Originally posted by heliosprime
reply to post by EnlightenUp
One more try at simplifying this for those who refuse to see the truth. In the link below is most of what you need to get YOUR math correct. The
bottom line is 1 out of every 4 units generated is usable to the "enduser".
I see the truth, my math is correct and I am talking about a very specific portion of the electrical distribution system. I am not continually
changing the boundaries of the portion in question. I have made clear in every post just what I mean and precisely why every minute detail of the
process is not required to understand the overall losses in energy utilization of the fuel used to generation by the customer. Your counter argument
and resources in reality support my position.
You problem is you are looking at a long series of variables (upto 300) and focusing on perhaps 2 of the 300...........
Overall efficiencies do not require consideration of each variable in question. Considering each variable within the black box does tell you which
portions of the system are most responsible for loss.
What you are doing is actually blackboxing the entire thing and not considering any factors at all.
Link
sites.energetics.com...
Most power plants are about 35 percent efficient. That means that for every 100 units of energy that go into a plant, only 35 units are converted
to usable electrical energy.
www.ferc.gov...
This divides the eletrical system into three stages much like I have done.
Generation->T&D->Consumer
I have been clear that I'm talking about the middle stage. Its figures seem slightly different than other sources from FERC but not wildly out of
bounds:
Generation: 40/100 units from fossil fuel become electrical energy = 40% efficiency which is rather high compared to other figures and even more so
than the sources you've quoted.
T&D: 30/40 units of electrical energy make it to the customers = 75% efficiency which is the lowest quote I've seen from any source by far, but still
far more efficient than inefficient-- not 25% for sure.
Consumer: 20/30 units of electrical energy are avaiable to devices and machinery = 66 2/3% efficiency at the outlet and is attributed to "inefficient
grounding".
T&D is the most efficient portion of the grid in its entirety.
Edit: Educated guess on the fuzzy boundary of the consumer end stated in that doc.
The "pole pig" transformer than provides the split-phase or three-phase power to the user has the neutral line connected to the ground on the pole
but independent from the main safety ground (reasons are outside scope). I'm guessing this is the ground to which they refer since normally equipment
doesn't rely on the ground itself as a conductor for normal operation. Sometimes one leg of the primary is attached to ground as well. I have also
seen setups with the primary attached to 2 of the three phases.
And lastly
greenfuture.blogspot.com...
Electric power generation is biggest source of lost energy in absolute terms. Only 31% of the energy used to generate electricity ends up as
distributed energy.
I have mentioned this in previous posts. I already agree based on data I have found about power plant thermodynamic and generator efficiency. The
power plants themselves suck and improving them would contribute to the greatest portion of energy savings which would render the electric car
superior overall-- in efficiency but not necessarily environmentally since more generating capacity would be used around the clock, requiring the need
for more extraction of power generating resources if all contributors to loss are not improved to compensate. As things currently are, they are equal
to slightly better than gasoline and inferior to diesel. Increasing plant efficiency would provide proportionally more energy for the same amount of
extracted resources.
It is clear to me from this and other source is that the 31% figure refers to the generation plants and not the T&D stage itself. I've seen figures
for overall generation efficiency from all sources (nuclear, hydroelectric, natural gas, etc.) that are a few percent better though. The factsheet.pdf
you provided states 35%.
This figure also treats the power plant like a black box where all forms of loss within it are compounded wihin the cited figure-- things like "brush
losses" from generator sliprings, friction, utilization of heat from the fuel source through the heat exchange system, resistive losses,
EM-radiation, etc.
When line losses, transfer stations, and the inefficiencies of the appliances and factories that use electricity are added, useable
energy can drop as low as 2 percent.
The latter two in bold are not in the domain of discussion at this point and never have been.
As low as also does not contribute anything
useful but makes for great hyperbole. The statement "useable energy" is ill-defined though I will make a guess that it means, for example, in the
case of a customer's electric motor, that as little as 2% of the energy available in the fuel used to generate electricity becomes rotating
mechanical energy at the output shaft.
To go back to your original statement and summarize:
Note about "plug in cars".......the most inefficient method of delivering energy is the electric grid. FACT 75% of all electricity generated
is LOST in transportation. YES only 1 out of every 4 kilowatts generated is consumed by the enduser.
A 75% loss is a roughly correct figure but not for the correct reasons nor would that include inefficiencies in the end users actual devices. 75% is
not "lost in transportation". What this means is that 25% of the of the energy available in the source fuels themselves actually make it to
the end user which is a very, very different situation.
What this also means, considering the various sources you and I have quoted, is the anywhere from 75% to 94% of the
electricity actually
generated is available to the end user after "transportation".
Improving the situation at every stage will help but most fingers should be pointing squarely at the generating plants.
Or as you had mentioned an efficient way of on-or-near-site generation should be used by getting away from the grid altogether. There is no doubt
security and robustness benefits to it as well with susceptibility being highly localized.
[edit on 8/27/2009 by EnlightenUp]
[edit on 8/27/2009 by EnlightenUp]
