Fossil Fuel Types

Trevor Craig

Energy Science 110

Fossil Fuel Types: Chemistry and Geology 13

10/21/11         

This lecture was about fossil fuels, different types of fossil fuels and how we can use them. We use a lot of fossil fuels to keep our daily lives going, for our total energy usage 35.03% come from oil, 20.44% from gas, and 24.59% come from coal. The United States primary use for petroleum is for transportation, the amount we use has grown dramatically throughout the years, in 1950 we were using about 3 million barrels of petroleum per day and in 2010 it was a little less than 15 million barrels of petroleum per day, which is a very large increase.

Why do we use fuels like petroleum instead of things like wood, well it all comes down to energy contents of the different substances. Methane or natural gasses have about 50 MJ/kg, where things like wood only has 12-16 MJ/kg, and things like gasoline have a much higher energy content of 42-44 MJ/kg in comparison to wood. Gasoline and oil both have high energy contents, but that is not the only thing that makes them so useful to people; they are liquids so are easy to transport and store, and until recently they have been very abundant.

Oil and coal are both biomasses and are made very similarly but are very different things. Oil starts as algae biomass and with increased temperature and pressure forms into oil shale, then heavy oil at about 100 C, then light oil at 125C, then wet natural gas at 150C, and then dry natural gas at 175C. For coal, it starts as woody biomass, then goes to peat, then lignite, then bituminous coal at 100C-200C, and then anthracite coal at 200C-300C, so as temperature goes up and pressure goes up it becomes its next form.

When we are looking for oil we need to look under the correct conditions, first we need to look in the oil window which is at about 3.5-6.5 kilometer underground and in the temperature between 90°C and 160°C. It also needs a source rock, and reservoir rock layers, and a cap rock layer, if one of these elements is missing then no oil will form, that is why oil fields are so rare only covering a little less than .1% of the land on earth. In oil reservoirs there are mainly 3 different substances in them, first is natural gas with a density of 0.7 kg/m3, then it is oil at 800-1000 kg/m3, then finally water at 960-999 kg/m3. So when companies start pumping out more water than oil we know they are almost out of oil. Oil runs so much of our lives what happens when we all start getting water instead of oil?

Geology- The structure of a specific region of the earth's crust.

Sector- A part or subdivision, esp of a society or an economy.

ENSC110 Fossil Fuel Types 13