the max temperature.

 

[Meldiron]

In general, a boiler would be favourable for a permanent and stationary machine that is going to be running constantly or for a very long time.
While biomass engines or combustion engines would be preferable for temporary, movable machines that only would run for a limited time.