Passive Solar Energy  Uses solar radiation to maintain a comfortable temp in the building without electrical aid  South-facing windows, which absorb maximum sunlight  Skylights  Trees planted on sides as insulation/channeling wind currents for temperature control  Water wall/thermal mass wall Heat collects throughout the day in the core of the walls and floors As temps begin to drop, heat is re- released to achieve equilibrium

Passive Solar Advantages vs. Disadvantages  Advantages  Nondepletable resource  After initial investment, no cost to harvest energy  Disadvantages/Waste products  Production produces waste products  Geographically limited  High initial costs

Solid Biomass  Biomass is any organic matter that can be used as an energy source -ie. wood, crops, seaweed, animal wastes  Burn it, heats water, creates steam, turns turbines, generates electricity

Solid Biomass Advantages vs. Disadvantages  Advantages  Potentially renewable  Eliminates waste from environment  Available to everyone  Can be carbon neutral  Disadvantages/waste products  Deforestation  Erosion; deprives soil of nutrients  Air pollution (carbon dioxide, nitrogen, sulfur, particulate matter)  Requires a lot of land

Ethanol  Usually made from corn or sugar cane  Corn or sugar cane is mashed up, enzymes and yeast are added- fermentation takes place where the sugar becomes ethanol and CO 2  Mixture of ethanol and CO 2 goes to the distillation columns where the ethanol is separated and is blended with gasoline

Ethanol Advantages vs. Disadvantages  Advantages  Potentially renewable  Domestically produced  Lower emissions than fossil fuels  Disadvantages/waste products  Releases carbon dioxide  Uses lots of land to grow crops  Higher food costs  Lower gas mileage

Hydroelectric  Water builds behind dam, falling water pushes turbine which transforms into electricity

Hydroelectric Advantages vs. Disadvantages  Advantages  Nondepletable resource  Low cost to run  Flood control  Recreation  No pollutants/waste released except for the production  Disadvantages/waste produced  Limited to rivers  High construction costs  Loss of habitat,  Disrupts flow of water  Reduces nutrients downstream since it builds up behind dam  Disrupts spawning patterns of fish

Tidal/Wave Energy  Turbines are placed in areas that have high tidal movements  Tides move the turbines that generate electricity  Works in both directions

Tidal/Wave Advantages vs. disadvantages  Advantages  Nondepletable resource  After initial investment, no cost to harvest energy  Tides are predictable and steady  No pollutants/waste released except for the production  Disadvantages/wastes produced  High initial costs  Geographically limited  Can harm marine life and affect migration patterns  Corrosion

Active Solar  Solar water heating systems  A nonfreezing liquid is circulated by an electric pump through a closed loop of pipes  Circulating liquid moves from a water storage tank to a solar collector on the roof, where it is heated and back to the tank, transferring the heat to water  Photovoltaic systems (solar panels)  Solar panels convert sunlight into direct current (DC). An inverter converts DC into alternating current (AC) which supplies electricity

Active Solar Advantages vs. Disadvantages  Advantages  Nondepletable resource  After initial investment, no cost to harvest energy  Solar panels can provide the grid with excess energy  Once the panels are made, emission free  Disadvantages/waste products  Manufacturing materials requires high input of metals and water  No plan in place to recycle solar panels  Geographically limited  High initial costs

Geothermal  A cold liquid (usually water) is pumped down into the earth where it is heated and returned to the surface; the pressurized steam turns the turbines to generate electricity

Geothermal Advantages vs. Disadvantages  Advantages  Nondepletable resource  After initial investment, no cost to harvest energy  Disadvantages/waste produced  Geographically limited  Can emit hazardous gases and steam (carbon dioxide, hydrogen sulfide)  Cannot be transported  High installation costs

Wind  Wind turns the turbine blades, which spin a shaft, which connects to the generator and makes electricity

Wind Advantages vs. Disadvantages  Advantages  Nondepletable resource  After initial investment, no cost to harvest energy  Once turbines are made, emission free  Disadvantages/waste produced  Turbine noise  Deaths of birds and bats  Geographically limited  Aesthetically displeasing to some  Initial costs are high

Hydrogen Fuel Cells  Hydrogen gas enters the cells, which strips electrons off of hydrogen  Oxygen molecules are split  Ionized hydrogen is positively charged which causes it to bind to oxygen to create water

Hydrogen Fuel Cells Advantages vs. Disadvantages  Advantages  Highly efficient  Only byproduct is water  Disadvantages/waste produced  Expensive and bulky  Transportation and storage of hydrogen is difficult