• Almost ALL energy ultimately comes from the sun, either directly or indirectly

Carbon cycle

Fig 15.3—Fossil fuel formation

Alberta tar sands

Fig 15.10—Alberta tar sands

Keystone XL pipeline

Petroleum/Crude Oil

• Oil in mud or clay (oil shale) difficult to remove; clay particles so close together

• Oil in sandstone easier to extract; sand particles not held as closely together as clay

• Ample supply for at least 40 years

Petroleum/Crude Oil—Pros

oil is relatively cheap easily transported high net energy yield efficient distribution system

Petroleum/Crude Oil—Cons

dependence on oil waste discourages use and exploration of

alternative sources of energy releases CO2 and other pollutants

Fig 15.9—Hubbert’s prediction

Fig 15.7—distillation of petroleum products

Fig 15.8—uses of petroleum products

Natural Gas

composed mainly of methane should last at least 50 years,

depending on Marcellus shale estimates

one of the cleanest burning of all fossil fuels

often found together with oil

Marcellus shale

Hydraulic fracturing

• Also called “fracking”

• Concerns about contamination of ground water and other types of pollution

Natural Gas—Pros

as cheap as oil easily transported high net energy yield burns cleaner

Natural Gas—Cons

must be converted to liquid form for transport (reduces net energy yield)

methane leaks

Coal—Pros

known reserves should last at least 200 years at current rate of use

high net energy yield

West Virginia strip mine

Coal—Cons

accidents and diseases harms land dirtiest fossil fuel to burn high in CO2 and other pollutants

Electricity generation in the US

Fig 15.12—carbon capture

Is there such a thing as “clean coal”?

• Involves carbon capture and sequestration

• Other impurities like sulfur, which contributes to acid rain, must be removed

• Still need to dispose of ash

Fig 15.18—Nuclear fission

Nuclear power—Pros

no air pollutants much less CO2 than fossil fuels water pollution and land disruption

are minimal

Nuclear power—Cons

uranium remains suitable for about 3 years, then needs to be replaced

fuel rods are highly radioactive and few waste facilities exist

low net energy yield but improving terror, nuclear weapons threat

Fig 15.19—light water reactor

Greenhouse effect

• Main greenhouse gas: carbon dioxide

Fig 14.10a—global temp change

Fig 14.10b—Northern Hemisphere temp changes

Climate change—what we know

Carbon dioxide levels have fluctuated; these levels correlate well with changes in surface temps

Fig 14.7—CO2, methane, temps

Intergovernmental Panel on Climate Change (IPCC)

• Established in 1988 by the World Meteorological Organization and the United Nations Environment Program

• IPCC does not conduct research but assesses available peer reviewed and published scientific/technical literature on climate change

• Produces reports about every 5 years

IPCC reports

• 2001 report: In the light of new evidence and taking into account the remaining uncertainties, most of the observed warming over the last 50 years is likely (66-90% chance) to have been due to the increase in greenhouse gas concentrations

• 2007 report: Most of the observed increase in global average temperatures since the mid-20th century is very likely (90-99% chance) due to the observed increase in anthropogenic greenhouse gas concentrations