Ch. 18 Renewable resources!!

Renewable energy – energy from sources that are constantly being formed

• Solar - sun• Hydroelectric – moving water• Wind• Biomass – organic material• Geothermal – Earth’s heat• Tidal - waves

Solar Energy - energy from the sun

• Nuclear Fusion creates energy on the sun– Only a fraction of this reached the Earth– But, this is enough to power:

• The wind (wind power)• Plant growth (biomass)• The water cycle (hydroelectricity)

• Nearly all renewable energy sources come from the sun!!!

Passive Solar – using the sun to heat something directly (ex: through windows)

Active Solar – collecting the suns energy to heat buildings or water (ex: solar cells or panels)

• Energy production from solar has doubled every 4 years since 1985!!

http://videos.howstuffworks.com/science-channel/5015-invention-nation-solar-panels-video.htm

http://solarsc.net/video/examples/how-solar-panels-work.html

Costs of Solar Energy

• All costs are up front costs, then savings follow– Solar pool heater - $3000 - $4000– Home solar water heater $1000 - $3500 (includes installation)– 1 kW power system $10,000 – $15,000– 2 kW power system $16,000 - $20,000– 5 kW power system $35,000 - $45,000

(will power most homes)– You can get federal tax credits up to $2000 and some state

tax credits as well

Wind Power

• Heat from the sun does not warm the earth evenly, causing the flow of air masses = wind

• Fastest growing energy source• Cost is decreasing

Wind Farms

• Farmers can sell excess energy back to their local utility!!

• The windiest places on Earth could generate 10 times more energy needed on earth!!

• Problem: Transporting the energy from rural areas to where it is needed

Biomass Power - any organic matter that is used as an energy source

• Plants material, manure, methane, alcohol• Major source of energy in developing countries!

• Problems: – cutting too many trees can cause severe environmental

problems– Burning can release large amounts of air pollution

Methane – a byproduct of decomposition

• Britain’s first Dung-Fired Power plant using the methane released from cow manure for energy

• US uses some energy from methane produced from landfills!

Ethanol

• Produced from biomass!• Benefits:

– Renewable– Less emissions

• Cons:– Takes lots of land– Rise in produce prices

Hydroelectricity – energy produced by moving water

• 20% of the worlds electricity• Leading Countries

– Canada– US– Brazil– China– Russia– Norway

Hydroelectric Energy

• Benefits– Inexpensive to

operate– No air pollution– Last longer than

fossil fuel plants– Flood control– recreation

• Disadvantages– Changes a rivers flow– Reservoir floods the

area• Displaces people

– Reduces water flow– Destroys salmon

fisheries– Dam failure– Sedimentation

Today: the era of large dam construction is most likely overWe are now using micro-hydropower

Geothermal Energy – energy from heat in the earth’s crust

• US is the worlds largest producer of geothermal energy

Costs of Geothermal Heat Pumps

• Heat pump = $3,500 - $7,500• Drilling/installation = $10,000 - $25,000• You can get federal tax credits up to $2000 and some

state tax credits

Alternative Energy – energy sources that are still in development

• How to get off the alternative list?– Prove it is cost effective– Environmental effects must be acceptable

• Current Alternative energy sources– Tidal Power Ocean– Ocean Thermal Energy Conversion (OTEC)– Hydrogen

Tidal Power

• Tides – the movement of water caused by gravitational attractions between the sun, Earth and the moon.

• Currently used in – France– Russia– Canada

Cost is high and not many placessuitable enough

Ocean Thermal Energy Conversion

• Warm ocean surface temperatures and cold subsurface temperatures are used to create electricity

• Surface temps boil water making steam….• Cold subsurface water cools the steam• Problems

– Pumping water costs too much– Pumping cold water to the surface could cause

problems

Hydrogen??

• The most abundant element in the universe!• Burning it produces water vapor – not pollution• Electricity is used to split water molecules to

get hydrogen gas• Challenges:

– Takes a lot of energy to make– Not safe to store

Fuel Cells

• Combining Hydrogen and Oxygen produces electricity and its byproduct is water!

• No Emissions!!

Energy Efficiency - % of energy put into a system that does useful work

• Ex: a light bulbs light output not its heat energy

• More than 40% of energy produced in the US is wasted!!

• How to improve– Public transport– More efficient engines, i.e. fuel cells

Hybrid Cars

• Less emissions• Small efficient gas engine• Electric motor• Convert breaking energy into electricity• Aerodynamic• Lightweight material

Cogeneration

• Using the same fuel source for two forms of energy– Ex: wasted heat from a furnace can be used to

produce electricity

Energy Conservation – saving energy by reducing use and waste

• How can we do this in our lives???

Energy Efficient Home