Population energy climate change
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Population energy climate change

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Population energy climate change Population energy climate change Presentation Transcript

  • Chapter 2.5 Population, Energy, and Climate Change
  • What are the Major Air Pollution Problems?
    • Troposphere
      • The atmospheric layer closet to earth ’ s surface
      • A dynamic system involved in the chemical cycling of the earth vital nutrients
    • Stratosphere
      • 17 to 48 kilometers above the earth ’ s surface
      • Ozone layer
    • Air pollution
    • Primary pollutants
    • Secondary pollutants
    • Carbon Oxides
      • Carbon monoxide (CO)
        • A colorless, odorless, highly toxic gas
      • Carbon dioxide (CO2)
        • Colorless, odorless gas
        • 93% found in the atmosphere is caused by the natural carbon cycle
  • What are the Major Air Pollution Problems?
    • Particles
      • A variety of solid particles and liquid droplets that remain suspended in the air for long periods.
    • Ozone
      • O3 is the major component of smog
    • Volatile Organic Compounds (VOCs)
      • Organic compounds that exist as gases in the atmosphere
    • Radioactive Radon (Rn)
      • A naturally occurring colorless & odorless radioactive gas found in rocks and soil
  • What are the Major Air Pollution Problems?
    • Temperature Inversion
      • The layer of warm air that lie atop of cooler air near the ground
      • Due to cooler air being denser than warmer air above, the result is the air near the surface
  • How Might the Earth ’s Temperature and Climate Change in the Future?
    • Enhanced Greenhouse Effect
      • Global Warming
        • Scientists warn that the concern is not just above how much the temperature changes but also how rapidly it occurs.
  • How can technology help?
  • Economies are powered by fossil fuels
    • 80% of our energy comes from oil, coal, and natural gas
  • Nations vary in the renewables they use
    • In the U.S., most renewable energy comes from hydropower and biomass.
  • The new renewables are growing fast
    • They are growing at much faster rates than conventional sources.
      • Wind power is the fastest growing.
      • However, since these sources began at low levels, it will take time to build them up.
    • Due to: population and consumption growth, increased energy demand, declining fossil fuel supplies, and the demand for a cleaner environment
    • Technological and economic barriers prevent a quick switch to renewables.
      • Renewables receive little government help.
    Rapid growth in renewables will continue The 2007 energy bill passed only after Congress dropped requirements to shift subsidies from non-renewables to renewables and for utilities to increase using renewables.
  • Biofuels can power automobiles
    • Ethanol : produced as a biofuel by fermenting carbohydrate-rich crops
      • Ethanol is widely added to U.S. gasoline to reduce emissions.
      • Any vehicle will run well on a 10% ethanol mix.
    In 2007, the U.S. produced 30 billion L (6.5 million gal) of ethanol in 100 ethanol plants.
  • Cars can run on ethanol
    • Flexible fuel vehicles : run on 85% ethanol
      • But very few gas stations offer this fuel
    • Biodiesel : a fuel produced from vegetable oil, used cooking grease or animal fat
    • Some people use straight vegetable oil in their diesel engines.
  • Hydroelectric power
    • Hydroelectric (hydro) power : uses the kinetic energy of moving water to turn turbines and generate electricity
    • The storage technique : impoundments harness energy by storing water in reservoirs behind dams
      • Water passing through the dam turns turbines.
    • The run-of-river approach generates energy without greatly disrupting the flow of river water.
  • A typical dam
  • Hydropower is clean and renewable
    • Hydropower has two clear advantages over fossil fuels for producing electricity:
      • It is renewable: as long as precipitation fills rivers, we can use water to turn turbines.
      • It is clean: no carbon dioxide is emitted.
    • Hydropower is efficient.
      • It has an EROI of 10:1, as high as any modern-day energy source.
  • Hydropower has negative impacts
    • Damming rivers destroys riverine habitats.
    • Natural flooding cycles are disrupted.
    • Sediment deposition
    • Thermal pollution of downstream water
    • Reducing fish populations and aquatic biodiversity
  • Hydroelectric power is widely used
    • Nations with large rivers and economic resources have used dams.
    • But hydropower is not likely to expand.
      • Most of the world ’ s large rivers have already been dammed.
      • People have grown aware of the ecological impact of dams.
  • Solar energy
    • The sun provides energy for almost all biological activity on Earth.
      • There is great potential in solar energy, but we are still developing technologies to efficiently use it.
    • Passive solar energy : the most common way to harness solar energy
      • Buildings are designed to maximize direct absorption of sunlight in winter and keep cool in summer.
    • Active solar energy collection : uses technology to focus, move, or store solar energy
  • Passive solar heating is simple and effective
    • Low south-facing windows maximize heat in the winter.
      • Overhangs shade windows in the summer.
    • Thermal mass : construction materials that absorb, store, and release heat
    • By heating buildings in winter and cooling them in summer, passive solar methods conserve energy and reduce costs.
  • Active solar energy collection
    • Flat plate solar collectors (solar panels) : one active method for harnessing solar energy
      • Installed on rooftops
      • Dark-colored, heat-absorbing metal plates
        • Water, air, or antifreeze pass through the collectors, transferring heat throughout the building.
        • Heated water is stored and used later.
        • Effective for heating water for homes
  • Focusing solar rays magnifies energy
    • Focusing solar energy on a single point intensifies its strength.
    • Solar cookers : simple, portable ovens that use reflectors to focus sunlight onto food
    • Power tower : mirrors concentrate sunlight onto receivers to create electricity
    In southern California, a power tower produces power for 10,000 households.
  • Solar power is little used but fast growing
    • Solar energy was pushed to the sidelines by fossil fuels.
      • Because of a lack of investment, solar energy contributes only a miniscule amount of energy.
      • But solar energy use has grown 25%/year since 1971.
    • Solar energy is attractive in developing nations.
      • Where hundreds of millions don ’ t have electricity
    • The U.S. may recover its leadership, given a 2005 federal tax credit and some state initiatives.
    • Solar energy use should increase as prices fall, technologies improve, and governments enact economic incentives.
  • Solar power offers many benefits
    • The sun will burn for 4 – 5 billion more years.
    • Solar technologies use no fuels, are quiet, safe, contain no moving parts, and require little maintenance.
    • They allow local, decentralized control over power.
    • Developing nations can use solar cookers and photovoltaics.
    • Net metering : PV owners can sell excess electricity to their local power utility
    • New jobs are being created.
    • Solar power does not emit greenhouse gases and air pollution.
      • Manufacturing units currently require fossil fuels.
  • Location is a drawback
    • Not all regions are sunny enough to provide enough power, with current technology.
      • Daily and seasonal variation also poses problems.
    • Up-front costs are high and solar power remains the most expensive way to produce electricity.
      • Future technologies will be much more efficient and have lower costs.
  • Modern wind turbines convert kinetic energy
    • Wind turbines : devices that turn wind energy into electricity
      • Wind blowing into a turbine turns the blades of the rotor, which rotate machinery inside a compartment ( nacelle ) on top of a tall tower.
    • Towers are 40 – 100 m (131 – 328 ft) tall.
      • Higher is better to minimize turbulence and maximize wind speed.
  • Wind is the fastest-growing energy sector
    • Wind farms : turbines erected in groups of up to hundreds of turbines
    • Wind power grew 26% per year globally between 2000 and 2005.
      • Five nations account for 80% of the world ’ s wind power.
    • California and Texas produce the most wind power in the U.S.
      • Wind power could be expanded to meet 30% of the U.S. electrical needs by 2030.
  • Wind power has many benefits
    • Wind produces no emissions once installed.
    • It prevents the release of CO 2, , SO 2 , NO x , mercury.
    • It is more efficient than conventional power sources.
    • Turbines also use less water than conventional power plants.
    • It can be used on many scales, from one turbine to hundreds.
    • Farmers and ranchers can lease their land.
      • Produces extra revenue
      • Landowners can still use their land for other uses.
  • Wind power has some downsides
    • We have no control over when wind blows.
      • This poses little problem if wind is one of several sources of electricity.
    • Good wind sources are not always near population centers that need energy.
    • Residents often oppose wind farms near population centers.
    • Wind turbines also kill birds and bats when they fly into rotating blades.
  • U.S. wind-generating capacity
    • Mountainous regions have the most wind capacity.
  • Conclusion
    • More people are becoming convinced that we need to shift to renewable energy sources.
      • Biomass and hydropower already play important roles.
      • Renewable sources include solar, wind, geothermal, and ocean energies.
      • Hydrogen fuel may produce electricity.
    • Most renewable sources have been hampered by inadequate funding for research and by artificially cheap fossil fuels.
      • But there is hope that we can shift to renewables with minimal disruption.
  • What do you know?
  • QUESTION: Review
    • We can harness power from wind by using devices called:
      • Wind turbines
      • Wind parks
      • Wind farms
      • Solar cells
      • Nacelles     
  • QUESTION: Interpreting Graphs and Data
    • Maine, Florida
    • Texas, Kentucky
    • Arizona, Idaho
    • North Dakota, Ohio
    • Louisiana, Oklahoma
    _____ is the best state for producing solar energy, while _____ is best for wind energy. Solar Wind