Physical Science Fundamentals
Physical Science Fundamentals
To understand energy, there are several topics from physics and chemistry for us to understand.
units of energy
power and energy
different types of energy
conservation of energy
laws of thermodynamics
chemistry of photosynthesis
chemistry of combustion
Learning Objectives
Able to estimate energy quantities
Able to move from a question to a mathematical estimation
Able to use energy formulas accurately
Basic Energy Concepts
Energy
Power
Energy Conversion
Energy Efficiency
Energy Units
briefly review
lecture on efficiency, energy conversion
Concepts
Energy
Power
Conservation of Energy
Energy Conversion
Energy Efficiency
Types of Energy
Gravitational Potential Energy
Kinetic Energy
Chemical Energy
Radiant Energy
Thermal Energy
Readings
HK-02 Energy Mechanics
HK-03 Conservation of Energy
HK-04 Heat and Work
ERG Toolkit
IPCC Energy Primer
Basic Concepts
Energy units
Force
Energy
Work
Power
Unit Conversions
Efficiency
Energy conversion
Conversion of energy is the key to making it useful
Energy and Power
Energy Units
Joule
SI Unit. One Newton-Meter.
Kilowatt-Hour
Energy consumed by 1 kW load over one hour
Calorie
Energy to heat one gram of water one degree Celsius
Kilo-calorie
One thousand calories. Used in food energy content.
British Thermal Unit (BTU)
Energy to heat one pound of water by one degree Fahrenheit
Quad
One quadrillion ($10^{15}$) BTU
Scale of energy quantities
from IPCC Energy Primer
What is energy?
Energy is defined as the capacity to do work
Energy can be thought of as an accounting device
Energy is never destroyed or lost, only converted
word coined by Aristotle meaning work within
Energy = power * time
Distance is a useful analogy
What is power?
Power is how quickly we are able to consume or convert energy
Measure in energy per unit time
The rate at which energy is delivered.
Speed is a useful analogy
Unit Conversions
We may wish to compare energy units that are not consistent
Often you can look up conversions in a table
Other times you may need to recreate the conversion
Back of the Envelope Calculations
Construct a model of appropriate complexity
Gather estimates of necessary quantities
Calculate estimate
Evaluate for feasibility
Possible Activities
Energy per person per year globally
Equivalent power per person per year globally
Unit conversions
Conversions
Factor-label method
Unit-factor method
Exercise
How much energy does the average person in the United States use each year?
Strategy
Find a figure for US energy use
Find a figure for the US population
Checking units says to divide the two
Exercise
The world uses 474 EJ of energy per year. How much is that per person per year?
Strategy
Find global energy use
Find global population
Divide
Worldwide (wikipedia) 474 Exajoules
population 7 billion
474E18 / 7E9 = 67 GJ per person
Exercise
What is the average power that each US person consumes?
Strategy
Use the definitions of power and energy with what we know about US
energy usage per year
100 Exajoules / population / (3.14 * 10^7 seconds)
Simplified Photosynthesis and combustion
Photosynthesis
CO~2~ + H~2~O + Sunlight (Radiation Energy) $\to$ C~X~H~Y~O~Z~ + O~2~
Combustion
C~X~H~Y~ + O~2~ $\to$ CO~2~ + H~2~O + Heat Energy
Real combustion
The atmosphere is not purely oxygen, it also has nitrogen and other
elements
Fossil fuels are not pure carbon and hydrogen, they contain impurities
like sulfur and mercury
When all these chemicals participate in combustion, they produce
sulfur oxides (SO~X~), nitrous oxides (NO~X~), and other chemicals
These chemicals are the cause of acid rain and other environmental
effects
Carbon Intensity
Fuel Source | Carbon Intensity |
Coal | 2249 lb CO2/MWh |
Natural Gas | 1135 lb CO2/MWh |
Proposed EPA Limit | ~ 1100 lb CO2/MWh |
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