Fossil Fuels and Non-Renewable Energy

the only non-renewable energy you should be fueling with is food so you can hit the gym.

What are fossil fuels? Why are they still the main component of our energy system?

What is a non-renewable resource? What about renewable resource or sustainable resource? Provide an example for each.

Non-renewable resource = when its regeneration flow is neglibible compared to its rate of extraction/consumption on any timescale that matters to humans → stock-limited

• E.g. coal, oil, natural gas → millions of years, so natural inflow is VERY low, aka for us humans we just consider it stock limited. It’s not regenerating in our lifetime…

Renewable resource = replenishes at rate comparable to/faster than rate it’s being use → flow limited

• E.g. solar energy

Sustainable resource = can be used long-term without depleting the resource or causing unacceptable environmental/social damage

• e.g. solar/hydro energy

So they are NOT the same!

What is energy? What types of energy are there?

Energy = the ability to do work

• Types: Kinetic, potential, mechanical, electrical, chemical

Energy quality is a measure of that ability to do useful work.

• High quality → high temp heat, sunlight, high speed wind

• Low quality → low temp heat, dispersed chemical enery

Not all energy forms are useful!

What are the laws of thermodynamics?

1. Energy is never created or destroyed, simply converted into different forms

2. Energy conversion always leads to losses (some energy is wasted

How are fossil fuels energy sources?

• Compounds like C and H

• Energy is stored in chemical bonds, then released by combustion (exothermic reaction, so releases heat)

Energy density = Amount of energy per unit mass or volume

• Different among different types of fossil fuels

• Useful to compare energy sources or energy carriers

Products of combustion are mainly CO2 and H2O (but also other compounds)

The pollutants produced → depends on the fuel type + type of combustion (e.g. NOx, SOx, PMs, ash)

How do we measure energy? What terms do we use?

Net energy = energy output - energy input

• Energy resources vary greatly in their net energy

Net energy ratio (NER) = energy output/energy input

• (Energy returned on investment)

• Measures total usable enery gained from a resource compared to the total energy spent to extract and process it.

Energy conversion efficiency = measures how well a specific device/process converts an energy input into useful work or output.

• Efficiency = (useful) energy output / energy input

What are the trade-offs of oil?

Trade-offs for natural gas?

Trade-offs for coal?

Overview of fossil fuel trade-offs

What are the basic energy/power formulas?

Power = Energy/Time

• Energy = joule, J

• Power = J/s (aka W, 1W = 1 J/s)

Energy = Power * Time

What are the two types of nucleaer power?

1. Nuclear Fission = Splits a larger atom into two or more smaller ones

2. Nuclear Fusion = Joins two or more lighter atoms into a larger one

Overall, it’s still chemical energy, but nuclear energy per nucleus is 1 million times the chemical energy per atom.

Explain how nuclear fission works, and what the main trade-offs are.

It’s a chain reaction initated by neutron.

1. Low-enriched U → fuel rods

2. Rods bombarded with nuetrons

3. U-235 atom hit, unstable U-236 produced, splits, etc. → chain reaction

4. More mass than the products, so difference in mass is released as neutrons and energy 🙂

For U: U-235 and U-238 are fissionable, while U-235 is fissile 9can undergo using low-energy/slow neutrons), but U-238 is super abundant, because it’s more stable (but therefore worse for energy generation).

• Drawback:

• Need to increase amounts of U-235 (enrichment)

• Neutrons are often lost bc U-238 is more abundant, neutrons are absorbed by other materials, they can escape

• 65% of energy produced is wasted, it flows into atmosphere through gigantic cooling towers instead

• Coolants can be faulty,… disaster

• Nuclear waste, rods must be replaced, waste facilities can be permanant

What is nuclear fusion? Explain the process and drawbacks.

Nuclear fusion = Merging small/light nuclei also releases large amounts of energy

• Making a little sun on Earth

• Isotopes of H, D, T

• D+T → He + heat

• A lot of obstacles in the way, sort of futuristic, but basically fusing of atoms.