Let's consider rock and petroleum. Which contains more energy per kilogram? Due to Einstein, we know mass is energy, and the energy contents of both are equivalent. However, let's forget this and consider only practically extractable energy in this question.
I have understood that several nuclear reactor types (breeder reactors) can utilize uranium 100 times more efficiently than current reactors do.
Current reactors work in the following way:
- Enrich uranium to have higher amounts of U-235, producing as a waste depleted uranium having lower amounts of U-235.
- Run enriched U-235+U-238 in a reactor. Some U-238 converts into plutonium. U-235 and plutonium are fissioned.
- When fission reaction becomes unsustainable, store the produced waste. It contains energy in the form of U-235, U-238 yet unconverted to plutonium and plutonium.
Now, you can run a closed fuel cycle:
- Enrich uranium to very high levels of U-235.
- Run enriched uranium in a fast breeder reactor, using extra neutrons produced to convert a blanket of uranium (mainly U-238) into plutonium
- When U-235 has mostly fissioned, replace it with produced plutonium and renew the blanket
Currently, uranium is mined from rich deposits. But actually even ordinary rock contains trace amounts of uranium. If you take one kilogram of ordinary rock, and extract the uranium from it, you can run the uranium (mostly U-238) in the closed fuel cycle of a breeder reactor.
My question is that is the energy content of kilogram of ordinary rock in a breeder reactor actually higher than the energy content of kilogram of petroleum when burned into energy? According to Wikipedia, earth's crust contains 1.8-2.7 ppm of uranium. However, on average granite contains slightly more of it: 4 ppm. These figures can be used as a basis of energy content calculation.
Bonus points will be awarded if somebody points out how many ppm of uranium are in petroleum, and that this uranium could be economically extracted given a high enough uranium price and used in a breeder reactor.