UNIT III C – Petroleum as an Energy Source
C.2 – Energy
Q: Where does ALL of our energy come from originally?
Q: How many different types of energy can you thinkof?
Q: Can you draw a picture showing how the energy from the sun becomes energy in my muscles (I’m a carnivore by the way!!)
Photosynthesis – radiant energy from the sun converted to chemical energy in plants
Biomolecules – organic molecules in plants and animals
Q: What sources of energy did we use 100 years ago?
Q: What changed? What made this become insufficient?
C.3 – Energy and Fossil Fuels
- “Fossil” fuels contain chemical potential energy
- Chemical reaction of burning fossil fuels results in release of energy we can use
- Determination of what is a “good” fuel depends on net result of the bond-breaking and bond-forming steps
- Consider the burning of methane:
- CH4 + 2 O2CO2 + 2H2O + energy
- Bond breaking – Endothermic (requires energy input)
- Energy + CH4 + 2O2C + 4H+ 4O
- Bond forming – Exothermic (gives off energy)
- C + 4H + 4OCO2 + 2 H2O + Energy
- This overall reaction is exothermic,… so methane is a pretty good fuel!!
- If a reaction is exothermic, then the reverse reaction will be endothermic
- CH4 + 2 O2CO2 + 2H2O + energy
- energy + CO2 + 2H2O CH4 + 2 O2
- Can you see why it would not be advantageous to put the combustion products of petroleum back together to make “new” fuel??
Q: How do you get the energy to cook your Ramen noodles (start from the very beginning…)
Q: Is each conversion 100% efficient?
Q: would it surprise you to know that gas engines are only 25% efficient at energy conversion?
- Law of conservation of Energy : total energy of the universe is constant – never created or destroyed