Pros and Cons: Energy Sources

Pros and Cons: Energy Sources — page 3 — CHAPTER 2 Energy From Fossil Fuels Most of the energy consumed on Earth comes from the three main fossil fuels oil coal and natural gas Between them those fuels accounted for 87 percent of global energy use in 2012 All fossil fuels are made from the remains of plants and animals that died millions of years ago Over time those remains became buried under decaying matter Squashed under layers of sand clay and rock the remains were compressed in very hot conditions until they turned into coal oil and natural gas Stored Carbon Fossil fuels contain large quantities of carbon an element that occurs naturally in our environment Because of their high carbon content fossil fuels are a valuable source of energy Coal in particular powered the Industrial Revolution which started in Great Britain in the late 1700s As a result of that revolution engines and machines largely replaced the work done by people and animals The process of burning fossil fuels to provide energy releases carbon as carbon dioxide CO2 Over the past 200 years and particularly since the beginning of the 20th century the buildup of CO2emissions has contributed to a warming of the atmosphere known as global warming 6 Global Warming Global warming is an increase in the average near-Earth atmospheric temperature Carbon dioxide CO2 and other gases act as a blanket around Earth allowing radiant energy from the Sun to pass through but trapping some of it in Earth’s atmosphere These gases are known as greenhouse gases because they trap heat in much the same way a greenhouse does Greenhouse gases are needed to keep our planet warm Without them Earth’s average temperature would be about 1 degree Fahrenheit 17ºC or well below freezing Since the Industrial Revolution however use of fossil fuels and the resulting CO2 emissions have increased dramatically The 2000s was the warmest decade since temperature records began in 1861 Many scientists predict that temperatures could increase by 0 5 to 8 6 degrees Fahrenheit 0 3 to 4 8ºC by 2100

Pros and Cons: Energy Sources — page 4 — Scientists have connected global warming to the melting of ice in polar regions to crops dying because of unusual weather patterns and to the increased risk of extreme weather Unsustainable Fuels Fossil fuels are spread unevenly around the world and they are nonrenewable Once they are gone they cannot be replaced That means fossil fuels are an unsustainable source of energy Experts predict that at current rates of use accessible and affordable oil supplies will run out in about 2050 natural gas in about 2070 and coal in about 2140 Heavy traffic pollutes the air in San Francisco California Human ingenuity has enabled people to use the energy stored in fossil fuels but at a cost Percentage of Proven Global Reserves of Major Fossil Fuels by Region Region Oil Coal Gas Africa 7 8 3 7 7 7 Asia Pacific 2 5 30 9 8 2 Europe Eurasia 8 4 35 4 31 2 Middle East 48 4 0 1 43 0 North America 13 2 28 5 5 8 South Central America 19 7 1 5 4 1 Source BP Statistical Review of World Energy 2013 7

Pros and Cons: Energy Sources — page 5 — ENERGY SOURCES Cleaner Coal Coal is an inexpensive and abundant fuel source that is used by many nations to meet their energy needs China is currently leading the world in its production of large coal-fired power stations But coal is a dirty fuel that emits more CO2 per unit of electricity than either oil or natural gas Proposed carbon capture and storage CCS technologies offer ways to reduce the impact of burning coal The CO2 is collected as the coal is burned and then the gas is pumped into rocks deep below the ground Empty oil fields are other possible storage sites CO2 is already being injected into near-empty wells as a way of forcing out any remaining oil About 38 5 million tons 35 million tonnes of CO2 are injected into U S oil wells each year New coal-fired CCS power stations could capture up to 95 percent of the carbon in coal and dramatically reduce emissions Coal at the Jing Hua Gong coal mine in Shanxi China is loaded into a truck for transportation to one of China’s coal-fired power stations China’s reliance on relatively low-quality coal has made it one of the world’s largest emitters of carbon dioxide

Pros and Cons: Energy Sources — page 6 — Energy From Fossil Fuels PROS ENERGY FROM COAL Carbon capture and storage CCS greatly reduces the impact of burning coal on global warming The storage methods are considered safe and are expected to retain 99 percent of the CO2 injected into them over 1,000 years CCS allows the continued use of coal as an inexpensive and widely available fuel CONS ENERGY FROM COAL CO2 emissions are only one of many problems of burning coal for energy Mining coal is also dangerous and environmentally harmful It is estimated that in 2010 more than 2,400 workers were killed in Chinese coal mines as a result of floods cave-ins or explosions Mining scars the landscape and pollutes the air and water and the burning of coal releases a wide range of pollutants in addition to CO2 The biggest problem with coal however is that it is nonrenewable and will one day run out or become too expensive to use Types of Coal There are three main types of coal They vary according to the pressure under which they were formed and how much carbon they contain Each L ign ite is a d ry and c rumb ly coa l con ta in ing on ly abou t 50 pe rcen t has different qualities carbon Also known as brown coal it gives off the least heat and the is a harder coal containing more carbon than lignite It is the most common coal and burns with a good heat but it still Anthracite is a very hard black coal that is about 90 percent carbon It burns at high temperatures giving off the most heat and the most pollution Bituminous coal causes pollution least pollution 9

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