UNIT 6 – ENERGY & CLIMATE CHANGE Chapters 17 – 18, 13

17-1: Energy Resources & Fossil Fuels Fossil fuels—remains of ancient organisms that changed into coal, oil, or natural gas Uses of fuels Cooking, transportation, manufacturing, heating & cooling buildings, generating electricity

Electricity Energy in fuels converted into electrical energy Electric generator converts mechanical energy into electrical energy Turbine converts moving gas or liquid into energy that produces electricity

Energy Use Developed countries use more energy than developing countries U.S. uses more energy per person than most countries Over 25% on transportation

How Fossil Fuel Deposits Form Coal Formed from the remains of plants in ancient swamps Produces 45% of U.S. energy Inexpensive & easy to mine Produces air pollution when burned

Petroleum (crude oil) Found in deep, impermeable rock layers Removed by oil wells or fracking Release greenhouse gases & excess CO 2 when burned

Natural gas Found underground, usually near oil reserves Produces about 20% of U.S. energy Produces fewer greenhouse gases when burned

Fossil Fuels and the Future Energy demands will increase by 30% by 2040 Oil reserves are known oil deposits Major new reserves not expected to be found Oil sands, deep-sea reserves are expensive to drill Future focus on using oil more selectively

17-2: Nuclear Energy Nuclear energy— energy in the nucleus of an atom Nuclei split through nuclear fission & release large amounts of energy

How Nuclear Energy Works 14% of world’s electricity comes from nuclear power Nuclear reactor contains uranium fuel rods Control rods slow rate of fission reaction Steam released from reaction generates electricity

Nuclear Energy Advantages Small amount of fuel produces large amounts of energy Do not produce greenhouse gases Disadvantages Building & maintaining reactors is expensive Hard to find safe places to store nuclear waste Uncontrolled reactions, used in weapons

18-1: Renewable Energy Renewable energy—can be replenished quick enough so that it won’t be used faster than it can be produced Solar—can be passive (windows) or active (solar panels) Wind—energy generated by wind turbines

Biomass—energy from organic material Methane, ethanol, biodiesel, gasohol Hydroelectricity—energy produced by moving water Geothermal—energy generated from heat within the Earth

18-2: Alternative Energy Alternative energy—energy sources that are still in development Tidal power—sea levels rise & fall to generate energy Ocean Thermal Energy Conversion (OTEC)— sea water boiled to generate electricity Hydrogen—can be used in fuel cells

Energy Conservation Energy conservation—saving energy by using energy-efficient devices & wasting less energy Conservation at home & in daily life Insulate doors, replace old windows, replace old furnace, unplug electronics not in use Car pool, drive fuel-efficient vehicle, wash clothes in cold water

13-2: The Ozone Layer; Ice Cores Ozone layer—layer in the atmosphere that absorbs UV radiation from the sun Chlorofluorocarbons (CFCs)—chemicals that cause the ozone layer to break down

The Ozone Hole Scientists in Antarctica noticed thinning of ozone layer over poles

Thinning ozone allows more UV radiation to Earth’s surface Promotes cancer, damages genes Montreal Protocol in 1987 limited production of CFCs Successful in reducing CFCs in atmosphere

Ice Cores Ice cores drilled out of polar ice help scientists reconstruct Earth’s climate history

Snow carries substances from atmosphere, air bubbles New layers deposited each year; indicate past climate

13-3: Climate Change Greenhouse effect—Earth’s surface is warmed by the atmosphere trapping energy from the sun

Greenhouse gases absorb & radiate sun’s energy Water vapor & CO 2 absorb most energy CO 2 levels in atmosphere measured at Hawaii Levels naturally rise & fall each season CO 2 levels increased each year; due to increased burning of fossil fuels

Increased greenhouse gases believed to be linked to increased global temperature, especially CO 2 Causes of increased release of CO 2 Increased burning of fossil fuels Clearing of forests & trees

Global Climate Change Global warming—gradual increase in Earth’s average temperature

Consequences of a Warmer Earth Changes in nesting, migration, flowering periods Rising sea levels could flood coastal areas More hurricanes, rainfall, flooding Increased heat-related deaths, more mosquitoes

Increased droughts affect agriculture Lower crop yields, need for more water Effects on plants Cool climate forests shrink, increased risk of fires Effects on animals Shift in animals’ ranges, reduced plankton levels, coral reef loss due to warm oceans

Reducing the Risk Solutions to global warming Use less fossil fuels Reforestation Kyoto Protocol—global treaty to reduce greenhouse gas emissions Developing countries signed, many developed countries (U.S.) did not sign

Prevent Global Warming! Save Santa!