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Tankless Water Heaters are Brutal
on the Grid When Popularized
Tankless water heaters draw energy
on demand, and do not have a
thermal energy storage facet.
Multiplied by many customers'
hot-water usage patterns, these
surges of energy amount to a
significantly higher peak load for
utilities, resulting in increased
costs and, more significantly, in
increased waste during non-peak
times.
by
Sterling D. Allan and
Paul Noel
Pure Energy Systems News
- Exclusive
Copyright © 2005
While
tankless water heaters do indeed
usually provide a customer with
substantial out-of-pocket savings
on their fuel bill, a problem
arises when a lot of people use
such a system. It puts a heavy
load on the grid during peak
times.
Individual customer savings may be
high, but a lot of customers using
the system results in increased
costs for the grid due to a net
increase in energy generation
required due to the increased peak
load spikes.
Tank vs. Tankless from the
Grid's Point of View
Compared to the tankless systems,
tank-based water heaters are
energy hogs because they have to
maintain that tank of water at a
high temperature during long
periods when no water is needed.
Though insulated, there is still a
constant loss of heat energy into
the environment.
The most obvious waste is during
those times when a family might be
away on vacation. But even the
spans at night while the family is
resting, or during the day while
they are away from home, the water
heater churns away, keeping that
tank of water hot.
"On-demand", tankless systems, on
the other hand, heat the water
from cold to hot as it is needed,
and then shut themselves off.
There is no interim period of
waste of heat into the
surroundings, other than the water
between the heater and the
fixtures.
So yes, you can see why the
"on-demand", tankless water heater
system would save as much as 60%
over the tank-based water heater
when compared side by side.
But now think of this in terms of
the electrical grid, and you will
see that the collective use
scenario creates a problem.
The water tank system, though
inefficient for the consumer,
serves as an energy storage system
as far as the grid is concerned.
It buffers the energy consumption
away from peak energy load times.
Peak usage is still the same, but
the energy required to heat the
water is spread out over a much
wider period of time. The tank of
hot water serves as thermal mass
storage unit. It is already hot
when you jump in the shower in the
evening, and then tops off as you
shower and after you get out, for
example.
Tankless systems, on the other
hand, draw a large spike of power
demand during times of use. The
overall usage may be 60% less, but
the spikes are much higher. The
tankless system has to heat that
water from cold up to hot during
the time that you are showering,
for example, not before or after.
Multiply that by many thousands of
people in a municipality, and you
create a real problem for the
electrical generating utilities.
Utilities Have to Match Peak
Requirement, and Vent During
Non-Peak
Utilities have to build and
maintain their systems to handle
peak load -- that time when people
tend to use the most energy, such
as at night as people return home,
turn on their lights, cook dinner,
run their washers and dryers, turn
on their televisions, vacuum the
floor.
The utility needs to have enough
electricity ready to go so that
when you turn on your switch, the
electricity flows immediately.
Collectively, that means that the
higher the peak load, the larger
they have to build their plants to
handle those peaks.
In Florida, where tankless water
heaters have been around for about
20 years, and have become quite
popular, the utilities are seeing
fourteen times as much energy
consumed during peak as during the
base load rate. In their case, it
is not considered a "peak" but a
"spike", that spike having been
created by the use of tankless
water heaters.
Now here is the real kicker. You
and I might think that the grid is
kind of like a rheostat. If you
need more power, you turn it up,
if you need less, you turn it
down. Who cares if you need more
power at one time, and less in
another, as long as the overall
usage is less, right?
Grid production is similar to
continuously-running drinking
fountain. It's on, whether or
not you are taking a drink. |
Wrong.
That is not how the grid
operates. Once you fire up a
nuclear power plant, it is running
full bore. Period. No up or
down, just on -- full blast.
You can't just flip a switch
several times a day to turn a 500
MW coal or gas generator on or
off. They are designed for
continuous running. They run the
best (are most efficient and
clean) at full throttle.
What that means is that much of
the non-peak energy being
generated, that is not being
consumed, is vented into the
environment. It is wasted. Not
used. Spilled. Kaput. Gone.
It is like one of those
drinking fountains you sometimes
see in a public park or walkway --
continually running, whether or
not someone is taking a drink.
Now here is a statistic for you to
put in your top ten things to
remember about energy. In
the United States, the amount of
energy vented (wasted) every day
by the utilities due to
lost energy of non-peak
production, is enough to run all
of the vehicles in the country.
Bringing Down the Peak
What we need to be thinking about,
therefore, to facilitate a very
substantial overall planetary
reduction in energy pollution, is
to even out the peak-base grid
demand through a combination of
two things. One way is for
customers to conscientiously
change their usage patterns, such
as to delay running washing
machines and other high-demand
machines until later at night.
The other is through discovering,
optimizing, and installing methods
by which energy from off-peak
times can be stored for use during
peak times. That way, utility
energy generators can run at full
throttle, which is where they
operate the most efficiently, and
the non-used energy will not be
wasted. In this way, the
difference between peak and base
is nearly eliminated; and
proportionately, the amount of
waste is likewise slashed.
There will be some losses any time
energy is converted from one form
to another. No storage system is
100% efficient. So the complete
eradication of the peak-base humps
is not likely to ever be achieved.
But it can be approached.
Awareness of the problem is a key
in resolving the problem.
Another
solution is for each household to
become grid-independent.
Small-scale generators are much
more likely to be able to handle
"on-demand" production and not
require continual running at the
same speed. And battery storage
is widely used to even out
production from intermittent
sources.
So are Tankless Water Heaters
Bad?
In order for a tankless water
heater to decrease the overall
footprint of energy pollution on
the planet, it needs to be used
during off-peak times. Then it is
contributing to an overall
solution. Those who use it during
peak times are contributing to the
overall problem, not helping.
A General Principle
And really, that goes for all
appliances. The tankless heater
is but an example of a principle.
One of the most effective things
people can do to do their part
individually to reduce the overall
dependence on oil, is to shift
their energy usage patterns such
that they are conscientious about
when they are using their
appliances. Can you do your
laundry during the day, rather
than in the evening? Or later at
night? Turn your dehydrator off
during peak hours. Perhaps you
could put some of your appliances,
such as a dehydrator or swimming
pool heater, on a timer, to turn
them off during peak hours.
If such timing devices are not
readily available, let's call upon
our major suppliers to stock them
and promote them. Give them a
copy of this article. And while
you're at it, pass a copy on to
your friends and associates. Send
one to your elected
representatives too!
The idea is to bring down that
spike on the grid. Every bit we
can do that together will mean
that the utilities can cut down on
their energy generation capacity,
and not vent so much wasted energy
during non-peak times.
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