U.S. patent application number 11/523061 was filed with the patent office on 2008-03-20 for method and apparatus for storing and using energy to reduce the end-user cost of energy.
Invention is credited to Ben M. Enis, Paul Lieberman.
Application Number | 20080071705 11/523061 |
Document ID | / |
Family ID | 34520230 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080071705 |
Kind Code |
A1 |
Enis; Ben M. ; et
al. |
March 20, 2008 |
Method and apparatus for storing and using energy to reduce the
end-user cost of energy
Abstract
The invention relates to an energy storing method and apparatus
for use by end-users of energy, such as commercial property owners
and operators. The system differs from past systems, insofar as it
is not intended to be used by and in connection with energy
suppliers, such as large utility and power supply plants and grids.
The system preferably relates to the manner in which an end-user of
energy can implement energy and costs savings, by using energy
storage and time-shifting methods, to control and regulate the
consumption of energy in a manner that achieves a cost savings over
a period of time. One aspect of the method relates to accurately
forecasting and predicting the energy demands and peaks that might
occur on a daily basis, by recording and analyzing the prior day's
history, as well as the overall energy demand histories, using
short and long term forecasts, and then setting up a variable
energy storage/use plan or schedule that helps to reduce the peak
demands by time-shifting the energy that is used, i.e., reducing
consumption during high demand/high cost periods, and using the
energy stored during low demand/low cost periods during the high
demand/high cost periods.
Inventors: |
Enis; Ben M.; (Henderson,
NV) ; Lieberman; Paul; (Torrance, CA) |
Correspondence
Address: |
J.John Shimazaki, PLLC
P.O. Box 650741
Sterling
VA
20165
US
|
Family ID: |
34520230 |
Appl. No.: |
11/523061 |
Filed: |
September 19, 2006 |
Current U.S.
Class: |
705/412 |
Current CPC
Class: |
H02J 3/28 20130101; Y02E
60/14 20130101; Y02E 60/16 20130101; Y02E 10/46 20130101; F28D
20/00 20130101; G06Q 10/00 20130101; F24D 2200/16 20130101; H02J
15/006 20130101; F24S 60/30 20180501; G06Q 50/06 20130101 |
Class at
Publication: |
705/412 |
International
Class: |
G06F 17/00 20060101
G06F017/00 |
Claims
1. A method of reducing the end-user cost of energy at a
predetermined location, comprising: providing an energy storage
system comprising at least one tank and compressor capable of
storing energy in the form of compressed air energy; locating said
system at an end-user site, wherein said end-user is a consumer of
energy rather than a supplier; determining how much energy will be
used at said site during a second period of time, during which the
energy cost is based on a second rate; determining the nature and
extent of the peak power surges and/or spikes that are expected to
occur at said site during said second period of time; storing in
said tank a predetermined amount of compressed air energy from an
energy source during a first period of time, during which the
energy cost is based on a first rate, which is lower than said
second rate, wherein said first period of time is prior to said
second period of time; and using the compressed air energy from
said tank in a manner that helps reduce and/or offset 1) the amount
of energy used at said site during said second period of time,
and/or 2) the peak power surges and/or spikes occurring during said
second period of time.
2. The method of claim 1, wherein the energy source is a power grid
connected to the system that can be accessed to supply energy into
storage.
3. The method of claim 1, wherein the method comprises developing
an energy usage schedule for the second period of time, to
determine how the energy from storage should be used.
4. The method of claim 1, wherein the method comprises determining
the amount of a demand charge that may be applied based on the
spikes and/or surges that may occur during said second period of
time, and developing an energy usage schedule to reduce and/or
offset the spikes and/or surges.
5. The method of claim 1, wherein said site is a commercial
property, and wherein the storage system is used to lower the
overall cost of energy at said commercial property.
6. The method of claim 1, wherein the energy storage system
comprises at least one turbo-expander and generator to release the
compressed air energy and generate electricity during said second
period of time.
7. The method of claim 1, wherein the energy storage system
comprises at least one device taken from the group consisting of:
a. a solar thermal collector; b. thermal inertia mass; c. thin
walled tubing with anti-freeze distributed inside the tank; d.
fossil fuel burner; e. circulation device for using hot air from
the compressor.
8. The method of claim 6, wherein the energy storage system is
adapted to use cold air from the turbo-expander for cooling and/or
refrigeration purposes at said site.
9. The method of claim 1, wherein the energy storage system
comprises an indicator for measuring the energy consumption rate at
said site to determine how much energy in storage should be
released at any given moment in time.
10. The method of claim 9, wherein the indicator is a consumption
meter.
11. A method of reducing the end-user cost of energy at a
predetermined location, comprising: providing an energy storage
system comprising at least one tank and compressor capable of
storing energy in the form of compressed air energy; locating said
system at an end-user site, wherein said end-user is a consumer of
energy rather than a supplier; forecasting how much energy will be
used at said site during a second period of time, during which the
energy cost is based on a second rate; storing in said tank a
predetermined amount of compressed air energy from an energy source
during a first period of time, during which the energy cost is
based on a first rate, which is lower than said second rate,
wherein said first period of time is prior to said second period of
time; and using the compressed air energy from said tank in a
manner that reduces and/or offsets the amount of energy used at
said site during said second period of time, to substantially
reduce the amount of energy cost used by said site.
12. The method of claim 11, wherein the energy source is a power
grid connected to the system that can be accessed to supply energy
into storage.
13. The method of claim 11, wherein the method comprises
determining the nature and extent of the peak power surges and/or
spikes that are expected to occur at said site during said second
period of time, during which demand charges are assessed based on
the level of said peak power surges and/or spikes, and then using
the stored energy to reduce and/or offset the peak power surges
and/or spikes occurring at said site during said second period of
time.
14. The method of claim 13, wherein the method comprises developing
an energy usage schedule for the second period of time to determine
how the energy from storage should be used.
15. The method of claim 14, wherein the method comprises
determining the amount of the demand charge that may be applied
based on the peak power spikes and/or surges that may occur at said
site during said second period of time, and developing the energy
usage schedule to reduce and/or offset the peak power spikes and/or
surges.
16. The method of claim 11, wherein said site is a commercial
property, and wherein the storage system is used to lower the
overall cost of energy at said commercial property.
17. The method of claim 11, wherein the energy storage system
comprises at least one turbo-expander and generator to release the
compressed air energy and generate electricity during said second
period of time.
18. The method of claim 11, wherein the energy storage system
comprises at least one device taken from the group consisting of:
a. a solar thermal collector; b. thermal inertia mass; c. thin
walled tubing with anti-freeze distributed inside the tank; d.
fossil fuel burner; e. circulation device for using hot air from
the compressor.
19. The method of claim 11, wherein the energy storage system
comprises an indicator for measuring the energy consumption rate at
said site to determine how much energy in storage should be
released at any given moment in time.
20. The method of claim 19, wherein the indicator is a consumption
meter.
Description
RELATED APPLICATION
[0001] This application claims the benefit of the filing date of
U.S. Non-Provisional application Ser. No. 10/973,276, filed on Oct.
27, 2004, having the same title, and U.S. Provisional Application
Ser. No. 60/514,801, filed on Oct. 27, 2003, entitled "Method And
Apparatus For Storing And Using Energy."
FIELD OF THE INVENTION
[0002] The present invention relates to the field of energy storage
systems.
BACKGROUND OF THE INVENTION
[0003] There are literally hundreds of thousands of office
buildings and other commercial property located in the United
States and throughout the world (hereinafter "commercial
properties"). And, because most businesses and commercial
properties are required to operate during the day, they typically
need substantial electrical energy during the daytime hours to
provide power for utilities, including lighting, heating, cooling,
etc. This is particularly true with heating and cooling
requirements, such as during the extreme winter and extreme summer
months, wherein the energy needed to maintain a comfortable work
environment can be relatively high.
[0004] These peak demands can place a heavy burden on utility
plants and grids that supply electrical power to commercial
properties. Utility plants and grids often have to be constructed
to meet the highest demand periods, which means that during the low
demand periods, they will inevitably operate inefficiently, i.e.,
at less than peak efficiency and performance. This may be true even
if the peak demand periods occur during only a small fraction of
the time each day. Failure to properly account for such high demand
periods, such as by over-designing the facilities to meet the peak
demands, can result in the occurrence of frequent power outages and
failures. Also, a failure in one area of the grid can cause
tremendous stress and strain in other areas, wherein the entire
system can fail, i.e., an entire regional blackout can occur.
[0005] These demands can also place expensive burdens on commercial
property owners and operators. Utility companies often charge a
significant premium on energy consumed by commercial properties
during peak demand hours. This practice is generally based on the
well known principles of supply and demand, e.g., energy costs are
higher when demand is high, and less when demand is low. And
because most commercial property owners are forced to operate
during the day, they are most often forced to pay the highest
energy costs during the highest demand periods.
[0006] Utility companies also charge for energy during peak demand
periods by assessing a penalty or surcharge (hereinafter "demand
charge") on the maximum rate of consumption that occurs during a
predetermined period, such as a one month period. A demand charge
may be assessed, for example, based on the maximum "peak" rate of
consumption that occurs during the period, wherein the demand
charge can be assessed regardless of how short the peak "spike" or
"surge" during that period is, and regardless of what rate may have
applied immediately before and after the spike or surge. This
demand charge can also be assessed regardless of the average
consumption rate that may have otherwise been in effect during the
period, which could be considerably lower than the peak. Even if
the overall average rate of use is substantially lower, the demand
charge can be based on a much higher peak spike or surge
experienced during that period.
[0007] These pricing practices are designed to help utility
companies offset and/or recover the high cost of constructing
utility power plants and grids that are, as discussed above,
designed to meet the peak demand periods. They also encourage
commercial property owners and operators to reduce energy
consumption during peak periods, as well as to try to find
alternative sources of energy, if possible. Nevertheless, since
most commercial property owners and operators must operate their
businesses during the day, and alternative sources of energy are
not always readily available, they often find themselves having to
use energy during the highest rate periods. Moreover, because
energy consumption rates can fluctuate, and surges and spikes can
occur at various times, potentially huge demand charges may be
applied.
[0008] Utility companies and other providers of energy have, in the
past, implemented certain time-shifting methods, wherein energy
supplied during low demand periods are stored, and then used later
during peak demand periods. These methods typically involve storing
energy, and then using that energy later, to supplement the energy
provided by the grid. This theoretically enables more energy to be
consumed when energy costs are low, and less energy to be consumed
when energy costs are relatively high, thereby potentially reducing
the higher rate costs.
[0009] Several such energy storage methods have been used in the
past, including compressed air energy storage systems, such as
underground caverns. Thus far, however, one of the main
disadvantages of such systems is that they are relatively energy
inefficient. For example, compressed air energy systems have a
tendency to lose a significant portion of the energy that is
stored, so that the energy used from storage ends up actually
costing more than the energy that was stored. These inefficiencies
can make it so that the economic incentives to install energy
storage systems of this kind are significantly reduced.
[0010] Even though there are some advantages to such energy storage
systems, the added costs associated with installing and operating
such systems can become a financial burden, especially at the
end-user level. Accordingly, commercial property owners and
operators that use energy often have difficulty justifying the cost
of installing and using such systems. Moreover, because of the
expense of installation, they may have difficulties obtaining
financing and approval, e.g., to attract investors and/or lenders
to spend the money needed to develop and install such a system,
because they often doubt whether they will be able to recoup the
costs.
[0011] A method and system is needed, therefore, that can be used
by individual end-users of energy or commercial property owners and
operators to control and regulate the end-user consumption of
energy from the power grid, so that more energy can be consumed
during low-cost, low-demand periods, and less energy can be
consumed during high-cost, high-demand periods, to achieve not only
a reduction in overall demand and reducing the spikes and surges
that can occur during peak demand periods, but to reduce the
overall stress and strain on the power grid, and provide a means of
forecasting the cost savings that can be achieved over an extended
period of time, which can justify the cost and expense of
installing and operating the system, thereby making the system more
widely used.
SUMMARY OF THE INVENTION
[0012] The present invention relates to a method and energy storage
system capable of being used by commercial property owners and
operators for storing energy during periods when energy costs are
relatively low, and then using the stored energy during periods
when energy costs are relatively high, to reduce reliance on the
power grid during the high demand periods, and therefore, reduce
the operating costs associated therewith, and to do so in a manner
that helps obtain a cost savings over an extended period of
time.
[0013] The present invention is preferably to be used by commercial
property owners and operators, such as office buildings, shopping
centers, and other end-users of energy, and in this respect, the
present system differs from past systems, insofar as it is not
intended to be used by and in connection with energy suppliers,
such as large utility and power supply plants and grids. That is,
the present system preferably relates to the manner in which an
"end-user" of energy can implement energy and costs savings, by
using energy storage and time-shifting methods, to control and
regulate the consumption of energy in a manner that achieves a cost
savings over an extended period of time. This cost saving method is
referred to as "Time-Of-Use" or TOU.
[0014] In this respect, one aspect of the present method and system
preferably relates to being able to accurately forecast and predict
the energy demands and peaks that might occur on a daily basis, by
recording and analyzing the prior day's history, as well as the
overall energy demand histories, using short and long term
forecasts, and then setting up a variable energy storage/use plan
or schedule that helps to reduce the peak demands by time-shifting
the energy that is used, i.e., reducing consumption during high
demand/high cost periods, by using the energy stored during low
demand/low cost periods during the high demand/high cost
periods.
BRIEF DESCRIPTION OF THE DRAWING
[0015] FIG. 1 shows a typical energy storage system to be used in
the present application; and
[0016] FIG. 2 shows a typical storage tank system with optional
heating devices.
DETAILED DESCRIPTION OF THE INVENTION
[0017] This discussion will begin by discussing some of the basic
components of the energy storage system apparatus that can be used
by the present invention. The invention contemplates that various
energy storage systems can be used in connection with the methods
discussed herein. Nevertheless, the following discussion describes
a preferred system that can be used in connection with the present
invention.
[0018] The system generally comprises a compressed air energy
storage system small enough to be housed within a commercial
property, whether an office building, shopping center, or other
end-user of energy. For example, the system can be installed in a
basement of an office building, shopping center or commercial
complex, where other utility equipment might be located. The
storage tank can also be located on the roof or other outdoor
location, and, for example, painted black, to enable the tank to
absorb heat energy from the sun, as will be discussed.
[0019] As shown in FIG. 1, the system 1 is preferably connected
directly to the power grid 3. This enables the system to draw power
from the grid 3 in the same manner as any other commercial
property. The difference, however, is in how the system can control
and regulate the consumption of energy, as will be discussed.
[0020] Storage system 1 preferably comprises components found in
energy storage systems of this kind, including a compressor 5, a
storage tank 7, an airflow control valve 9, a turbo-expander 11, an
electrical generator 13, etc. The compressor 5 is preferably
connected to the power supply so that electrical energy from the
grid 3 can be converted to compressed air energy during off-peak,
low demand hours, such as during the nighttime hours. The
compressor 5 preferably uses electrical energy from the grid 3 and
compresses air into the storage tank 7, wherein the compressed air
is stored until it can be used later when energy demands and costs
are relatively high.
[0021] In general, the energy storage portion of the present system
preferably comprises means for storing and making use of the
compressed air energy. In this respect, storage tank 7 is
preferably designed to withstand the pressures likely to be applied
by compressor 5, and insulated to maintain existing temperatures in
tank 7. Tank 7 is also preferably located in proximity to where the
system 1 is connected to the power grid 3, such that compressed air
can be conveyed to tank 7 without significant pressure losses.
[0022] Although the present invention contemplates that various
size tanks can be used, the size of the storage tank 7 depends on
the amount of compressed air energy required for a given
application, as well as other factors, such as the capacity of the
compressor 5, the capacity of the turbo-expander 11, amount of the
expected energy demand at the location, the size of the available
space, etc.
[0023] The present invention contemplates that any of many
conventional means of converting the compressed air into electrical
energy can be used. In one embodiment, one or more turbo-expanders
11 are used to release the compressed air from storage tank 7 to
create a high velocity airflow that can be used to power a
generator 13 to create electrical energy. This electricity can then
be used to supplement the energy supplied by the grid 3 when
needed, as will be discussed. The turbo-expander 11 preferably
feeds energy to an alternator, which is connected to an AC to DC
converter, followed by a DC to AC inverter.
[0024] The turbo-expander 11 is used to release and expand the
compressed air energy at the appropriate time, i.e., "on demand,"
such as during peak demand periods, wherein the released and
expanded air can drive the electrical generator 13. This way, the
stored energy in the tank can be used to generate electrical power
on an "as needed" basis. For example, the turbo-expander 11 can be
turned on when demand is low and there an expectation that extra
energy will be needed during an upcoming high demand period, based
on the monitored demand power history, as will be discussed below.
On the other hand, the turbo-expander 11 can be shut down during
the relatively high demand, high cost periods, so that high cost
energy is not used to compress air into the tank 7. The criteria
preferably takes into account that the turbo-expander 11 starts
from rest and accelerates to a peak rotational rate and then
decelerates back to rest.
[0025] The present invention contemplates that storage tank 7
and/or related components, and their thermal inertia masses, can be
designed to absorb and release heat to maintain the stored and
compressed air in the tank 7 at a relatively stable temperature,
even during compression and expansion. For example, in one
embodiment, a heat transfer system made of tubing 8 extended
through the inside of storage tank 7 can be used, wherein heat
transfer fluid (such as an antifreeze) can be distributed through
the tubing 8 to provide a cost-efficient way to stabilize the
temperature in the tank 7. This enables the system 1 to statically
stabilize the temperature in a manner that is more cost efficient
than mechanical systems.
[0026] In this embodiment, the means by which heat from various
collectors (to be discussed) can be distributed to the compressed
air in the tank 7 comprises a large surface area of thin walled
tubing 8 that extends through tank 7. The tubing 8 preferably
comprises approximately 1% of the total area inside the tank 7, and
preferably comprises copper or carbon steel material. They also
preferably contain an antifreeze fluid that can be heated by the
collectors and distributed by the tubing 8 throughout the inside of
tank 7. The thin walled tubing 8 preferably act as a heat
exchanger, which is part of the thermal inertia system. The tank 7
is preferably lined by insulation 19 to prevent heat loss from
inside.
[0027] In another embodiment, the relatively thick walls of the
storage tank 7 can, by itself, act as a thermal sink and source.
For example, when air is compressed into storage tank 7, and the
air is heated, this heated air can help raise the temperature of
the storage tank walls, i.e., the walls absorb the heat.
Furthermore, when tank 7 is located outdoors, and painted black,
the walls of the tank can absorb the heat from the sun, wherein the
tank walls can act as a heat sink.
[0028] Extra metal, in such case, can be added to the walls, so
that they provide a similar thermal inertia function as the
anti-freeze filled tubing 8, but with the added safety of being
able to retain the storage tank 7 service-free for longer periods
of time, i.e., considering the long term effects of corrosion.
Moreover, a reduced number of problems can be expected, such as
from corrosion, since the air inside the tank cannot contain a
significant amount of water vapor at higher pressures. In this
respect, compressor 5 will help to remove most of the water vapor
during air compression, and the water condensed in tank 7 is
preferably drained each day, i.e., such as by a draining means,
wherein the air in storage tank 7 can be extremely dry.
[0029] The mass of the tank 7 can also be made relatively large
compared to the air mass inside the tank 7. Accordingly, the tank
walls do not have to increase in temperature by a significant
amount to help sustain the temperature of the air inside the tank
7. For example, when air is exhausted by the turbo-expander 11, the
air temperature in the tank 7 will try to drop according to
isentropic laws, but a heat exchange process will occur as a result
of the heat absorbed by tarik walls, which act as a thermal source
to maintain the temperature in the tank 7. Thus, the temperature
drop is limited so that reasonable air temperatures are available
inside the tank 7, i.e., for use by turbo-expander 11.
[0030] The present system can also incorporate other energy
efficient methods and systems, as shown in FIG. 2, including a
means of using the heat absorbed in the interstage coolant water of
the multi-stage compressor to provide supplemental heat for water
heaters and boilers and other areas of the building or property, so
that the heat can be put to efficient use. Also, the present
invention contemplates the possibility of using one or more of a
combination of solar heat (using a solar thermal collector 15),
waste heat from the compressor 5, combustors, low-level fossil fuel
power 17, etc., to provide the necessary heat to increase the
temperature and pressure in the storage tank 7. In this respect,
the heat generated by compressor 5 can be used to maintain the
stability of the temperature in tank 7, to offset the cooling
effect of the turbo-expander 11, as it releases and expands air
from the tank 7.
[0031] For example, the storage tank 7 is preferably very effective
in using the waste heat that needs to be removed from
ammonia-refrigerated plants. For example, whenever the storage tank
temperature drops to below 120 degrees F., the hot ammonia from the
refrigeration cycle of the plant can flow through the tubing 8 in
tank 7. In this respect, it should be noted that turbo-expander 11
not only depends on the air supply pressure, but the higher the air
supply temperature, the greater the energy produced by the
turbo-expander 11.
[0032] The increased temperature inside the storage tank 7 provides
several advantages. First, it has been found that heat contributes
greatly to the efficiency of overall work performed by the
turbo-expander 11, and therefore, by increasing the temperature of
the compressed air in the storage tank 7, a greater amount of
energy can be generated from the same size storage tank. Second, by
increasing the temperature of the air in the storage tank 7, the
pressure inside the tank can be increased, wherein a greater
velocity can be generated through the turbo-expander 11. Third,
heating the air in the tank 7 helps to avoid freezing that can
otherwise be caused by the expansion of the air in the tank 7.
Without a heating element, the temperature of the air released from
the tank 7 can reach near cryogenic levels, wherein water vapor and
carbon dioxide gas within the tank 7 can freeze and reduce the
efficiency of the system. The present invention is preferably able
to maintain the temperature of the expanding air at an acceptable
level, to help maintain the operating efficiency of the system.
[0033] Likewise, the cooling effect resulting from the
turbo-expander 11 expanding the compressed air can be used to
supplement air conditioners and other cooling systems within the
building or property. The present system contemplates that the cold
air created by the expansion of the compressed air exhausting from
the turbo-expander 11 can be used for additional refrigeration
purposes, i.e., for cooling needed to keep refrigerators and
freezers cold, as well as during the summer months to supplement
energy needed to run air conditioners. This way, the system can be
used to supplement the existing energy systems that are already in
place within the commercial property. The cold air can also be
rerouted through pipes to the compressor 5 to keep the compressor
cool, as shown in FIG. 2.
[0034] The system also preferably comprises a control system to
control the operation of storage tank 7, compressor 5, turbo
expander 11, heating units, refrigeration components, etc. The
control system is preferably designed to be able to maintain the
level of compressed air energy in the tank 7 at an appropriate
level, by regulating the flow of compressed air into and out of
tank 7. The controls are also used to control and operate the heat
exchangers that are used to help control the temperature of the air
in the tank 7. The controls determine which heat exchangers are to
be used at any given time, and how much heat they should provide to
the compressed air. The control system preferably has a
microprocessor that is pre-programmed so that the system can be run
automatically. The control system preferably enables the user to
determine when to use the compressed air energy.
[0035] The invention also preferably comprises a computer operated
control system to help control and regulate the consumption of
energy from the grid, to enable the system to decrease consumption
during high demand periods, and, in turn, increase consumption
during low demand periods, and to do so in a manner that enables
the system to achieve a cost savings over an extended period of
time. On a micro-level, the present system preferably enables the
commercial property owner or operator to experience an energy cost
savings, by consuming more energy during low cost periods, and less
energy during high cost periods, and by reducing the occurrence of
spikes and surges that can otherwise result in significant demand
charges being assessed. The methods and systems contemplated by the
present invention also make it possible, at a macro-level, to
reduce the overall demand placed on utility plants and grids, such
as during peak demand periods, which can help reduce the overall
stress and strain on the grid, and thereby help reduce the
likelihood that blackouts and other failures to the entire system
could occur in the future.
[0036] The unique methods applied by the present system involve the
following:
[0037] The initial steps preferably involve doing some research to
determine the costs involved in installing and operating different
size and capacity storage systems. Once these amounts are
determined, the method contemplates using the information to
determine what the rate of cost savings will have to be for the
system to achieve an overall cost savings over the course of a
predetermined time period, such as by the end of the depreciation
cycle. That is, the method contemplates using a process to
determine, for any given system, what the rate of cost savings will
have to be, i.e., on a daily basis, to achieve an overall cost
savings over an extended period of time, such as ten or fifteen
years.
[0038] Based on the size and nature of the end-user property, the
owner or operator may make several selections regarding what system
components to use. The selection of such systems may be based on
many factors, including but not limited to, the overall amount of
energy to be consumed by the commercial property, what the maximum
or peak demand for energy is expected to be, the expected growth
and/or modifications that might have to be made to the property,
where the system will be located, how much space there is to
install the storage tank 7, etc. Upon determining these amounts, or
making these selections, the method preferably contemplates
calculating and estimating the total cost of installation and
operation over the estimated depreciation cycle. For example, the
total cost over a ten-year period for one system might be
$600,000.00.
[0039] Once that amount is known, the method preferably involves
selecting the most energy and cost efficient system to use, based
on a comparison between its cost and the ability to produce an
adequate rate of cost savings over time, to off-set the
installation and operation costs associated therewith.
[0040] To do so, the next step preferably involves determining how
much energy is typically used by the end-user, such as over the
course of a given 24-hour period, and to make this determination
every day over the course of the year. This preferably involves
measuring energy consumption rates at the property for the previous
24 hour or longer period, and charting that data to track energy
consumption levels throughout the day and night, and to use that
data to chart a curve that shows how much energy might be expected
to be used during the next upcoming 24 hour period. The curve also
preferably includes an estimate of the spikes and surges that might
occur during that day or period, including the size of the spikes
and surges, when they might occur, and how long they might
last.
[0041] The method also preferably involves taking data over the
course of several days, weeks, or months, etc., i.e., during the
course of several seasons, if necessary, to determine whether there
are significant changes in energy consumption that might occur from
one season of the year to another. By looking for patterns during
different times of the year, system operators can use this
information to help forecast and predict when significant changes
in energy consumption might occur, which can be used to more
accurately forecast and predict when consumption rates might
increase or when spikes and surges might occur.
[0042] In this respect, the method contemplates that the curve can
be adjusted if necessary, based on the historical data for that
period of the year, wherein the system can take into account the
short and long-term data to determine the nature of the curves that
are developed. This helps to ensure that the short-term analysis of
the data is consistent with the long-term analysis for that
particular property during that particular time of year.
[0043] The information obtained by these processes can then be used
to accurately forecast and predict the expected consumption rate by
the end-user during any given 24 hour period, during any given time
of day. That is, for any given 24 hour period, the method
contemplates using the data from the previous 24 hour period, as
well as other historical data, to forecast and predict how much
energy might be expected to be used on that day and when.
[0044] The present method contemplates using these forecasts and
predictions to know in advance when the consumption rate will
likely be at its highest, and to attempt to predict when and how
long the spikes and surges might be, so that the proper controls
and limitations can be implemented to time-shift energy consumption
away from the peak demand periods, i.e., by storing energy during
the low demand periods, and using the stored energy during the high
consumption rate periods, and/or whenever spikes and surges might
occur. This way, the amount of energy consumption during the
highest rate periods, and the level of spikes and surges that might
otherwise occur, can be reduced to reduce the energy costs that
might apply during that period.
[0045] The system contemplates making these predictions and
forecasts in conjunction with the actual energy rates and demand
charges that are assessed by the utility power plants. That is, the
method contemplates that by knowing the end-user's expected
consumption rate, and knowing what the actual cost of energy will
be during that same period, an evaluation can be made as to how the
system can be adjusted and controlled to maximize the cost savings
that can be achieved. In short, the information is used to know
when and how much energy should be stored during the low demand
periods, and when and how much energy should be used during the
higher demand periods, and to make this determination on a daily
basis throughout the year.
[0046] In many cases, energy pricing schedules are typically broken
down into three periods each day, based on the level of demand,
i.e., high demand, mid demand, and low demand periods. A schedule
that involves three different rates, for example, is often used by
utility plants, as follows: a first mid-cost, mid demand rate might
apply, for example, between 8:00 a.m. and noon, a high-cost, high
demand rate might apply between noon and 6 p.m., a second mid-cost,
mid demand rate might apply again between 6 p.m. and 11:00 p.m.,
and a low-cost, low demand rate might apply between 11:00 p.m. and
8:00 a.m. In this respect, utility companies typically have a
graduated pricing schedule that applies a different rate per kW-H
for energy consumed during different times of the day.
[0047] Utility companies also typically assess "demand charges," as
defined above, based on the peak "spike or surge" demand energy
consumption rate experienced during any predetermined period of
time, such as a one-month period. For example, in some areas of the
country, in addition to the graduated pricing schedule discussed
above, a utility company may charge an additional penalty or
surcharge based on the maximum peak consumption of kW's experienced
during that period. That is, a penalty or surcharge may be assessed
for the period, based on a single maximum rate of consumption that
occurs during that period, even if that single maximum peak rate
lasts for only a few minutes. This demand charge is typically
assessed regardless of how low the rate is immediately before and
after the peak, and regardless of the average consumption rate
experienced during the period. That is, the penalty or surcharge is
assessed based on the peak demand consumption rate, even if the
peak is a random spike or surge lasting only a few minutes, and
even if that peak does not reflect the average consumption rate
experienced during the remainder of the period.
[0048] Moreover, in many situations, the amount of the demand
charge is highest during the peak summer months when energy
consumption due to air conditioning needs are at their highest.
This is particularly true within the warmer climate areas where the
demand for air conditioning is extremely high. And, during those
months, the price of energy is highest during the mid-day hours,
which represents the highest demand period. For example, during the
summer months, a typical demand charge that may be applied to a
period may be $20.00 per kW based on a single peak spike rate
experienced during that period, i.e., between noon and 6:00 p.m. On
the other hand, only $2.45 per kW may apply during the mid-demand
period, and $0.00 during the low demand period. Thus, even if the
average rate during any given day of the peak summer month is
relatively low (say 300 kW), if there is a single fifteen minute
spike or surge during that month (i.e., at a rate of say, 700 kW),
the amount of the demand charge that may be assessed for that month
could be based on the higher rate (of 700 kW), and not the lower
rate (of 300 kW), even though the higher rate was experienced
during only a fifteen minute spike. Therefore, during peak hours,
the amount of the demand charge can be prohibitively high, wherein
it can be based on a single surge or spike, no matter how random,
or how brief, it might be.
[0049] An example of a typical demand charge in such circumstances
might be something like this: During the hottest summer months,
i.e., the four hottest months, in addition to the usage rates
discussed above, an additional one time demand charge may be
assessed based on the maximum peak usage that occurs during that
month. In the above example, the higher demand charge rate of
$20.00 per kW might be applied to the highest rate spike or surge
that occurs during the month, so that if the highest spike or surge
is 700 kW, the higher rate will be multiplied by 700 kW, for a
total demand charge of $14,000.00 for that month. On the other
hand, when no spikes or surges occur during the month, or the spike
or surge is lower, i.e., say 400 kW, the demand charge would be
based on the lower rate, i.e., 400 kW instead of 700 kW. In such
case, when multiplying $20.00 times 400 kW, the demand charge would
be only $8,000.00 , which would, in this example, represent a cost
savings of $6,000 per month.
[0050] What this shows is that there are significant cost
advantages that can be achieved by reducing or altogether
eliminating the spikes and surges that can result in significant
demand charges being assessed. When energy is used during the
higher cost, high demand periods, the end-users are likely to be
charged a significant demand charge, which means that the more the
end-user uses energy during those periods, the greater the overall
energy costs will be.
[0051] The way the present method addresses these additional costs,
penalties and surcharges, is shown by the following example:
[0052] Based on the daily forecasts and predictions discussed
above, the system determines each day how much energy is likely to
be needed in storage for the upcoming 24 hour period. For example,
during the summer months, because demand may be high, the system
may need to store the maximum amount possible during the low demand
periods, such as between 11:00 p.m. and 8:00 a.m. that morning.
This additional energy can then be used during the high demand
periods, to control and limit the maximum consumption rates, as
well as the spikes and surges that may otherwise be experienced,
and therefore, reduce the costs associated with the high demand
rates.
[0053] The plan preferably calls for reserving the stored energy
each day for the upcoming high demand periods for the next day,
although in some cases, there may be a desire to reserve some of
the energy for the upcoming mid-demand periods as well. This will
depend on whether there is enough energy in storage to sufficiently
control the consumption rate during the peak demand periods, and/or
whether there is any excess energy available, and how much benefit
there would be in applying the energy to the mid-demand
periods.
[0054] Note that if the electrical power rates during the day are
sufficiently high compared to the nights during the critical summer
months, there may be an additional mode of operation. For example,
one can use a lull in the power usage during the course of the day
and actually use power to drive the compressor to further compress
air into the storage tank. Thus, if there is a late afternoon surge
in demand, one could defeat that spike in demand power without
having to fear that the storage tank will be exhausted from
excessive previous excitation of the turbo-expander. Even though
there is use of daytime energy at off-peak power, it may still be
economical to follow this mode of operation in order to avoid a
subsequent critical spike. Daytime operation of the compressor
during low power periods can be the equivalent to having a larger
storage tank.
[0055] Once the appropriate amount of energy is in storage, the
system waits for the higher demand periods to occur the next day,
and saves the energy so that it can be released at the appropriate
time. In this respect, the system preferably has a consumption
meter or other indicator that instantly measures the consumption
rate that might occur at any given moment in time, so that the
system will know when the energy in storage should be released and
how much should be released at the appropriate time, i.e., to
off-set the higher consumption rates and/or spikes and surges that
may otherwise occur during that day.
[0056] For example, if the forecast predicts that there will be a
surge lasting for five minutes during the peak demand period,
and/or several spikes lasting three minutes each, and the predicted
amount of the surge and/or spike is say, 800 kW, the system will
reserve an amount in storage sufficient to reduce the draw of power
on the grid during that time to a predetermined threshold amount,
which can be, say 400 kW. This way, for that day, the highest
consumption rate that occurs can be reduced from 800 kW, which
would have occurred without the present system, to 400 kW, which
can result in a significant reduction in the demand charge applied.
In this example, if the peak spikes and surges are reduced to 400
kW or less each day during the month, there will be a total
reduction of 400 kW or more that month, i.e., for purposes of
determining the demand charge, in which case a cost savings of
$8,000.00 can be obtained for that month. This is based on $20.00
per kW multiplied by the difference of 400 kW. Also, it can be seen
that if this is repeated everyday of the month, during the four
high demand months, there could potentially be a cost savings of
$8,000.00 every month, which can lead to a cost-savings of
32,000.00 every year, which can lead to a cost savings of
$320,000.00 over the course of ten years.
[0057] Additional energy saved each day can also be released during
the peak demand periods to reduce the total consumption of energy
experienced during that day and therefore reduce the overall usage
costs that day. For example, if the rate is $0.20 per kW-H during
the high demand period, $0.10 per kW-H during the mid-demand
period, and $0.08 per kW-H during the low demand period, by
time-shifting the energy from $0.20 per kW-H to $0.08 per kW-H, a
potential cost savings based on the difference between the two
rates can be achieved. Nevertheless, since there is a reduced
efficiency associated with energy storage, the cost savings that
can actually be achieved by time shifting to the low demand period
is not as large as it could be. That is, even if all the energy
used during the peak demand period could be purchased at the lower
rate of $0.08 per kW-H, instead of the higher rate of $0.20 per
kW-H, because of the potential reduced efficiency of potentially as
much as 50% resulting from energy storage, the actual cost savings
may only be $0.04 per kW-H, instead of $0.12 per kW-H. Of course,
these cost savings will vary depending on the actual efficiency of
the system being used. The system is preferably designed to be as
efficient as possible, using the various heating devices and
collectors discussed above, wherein an efficiency percentage of
about 70% could potentially be obtained.
[0058] The cost savings associated with this aspect of the
invention can be based on the cost savings per kW-H multiplied by
the total kW-h expended by the system during the entire year, which
can be significant. For example, if the system expends 2,000,000
kW-H per year during the peak demand periods, the cost savings can
potentially be 2,000,000 kW-H multiplied by the difference in the
per kW-H rate of $0.04 kW-H, which in the above example, may lead
to an additional cost savings $80,000.00 per year (2,000,000 times
$0.04 kW-H per year). Thus, it can be seen that this can lead to an
additional cost savings of $800,000.00 over the course of ten
years.
[0059] Using the above examples, it can be seen that a potential
cost savings of $1,120,000.00 can be achieved over a ten-year
period ($320,000 plus $800,000). And as storage efficiencies are
improved by using the heating devices and collectors described
above, these amounts could potentially be increased. Accordingly,
if the cost of installing and operating the system over the same
period is $600,000.00, there is potentially a net savings of
$520,000.00, which would justify the cost of installing and
operating the system.
[0060] U.S. application Ser. No. 10/973,276, filed Oct. 27, 2004,
and Ser. No. 10/263,848, filed Oct. 4, 2002, and U.S. Provisional
Application Ser. Nos. 60/474,551, filed May 3, 2003, and
60/478,220, filed Jun. 13, 2003, are incorporated herein by
reference in their entirety.
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