E N D
NATURAL GAS
What is it? Waste product produced by bacteria and enzymes that breakdown organic matterMostly methane (CH4) with a small amount of other hydrocarbonsCan be associated with both oil and coal; produced by breakingdown bothAlso associated with swamps, rice fields, termites, and cattle
Characteristics Good - 1) Burns cleanly, with very few pollutants 2) Easier to use in fuel cell (more efficient) 3) Large supplies worldwide Bad - 1) Hard to transport and store 2) Leaks result in greenhouse gas emissions
Types • Dry natural gas - consists of only gaseous component; mostly methane, with butane and propane • Natural gas liquids - the non-gaseous, organic components of natural gas; heavier hydrocarbons such as pentane • Wet natural gas - natural gas that is mixed with non-organic substances such as water vapor, carbon dioxide, and nitrogen
Consumption U.S. World Use Percent Residential 21.7 Commercial 14.0 Industrial 31.8 Electricity Generation 25.0 Automobiles 0.1 Pipeline 2.8 Lease and plant 4.6 eia.doe.gov, 2004 data Data from the Dept. of Energy, Most natural gas in U.S. is used for industrial processes. Residential usage accounts for about 1/4 of the total. The U.S. uses the most natural gas in the world
Production Produced with wells, just like oilUnlike oil, natural gas does not cling to rock; rock permeabilityvery importantIn stable rock environments, can increase flow by fracturingthe rock with dynamite or waterCan use pumps and injector wells to increase flow throughrock
Natural gas - recovery Gas reserves usually associated with oil or coal deposits
Processing Natural gas normally requires very little processing before itcan be moved to market put it directly into pipelineSubsea completion - some gas wells are fed into pipelinedirectly at the ocean floor; saves tremendous amount of moneyin deepwater environment Occasionally, need to remove excess water and sulfur; can bedone on nearby platformBefore it is sold commercially, need to put in mercaptans
U.S. Production Production peaked in 1973Production bottomed outin the mid 1980’s; price surge increased demand afterthat We currently produce almost 20 TCF of natural gas per year To meet consumption needs, we import from Canada and MexicoLack of infrastructure to Alaska means that we pump 3 TCFback into the ground each year
Gas Reserves Data from Hubbert Center, http://www.oilcrisis.com/gas/ This data is 8 years old. Current consumption is 26 TCF inNorth America and 90 TCF
Coal Bed Methane This is natural gas that is trapped within the coal seam;used to be the reason that coal miners took canaries withthem into minePotentially huge reserves of this Easier to drill than other wells, as coal is closer to surface; cheaperWater that must be removed first is saline; disposal problemEstimated at 700 TCF in U.S.; 100 TCF developable now
Methane Hydrates Methane locked in an ice lattice; foundmost often on ocean floorVery little known about these deposits- Unknown how they form- Unknown how stable they are- Unknown how to produce reserves- Unknown how much there is in the world Potentially, more than twice the amount of carbon in methanehydrate deposits than all other fossil fuels combined
Outlook Even with our usage, we have been able to add to reservesrecently; if have to rely on conventional sources, will run out in15-20 years If coal bed methane proves feasible, could add many years to this outlook If methane hydrates prove producible and as plentiful as thought,natural gas could be fossil fuel of futureEffect on global warming unknown