Craving energy Supplying our energy needs: Source of energy in the US Resources: Fossil Fuels Energy consumption in the US Reading: Ch 13 Oil and gas formation Oil and gas formation 1. Need accumulation of carbon and hydrogen organic matter microorganisms in the oceans 3. The hydrocarbons need to mature with increasing pressure and temperature the organic material breaks down into smaller hydrocarbon molecules 2. Need rapid burial to prevent decomposition continental margins The continental rifting process provides the right environment for oil formation within continental margin sediments []n 1
Oil and gas reserves Source rock high concentrations of organic material e.g. shales (typically fine grained) Reservoir courser grained with sufficient porosity e.g. sandstones Global oil reserves Global usage to date: 500 billion barrels Global reserves: 1000 billion barrels Remember: usage is accelerating Hubbert s peak: Oil reserves are projected to last only the next few decades Trap impervious layer to prevent hydrocarbons seeping to the surface e.g. fine grained shales Where are the reserves? Saudi Arabia, Kuwait, Iran, Iraq, UAE U.S. oil reserves Initially had 10% of global reserves Already used 200 bill barrels 25 billion barrels remain We use 7 bill barrels per year to supply 40% of our energy needs Interested in the future of world oil production? Read Hubbert s Peak by Ken Deffeyes and Alaska, estimated reserves 10 billion barrels Strategic Petroleum Reserve Maintained at ~550 billion barrels Equivalent to ~60 days of imports Hubbert accurately predicted when US reserved would start to decline. In this book the same analysis is applied to global oil reserves. It also includes everything you could ever want to know about the oil industry. 2
Natural gas reserves In the U.S. 200 trillion cubic feet of reserves We consume 20 trillion cubic feet per year Similar issues to oil: dwindling resources for the future But wait Future prospects We expect to find more reserves But, we do not expect to find entire new oil-rich regions, only additional (smaller) reservoirs Enhanced recovery Primary and secondary recovery removed 1/3 of reserves Enhanced recovery could extract another 1/3 Includes: fracturing the reservoir rock, increasing the pressure and temperature of the reservoir But, costly Conservation Will undoubtedly help stretch current reserves Increasing demand in the developing world is difficult to stop New sources Geopressurized natural gas dissolved in deep fluids Expensive to extract, plus waste fluid Coal formation Coal forms from dense surface vegetation which is buried Methane hydrates Crystalline gas + water in ocean sediments Large supplies How do we recover them economically? Over time as heat and pressure are applied peat becomes soft brown and then hard black coal 3
Coal reserves Coal reserves in the US Coal reserves are more substantial than oil and gas Global reserved should last several hundred years The US has 25% of global reserves 20-25% of our current energy usage comes from coal Our reserves are sufficient to supply all US energy needs for several hundred years BUT, there are limitations to coal usage Coal is no hydrocarbon The solid nature of coal and dirty burning process limit its use e.g. for transportation and home heating Gasification and liquefaction Converting coal to liquid and gaseous hydrocarbons Pass a stream of hydrogen through the coal at high temperature Environmental impacts Products of burning CO 2 production Burning oil, gas or coal produce CO 2 But, burning coal produces far more CO 2 oil and gas burn more cleanly This may be in our future Sulfur Up to 3% sulfur in coal becomes SO2 when burnt Mixes with H2O in the atmosphere and becomes sulfuric acid responsible for acid rain Can be removed before or after burning but this process is expensive Oil contains far less sulfur which can be removed during refining Ash Silicate minerals and metals toxic Up stack or landfill disposal 4
Environmental impacts Coal mining Coal mining: one of the most hazardous professions Strip mining has become more prevalent higher safety for workers produces more significant footprint (although reclamation helps) coal miner deaths Environmental impacts: Oil transportation Trans-Alaska Pipeline Transports 1.6 million barrels of oil per day from the Alaskan North Shore to the port of Valdez Environmental impacts: Oil transportation Trans-Alaska Pipeline Crosses several fault zones Environmental impacts: Oil transportation Oil tankers: the Exxon Valdez March 1989 the Exxon Valdez ran aground in Prince William Sound Denali Earthquake She was carrying 1.2 million barrels of crude oil which eventually spread over 900 square miles Magnitude 7.9 in November 2002 14 feet of offset beneath the pipeline the pipeline survived (just) Boom and skimmer operation 5
Environmental impacts: Oil transportation Oil tankers: the Exxon Valdez Hot water was used to clean up some beaches, fertilizer was used on others to encourage microbial growth to breakdown the oil Oil accumulations on beaches 6