SVN3M - Energy
Introduction to Energy
Energy – what is it? the ability to do workLaw of Conservation of Energy:
energy cannot be created or destroyed – it can only be changed from 1 form to another.
Forms of Energy:
- Chemical:
energy stored in the bonds of molecules; e.g. food, fossil fuels, wood, alcohol
- Kinetic/Motion:
energy of objects in motion, usually due to the force of gravity; e.g. wind, falling water for hydroelectric power, tides
- Nuclear:
energy that comes from joining or splitting atoms; e.g. the Sun - nuclear fusion reactor, nuclear power plant – fission reactor
- Heat and Light:
comes primarily from the sun, often “unusable” energy from chemical reactions
- Sound:
energy transferred as waves through collision of air particles
All energy on Earth comes directly or indirectly from the Sun.
Example 1: Light energy to heat and motion energy
Sun (light energy)→
plants make sugar moleculesthrough photosynthesis (chemical energy) →
humans and animals eat and digest plants (heat energy, motion energy)
Example 2: Light energy to electricity through wind turbines
Sun (light energy) →
Earth’s surface and atmosphere warm and cool (heat energy) →
Air currents move due to convection (wind energy) →
Wind turbines turn generators (electrical energy)
Main Uses of Energy
Three main purposes of energy in industrialized societies:
Transportation: oil, gas, diesel for vehicles, trains, planes
Heating and cooling of buildings: electricity, gas, oil
Providing power for machinery and appliances: electricity
Measuring Energy and Power
Power:
The rate at which work is done (how much work is done every second), measured in watts (W)
Energy:
To find energy used, multiply the power rating (in watts) of an appliance by the number of hours that the appliance is used, to get watt-hours (Wh), or kilowatt-hours (kWh).
Example:
100 W light bulb used for 24 hours uses 100 × 24 = 2400 watt-hours (Wh)
Since there are 1000 watt-hours in 1 kilowatt hour, this is 2400 1000 = 2.4 kilowatt hours (kWh)
The average Canadian household uses about 35 kilowatt hours (kWh) a day.
Three Main Ways to Improve Energy Use:
- Conservation:
design systems to use less energy, e.g. electronics without standby power (aka“vampire power” or “phantom load”
e.g. appliances with remote controls, LED displays – standby power accounts for up to 10% of household use
- Efficiency:
make better use of energy (get more from the same amount of energy)
e.g. incandescent light bulbs uses 10% of its energy to produce light, 90% to produce heat
- Renewable Energy Sources:
use “green”, sustainable energy instead of non-renewable resources
need to “kick our oil addiction”
Introduction to Energy
Energy – what is it? the ability to do workLaw of Conservation of Energy:
energy cannot be created or destroyed – it can only be changed from 1 form to another.
Forms of Energy:
- Chemical:
energy stored in the bonds of molecules; e.g. food, fossil fuels, wood, alcohol
- Kinetic/Motion:
energy of objects in motion, usually due to the force of gravity; e.g. wind, falling water for hydroelectric power, tides
- Nuclear:
energy that comes from joining or splitting atoms; e.g. the Sun - nuclear fusion reactor, nuclear power plant – fission reactor
- Heat and Light:
comes primarily from the sun, often “unusable” energy from chemical reactions
- Sound:
energy transferred as waves through collision of air particles
All energy on Earth comes directly or indirectly from the Sun.
Example 1: Light energy to heat and motion energy
Sun (light energy) →
plants make sugar molecules through photosynthesis (chemical energy) →
humans and animals eat and digest plants (heat energy, motion energy)
Example 2: Light energy to electricity through wind turbines
Sun (light energy) →
Earth’s surface and atmosphere warm and cool (heat energy) →
Air currents move due to convection (wind energy) →
Wind turbines turn generators (electrical energy)
Main Uses of Energy
Three main purposes of energy in industrialized societies:
Transportation: oil, gas, diesel for vehicles, trains, planes
Heating and cooling of buildings: electricity, gas, oil
Providing power for machinery and appliances: electricity
Measuring Energy and Power
Power:
The rate at which work is done (how much work is done every second), measured in watts (W)
Energy:
To find energy used, multiply the power rating (in watts) of an appliance by the number of hours that the appliance is used, to get watt-hours (Wh), or kilowatt-hours (kWh).
Example:
100 W light bulb used for 24 hours uses 100 × 24 = 2400 watt-hours (Wh)
Since there are 1000 watt-hours in 1 kilowatt hour, this is 2400 1000 = 2.4 kilowatt hours (kWh)
The average Canadian household uses about 35 kilowatt hours (kWh) a day.
Three Main Ways to Improve Energy Use:
- Conservation:
design systems to use less energy, e.g. electronics without standby power (aka “vampire power” or “phantom load”
e.g. appliances with remote controls, LED displays – standby power accounts for up to 10% of household use
- Efficiency:
make better use of energy (get more from the same amount of energy)
e.g. incandescent light bulbs uses 10% of its energy to produce light, 90% to produce heat
- Renewable Energy Sources:
use “green”, sustainable energy instead of non-renewable resources
need to “kick our oil addiction”
Activity: Measuring the Power Rating of Electrical Devices
Measure the power ratings for the following devices when in use, and in standby mode where appropriate.
Device / Power When in Use (W) / Power When in Standby (W)Christmas lights
Lamp, incandescent light bulb
Lamp, compact fluorescent bulb
Night light
Iron
VCR
TV
Standby Power for Selected Devices
Product/Mode / Average (W) / Min (W) / Max (W)Charger, mobile phone
On, charged / 2.24 / 0.75 / 4.11
On, charging / 3.68 / 0.27 / 7.5
Power supply only / 0.26 / 0.02 / 1
Clock, radio
On / 2.01 / 0.97 / 7.6
Computer Display, CRT
Off / 0.8 / 0 / 2.99
On / 65.1 / 34.54 / 124.78
Sleep / 12.14 / 1.6 / 74.5
Computer Display, LCD
Off / 1.13 / 0.31 / 3.5
On / 27.61 / 1.9 / 55.48
Sleep / 1.38 / 0.37 / 7.8
Computer, desktop
On, idle / 73.97 / 27.5 / 180.83
Off / 2.84 / 0 / 9.21
Sleep / 21.13 / 1.1 / 83.3
Computer, notebook
Fully on, charged / 29.48 / 14.95 / 73.1
Fully on, charging / 44.28 / 27.38 / 66.9
Off / 8.9 / 0.47 / 50
Power supply only / 4.42 / 0.15 / 26.4
Sleep / 15.77 / 0.82 / 54.8
Phone, cordless
Ready, handset / 2.81 / 1.05 / 4.89
Ready, no handset / 1.58 / 0.59 / 3.09
Active (talking) / 1.9 / 0.59 / 3.38
Off / 0.98 / 0.54 / 1.8
Printer, inkjet
Off / 1.26 / 0 / 4
On / 4.93 / 1.81 / 22
Speakers, computer
On, no sound / 4.12 / 0.69 / 9.84
Off / 1.79 / 0 / 5.6
Television, CRT
Off by remote / 3.06 / 0.3 / 10.34
Off by switch / 2.88 / 0 / 16.1
Clock
On / 1.74 / 0.99 / 3.61
Radio playing / 2.95 / 1.7 / 4.2
Coffee Maker
Off / 1.14 / 0 / 2.7
DVD/VCR
On, not playing / 13.51 / 8.48 / 20.5
On, playing / 15.33 / 9.43 / 22.37
Off / 5.04 / 0.09 / 12.7
Game Console
Active / 26.98 / 5.4 / 67.68
Off / 1.01 / 0 / 2.13
Ready / 23.34 / 2.12 / 63.74
Microwave Ovens
Ready, door closed / 3.08 / 1.4 / 4.9
Ready, door open / 25.79 / 1.6 / 39
Cooking / 1433. / 966.2 / 1723.
All data from Lawrence Berkeley National Laboratory, accessed February 2011