Teaching Energy and Climate in SchoolsChris Waltham

UBC Physics & Astronomy2015.10.23

A Crash CourseBasic introduction to energy and climate science

Energy, work, power, efficiency:

What? Energy is the capacity to do WORK

ENERGY is neither created nor destroyed, but it can be changed from one form into another, e.g. chemical energy in oil to mechanical energy in a moving vehicle; mechanical energy from wind converted to electrical energy

The rate at which energy is converted from one form into another is called POWER

EFFICIENCY is the fraction of input energy converted into the form you want, i.e. the fraction not lost to some unwanted form (usually heat).

Why? Energy = $$$ = CO2 (crudely speaking)

A Crash CourseBasic introduction to energy and climate science

Energy, work, power, efficiency: Units

The unit of energy, and of mechanical work, is the joule (J)

The unit of power is the watt (W) = one joule per second

The joule is the amount of energy to

• Push against a force of 1 newton for 1 metre

• Run a current of 1 amp for 1 second through a potential difference of 1 volt

Efficiency is a ratio, often expressed as a percentage

A Crash CourseBasic introduction to energy and climate science

Energy, work, power, efficiency: Examples

• Your gas bill comes in GJ (1 billion joules)

• Your electricity bill comes in kWh (energy use for 1 hour at 1000 watts of power = 3.6 MJ)

•Food is rated by “calories” (4.2 kJ) – mech eff. ~ 20%

•Gasoline comes in litres (~ 36 MJ) - mech eff. ~ 20%

•Car engines are rated by HP = 746 W

•How much power does it take to run a Canadian?

~ 10 kW total

A Crash CourseBasic introduction to energy and climate science

Energy: Why is this an issue?80% of the world’s energy comes from fossil fuels (87% in Canada*)Energy use → carbon dioxide dumped in the atmosphere

*http://www.nrcan.gc.ca/publications/statistics-facts/1239

A Crash CourseBasic introduction to energy and climate science

Canada’s carbon dioxide emissions17 tonnes CO2 per capita per year

And 23 tonnes CO2e per capita per year – “e” means “equivalent”, i.e. includes other greenhouse gases

http://www.conferenceboard.ca/hcp/details/environment/greenhouse-gas-emissions.aspx

A Crash CourseBasic introduction to energy and climate science

Why is this a problem?

http://data.giss.nasa.gov/gistemp/graphs_v3/

• Carbon dioxide is a greenhouse gas• Allows visible light from the Sun the warm the Earth• Blocks Earth’s own radiation (thermal infrared) from cooling the Earth

...doesn’t work very well.

ApproachesObservations from a dozen years of teaching energy and climate issues to undergraduates

FRONTAL “CRISIS”

APPROACH

Ennui

Fatalism

Blame Others

I’m alright, Jack

Denial

Profound Worry

In-class science learning makes little connection to the external, real world, or to personal behaviour

ProblemsObservations from a dozen years of teaching energy and climate issues to undergraduates

THE UNDERLYING ISSUES

Back off and consider:

o Tactile experience of physical world outside

o Contact with Nature

o Hands-on lab experience

o Logic skills (cause and effect in right order)

o Knowledge of non-US current affairs

o Time spent inside classrooms

(tutors, degrees...)

o Life experience mediated by

computer/phone screen

Decreasing Increasing

Role of educators

What educators can address at all levels (the sooner the better!)

OBSERVATION DATA TAKING

SPATIALREASONING

INTERNETRESEARCH

Observations from a dozen years of teaching energy and climate issues to undergraduates

Role of educators

OBSERVATION

Observing temperatures of the surrounding environmente.g.:

Role of educators

DATA TAKING

Measuring the power output from a solar cell

e.g.:

Role of educators

DATA TAKING Measuring the power output from a solar cell

Recording data

Role of educators

DATA TAKING Measuring the power output from a solar cell

Proper labelling (including units)

Role of educators

DATA TAKING Measuring the power output from a solar cell

Good notebook habits

Role of educators

DATA TAKING Measuring the power output from a solar cell

Elementary “programming”

Role of educators

DATA TAKING Measuring the power output from a solar cell

Measured vs calculated quantities

Role of educators

DATA TAKING Measuring the power output from a solar cell

Meaningful graphing

Role of educators

DATA TAKING Measuring the power output from a solar cell

What do those numbers mean?

This tyrannosaurus is 70,000,003 years old.Photo Credit: mharrsch via Compfight (CC BY-NC-SA 2.0)

ProblemsObservations from a dozen years of teaching energy and climate issues to undergraduates

?!

Role of educators

SPATIAL REASONING

Mapping and graphing

Role of educators

SPATIAL REASONING

Linear, area and volume measurements

= 1 m3 ...?

Role of educators

INTERNET RESEARCH

Finding useful and reliable information

• Searching with precise wording• Appropriate specificity• Good places to look• Differentiate between primary sources,

summaries and junk• Don’t be afraid of Wikipedia!• Many students need to be guided

Role of educators

INTERNET RESEARCH

What mass of CO2 is produced by burning 1L of gasoline?

e.g.:

Can be done at various complexities

Photo Credit: mhall209 via Compfight (CC BY-NC-SA 2.0)

→ Look up the answer

→ Dig deeper...

Role of educators

INTERNET RESEARCH Mass of CO2 from burning 1L gasoline

→ Dig deeper...

Look up elemental components of gasoline• A mix of complicated hydrocarbons...

› Or, recognize that C:H ≈ 1:2

etc., etc. etc.....

Role of educators

INTERNET RESEARCH Mass of CO2 from burning 1L gasoline

→ Dig deeper...

How does it burn?• 2C8H18 + 25O2 -> 16CO2 + 18H2O

and similar for other components...

› Or, recognize that CH2 + _O2 -> CO2 + …

• Look up molar masses on periodic table (or Google) to convert from moles to grams, to kilograms.Recognize that 14 kg of gasoline gives 44 kg of CO2

• Now look up the density of gasoline on Wikipedia to convert kg to L

Role of educators

INTERNET RESEARCH Mass of CO2 from burning 1L gasoline

→ Dig deeper...

Now you have really learned something!• 1 L gasoline burns to 2.2 kg CO2

• One atom of carbon in a fossil fuel makes one molecule of CO2 – no way out of that

• Similar questions about emissions froma tonne of coal (C:H ≈ 1:1) or a m3 of natural gas (C:H = 1:4) should be easy after doing this

Now to food:Bicycling and Walking

• Human body is a thermodynamic engine like any other, and reasonably efficient (20-25%)

• But…the fuel source (i.e. food), in terms of kgCO2/MJ, can be horribly inefficient

• So which is better for the environment: human or fossil power?

Alice Lam, UBC

”Modern agriculture is the use of land to convert petroleum into food”

Albert Bartlett

• So even a vegan makes ~10x the GHGs per MJ of energy than a car engine does.

• Mass of me + bicycle: 90 kg• Mass of me + Honda Civic: 1400 kg• Even if I was a vegan, its going to be a tight race between cycling

and driving…

http://c21.phas.ubc.ca/article/commuting-car-or-cycle-which-better

“Fuel” Emissions (kgCO2/MJ)

Gasoline 0.07

Vegetables (average) 0.6

Meat (average) 2.7

Detailed calculation

• Easy but long winded (spreadsheet available on web http://c21.phas.ubc.ca/article/commuting-car-or-cycle-which-better)– The person in question weighs 70kg, is 180cm tall, 25 years old– The person loses 1kg in weight by biking to work instead of driving– Cycling speed is 20km/h– The commute is 10 km (one way) and is done 200 days per year– The comparison vehicle is a Honda Civic

• Conclusion:

• This is “in the noise” of our 23 tonne annual average - BUT…

Food Choice for cyclist Annual difference over driving a Civic (CO2e)

Vegan - 300 kg

Carnivore (exclusive) + 600 kg

A note on the stuff we own and the services we purchase:

a rough calculation

• Canada’s GDP $1.3 trillion• National annual emissions 690 Mtonnes CO2e• In the absence of more detailed information, reckon

on about ½ tonne per $1,000– Some economic activity worse (e.g. flying)– Some economic activity better (e.g. insulating your home)

• So…

http://www.ec.gc.ca

If, by cycling, you OWN one less car:• Cars need servicing and eventually replacing, even if left in

the driveway.• Do life-cycle analysis assuming 10y between buying new

cars…• Cycling wins hands-down, no matter what you eat.• Even considering that exclusive carnivores produce 11 tonnes

CO2e per year just feeding themselves (compared to a vegan’s 2.5 tonnes, and an average Canadian’s 6 tonnes).

Who needs a truck when you have a workmate to sit on the pile of plywood sheets to stop them blowing away?

Cycling/eating: conclusion• Try to arrange your life so you can walk/cycle to work (this is

needs some planning ahead).• Don’t spend more money buying bicycles than you would

buying a car.• Eat mostly vegetables!

– Better for your health– Better for your wallet– Better for the environment– Better for the animals you would have eaten

CH2O in one end, CO2e out the other.

Heating (and cooling) buildings• Buildings loose (gain) heat from the inside wall to the outside wall through

conduction.• Thereafter the heat is lost to the environment by convection and

radiation.• Power lost = conductivity x area x temp difference/thickness

6 tonnes of CO2 p.a. just to heat my 33’ lot house.

Heating/Cooling Conclusion

• Decrease k: insulate, double-glaze (low-E)• Decrease A: choose a smaller home, reduce outside wall area (condo)• Reduce average ΔT:

– put a sweater (shorts) on.– don’t leave the heat on if you are not in. (The inability to do this with a heat

pump reduces its apparent advantage).• Don’t pump heat up the chimney (use a high efficiency furnace).• Beware of power sources that are horribly expensive (PV) and/or eccentric

(urban wind turbines): why? – see note on “stuff”.

Final Conclusion• With a little thought and effort we can knock several tonnes off our personal

annual CO2 emission total (and save money in the process)• But: if you are not saving money you are probably making things worse• However, most emissions remain out of our immediate control• Reason for hope: consider the tobacco industry (63 years since Richard Doll

proved cancer link).• Vote

References

withouthotair.comc21.phas.ubc.ca