Energy and OilLT 8A: Describe the importance of net energy and

discuss the implications of using oil to produce energy.

Net Energy• The usable amount of high-quality energy available

from a given quantity of an energy resource.

Net Energy = Total Energy – Energy of Production

I do: Suppose it takes about 9 units of energy to produce 10 units of energy by growing and processing corn to produce ethanol fuel for cars. What is the net energy of this?

Net Energy

• Can be expressed as a ratio• Energy produced/Energy used to produce it• Ex:

• When the net energy ratio is less than 1 there is a net energy lost.

Net Energy

• Any energy resource with a low or negative net energy yield cannot compete in the open marketplace with other energy alternatives with higher net energy yields unless it is subsidized by the government or by some other outside source of funding.

N

Fig. 15-3a, p. 373

Space HeatingPassive solar 5.8

Natural gas 4.9

Oil 4.5

Active solar 1.9

Coal gasification 1.5Electric heating

(coal-fired plant) 0.4

Electric heating (natural-gas-fired plant) 0.4

Electric heating (nuclear plant) 0.3

Net Energy

Net Energy• Reducing waste improves net energy yields• 84 % of all commercial energy used in the US is wasted• 41% automatically wasted because of the second law of

thermodynamics:• When energy is converted from one form to another in a

physical or chemical change, we end up with lower quality energy than we started with.

• 43% wasted by:• Driving gas-guzzling motor vehicles• Inefficient coal-burning and nuclear power plants• Poorly designed, underinsulated, and leaky buildings equipped

with inefficient lighting, furnaces, air conditioners, and other applicances

Think Box

• What do you think the importance of net energy is? Explain.

Oil• Supplies about 1/3 of the world’s commercial

energy and about 40% of that used in the U.S.• Petroleum (crude oil; conventional): oil as it comes

out of the ground; black, gooey liquid; consists of hundreds of different hydrocarbons along with small amounts of sulfur, oxygen, and nitrogen• Makes up about 30% of the world’s oil

• Unconventional oil: thick; oil left behind in wells or extracted from deposits of tar sands and oil shale rock.

Oil

• Oil extraction• well is drilled vertically or horizontally into the

deposit beneath the ground• drawn by gravity out of the rock pores flows

into the bottom of the well and is pumped to the surface

• Oil refining• heated to separate it into components

Oil

• Peak production: After years of pumping the pressure in a well drops and its rate of production starts to decline

Think Box: When do you think we will reach our global

peak production of oil? Explain.

Oil

• Petrochemicals: products of crude oil distillation• Used as raw materials in industrial organic

chemicals, cleaning fluids, pesticides, plastics, synthetic fibers, paints, medicines and other products

Oil

• Rapid increase since 1950• In 2009 world used the equivalent of almost

31 billion barrels of oil• Largest consumers in 2009• United States, 23%• China, 8%• Japan, 6%

• Oil use is expected to increase by 37% by 2030

Oil

• Proven oil reserves: identified deposits from which conventional crude oil can be extracted profitably at current prices with current technology.

• Unproven reserves: probable reserves with a 50% chance of recovery and possible reserves with a 10% to 40% chance of recovery

Oil

• Predicted that proven and unproven oil reserves will be 80% depleted sometime between 2050 and 2100

• The U.S. gets about 85% of its commercial energy from fossil fuels with about 40% coming from crude oil• Produces about 9% of the world’s oil but uses

23% • Has only 1.5% of the proven reserves

Oil

• Organization of Petroleum Exporting Countries (OPEC)• Controls Most of the World’s Oil Supplies (39%

in 2009)• 13 countries have at least 60% of the world’s

crude oil reserves

OilAdvantages

• Ample supply for several decades

• High net energy yield but decreasing

• Low land disruption

• Efficient distribution system

Disadvantages• Water pollution from oil

spills and leaks

• Environmental costs not included in market price

• Releases CO2 and other air pollutants when burned

• Vulnerable to international supply interruptions