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