ES101 Lecture Notes - Lecture 12: Carbon-Based Fuel, Kinetic Energy, Electric Generator
Week 3, Lecture 2: Energy
***midterm
10 multiple choice (11)
5-10 short answer qs
2 long answer questions (real world problem → one might be related to video lecture but will get
choice)
Photosynthesis
● What is energy
● Origins of energy
● Laws of conservation of matter and thermodynamics
● The turbine
● Nuclear energy
● Energy as a system
● We humans consume a lot of energy to make our systems work
● Many of the environmental problems/challenges we face today arise from how we obtain
the energy we use
● To readjust our energy acquisition and energy use systems so that they cause less harm
to natural systems, we 1st need to recognize basic properties of energy
Hydrogen Fuel
● Hydrogen is plentiful
● It powers a car very efficiently
● Is not a fossil fuel, so combustion creates no new greenhouse gases
● The only thing that comes out of the tailpipe is steam (like a kettle)
● You don’t need to modify existing car designs very much to use hydrogen
● So why not use hydrogen fuel?
○ Pure hydrogen H2 is rare in nature
○ To make hydrogen fuel, existing technologies usually burn fossil fuels, use
methane (break methane or water to get to hydrogen)
find more resources at oneclass.com
find more resources at oneclass.com
○ The process of making hydrogen is inefficient and generates a lot of greenhouse
gases (have to burn energy to break apart molecular bonds)
○ Problem with hydrogen is an example of running into the laws of thermodynamics
What is Energy?
● What allows you to move matter
● Moving matter = work
● We typically recognize energy in the form of heat
● 3 types:
○ Kinetic = when matter is moving (e.g. wind blowing, streams flowing, electricity)
○ Potential = energy not in use at this moment but that could be released (e.g.
unlit match, tank of gas)
○ Electromagnetic radiation = waves of energy that are emitted and passed
through space via + and - charged particles (e.g. sunlight, x-rays)
Nissan Leaf SV (electric car)
● Range = 170km/charge
● Cost to recharge = ~$1.30
● Time to recharge at home = ~2 hours
● Price = $33 000 +
Where Does the Biosphere’s Energy Originate?
● Mostly from the sun, either in real time or as stored energy from past sunshine
● A spectrum of electromagnetic radiation of various wavelengths and energy content is
emitted from the sun
● The shorter the wavelength, the more energy delivered; longer wavelengths deliver less
energy
Low Quality vs High-Quality Energy
● Some substances store more energy per unit volume than others
● E.g. gasoline (high) vs water (low)
● To generate lots of electricity to power a city, you need high quality energy sources
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find more resources at oneclass.com
● To heat your home, passive sunlight can do most of the job in the daytime
● Human systems use a lot of high quality energy
Heat vs Temperature
● Heat = total amount of kinetic energy of all the atoms, molecules moving about within an
object (or other unit of matter)
● Heat also describes the amount of energy that can be transferred between 2 objects
(e.g. how much heat you would lose if you jumped into a lake)
● Temperature = the average speed of all the atoms and molecules moving about within
an object
● How heat (energy) gets transferred → pot on stove
○ Convection: bubbles inside pot of water, water in contact with hot metal surface
heats up and moves away from surface, replaced but other water molecules
○ Conduction: spreads through metal
○ Radiation: energy transferred from hot surface through air
Physical, Chemical, and Nuclear Change
● Physical change = allowing an ice cube to melt
● Chemical change = changing the composition of the substance (burning a carbon based
fuel combines carbon with oxygen to release stored energy and produces carbon dioxide
as by-product)
● Nuclear change = a spontaneous change in the nucleus of an isotope
Brief Intro to Nuclear Energy
● Ontario nuclear plants → Darlington, Bruce, Pickering
● Nuclear fission
○ Starts with radioactive isotopes
○ Isotope is atom that has a different number of neutrons than is commonly found
○ There are unstable isotopes that spontaneously emit particles and radiation and
fixed rate as the nucleus decays (measured by half life)
○ Various elements may have unstable isotopes; most commonly known one is
Uranium 235 (ordinary uranium atomic mass 238), 235 unstable and rare in
nature
○ Atomic mass = protons + neutrons
○ Take an unstable isotope, blast it to split apart and release energy and some
loose neutrons
○ Imagine hitting a lego block with a hammer… shards
○ If you can cause the fast moving free neutrons to collide with other unstable
isotopes, you can cause a chain reaction that continues until you run out of fuel
○ This generates a lot of heat
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
2 long answer questions (real world problem one might be related to video lecture but will get choice) Laws of conservation of matter and thermodynamics. We humans consume a lot of energy to make our systems work. Many of the environmental problems/challenges we face today arise from how we obtain the energy we use. To readjust our energy acquisition and energy use systems so that they cause less harm to natural systems, we 1st need to recognize basic properties of energy. Is not a fossil fuel, so combustion creates no new greenhouse gases. The only thing that comes out of the tailpipe is steam (like a kettle) You don"t need to modify existing car designs very much to use hydrogen. Pure hydrogen h2 is rare in nature. To make hydrogen fuel, existing technologies usually burn fossil fuels, use methane (break methane or water to get to hydrogen)
