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SPEAKER_00Energy is all around us, a
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SPEAKER_00physical quantity that follows precise natural laws.
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SPEAKER_00Our universe has a finite amount of it.
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SPEAKER_00It's neither created nor destroyed,
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SPEAKER_00but can take different forms, such
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SPEAKER_00as kinetic or potential energy,
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SPEAKER_00with different properties and formulas to remember.
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SPEAKER_00For instance, an LED desk lamp's
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SPEAKER_006-watt bulb transfers 6 joules of light energy per second.
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SPEAKER_00But let's jump back up into space
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SPEAKER_00to look at our planet, its systems, and their energy flow.
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SPEAKER_00Earth's physical systems include the atmosphere,
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SPEAKER_00hydrosphere, lithosphere, and biosphere.
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SPEAKER_00Energy moves in and out of these systems,
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SPEAKER_00and during any energy transfer between them,
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SPEAKER_00some is lost to the surroundings
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SPEAKER_00as heat, light, sound, vibration, or movement.
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SPEAKER_00Our planet's energy comes from
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SPEAKER_00internal and external sources.
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SPEAKER_00Geothermal energy from radioactive isotopes
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SPEAKER_00and rotational energy from the spinning
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SPEAKER_00of the Earth are internal sources of energy,
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SPEAKER_00while the sun is the major
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SPEAKER_00external source, driving certain systems like
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SPEAKER_00our weather and climate.
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SPEAKER_00Sunlight warms the surface and
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SPEAKER_00atmosphere in varying amounts, and
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SPEAKER_00this causes convection, producing winds
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SPEAKER_00and influencing ocean currents.
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SPEAKER_00Infrared radiation, radiating out from
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SPEAKER_00the warmed surface of the Earth,
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SPEAKER_00gets trapped by greenhouse gases and
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SPEAKER_00further affects the energy flow.
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SPEAKER_00The sun is also the major source of energy for organisms.
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SPEAKER_00Plants, algae, and cyanobacteria use
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SPEAKER_00sunlight to produce organic matter from
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SPEAKER_00carbon dioxide and water, powering
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SPEAKER_00the biosphere's food chains.
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SPEAKER_00We release this food energy using
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SPEAKER_00chemical reactions like combustion and respiration.
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SPEAKER_00At each level in a food chain,
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SPEAKER_00some energy is stored in newly made chemical structures,
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SPEAKER_00but most is lost to the surroundings
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SPEAKER_00as heat, like your body heat, released
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SPEAKER_00by your digestion of food.
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SPEAKER_00Now, as plants are eaten by primary consumers,
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SPEAKER_00only about 10% of their total energy
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SPEAKER_00is passed on to the next level.
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SPEAKER_00Since energy can only flow in one
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SPEAKER_00direction in a food chain, from producers on to consumers
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SPEAKER_00and decomposers, an organism that eats
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SPEAKER_00lower on the food chain is more efficient than one higher up.
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SPEAKER_00So eating producers is the most
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SPEAKER_00efficient level at which an animal can get its energy.
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SPEAKER_00But without continual input of energy to those producers,
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SPEAKER_00mostly from sunlight, life on Earth as
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SPEAKER_00we know it would cease to exist.
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SPEAKER_00We humans, of course, spend our energy
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SPEAKER_00doing a lot of things besides eating.
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SPEAKER_00We travel, we build, we power all sorts of technology.
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SPEAKER_00To do all this, we use sources like fossil fuels.
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SPEAKER_00coal, oil, and natural gas, which contain energy
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SPEAKER_00that plants captured from sunlight long
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SPEAKER_00ago and stored in the form of carbon.
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SPEAKER_00When we burn fossil fuels in power plants,
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SPEAKER_00we release this stored energy to generate electricity.
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SPEAKER_00To generate electricity, heat from burning
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SPEAKER_00fossil fuels is used to power turbines
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SPEAKER_00that rotate magnets, which in turn
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SPEAKER_00create magnetic field changes relative to
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SPEAKER_00a coil of wire, causing electrons to be
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SPEAKER_00induced to flow in the wire.
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SPEAKER_00Modern civilization depends on our
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SPEAKER_00ability to keep powering that flow of electrons.
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SPEAKER_00Fortunately, we aren't limited to
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SPEAKER_00burning non-renewable fossil fuels to generate electricity.
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SPEAKER_00electrons can also be induced to
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SPEAKER_00flow by direct interaction with light
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SPEAKER_00particles, which is how a solar cell operates.
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SPEAKER_00Other renewable energy sources, such
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SPEAKER_00as wind, water, geothermal, and biofuels,
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SPEAKER_00can also be used to generate electricity.
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SPEAKER_00Global demand for energy is increasing,
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SPEAKER_00but the planet has limited energy
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SPEAKER_00resources to access through a complex energy infrastructure.
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SPEAKER_00As populations rise alongside rates
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SPEAKER_00of industrialization and development, our
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SPEAKER_00energy decisions grow more and more important.
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SPEAKER_00Access to energy impacts health, education,
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SPEAKER_00political power, and socioeconomic status.
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SPEAKER_00If we improve our energy efficiency,
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SPEAKER_00we can use our natural resources
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SPEAKER_00more responsibly and improve quality of life for everyone.