How do i convert energy into carbon dioxide in (grams)?

Question

How do i convert energy into carbon dioxide in (grams)?

Answer 1

Stoichiometry

Answer 2

It depends on a number of things.

Firstly, what kind of fuel are you using? Different molecules will have different chemical potential energy, and will also release different by-products (like CO2, or other greenhouse gasses, or other things like sulphates).

Secondly, how are you using it? Burning the fuel is one way, but there are other chemical reactions that are sometimes used with coal (like gassification).

Thirdly, what efficiency are you converting the stored chemical energy at? Most processes we commonly use aren't particularly efficient, so a lot of energy is lost as heat or sound.

A good example is coal, burning in a coal powerstation: One tonne of black coal releases about 2.6 tonnes of carbon(1), but most coal powerstations are less than 40% efficient, because of all the waste heat. One tonne of coal coal burn produces between around 24 Gigijoules (3), which is equivalent to about 6.6 megawatthours (1 joule = 1 watt/s, so divide by 60sec, and again by 60min)

6.6mwh = 1tonne = ~2.6tonnes of CO2

take into account 40% efficiency

6.6mwh = ~6.6 tonnes of CO2

So for black coal, around 1 tonne of CO2 per MegaWattHour, depending on the quality of the coal, the method of burning, and the energy conversion efficiency. This might be fairly different for different fuels.