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Weaving Climate Change Concepts Into High School Science Teaching. PCCE Convention – Edmonton October 16-17, 2012 Brian Martin – The King’s University College. Contexts for Good Science Teaching. - PowerPoint PPT Presentation
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Weaving Climate Change Concepts Into
High School Science Teaching
PCCE Convention – EdmontonOctober 16-17, 2012
Brian Martin – The King’s University College
Contexts for Good Science Teaching
• Good science teaching provides conceptual hooks that connect a student’s lived world with the world of scientific ideas
• Climate Change Science is a complex subject that reaches into virtually every part of the science curriculum – this is a natural and fruitful area in which to create these “hooks”
• Climate Change represents one of humanities greatest challenges and developing climate change literacy in students and the general population is a critical need
Five Sample “Lessons”Idea Concept(s) Suggested Curricular
LinksWhat is the mass of the atmosphere
Force, Pressure, mol Science 10Phys 20 – Unit BChem 20 – Unit B
How does the burning of CO2 change the atmosphere?
Stoichiometry Chem 20 – Unit D
Acidification of the Oceans Solutions, PH Chem 30 – Unit D
The Physics of Wind Power Conservation of Momentum and Energy, Power
Chem 20 – Unit CPhys 30 – Unit A
Photovoltaic Energy Energy and Power, dimensional arguments
Science 10Phys 20 – Unit C
(1) Mass of the AtmosphereBasic Facts:• Atmospheric pressure 100 kPa• 1 Pa = 1N/m2
• Radius of Earth 6.38 X 106m
What is the mass of a column of air 1m2 at the base which exerts a force of 100 kN ?
Ans: mg = 100 000 Nm = 104 kg
Every square m of the Earth’s surface supports 104 kg of air
2
2 4 2
6 2 4 2
18
4
4 (10 / )
4 (6.38 10 ) (10 / )
5 10
SA RMass R kg m
m kg mkg
How many molecules are there in the atmosphere?
Basic Facts:• Atmospheric is mostly N2 and O2
• “molar mass” approximately 30 g/mol
• Mass of atmosphere 5 X 1018 kg
21205 10
30 / 1.7 10
mass of atmosphereNumber of molsmolar mass
gg mol
mol
(2) How Much CO2 in ppm Does a Barrel of Oil Produce? Basic Facts:
• Carbon-based fuel releases 3.15 times its mass in CO2
• Mass of a barrel of oil is about 135 kg or
• 1 barrel releases 425 kg CO2
• CO2 has a molar mass of 44g/mol
1 barrel releases 425 kg of CO2; in moles this is
Since the atmosphere contains 1.7 X 1020 mol one barrel will release
kg molkg mol
4425 100.044 /
417
2010 6 101.7 10
This is the fraction of CO2 relative to the entire atmosphere – multiply by 1 million to get the parts-per-million or ppm. So, 1 barrel releases an additional
ppm116 10
Is the observed increase in CO2 “natural” or …Basic Facts:• 1 barrel of oil releases 6 X 10-11
ppm of new CO2 into the atmosphere
• 30 billion barrels of oil are consumed annually
bbl/a ppm/bblppm/a
9 11(30 10 )(6 10 )1.8
Slope = 1.8 pm/a
46 ppm
25a
A Bit Closer to home…what is the annual Carbon footprint of the Alberta Oil Sands in ppm?
Basic Facts:• Fort Mac produces 1.5 million
barrels of oil per day• Annual Carbon footprint is 40
million tonnes of carbon dioxide• 1 barrel of oil releases 6 X 10-11
ppm of new CO2 into the atmosphere
Mt CO bblkg bbl
7240 9.4 10425 /
bbl/a ppm/bblppm/a
7 11(9.4 10 )(6 10 )0.006
…but – that’s not the end of the story!
Components of Fossil Fuel Emissions
Le Quéré et al. 2009, Nature Geoscience
How about Coal-Generated Power?Basic Facts:• The Sundance Coal-fired Power
Generation Plant on Lake Wabamum produces 2126 MW
• Annual Carbon footprint is 17.5 million tonnes of carbon dioxide
The Sundance plant produces roughly 17.5/40 times as much CO2 as The Alberta Oil Sands
In other words – Sundance adds
ppm/a)= 0.003 ppm/a(17.5 / 40)(0.006
(or about “half-a-Fort Mac”)
Let’s Re-run the Numbers…Basic Facts:• CO2 sources by percent:
• Coal 40%• Oil 36%• Natural Gas 20%• Other 4%
If the burning of oil accounts for only 36% of the total CO2 loading then the total (anthropogenic) loading is …
1.8 / 5 /0.36
ppm a ppm a
So – where is the rest going?
(3) Ocean Acidification• The ocean buffers atmospheric
CO2
• The ocean’s pH has dropped from 8.20 to about 8.05 since the industrial revolution
D pH is only 0.15 – why Worry?
• At [8.20] H3O+ concentration is 6.31 × 10-9 mol L-1
• At [8.05] H3O+ concentration is 8.91 × 10-9 mol L-1
• This represents a 41% increase in hydronium ions – the ocean is being acidified
pH
pH H OsoH O
10 3
( )3
log [ ]
[ ] 10
(4) The Physics of Wind Power• How much power can a 100 m
diameter windmill produce?• Estimate the size of a wind farm
capable of producing the power output of the Sundance thermoelectric plant (2100 MW)
Energy from the wind• A packet of air of mass ‘m’ moving
with velocity ‘v’ has energy given as
kE mv212
m Av t A v t A v t1 1 2 2 D D D
kE Av tv212 D
P Av Av v3 212 D
Energy and power scale with the CUBE of wind velocity!
The total energy available is the difference between the energy of the incident air packet and the exiting air packet – Power that can be extracted is expressed as:
effectiveP P Av v v2 21 2
1 ( )2
Note the crucial role of the incident and exit wind velocity – we want to find the “sweet spot” – what is the maximum value for Peffective?
Force and Power on a Windmill
• A variation on Newton’s 2nd Law
• Combine the two differently derived expressions for P
v mF ma m vt t
Av tF v Av vt
D D
D DD
D DD
P Fv Av v2 D
Av v v Av v
v v v v v v v
2 2 21 2
2 21 2 1 2
1 ( )21 ( ) ( )2
D
D
This is known as Betz’s Law (circa 1920) and leads to a remarkable result – the velocity across the rotor of the windmill is
v vv 1 2( )2
Insert this into the power equation to get…
v vP A v v2 21 21 2
( )1 ( )2 2
Let x = v1/v2 to get…
P Av x x3 21
1 (1 )(1 )4
p
P Av
Av or
C Av
31
31
31
1 1 1(1 )(1 )4 3 916 1( )27 212
Cp is the power coefficient for a wind turbine and the ratio 16/27 = 0.59 represents the maximum possible power that can be extracted. More typically wind turbines achieve 80% of this or 0.47
Example – Enercon101 Wind Generator
Optimal wind speed is around 10 m/sCp = 0.47 so
P kg/m m m/s
kW
3 2 31 (0.48)(1.2 ) (50 ) (10 )22400
How Many?• To produce 2100 MW you will need…
• “Rule of thumb” – generator spacing is 7 times the diameter of the rotor or (0.1km)(7) = 0.7km
• Place in a grid 30 units X 30 units = 21 km X 21 km• Cost? A 2008 figure commonly used is 1.3 million/MW so a
2100 MW wind farm would cost approximately $275 million• From the TransAlta web site… “A 53-megawatt uprate to
Sundance 5 was completed in 2009 at a cost of $75 million.”
MWn unitsMW/unit
2100 8752.4
(5) Photovoltaic Energy• By how much can I hope to
reduce my annual CO2 footprint if I install 12, 235 W solar panels on the roof of my house?
• How does the cost of electricity produced by a PV panel compare with current costs @12 c/kWh? kW = 1000 W is a power unit
kWh = 1000 W × 3600 s = 3.6 MJ which is an energy unit
My Annual Electricity Use• Total electrical energy
consumption 2011 was 10 MWh• Under bright sunlight each panel
averages 140 W (averaged over the year)
• Edmonton receives on average 2300 h bright sunshine per year
E panels W hMWh
(12 )(140 )(2300 )3.86
I can offset about 40% of my (electrical) CO2 footprint
Cost of Solar Energy
• Total cash outlay for system = $15000
• Warranty period = 25 years; estimated lifetime > 40 years
• Assume an average annual energy production of 3.6 MWh
-1
-1
-1
Net Cost $15000/25 a aso
$600a 17 c/kWh3600 kWh a
( ) $600...
But the cost of sunlight won’t go up!
And there are a lot more…
• Compare CO2 footprints of Methane and Coal• Look at Isotopic Mass Ratios and Ice-cores• Look at Carbonate-biCarbonate speciation• Greenhouse gas heating through collisional de-excitation• Declining sea ice and slope• IR spectroscopy and spectral windows• etc
Resources…
• www.kcvs.ca• www.explainingclimatechange.ca• Using Climate Change to Creat
Rich Contexts for Physics and Chemistry Education. Brian Martin and Peter Mahaffy
Thank You!