Energy- renewable’s Students will be able to identify the pros and cons for the renewable and nonrenewable energy sources.

Looking back… What types of non-renewable energy have we discussed? Fossil fuels -Coal -Natural Gas -Petroleum nuclear power

Benefits of Fossil Fuels Able to generate large amounts of electricity Convert approx. 40% of energy to electricity Location not very limited (only to transportation)

Drawbacks Nonrenewable – We will run out! Coal produces SO 2 - acid rain Crude oil- poses environmental hazards (Spills) Coal mining causes destruction of land Pollution!- CO 2

Much air pollution is caused by the burning of fossil fuels…

Nuclear Energy Benefits Emission-free energy –No GHGs or particulates Generates large quantities of energy Drawbacks Limited amount available Radiation if meltdown occurs Estimated 3,256,000 tons uranium that is recoverable. 75,000 tons/year to produce 17% of the world power requirements Only enough to meet energy demands for 42 years.

What will happen when these are gone? Renewable Energy

Solar Power Benefits -No Pollution! -Can be installed on rooftops (save space) -After initial installation, the cost is low

Drawbacks -Only generates electricity during daylight -Efficiency affected by weather (cloudy/hazy days) -Inefficient Solar Power Energy from the sun on a surface directly facing the sun

Wind Power

Benefits -Clean energy (no pollution) -Renewable -35% energy efficiency Wind Power

Drawbacks -Wind isn’t dependable -Unable to function in bad weather -Blades can be damaged -Considered to be an eyesore by some -Loud -Kills birds and bats Wind Power

Cape Wind Controversy Proposed wind farm off the shore of Nantucket Sound’s Horseshoe Shoal

Hydropower

Benefits -Requires little maintenance to operate -Plants last a long time (at least 50 years)

Hydropower Drawbacks -Requires a strong river to be dammed -Can be destructive -Flood large areas and cut off streams -Dams cut migrating fish off from their spawning areas

Three Gorges Dam, China Flooded 13 cities, 140 towns, 1,350 villages Submerged factories  waste to be introduced into the reservoir

How much power can one dam produce? The Three Gorges dam produces as much energy each year as:  25 million tons of crude oil  50 million tons of coal  15 nuclear power plants

Geothermal Energy Use of heat from within the Earth. -Steam or hot water Geothermal resources in US

Drawbacks Location dependent Potential danger of noxious gases Noise problems from steam valves Geothermal Energy Benefits Emit water vapor (no air pollution!) Generates continuous power

Current Status for Geothermal Energy Geothermal power could serve 100% of the electrical needs of 39 countries (over 620,000,000 people) in Africa, Central/ South America and the Pacific.

Today, about 95% of the buildings in Reykjavik are heated with geothermal water. Reykjavik is now one of the cleanest cities in the world.

U.S. Geothermal Potential

Biofuel Energy from plants Organic material converted into a combustible fuel – Example: Corn or sugar cane converted to ethanol

Biofuel Advantages Easy to grow Can convert waste parts of plants into fuel Mixed in with or used instead of gasoline, thus saving fossil fuels Can be used anywhere Disadvantages CO 2 still released when it is burned. (But this is currently part of the current carbon cycle already) Farm land used for fuel, thus not as much food produced Sometimes the amount of energy needed to harvest, convert, and transport the fuel uses as much oil as it saves.

Brazil is a leader in biofuel. 50% of its vehicles can run on 100% biofuel

Fuel Cell Fuel cells use hydrogen and oxygen to make water. Electricity is produced in the process.

Fuel Cell Advantages No pollution – just water! Quiet Doesn’t use up fossil fuels Can be used in cars Disadvantages Most hydrogen has to be produced by breaking apart water molecules and that TAKES energy. Hydrogen gas is very flammable and explosive (greenwichps / gps2009)