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kristopher

(29,798 posts)
2. Poor Nnads
Wed Aug 7, 2013, 02:33 AM
Aug 2013

Just as food for thought, here is the status of world final energy consumption by source.



This is the concept behind calls for energy efficiency (a strategy that is anathema to the coal and nuclear industry because it slashes their profits).

The energy wasted from thermal sources is a very significant factor in understanding the issue of what energy source is doing what. Primary energy measures the total amount of energy that a fuel source yields - no matter whether it is powering our lives (ie electricity or or propulsion for autos) or whether it is waste heat being transferred to our waterways from nuclear plants or heat causing NO2* emissions off the hot engine block of an internal combustion.

An alternative (and most say better) way of looking at the production and use of energy is to measure what is needed and consumed by the actual work being accomplished. For example, an average internal combustion engine (ICE) powered car ejects 85% of the energy content of the gasoline it consumes as heat and only uses 15% for motive power. When we look for alternatives to gasoline do we think biofuels, and duplicate the efficiencies of the gasoline powered ICE or do we focus on batteries and electric motors that have far better efficiencies - typically using 90% of the input energy for locomotion?

Writ large, what does that mean? Take a look at this flow chart and note that the "rejected energy" comprised 58.1 quads of the total 95.1 quads of primary energy used in the US last year. How much was actually used to do the work of the nation? Only 37 quads.



If we look more closely at the various sectors we can see where the major opportunities for energy efficiency improvements are to be found:

Sector: Gross - Useful Energy; Rejected Energy (proportion of useful to rejected)

Transportation: 26.7 - 5.6; 21.1 (21 : 79)
Electric Generation: 38.10 - 12.40; 25.70 (33 : 67)

In sectors where the heat value of the energy is useful we see much higher efficiency
Industrial: 23.9 - 19.1; 4.77 (80 : 20)
Commercial: 8.29 - 5.39; 2.90 (65 : 35)
Residential: 10.60 - 6.9; 3.72 (65 : 35)

Now let's look at the Solar, Wind and Hydro Subset of Electric Generation. These produce electricity directly with insignificant primary energy lost as heat in the generation phase, however they do incur line losses of about 7%.

SolarWindHydro: 4.07 - 3.78; 0.285 (93 : 7)

Let's compare that to
Nuclear: 8.05 - 2.62; 5.43 (33 : 67)

In the US, the our fleet of nuclear reactors (what is it, down to 99 and falling fast?) might have produced 8.05 quads of primary energy, but at about 35% efficiency at the busbar and a further 7% line loss, (8.05q x 0.35 = 2.82q x 0.93) that only equals 2.62 quads actually delivered to the end user for work.

3.78q > 2.62q

See also: http://www.nawindpower.com/e107_plugins/content/content.php?content.11788#utm_medium=email&utm_source=LNH+07-19-2013&utm_campaign=NAW+News+Headlines

Oh yes, and then there is this.

Latest Discussions»Issue Forums»Environment & Energy»It would seem some people...»Reply #2