Renewable Energy Technology• Solar Power• Wind Power• BioFuels• Geothermal Power• Hydroelectric Power• Hydrogen
What are Our Energy Needs?1. Energy for Transportation2. Energy for Buildings3. Energy for Industry
What Role DoesEnergy Efﬁciency Play?Approximately 84% of commercial energy in US iswasted.1. 41% because of the second law of thermodynamics(high quality energy to low quality energy inreactions)2. 43% because of inefﬁcient cars, furnaces,appliances, and poorly insulated buildings.
Solar Power Pro’s Con’s• High net • Need access to energy sun• No CO2 • Need storage/ backup system• Low environ- mental impact • High cost• Reduces • High land use* Solar Array in Arizona dependence on fossil fuels • Low efﬁciency• Work on cloudy days*
Wind PowerAdvantages1. Most rapidly growing source of energy.2. Only 1% in US now, but 1.5% in CA.3. Inexpensive and clean.Disadvantages1. Need lots of space and wind.2. Midwest US (Texas and the Dakotas, too).3. Primary drawbacks are visual pollutionand migratory and predatory bird mortality.
BioFuelsPro’s of Biofuels • Stimulate rural agrarian communities • Relieve dependence on Middle East oil • Cut CO2 emissions (biofuels release CO2 taken from atmosphere, theoretically carbon- neutral)
Biofuels Continued...Con’s of Biofuels 1. Herbicides, pesticides, fertilizers used now on corn 2. Soil erosion 3. Producing corn ethanol uses as much fossil fuel as it replaces 4. Biodiesel from soybeans is similar Sugarcane in Brazil
BiofuelsCons (continued)4. Rising prices for these crops will push farmers to cultivate 35 million more acres of marginal farmland that are now set aside for soil conservation and wildlife management6. This production for biofuels will raise prices for food from beef to corn ﬂakes Ethanol facility in Brazil
Geothermal Power Pro’s Con’s• High efﬁciency • Shortage of suitable sites*• Lower CO2 • Depleted if used• Low cost at too rapidly favorable sites • CO2 emissions• Low land use and distubance • Moderate/High air pollution Geothermal Plant in California• Moderate environmental • High cost* impact
Hydroelectric EnergyHydroelectric. Produces 6% ofthe world’s commercial energy(4% in US), but 20% of theworld’s electricity (10% US).This can be misleading… on theWest Coast 63%.Large Scale: High Dam is buildacross the river, creates lake.Water ﬂows through pipes in thedam to turn turbines and powergenerators which produceelectricity.Small Scale: Low dam built (nolake) turbines power generator toproduce electricity.
More on HydroelectricPluses1. High net energy, high efﬁciency, low cost2. No CO23. Flood control4. Irrigation possibilitiesNegatives1. Disrupts natural water/nutrient ﬂow of river2. Interrupts ﬁsh migrations3. Floods land areas (large scale dams)4. High construction costs
Hydrogen and Fuel Cell Technology• Advantages • abundant sources of H2 • clean fuel (H2O produced as waste)• Disadvantages • obtaining the H2 from water and other sources uses a lot of energy (carbon footprint) • lack of hydrogen delivery infrastructure