First, I just want to apologize to international visitors and give an explanation for the fact that this comes across as blatantly Ameri-Centric. The fact is that energy sources and end use varies widely around the world and some countries do not have the best data avaliable. The US has very good data avaliable from the Energy Information Agency, which is part of the Department of Energy. World use of energy is also heavily skewed by a few countries, such as Middle Eastern countries, which use enormous amounts of oil for power generation, desalination and running refineries. The United States is a pretty good example of an industrial country. The numbers are similar to those in Canada, although Canada uses less air conditioning, more heat and uses more natural gas for heating and less heating oil. The numbers are similar to most of Europe, although much of Europe uses proportionately more gas for electrical generation. Australia is also similar, although the power generation there is even more coal intensive and they use slightly more energy for transportation. Hopefully this will be worthwhile to use as an example, even if it fails to offer a world perspective.

Energy is important not only for the economic and national security concerns but it also produces most of the pollution, especially greenhouse gases.

First, a nifty Chart from the US Department of Energy which sums up the flow of energy:

(Click To Enlarge)

Now, some breakdowns of exactly what this means. Primary sources of energy show petroleum to be the single largest source of energy, although it does not make up the majority of energy used in the US. Much is domestic, but more than half is forign. The single largest country for imports is Canada. However, middle eastern countries also produce a large share of US Oil imports.

 

 

 

End use of energy can be divided into several methods of energy delivery and use:

Or by end user:

Electricity:

Electricity immediately jumps out as one of the most important energy sectors. Not only is it the single largest, but it also will become increasingly important if cleaner transportation and industrial systems are to be utilized. Electricity is the foundation energy sector to which such areas will become increasingly dependent. Here’s how we generate it in the US:

 

 

The US is typical of much of the world. Coal is the single largest source of electricity worldwide and natural gas is the second. Canada and a few other countries have been able to make fossil fuels only a secondary source of electricity, primarily due to hydroelectric reserves. Others have transitioned to nuclear energy. France leads the way with nearly all electricity generated from clean nuclear energy. Oil is used primarly for “peak” electrical generation in the US due to its expense. It is a primary electric baseload source in many Middle Eastern and African countries. Isolated areas, island nations and others with only limited electrical supplies also use oil-based electrical generation as it is more economical for such small operations.

 

 

Electricity end use varies widely, however, like total energy, considerably more is generally used for commercial and industrial purposes than for residential. This is not always the case, however, and in areas with less industry it may be more skewed toward residential. The one factor which makes the biggest difference is heat. Areas with high summer temperatures tend to see a much greater proportional demand from residential and commercial use of air conditioning. Industrial use is less effected.

One thing to bare in mind is that generating and transmitting electricity involves a net energy loss. About 65% of the energy in most systems is lost to waste heat. This is not due to poor system design and cannot really be fixed. It is an inherent aspect of any thermal engine that a large portion of energy is lost to waste heat. The highest effeciency power plants are combined cycle gas-fired and have a thermal effeciency of up to 60%. Most power plants do not reach this. Energy is also lost in transmission as well as in the process of phasing, voltage regulation and conversion. Better transmission systems can cut this down, but the only way to improve thermal effeciency in most power plants is to reuse the waste heat for other purposes, such as structure heating.

 

This is the reason why most heating is done on-site by burning of fuels. The return of energy is better because nearly all the thermal energy can be used for heating. On site electrical generation, however would not result in savings. Although line loss would be lower, the higher effeciency of large power plants offsets this when compared to smaller units. However, it is worth noting that using a certain amount of energy to heat a site versus an equal amount of electrical energy is actually less energy intensive. For each watt of electricity used, about three watts of energy is consumed.

 

Fuel Use breakdown:

Hydroelectric and Nuclear energy are obviously used nearly entirely for electrical generation.

Coal is used mostly for electricity but also for industry, especially metal smelting, cement and other processes that need a lot of heating.

 

About two thirds of oil is used as a fuel for transportation. The remainder is mostly used directly by industry. Some is used for electricity and the remainder for heating. Use of oil heat is found primarily in the Northeastern US, where gas service is not as widely avaliable. It is used more for homes and small commercial applications than for large buildings.

 

Natural Gas is used heavily by industry as well as for power generation. In industry, natural gas is used for heat, as in metal working. It is also heavily used by the chemical industry as both an energy source and a raw material for chemicals like methanol. In commercial and residential settings it is used mostly for heating and hot water, but it also is used for cooking.

 

 

Transportation fuel is dominated by petrolium. This is true of most of the world. The only major exception in the US is electric transit, which is relatively small. In other countries this proportion may be larger, but oil remains the primary motor fuel. Only Brazil, which gets much of its fuel from cane sugar ethanol stands out in this respect. In the US, gasoline may contain 5 to 10 percent ethanol, however it’s disputed that this actually saves energy and the amount is small compared to oil used.

 

 

Residential energy use is relatively small compared to other sectors. It also varies widely depending on temperature. In hot areas, during the summer, more than 50% of the electricity used may be for air conditioning and cooling and there may be little energy used that is not electricity. However, in colder areas more than half of the energy used may be for heating. In general, this is done by direct burning of fuels. It is more effecient than transporting energy for heat by electricity. As thermal energy often comes from cheaper sources, it may not be as noticed, but home heating can easily exceed 60% of home energy use in the winter. Much of the US uses electricity for heating, but this is generally found in the warmer areas where heat is only occasionally used.

 

As mentioned, electric use will vary widely based on the temperature and thus the amount of air conditioning used. This means that region to region energy use as well as season to season use can be dramatically different. This is true for much of the world as well. In Northern European countries may use very little electricity for cooling, while Southern European countries may use considerably more. The following chart represents the national average:

 

If you live in a temperate area, then this chart may be a relatively representative of your energy use at home. However, high temperatures can easily push cooling past the 50% point. Cold does not tend to have the same affect, since most homes in colder areas do not use electricity for heating. For homes in colder areas, heating is often more than 50% of total energy, although when the electric generating losses are factored in, it is rarely more than 30% of the total effective energy.

Commercial use of energy is similar to that of residential in that it also is strongly influenced by temperature. In southern states, air conditioning may be the largest energy use in a commercial building. However, the following is represents the national average and is also a good reflection of the temperate areas:

 

 

 

Industrial Energy Use: I’m still working on the industrial use of energy and electricity. That one turns out to be even more difficult than the others.

 

Sources:   http://en.wikipedia.org/wiki/Electricity_generation  http://www.fypower.org/about/faq.html  http://www.eia.doe.gov/emeu/consumptionbriefs/cbecs/pbawebsite/office/office_howuseelec.htm   http://www.gulfcoastchp.org/Markets/Commercial/OfficeBuildings  http://www.eia.doe.gov/  http://pewclimate.org/   All charts are original except for the electrical sources one which is from Wikipedia and the above mentioned DOE chart.

Disclaimer:
The data presented here is not guaranteed acurate and should not be cited for research.  No, that doesn’t mean I made it up.  However, it does mean that I did not do the intensive verification and sourcing which would be necessary to present this kind of data with 100% certainty.  So in other words, don’t go thinking you can use this to make a policy decision and then turn around and sue me because I rounded off a number by a few tenths of a percent.   These numbers represent avaliable data for the most recent time periods of reliable reporting and do contain values which have been estimated based on avaliable information

 

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This entry was posted on Friday, February 8th, 2008 at 3:32 pm and is filed under Enviornment, Good Science, Misc, Politics. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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