Net Energy Net energy = Higher ratio means greater net energy (high-quality usable energy) – (energy needed to make it available) (find, extract, process) Example: If oil produces 10 units of energy, and it costs 8 to get the oil, then you only have 2 units you can use. The ratio would be 10/8 or 1.25. Higher ratio means greater net energy What does it mean if your ratio is less than 1? Net energy loss

Electric resistance heating (coal-fired plant) 0.4 Space Heating Passive solar 5.8 Natural gas 4.9 Oil 4.5 Active solar 1.9 Coal gasification 1.5 Electric resistance heating (coal-fired plant) 0.4 Electric resistance heating (natural-gas-fired plant) 0.4 Electric resistance heating (nuclear plant) 0.3 High-Temperature Industrial Heat Surface-mined coal 28.2 Underground-mined coal 25.8 Natural gas 4.9 Oil 4.7 Coal gasification 1.5 Direct solar (highly concentrated by mirrors, heliostats, or other devices) Figure 16.4 Science: Net energy ratios for various energy systems over their estimated lifetimes: the higher the net energy ratio, the greater the net energy available. QUESTION: Based on these data which three resources in each category should we be using? Compare this with the major resources we are actually using as shown in Figure 16-3. (Data from U.S. Department of Energy and Colorado Energy Research Institute, Net Energy Analysis, 1976; and Howard T. Odum and Elisabeth C. Odum, Energy Basis for Man and Nature, 3rd ed., New York: McGraw-Hill, 1981) 0.9 Transportation Natural gas 4.9 Gasoline (refined crude oil) 4.1 Biofuel (ethyl alcohol) 1.9 Coal liquefaction 1.4 Oil shale 1.2 Fig. 16-4, p. 358

OIL

OIL Crude oil (petroleum): a thick liquid containing hydrocarbons Extract from underground deposits Plants and animal matter from millions of years ago Oil is widely used because it is: Cheap easily transported high net energy yield

Primary vs. Secondary Recovery Primary recovery of oil: Drill a hole and pump out the light weight crude that fills the hole Secondary recovery – pumping water into the well to force oil out of the pores The oil and water mixture is separated after pumping Only about 35% of the oil is removed by primary and secondary recovery So how do we get more out of these wells?

Tertiary recovery: Tertiary is expensive! Either a heated gas or a liquid detergent is pumped into the well to help remove more oil You an also use bacteria to loosen the heavy crude Tertiary is expensive! So what do you think will happen to the net energy ratio of oil in the future? What the Frack?

Refining crude oil: Separate by distillation Based on boiling points, separates into layers Net energy yield is decreasing as oil is refined

OIL Oil is converted into petrochemicals and used to create… industrial organic chemicals, fertilizers, pesticides, plastics, synthetic fibers, paints, medicines and more. So if oil prices go up…

OPEC – organization of petroleum exporting countries control 67% of the worlds oil and maintain control over pricing

U.S. Oil Supplies The U.S. – the world’s largest oil user has only 2.9% of the world’s proven oil reserves. What do you think most of the oil is used for in the U.S.? Transportation

Heavy Oils from Oil Sand and Oil Shale: Oil shale: fine grained sedimentary rock containing solid combustible organic material called kerogen Shale oil is made from heating oil shale rock then collect the liquid, take out the impurities like sulfur and nitrogen, send to refinery Utah, Wyoming, Colorado

Tar Sand or Oil Sands Tar sand contains bitumen another combustible organic material is high in sulfur Uses more energy to refine It takes about 1.8 metric tons of oil sand to produce one barrel of oil. So compared to oil, Shale oil and tar sands have a lower net energy ratio than conventional oil deposits. CANADA!

Keystone XL pipeline

1 barrel of oil = 158.987295 liters or 42 gallons