Fossil Fuels – Energy for a Nation Environmental Science 6.2

First Wake-Up Call There was an energy crisis in the 1970s ▫Shortages of gasoline and natural gas caused schools and industries to shut down Prices began to climb quickly Congress passed the Energy Policy and Conservation Act ▫Speed limit on interstates was reduced to 55 mph ▫Car manufacturers were required to develop cars that would get better mileage ▫Manufacturers were required to label certain electrical appliances w/ an EnergyGuide ▫Tax breaks offered to homeowners making homes more energy efficient

The Changing American Scene Renewable resource – one that is produced at least at the same rate it is used ▫Most of the energy we use is derived from nonrenewable fossil fuels – oil, natural gas, coal Arab Oil Embargo occurred in ▫Arab oil-producing countries shut off all shipments of oil to the U.S. Consumption of oil in the U.S. has increased dramatically, but production has declined

U.S. remains world’s largest importer of petroleum 2/3 of world’s proven oil reserves surround the Persian Gulf ▫Political stability of this region is important to the U.S., Japan, and other countries that have become dependent upon imported petroleum

It Began a Long Time Ago Coal ▫Plants died and fell into the water, forming layers of partially decayed plant material called peat ▫Weight of water and sediments created heat and pressure that changed the peat to coal – any black or brown rock that contains hydrocarbons formed from decayed plants ▫Lignite - when coal is first formed from peat  Takes 1 million years to form  Heat content is lower than other coals

▫Subbituminous  Higher heat content than lignite ▫Bituminous (soft coal)  Higher heat content than subbituminous  100 million years  Most of coal in U.S. is bituminous ▫Anthracite (hard coal)  Highest heating value  Nearly all anthracite in U.S. is in PA

Other fossil fuels ▫As plants and animals living in the ancient seas died, the drifted down to the bottom; layers were buried deeper and deeper  Heat and pressure caused chemical changes  Mixtures of hydrocarbons – natural gas and petroleum – were formed from the organic matter ▫First requirement is a source rock – rock that is rich in organic matter ▫Second requirement is sufficient heat and pressure for a period of time that allows the organic matter to be changed into hydrocarbons

▫Oil and gas must then move into a reservoir rock – a rock that contains many tiny pores w/ connecting passageways through which the oil and gas can move ▫A trap – rock w/o pores - forms a lid that keeps the oil and gas from escaping ▫Reserve – deposit of oil or gas that can economically be recovered w/ present technology

Natural Gas Supply and demand ▫U.S. has 3% of the world’s reserves ▫About 19% of the natural gas used in U.S is imported (mainly from Canada) ▫Industrial: Industry consumes 32%  Pasteurize milk, dry paper, make many products ▫Residential: Homes consume 23% ▫Electricity: 23% used to generate electricity  Allows power plants to increase production of electricity w/o installing expensive air pollution controls

▫Commercial: 14% used by businesses ▫Transportation: Some company and city vehicles run on CNG  Clean-fuel alternative to gasoline

Processing ▫Natural gas is mostly methane ▫Processed to remove impurities Transportation ▫By weight, natural gas produces 50% more heat than coal, and 30% more than oil ▫Pipelines are most efficient means of transport Environment and Health ▫Cleanest burning fossil fuel ▫No odor/color so mercaptan is added as a safety precaution

Petroleum (Crude Oil) Supply and Demand ▫Products made from crude oil, gasoline, and diesel provide energy for most methods of transportation ▫Also provides raw materials used to make many products Production ▫When a well is drilled, petroleum is usually under pressure and flows w/o pumping ▫Secondary recovery methods are then used to remove more of the oil from the rock

Processing ▫Distillation – as oil is heated, vapors pass through a series of perforated trays in a fractionating tower  Different hydrocarbons condense at different temperatures ▫Some requires further processing ▫Refining – processes that are used to separate crude oil into its parts and to produce petroleum products ▫Catalysts are used to speed up these chemical reactions

Transportation ▫Pipelines are most energy-efficient ▫Ships, barges ▫Tanker trucks Environment and Health ▫Large quantity of oil is spilled into the environment each year  Massive kills of marine animals  May affect water supplies ▫Automobile is major source of air pollution

Future ▫American Petroleum Institute (API) says U.S. production of oil could cease within 20 years if we stop drilling new wells ▫API supports opening Arctic National Wildlife Refuge for oil and natural gas exploration and production but U.S. Senate rejected the legislation

Coal Supply and Demand ▫Most abundant fossil fuel in U.S. ▫U.S. has 25% of world’s coal reserves ▫Used mainly for generation of electricity ▫Factors affecting use of coal are price of other fuels and amendments to the CAA ▫Steel mills heat bituminous coal in airtight ovens  Coal doesn’t burn but changes some of the solids into gases  Coke - remaining solid mass that is almost pure carbon

Mining ▫Most surface mining is strip mining – where the soil and rock over the coal deposit are removed ▫Reclamation – process of restoring the land to the condition that existed before mining ▫Room and pillar system – as the miners dig large rooms, they leave pillars of coal to support the roof ▫Longwall system – workers cut coal from a wall which joins the main tunnel

Processing ▫Coal is crushed and sorted according to size ▫Washed to remove impurities Transportation ▫Pipeline – coal is crushed and mixed w/ water to form slurry ▫Train, barge

Environment and Health ▫Since 1900, more than 100,000 workers have been killed in coal mine accidents in the U.S. ▫Methane is explosive  Automatic detectors ▫CO if not ventilated ▫Black lung disease from breathing coal dust ▫Rock dusting – water is sprayed on surfaces being mined to control dust

After more than 20 years and $7 million, government gave up attempts to try to stop the fire burning in the abandoned coal mine beneath the streets of Centralia, PA