 ~85% of energy in US comes from Fossil fuels. What are they?  Decomposed remnants of ancient forests and algae buried deep under ground  Solid = coal  Liquid = oil/petroleum  Gas = natural gas

 Like pockets of sunshine buried underground  Through photosynthesis, plants stored sunlight energy, CO2, and H2O in their tissues  When dug up and burned, the energy is released along with the CO2 and H2O (causes global warming)  Takes millions of years to reform

 Burning fossil fuels  Respiration from plants and animals  Decaying organic matter  Burning fossil fuels  Volcanoes How is Carbon Released? How is Carbon Taken Up?  Photosynthesis by plants and algae  Dissolves in ocean

 Coal – solid fuel from compressed ancient plants  Found in sediment layers underground (up to 100 m thick) – mostly million years old  Mined by tunnels or by strip mining.  Coal deposits 10X than oil and gas combined  If all coal on Earth could be extracted, it would last several 1000 years at current consumption rates (2007).  Problems with this estimate?  At current consumption rates (2007), known reserves will last around 200 years  Problems with this estimate?

 Crude oil – found in huge underground reservoirs.  Pumped out through wells.  Can also be extracted from tar sands and oil shales (rocks) but expensive and messy.  Separated at refineries into components like gasoline, diesel fuel, grease, asphalt.

 We have oil in the US, but supply is limited and it’s cheaper to pump in Saudi Arabia  higher production capacity  Can only extract 30-40% from a reservoir  At current rates of production and with known, recoverable reserves, oil is expected to last 40 years  Estimate may be higher if we account for currently undiscovered and unrecoverable reserves with current prices and technology  US has used 40% of its recoverable oil  10 year supply remains  What about the Arctic National Wildlife Refuge?

 Conventionally found above reservoirs of crude oil.  Includes methane (90%), propane, and ethane.  Convenient, cheap, and clean-burning  produces half has much CO2 as coal  Compressed and liquefied for transport

 Often occurs with oil and extracted simultaneously  Piped under pressure to homes and industry.  At current rates of consumption, current reserves will last 60 years  10-year supply in US  We know about more reserves and are learning of new sources (arctic permafrost, beneath ocean sediments)

 CA – about 45% of energy comes from Natural Gas  We may experience increased competition for supply