Chapter 14.2Indirect Solar Energy
HYDROPOWER dammed water flows under high pressure through
channels to drive turbogenerators amount of power generated is proportional to both the
height of the water behind the dam and the volume of water that flows through
about 6.7% of the electrical power generated in the U.S. currently comes from hydroelectric dams
About 17% of electricity in the world is generated by hydropower, making it the most common formof renewable energy in use
hydropower—advantages
costs and environmental effects of fossil fuel and nuclear power plants are eliminated
hydropower plants have longer lifespan than those that are fuel-fired
provide flood control on rivers provide water for irrigation of agricultural land provide recreational opportunities
hydropower--disadvantages reservoir created floods ecosystem behind
dam dams often displace large rural
populations dams impede migration of fish and other
species downstream ecosystems are impacted by
changing water levels
state of dams
few sites conducive to large dams remain only about 2% of America rivers remain
free flowing most of Fraction without dams are
protected by the Wild and Scenic Rivers Act of 1968
trend is to start removing some dams to return flow of water to its natural course
WIND POWER King Wind Ranch in Texas is example of large-
scale wind farm consists of 214 wind turbines capable of generating
278 MW generates enough electricity to supply 100,000 homes development encouraged by Texas Renewable
Portfolios Standard which mandated that 2000 MW of renewable capacity be added within a decade
benefits from energy Production Tax Credit of 1.5 cents per kWh initiated by the Energy Policy Act of 1992
wind power around the world
in 2005, U.S. wind energy-generating capacity was 9100 MW
U.S is third behind Germany and Spain in utilizing wind power
global wind power capacity has increased 28% per year over the last 5 years, with worldwide capacity of over 59000 MW
wind is 2nd fastest-growing energy source behind solar because has become economically competitive with conventional sources
wind machine designs wind-driven propeller blades have proven to be
most effective design propeller shaft is geared directly to a generator
wind farms, with up to several thousand turbines, now produce pollution-free, sustainable power for less than 5 cents per kWh great potential in the Midwest where land could still
be used for farming farmers receive royalties on the order of $2000 -
$3000 per turbine per year for leasing land
wind power--disadvantages intermittent source—requires storage or
backup system disrupts aesthetic beauty of landscape
large consideration in proposed offshore wind farm in Nantucket Sound off Cape Cod
concerns included “visual pollution” and threats to tourism, navigation, fishing, and migrating birds
hazard to birds (a consideration near migratory routes and critical habitats)
BIOMASS ENERGY biomass energy: energy derived from present-
day photosynthesis leads hydropower in renewable energy
production in the U.S. means of producing biomass energy include:
burning wood in a stove burning wastepaper or organic waste generating methane from the anaerobic digestion of
manure producing alcohol from fermenting grains
burning firewood wherever forests are abundant, fuelwood (firewood)
can be a sustainable energy resource primary source for 2.6 billion people most recent development is the pellet stove
burns compressed wood pellets made from wood wastes pellets are loaded into hopper (controlled by computer) that
feeds fuel when it is needed although worries that consumption of fuelwood would
lead to widespread deforestation, it appears that global use of fuelwood is declining (developing countries are slowly shifting to other fuels)
waste and methane burning wastes is a productive and
relatively inexpensive way to dispose of biological wastes Ex. wastes from olive oil production power 3
power plants in Spain, generating over 32 MW of power to supply 100,000 homes
anaerobic digestion of sewage yields biogas (mostly methane) plus a nutrient-rich sludge that is a good organic fertilizer
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