Pros and Cons: Energy Sources

Pros and Cons: Energy Sources — page 1 — CHAPTER 1 A World of Energy Everything on Earth depends on energy to survive Humans need energy from food to stay alive We also use various forms of energy to warm or cool ourselves and to move around Virtually all of the energy used on Earth comes from the Sun Plants use energy from the Sun to grow for example Even the gas we put in our cars can be traced back to the Sun because it is made from the fossilized remains of plants and animals that lived millions of years ago Those ancient plants and animals depended on the Sun for energy and when they died some of that energy was captured and stored in their remains Everlasting Energy In scientific terms energy is the ability to do work Energy cannot be created or destroyed It can be transformed from one form to another but the total amount of energy in the universe is always the same For example a photovoltaic cell in a solar panel converts radiant energy from the Sun into electrical energy Your 4 Forms of Energy The re a re man y d i f fe ren t fo rm s o f ene rg y bu t they are catagorized into two main groups k i n e t i c e n e r g y a n d p o t e n t i a l e n e r g y Kinetic energy is the energy of motion Here are some examples Radiant energyis electromagnetic energy that travels in waves It includes visible light X-rays and radio waves Solar energy from the Sun is an e x a m p l e o f r a d i a n t e n e r g y Thermal energyis the internal energy in a substance created by the vibration or movement of molecules Geothermal energy comes from heat beneath Earth’s surface Motion energyis the movement of objects f r o m o n e p l a c e t o a n o t h e r W i n d i s a n e x a m p l e o f m o t i o n e n e r g y P o t e n t i a l e n e r g y i s s t o r e d e n e r g y H e r e a r e some examples Chemical energyis the energy stored in the bonds between atoms The energy stored in oil coal or biomass such as plants is an example Gravitational energyis the energy in an object t h a t i s h e l d a g a i n s t t h e f o r c e o f g r a v i t y Th e w a t e r i n a d a m i s h e l d a g a i n s t g r a v i t y f o r e x a m p l e Nuclear energyis the energy stored in the released when nucleus of an atom the nucleus is split or joined with other nuclei is It

Pros and Cons: Energy Sources — page 2 — A World of Energy body obtains chemical energy from the food you eat and converts some of it into motion energy to enable you to move Energy for Good and Bad In the 21st century people use energy in a wide variety of ways to power computers to light and heat homes to fly across the world and to manufacture goods Almost all of that energy comes from fossil fuels such as coal and oil The ability to make use of these ancient stores of energy is one of the greatest technological triumphs of all time but it has downsides too Fossil fuels will run out one day and they are already becoming harder to find and more difficult to extract Burning fossil fuels creates air pollution and has a major impact on the global environment Time to Change Direction Less damaging sources of energy such as the Sun wind and water were in use long before fossil fuels were discovered Those renewable resources are now being reconsidered in a bid to prevent further harm to our environment The technologies to harness that energy are developing rapidly but face many obstacles They are more expensive and the energy sources may be less reliable the wind does not always blow for example More reliable but perhaps more risky technologies such as nuclear power could solve that problem However the safety concerns and unknown long-term effects make nuclear energy an unpopular choice for many people Whatever direction energy takes in the future science and technology will play a key role in what is possible affordable and acceptable This book explores some of the options and considers the developments in each energy source over recent decades Energy is essential for everything we do from unconscious actions such as breathing to the conscious actions of playing sports such as basketball 5

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

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