28
For his contributions to the field of thermodynamics, the International Standard
base unit of energy in any form is the “Joule.” One human-scaled example of the
amount of energy measured in a single Joule is the work done by lifting an apple
(with a mass of a bit over 100 grams) off the floor to a height of 1 meter. A less relatable example connecting thermodynamics to electrodynamics is 1 joule of heat that
is given off each second as 1 ampere of electrical current flows through 1 ohm of
resistance. For many, unfamiliar with electrical units, this requires clarification and
further definition of terms.
2.6.1 Power Is Flowing Energy Measured Over Time
Power is often confused with energy. Power is distinct from energy in that it is measured over time. Energy is an amount, and power is the rate at which this quantity is
converted from one type of energy to another. A watt is a unit of power. Whether
referring to electrons, wind, or steam, the flow of electrical, mechanical, chemical,
or thermodynamic energy can all be expressed in watts. A year before his death,
William Siemens proposed in 1882 that the unit be named after the Scottish inventor
of the steam engine, James Watt, who a hundred years earlier “first had a clear
physical conception of power, and gave a rational method of measuring it” (Siemens
1883). Watt recorded the mechanical power output of a mill horse of 32,400 foot
pounds per minute. Today watt is used by most to describe electrical power such as
how much a lightbulb consumes to generate illumination.
Any discussion of the power output or consumption of something, whether it is
a hydroelectric dam or a 60 watt lightbulb, must refer to a duration even if not
explicitly stated. Seconds, hours, days, years, or some other time unit can be used,
but when referring to power ratings of things as large as power generation plants to
relatively small domestic appliances or devices, we typically express power flow
in hours.
Harnessed electricity plays an enormous macro scale role in the industrialized
world. The 23,000 terawatts/hour used in 2019 according to Enerdata’s Global
Statistical Yearbook 2020 (World Energy Statistics 2020) can obscure the ceaseless
action of electron transfer at the microscopic scale in all chemical and biological
activities. From galvanic reactions that cause one metal to dissolve when touching
another that can result in structural failure to the reduction-oxidation reactions of
burning fuel, these are examples of electrons naturally moving in a way that can be
anticipated and controlled. Net environmental damage results largely through energetic reactions at this atomic scale. Large flows of harmful substances released into
the soil, water, and air chemically react to form persistent compounds, not readily
metabolized, destabilizing the earth’s natural systems.
Whether considering environmental electrochemistry, industrial-scale electricity
production, or consumer-scale power usage and needs, the terminology is the same.
One watt of power equals the flow of 1 joule per second. One watt is the force of 1
2 The Energy Essential: Physical Forces Animate All Things
For his contributions to the field of thermodynamics, the International Standard
base unit of energy in any form is the “Joule.” One human-scaled example of the
amount of energy measured in a single Joule is the work done by lifting an apple
(with a mass of a bit over 100 grams) off the floor to a height of 1 meter. A less relatable example connecting thermodynamics to electrodynamics is 1 joule of heat that
is given off each second as 1 ampere of electrical current flows through 1 ohm of
resistance. For many, unfamiliar with electrical units, this requires clarification and
further definition of terms.
2.6.1 Power Is Flowing Energy Measured Over Time
Power is often confused with energy. Power is distinct from energy in that it is measured over time. Energy is an amount, and power is the rate at which this quantity is
converted from one type of energy to another. A watt is a unit of power. Whether
referring to electrons, wind, or steam, the flow of electrical, mechanical, chemical,
or thermodynamic energy can all be expressed in watts. A year before his death,
William Siemens proposed in 1882 that the unit be named after the Scottish inventor
of the steam engine, James Watt, who a hundred years earlier “first had a clear
physical conception of power, and gave a rational method of measuring it” (Siemens
1883). Watt recorded the mechanical power output of a mill horse of 32,400 foot
pounds per minute. Today watt is used by most to describe electrical power such as
how much a lightbulb consumes to generate illumination.
Any discussion of the power output or consumption of something, whether it is
a hydroelectric dam or a 60 watt lightbulb, must refer to a duration even if not
explicitly stated. Seconds, hours, days, years, or some other time unit can be used,
but when referring to power ratings of things as large as power generation plants to
relatively small domestic appliances or devices, we typically express power flow
in hours.
Harnessed electricity plays an enormous macro scale role in the industrialized
world. The 23,000 terawatts/hour used in 2019 according to Enerdata’s Global
Statistical Yearbook 2020 (World Energy Statistics 2020) can obscure the ceaseless
action of electron transfer at the microscopic scale in all chemical and biological
activities. From galvanic reactions that cause one metal to dissolve when touching
another that can result in structural failure to the reduction-oxidation reactions of
burning fuel, these are examples of electrons naturally moving in a way that can be
anticipated and controlled. Net environmental damage results largely through energetic reactions at this atomic scale. Large flows of harmful substances released into
the soil, water, and air chemically react to form persistent compounds, not readily
metabolized, destabilizing the earth’s natural systems.
Whether considering environmental electrochemistry, industrial-scale electricity
production, or consumer-scale power usage and needs, the terminology is the same.
One watt of power equals the flow of 1 joule per second. One watt is the force of 1
2 The Energy Essential: Physical Forces Animate All Things