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A bar graph depicting world energy consumption is shown. The year is listed on the horizontal axis and energy consumed is listed on the vertical axis. Energy consumption by the world is shown for different years. Energy consumption rises over time. In the year nineteen hundred and ninety it was three hundred seventy three multiplied by ten to the power eighteen joules, and the projection is that it will become eight hundred twelve multiplied by ten to the power eighteen joules by the year twenty thirty five.
Past and projected world energy use (source: Based on data from U.S. Energy Information Administration, 2011)
Solar cell arrays lined up in a field.
Solar cell arrays at a power plant in Steindorf, Germany (credit: Michael Betke, Flickr)

[link] displays the 2006 commercial energy mix by country for some of the prime energy users in the world. While non-renewable sources dominate, some countries get a sizeable percentage of their electricity from renewable resources. For example, about 67% of New Zealand’s electricity demand is met by hydroelectric. Only 10% of the U.S. electricity is generated by renewable resources, primarily hydroelectric. It is difficult to determine total contributions of renewable energy in some countries with a large rural population, so these percentages in this table are left blank.

Energy consumption—selected countries (2006)
Country Consumption, in EJ (10 18 J) Oil Natural Gas Coal Nuclear Hydro Other Renewables Electricity Use per capita (kWh/yr) Energy Use per capita (GJ/yr)
Australia 5.4 34% 17% 44% 0% 3% 1% 10000 260
Brazil 9.6 48% 7% 5% 1% 35% 2% 2000 50
China 63 22% 3% 69% 1% 6% 1500 35
Egypt 2.4 50% 41% 1% 0% 6% 990 32
Germany 16 37% 24% 24% 11% 1% 3% 6400 173
India 15 34% 7% 52% 1% 5% 470 13
Indonesia 4.9 51% 26% 16% 0% 2% 3% 420 22
Japan 24 48% 14% 21% 12% 4% 1% 7100 176
New Zealand 0.44 32% 26% 6% 0% 11% 19% 8500 102
Russia 31 19% 53% 16% 5% 6% 5700 202
U.S. 105 40% 23% 22% 8% 3% 1% 12500 340
World 432 39% 23% 24% 6% 6% 2% 2600 71

Energy and economic well-being

The last two columns in this table examine the energy and electricity use per capita. Economic well-being is dependent upon energy use, and in most countries higher standards of living, as measured by GDP (gross domestic product) per capita, are matched by higher levels of energy consumption per capita. This is borne out in [link] . Increased efficiency of energy use will change this dependency. A global problem is balancing energy resource development against the harmful effects upon the environment in its extraction and use.

A scatter plot of power consumption per capita versus G D P per capita for various countries. Power consumption in kilowatt per capita is shown along the horizontal axis and G D P per capita is show along the vertical axis.
Power consumption per capita versus GDP per capita for various countries. Note the increase in energy usage with increasing GDP. (2007, credit: Frank van Mierlo, Wikimedia Commons)

Conserving energy

As we finish this chapter on energy and work, it is relevant to draw some distinctions between two sometimes misunderstood terms in the area of energy use. As has been mentioned elsewhere, the “law of the conservation of energy” is a very useful principle in analyzing physical processes. It is a statement that cannot be proven from basic principles, but is a very good bookkeeping device, and no exceptions have ever been found. It states that the total amount of energy in an isolated system will always remain constant. Related to this principle, but remarkably different from it, is the important philosophy of energy conservation. This concept has to do with seeking to decrease the amount of energy used by an individual or group through (1) reduced activities (e.g., turning down thermostats, driving fewer kilometers) and/or (2) increasing conversion efficiencies in the performance of a particular task—such as developing and using more efficient room heaters, cars that have greater miles-per-gallon ratings, energy-efficient compact fluorescent lights, etc.

Questions & Answers

sound waves can be modeled as a change in pressure ,why is the change on in pressure used and not the actual pressure
Dotto Reply
what is the best
Kelly Reply
Water,air,fire
Maung
I am a university student of Myanmar.I am first year,first semester.I want to learn about physics.
Maung
two charges qA and qB are separated by a distance x. if we double the distance between the charges and triple the magnitude of the charge A, what happens to the magnitude of the force that charge A exerts on charge B. what happens to the magnitude of the force that charge B exerts on charge A
tanla Reply
how to get mcq and essay?
Owen Reply
what is force
Ibrahim Reply
force is a pull or push action on an object or a body.
joseph
what is a significant figure? and give example
Frederick
numerical chapter number 3
Sajid Reply
joined
Ibrahim
a reflected ray on a mirror makes an angle of 20degree with the incident ray when the mirror is rotated 15degree what angle will the incident ray now make with the reflected ray
Akinyemi Reply
what is simple harmonic motion
Solomon Reply
how vapour pressure of a liquid lost through convection
Yomzi Reply
Roofs are sometimes pushed off vertically during a tropical cyclone, and buildings sometimes explode outward when hit by a tornado. Use Bernoulli’s principle to explain these phenomena.
Aliraza Reply
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Aliraza
what's the basic si unit of acceleration
ELLOIN Reply
Explain why the change in velocity is different in the two frames, whereas the change in kinetic energy is the same in both.
Fabian Reply
Insulators (nonmetals) have a higher BE than metals, and it is more difficult for photons to eject electrons from insulators. Discuss how this relates to the free charges in metals that make them good conductors.
Muhammad Reply
Is the photoelectric effect a direct consequence of the wave character of EM radiation or of the particle character of EM radiation? Explain briefly.
Muhammad
Determine the total force and the absolute pressure on the bottom of a swimming pool 28.0m by 8.5m whose uniform depth is 1 .8m.
Henny Reply
how solve this problem?
Foday
P(pressure)=density ×depth×acceleration due to gravity Force =P×Area(28.0x8.5)
Fomukom
for the answer to complete, the units need specified why
muqaddas Reply
That's just how the AP grades. Otherwise, you could be talking about m/s when the answer requires m/s^2. They need to know what you are referring to.
Kyle
Practice Key Terms 2

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Source:  OpenStax, College physics for ap® courses. OpenStax CNX. Nov 04, 2016 Download for free at https://legacy.cnx.org/content/col11844/1.14
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