360 likes | 660 Vues
Chapter 13 Renewable Energy and Conservation. Overview of Chapter 13. Direct Solar Energy Heating Buildings and Water Solar Thermal Electric Generation Photovoltaic Solar Cells Indirect Solar Energy Biomass Energy Wind Energy Hydropower Other Renewable Energy Sources Geothermal Energy
E N D
Overview of Chapter 13 • Direct Solar Energy • Heating Buildings and Water • Solar Thermal Electric Generation • Photovoltaic Solar Cells • Indirect Solar Energy • Biomass Energy • Wind Energy • Hydropower • Other Renewable Energy Sources • Geothermal Energy • Tidal Energy • High and Low Technology Energy Solution • Hydrogen and Fuel Cells • Energy Efficiency
Direct Solar Energy • Varies with latitude, season, time of day, and cloud cover
Heating Buildings and Water • Passive solar energy • system of putting the sun’s energy to use without requiring mechanical devices to distribute the collected heat • Certain design features can enhance passive solar energy’s heating potential • South facing windows (in N. hemisphere) • Well insulated buildings • Attic vents • Overhangs and solar sunspaces
Solar sunspace • Utilizes passive solar energy to heat and cool homes • Can be added to existing homes
Heating Buildings and Water • Active Solar Energy • System of collecting and absorbing the sun’s energy, and using pumps or fans distribute the collected heat • Most common • Series of collection devices on roofs or in fields • Typically a black panel or plate • Used to heat water
Heating Buildings and Water • Solar Thermal Electric Generation • Means of producing electricity in which the sun’s energy is concentrated by mirrors or lenses to either heat a fluid filled pipe or drive a Stirling engine • More efficient than other solar technologies • Benefits • No air pollution • No contribution to global warming or acid precipitation
Photovoltaic Solar Cells • Thin cells are treated with certain metals so that they generate electricity when they absorb solar energy • Convert sunlight directly into energy • No pollution and minimal maintenance • Used on any scale • Lighted road signs • Entire buildings
Photovoltaic Solar Cells • Can be incorporated into building materials • Roofing shingles • Tile • Window glass
Indirect Solar Energy • Biomass • Plant materials used as fuel • Ex: wood, crop wastes, sawdust, and animal wastes • Contains energy from sun via photosynthesizing plants • Renewable when used no faster than it can be produced • Can convert to biogas or liquids • Ethanol and methanol
Advantages and Disadvantages of Biomass • Advantages • Reduces dependence on fossil fuels • Often uses waste materials • If trees are planted at same rate biomass is combusted, no net increase in atmospheric CO2 • Disadvantages • Requires land, water and energy • Can lead to • Deforestation • Desertification • Soil erosion
Indirect Solar Energy • Wind Energy • Electric or mechanical energy obtained from surface air currents caused by solar warming of air • World’s fastest growing source of energy • Wind results from sun warming the atmosphere • Varies in direction and magnitude • New wind turbines harness wind efficiently
Wind Energy • Most profitable in rural areas with constant wind • Few environmental problems • Kills birds and bats • No waste- clean source of energy • Biggest constraints • Cost • Public resistance
Indirect Solar Energy • Hydropower • Form of renewable energy reliant on flowing or falling water to generate mechanical energy or electricity • Sun’s energy drive hydrologic cycle • Most efficient energy source (90%)
Hydropower • Generates 19% of world’s energy • Traditional hydropower • Only suited for large dams • New technology • May be able to utilize low flow waterways • Problems with Dams • Changes natural flow of rivers • Disrupts migratory fish patterns • Potential dam breaks
Other Indirect Solar Energy • Ocean waves • Produced by winds • Has potential to turn a turbine- and create electricity • Ocean Temperature Gradients • Use difference in temperature of surface and deep water to create electricity
Other Renewable Energy Sources • Geothermal Energy • Energy from the Earth’s interior for either space heating or generation of electricity • From Hydrothermal Reservoirs (left) • Created by volcanoes • Reservoirs used directly for heat or to generate electricity
Geothermal Energy • From hot, dry rock • Geothermal heat pumps • Use difference in temperature between surface and subsurface • Great for heating buildings • Expensive installation
Other Renewable Energy Sources • Tidal Energy • Form of renewable energy that relies of the ebb and flow of the tides to generate electricity • Typical difference between high and low tide is 1-2 ft • Narrow bays may have greater variation • Energy can be captured with • A dam across the bay • A turbine similar to a wind turbine
Hydrogen as a Fuel Source • Advantages to Hydrogen as a fuel source • Very high energy density • Can be produced from any electrical source • Electrolysis (see illustration on next slide) • No greenhouse gases and few other pollutants • Can be use in vehicles • Disadvantages to Hydrogen as a fuel source • Highly volatile (requires special storage) • Relatively inefficient
Hydrogen Fuel Cell • Fuel cell • Device that directly converts chemical energy into electricity • Requires hydrogen from a tank and oxygen from the air • Similar to a battery, only the reactants are supplied from outside source
Future Applications of Fuel Cells • Vehicles • Not yet commonly available • Hydrogen is not yet readily available as a fuel source • Batteries in cells phones or laptops
Energy Efficient Technologies • Super-insulated buildings (right) • Energy efficient appliances (ENERGYSTAR) • Compact Fluorescent light bulbs • Condensing furnaces
Energy Efficient Technologies • Automobiles – we could do much better, but the foreign manufacturers are already much improved! • USA avg. auto fuel efficiency doubled between mid-1970’s and mid 1980’s, but has actually declined since then!!!!! • Current technology could routinely produce autos that get 60-65 mpg within next 10 years • Aircraft technology • Papermaking industry also much more efficient
Cogeneration • Production of two useful forms of energy from the same fuel