On Feb 12, 1:31 pm, Paul M. Eldridge
wrote:
I'm not so sure about that. My utility, Nova Scotia Power, like
virtually ever utility here in Canada, is winter peaking and these
peaks typically occur around 17h30 when street lights start coming on
and electric ranges are being used to prepare evening meals.
**Anything** that helps minimize concurrent demand, no matter how
small, would be helpful from the utility's perspective, especially in
light of the high percentage of homes that are electrically heated in
this country.

Let's say the average electric oven draws 3.0 kW (my convection oven
happens to be 5.5 kW). We might expect the typical household oven to
operate at full power for the first ten minutes or so, then cycle on
perhaps one third of the time thereafter (i.e., an average of one
minute on for every two minutes off). Let's also assume there are
100,000 electric ovens in use province-wide during the suppertime peak
(and here in Nova Scotia, virtually all ovens are electric since only
500 or so homes are currently served by natural gas).

If all 100,000 ovens were energized at the same time, we would expect
this load to be 300 MW. We're assuming, of course, that as each of
these ovens come up to temperature, the actual load at a 33% duty
cycle, would be closer to 100 MW, and since these ovens are not all
turned on at the same time, a coincidental peak of 100 MW is probably
within spitting distance of the mark. If, however, each of these
ovens were equipped with variable wattage controls and, again,
assuming a 33% duty cycle, our coincidental peak should drop to just
33 MW.

This also means that you have eliminated the normal full on heating
mode of the oven and reduced it to 1/3 of that. Which means now
everyone has to wait 3X as long for the oven or burner to warm up,
which few people are going to put up with. After that, the oven or
burner will be cycling randomly anyway and the sum of them all cycling
randomly is the same And presumably, this cooking load comes late in
the day, like 6PM+, which is after industrial/commerical use is
decreasing. With all the other loads I fail to see how this is going
to make any difference in the generating capacity needed to meet peak
demand or save the utiltiy even 5cents. It will mean a lot of ****ed
off users though, who can't get their oven hot in a reasonable time.




On a typical winter's day, Nova Scotia Power's peak falls between
1,500 to 2,000 MW, so a 67 MW reduction in provincial demand would
represent a peak savings of perhaps as much as 3 to 5 per cent. In
theory, it would exceed the province's total installed wind capacity
of some 60 MW (which, assuming a 40 per cent annual capacity factor, I
take it might be closer to just 25 MW). Even if we were to cut the
number of ovens in operation by half, the impact on a utility such as
Nova Scotia Power is not exactly insignificant.

So, you have just as many ovens running longer. Unless you have
proof that ovens are causing a peak demand that results in either
higher capital cost for generators to meet peak capacity or are
causing the need to kick in some higher cost energy source during
dinner time, this is just a pipe dream.



Cheers,
Paul

On 12 Feb 2007 07:49:37 -0800, wrote:



This makes no difference to the utility, because they have thousands
of stoves and similar loads, which are all randomly cycling on and
off, effectively averaging it all together, so smoothing out demand
from one stove doesn't do anything. They would never see it.- Hide quoted text -

- Show quoted text -