NATURAL GAS

What is it? Waste product produced by bacteria and enzymes that break down organic matter Mostly methane (CH 4 ) with a small amount of other hydrocarbons Can be associated with both oil and coal; produced by breaking down both Also 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 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 Data from the Dept. of Energy, U.S. World eia.doe.gov, 2008 data UsePercent Residential20.7 Commercial13.6 Industrial26.8 Electricity Generation30.3 Automobiles.1 Pipeline2.8 Lease and plant5.5 CountryUsage (TCF) U.S.23.2 Russia16.8 Iran4.2 Japan3.6 United Kingdom3.4

Production Produced with wells, just like oil Unlike oil, natural gas does not cling to rock; rock permeability very important In stable rock environments, can increase flow by fracturing the rock with dynamite or water Can use pumps and injector wells to increase flow through rock

Natural gas - recovery Gas reserves usually associated with oil or coal deposits

Processing Natural gas normally requires very little processing before it can be moved to market  put it directly into pipeline Subsea completion - some gas wells are fed into pipeline directly at the ocean floor; saves tremendous amount of money in deepwater environment Occasionally, need to remove excess water and sulfur; can be done on nearby platform Before it is sold commercially, need to put in mercaptans

U.S. Production Production peaked in 1973 Production bottomed out in the mid 1980’s; price surge increased demand after that We currently produce almost 20 TCF of natural gas per year To meet consumption needs, we import from Canada and Mexico Lack of infrastructure to Alaska means that we pump 3 TCF back into the ground each year

Gas Shale Picture from DOE Increase in U.S. production is owed to previously unconventional sources such as gas shale. These reservoirs rely on horizontal drilling and hydraulic fracturing.

Coal Bed Methane This is natural gas that is trapped within the coal seam; used to be the reason that coal miners took canaries with them into mine Potentially huge reserves of this Easier to drill than other wells, as coal is closer to surface; cheaper Water that must be removed first is saline; disposal problem Estimated at 700 TCF in U.S.; 100 TCF developable now

Methane Hydrates Methane locked in an ice lattice; found most often on ocean floor Very 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 methane hydrate deposits than all other fossil fuels combined

Outlook Even with our usage, we have been able to add to reserves recently; if have to rely on conventional sources, will run out in 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 future Effect on global warming unknown