Population energy climate changePresentation Transcript
Chapter 2.5 Population, Energy, and Climate Change
What are the Major Air Pollution Problems?
The atmospheric layer closet to earth ’ s surface
A dynamic system involved in the chemical cycling of the earth vital nutrients
17 to 48 kilometers above the earth ’ s surface
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?
A variety of solid particles and liquid droplets that remain suspended in the air for long periods.
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?
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
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 (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.
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.
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.
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?
We can harness power from wind by using devices called:
QUESTION: Interpreting Graphs and Data
North Dakota, Ohio
_____ is the best state for producing solar energy, while _____ is best for wind energy. Solar Wind