Okay, so i get that it's a gameplay mechanic but let me get this straight..... The humans return to the planet that is extremely cold and basically uninhabitable due to this cold because they encountered some giant insects that produce (well, have inside of them) heat energy which gets dropped when they are killed. Now, when you're in the game you pick up this energy and it gets used up by your suit and the mechs that you pilot to keep you alive in the cold.
The rate at which you run through this energy is around 2 units per second at idle but when in a VS suit it increases to somewhere between 5-15 per second if you're doing anything other than walking.... you can effectively run through 1000 units easily in a combat situation that lasts less than two minutes.
Oh, did i mention that the amount of heat energy you pick up from the deceased insects is pretty negligible most of the time, like 50-100 units or so? The larger units like mechs and huge things usually have 200-500 units but they're far fewer in numbers.
It makes no logical sense... i'm burning through this stuff while killing these things. It's not cost effective or an energy efficient process. In one mission that took me 42 minutes I collected 32,000 heat units but ended the mission with only 8000.... That's 24000 units completely lost. Why are we on this planet again?
Despite running down so quickly you get a lot from the beacons which inexplicably contain 1000 or so units which kind of makes the whole mechanic pointless since you're always able to keep your heat units topped up by these frequent reservoirs. The game would have been better served by just having regenerating health (as it already does) and none of this heat unit collecting stuff.