Page 15 - Microsoft Word - LessonPlan-Overview.doc
P. 15
Unit 12: Alternative Energy Page 15 of 31
Currently, geothermal energy (heat requirements of a home, while
inside the earth), biomass (energy water and space heating are the
from plants), solar energy (light most important heating
from concentrated sunlight), and requirements.
wind are being used to generate
electricity. For example, in Solar Energy
California there are more than
sixteen thousand (16,000) wind The energy of sunlight powers our
turbines that generate enough biosphere (air, water, land, and life
power to supply a city the size of on the earth's surface). About 50
San Francisco with electricity. percent of the solar energy striking
the earth is converted to heat that
In addition to producing more warms our planet and drives the
energy, we can also help meet our winds. About 30 percent of the
energy needs through solar energy is reflected directly
conservation. Conservation means back into space. The water cycle
using less energy and using it more (evaporation of water followed by
efficiently. rain or snow) is powered by about
20 percent of the solar energy.
Cooling and Heating
Some of the sunlight that reaches
Cooling and heating are opposite the earth is used by plants in
processes. Cooling is the removal photosynthesis. Plants containing
of heat energy from an object or chlorophyll use photosynthesis to
space and heating is the addition of change sunlight to energy. Since
heat energy to an object or space. these green plants form the base
We use these opposite processes a of the food chain, all plants and
great deal in our daily lives. For animals depend on solar energy for
example, in the kitchen we use the their survival.
cooling provided by a refrigerator
to keep food cold. We also use the When the sun is overhead, about
heat from a stove to cook food. 1,000 watts of solar power strike 1
square meter (10.8 square feet) of
Nearly 75 percent of the energy the earth's surface. Using solar
used by the average family cells, this solar energy can be
household in the United States converted to electricity. However,
goes for cooling and heating because sunlight cannot be
purposes. Air conditioning and converted completely to electricity,
refrigeration are the major cooling it takes at least a square meter of
© 2011 Supercharged Science www.ScienceLearningSpace.com
417
