BACKGROUND OF THE INVENTION
The field of the invention relates generally to power systems
and, more particularly, to a computing device that enables the sale and purchase of
energy for use with a power system.
The combination of the increasing world population and the
increased use of electric vehicles has created an increased electricity energy demand.
Energy demand has also increased for use to power buildings, homes, and/or to
charge batteries or other energy sources used in electric vehicles. The demand on the
power grid has increased as the cost of he1 has increased. Such demands will likely
cause an increase in the price of energy fiom the power grid. In particular, initially at
least, the price of energy is likely to increase during peak times of high demand.
Currently, at least some known utility companies use demand
response to manage the consumption of energy by their customers in response to
supply conditions. For example, at least some known utility companies may have
customers reduce their consumption at critical times and/or in response to market
prices. To better manage their customers, at least some known utility companies may
use smart grid applications that provide time-based pricing that enables customers to
selectively adjust their usage to take advantage of fluctuating prices. Moreover, some
known utility companies may provide information, regarding their fluctuating prices
for example, to customers using various notification methods, such as e-mails and/or
text messages.
In addition, more renewable energy and storage options are
generally available online via a network that enables grid operation centers and/or
utilities to have access to additional energy sources that may be owned andlor
operated by individuals. Such energy sources may include electric vehicle batteries,
wind turbines, solar panels, and/or generators. Currently, however, consumers have
very little ability to negotiate and/or to sell power, at a relatively competitive rate,
from their energy sources back to a grid and/or a utility.
In one embodiment, a computing device for use with a power
system is provided. The computing device includes a communication interface that is
configured to receive energy data from at least one utility, wherein the energy data
includes at least one of at least one quantity of energy and at least one energy price.
A processor is coupled to the communication interface and programmed to generate at
least one offer to purchase energy based on the energy data. A user interface is
coupled to the processor and configured to enable at least one operator of at least one
energy source to sell energy to the utility by responding to the offer to purchase
energy.
In another embodiment, a power system is provided. The
power system includes at least one energy source that is configured to supply energy
to a power grid and at least one computing device that is coupled to the energy source.
The computing device includes a communication interface that is configured to
receive energy data from at least one utility, wherein the energy data includes at least
one of at least one quantity of energy and at least one energy price. A processor is
coupled to the communication interface and programmed to generate at least one offer
to purchase energy based on the energy data. A user interface is coupled to the
processor and configured to enable at least one operator of at least one energy source
to sell energy to the utility by responding to the offer to purchase energy.
In yet another embodiment, a method for use in the sale and
purchase of energy is provided. The method includes' receiving, via a communication
interface, energy data from at least one utility, wherein the energy data includes at
least one of at least one quantity of energy and at least one energy price. At least one
offer to purchase energy is generated, via a processor, wherein the offer to purchase
energy is based on the plurality of energy prices. A response from at least one
operator of at least one energy source is received to the offer to purchase energy, via a
user interface, such that the operator is enabled to sell energy to the utility.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram of an exemplary power system; and
Fig. 2 is a block diagram of an exemplary computing device
that may used with the power system shown in Fig. 1.
DETAILED DESCRIPTION OF THE INVENTION
The exemplary systems and methods described herein
overcome at least some known disadvantages of known power systems by providing a
platform that enables operators and/or owners of energy sources to negotiate, andlor
to sell power, at a relatively competitive rate, from their own energy sources back to a
grid and/or a utility. More specifically, the embodiments described herein provide a
computing device for use with a power system. The computing device includes a
communication interface that is configured to receive energy data fiom at least one
utility, wherein the energy data includes at least one of at least one quantity of energy
and at least one energy price. A processor is coupled to the communication interface
and programmed to generate at least one offer to purchase energy based on the energy
data. A user interface is coupled to the processor and configured to enable at least
one operator of at least one energy source to sell energy to the utility by responding to
the offer to purchase energy.
Fig. 1 is a block diagram of an exemplary power system 100.
In the exemplary embodiment, power system 100 includes at least one energy source,
such as energy source 102 and energy source 104, wherein energy source 102 and
energy source 104 are each configured to supply power to a power grid 106. Energy
source 102, in the exemplary embodiment, is an energy storage device, such as a
battery. More specifically, in the exemplary embodiment, energy source 102 may be
battery that may be coupled within or to an electric vehicle 108. In the exemplary
embodiment, energy source 102 is a rechargeable lithium-ion battery. Alternatively,
energy source 102 may be any other lithium-based battery or any other type of battery
that enables power system 100 to function as described herein. Energy source 102 is
coupled to an electric vehicle charging station 109, and charging station 109 is
coupled to power grid 106. Moreover, energy source 104, in the exemplary
embodiment, is an energy generating device, such as a wind turbine, a solar panel,
and/or a fuel cell. Energy source 104 is coupled to a generator 1 10 that is coupled to
power grid 106. Alternatively, energy source 104 may be coupled directly to power
grid 106. Energy source 104 may also include a battery 11 1 that is coupled to a
convertor (not shown) and/or a transformer (not shown), wherein the convertor is
coupled to generator 1 10. Alternatively, battery 1 11 may be coupled to the convertor,
wherein the convertor is coupled directly to power grid 106.
It should be noted that, as used herein, the term "couple" is
not limited to a direct mechanical, electrical, and/or communication connection
between components, but may also include an indirect mechanical, electrical, andlor
communication connection between multiple components.
Moreover, it should be noted that the term "electric vehicle"
refers generally to a vehicle that includes one or more electric motors (not shown) that
are used to provide propulsion to the vehicle. Energy, such as electrical energy, used
to generate power and propel electric vehicles may come from various sources, such
as, but not limited to, an on-board rechargeable battery andlor an on-board fuel cell.
In one embodiment, the electric vehicle is a hybrid electric vehicle, which captures
and stores energy generated by braking. Moreover, a hybrid electric vehicle uses
energy stored in an electrical source, such as a battery, to continue operating when
idling to conserve fuel. Some hybrid electric vehicles are capable of recharging the
battery by plugging into a power receptacle, such as a general power outlet. Another
example of an electric vehicle is a fuel-cell vehicle, which uses only electrical energy
for propulsion. Accordingly, the term "electric vehicle" as used herein may refer to a
hybrid electric vehicle, a fuel-cell vehicle, or any other vehicle to which electrical
energy may be delivered via a power grid, such as power grid 106.
.)
In the exemplary embodiment, power system 100 includes at
least one computing device 112. More specifically, in the exemplary embodiment,
power system 100 includes two computing devices 112 such that each energy source
102 and energy source 104 are each coupled to one computing device 112.
Alternatively, power system 100 may include any number of computing devices 112
that enables system 100 to function as described herein. Moreover, in the exemplary
embodiment, energy source 102 is coupled to a communication module 113 and
energy source 104 is coupled to a communication module 1 14. Modules 1 13 and 1 14
enable energy source 102 and energy source 104, respectively, to communicate with
their respective computing device 112. For example, modules 113 and 114 may
enable energy sources 102 and 104, respectively, to transmit various information
regarding energy sources 102 and 104 to respective computing device 112, such as the
energy capacity within each energy source 102 and 104 and/or the amount of energy
contained within each energy source 102 and 104 to respective computing device 1 12.
Each computing device 112 is also coupled to at least one
utility 115. In the exemplary embodiment, each computing device 112 is coupled to
two utilities 115 such that at least one owner and/or operator of each energy source
102 and/or energy source 104 is enabled to communicate with each utility 115. More
specifically, each computing device 112 enables the operator of energy source 102
and/or the operator of energy source 104 to purchase energy from each utility 115
and/or sell energy from energy source 102 and/or energy source 104 to each utility
115. In the exemplary embodiment, owner and/or operator may include an individual
owner and/or operator and/or a cooperative group of owners and/or operators.
In the exemplary embodiment, each utility 115 includes a
network interface 1 16 that is coupled to a network 1 18 to enable each utility 1 15 to
communicate with each computing device 112. In the exemplary embodiment, each
utility 115 may communicate with at least one of computing devices 112 using a
wired network connection (e.g., Ethernet or an optical fiber), a wireless
communication means, such as radio frequency (RF), e.g., FM radio and/or digital
audio broadcasting, an Institute of Electrical and Electronics Engineers (IEEEB)
802.1 1 standard (e.g., 802.1 l(g)) or 802.1 l(n)), the Worldwide Interoperability for
Microwave Access (WIMAXO) standard, a cellular phone technology (e.g., the
Global Standard for Mobile communication (GSM)), a satellite communication link,
and/or any other suitable communication means. WIMAX is a registered trademark
of WiMax Forum, of Beaverton, Oregon. IEEE is a registered trademark of the
Institute of Electrical and Electronics Engineers, Inc., of New York, New York. In
the exemplary embodiment, for example, each utility 115 may be configured to
transmit energy data, such as at least one quantity of energy (watts) andlor at least one
energy price to each computing device 112, wherein each energy price may be
associated with certain limitations, such as, for example, a time range, a duration of
time, quantity of energy, and/or operating ranges of energy sources, such as energy
source 102 and/or energy source 104. Certain limitations may also include weather
conditions, grid status, such as an outage or gird capacity. Alternatively, utility 115
may be configured to transmit any other information to each computing device 112
that enables power system 100 to function as described herein.
During operation, an operator of an energy source, such as
energy source 102 and/or energy source 104, couples each energy source 102 and 104
to power grid 106. For example, an operator of energy source 102 may couple energy
source 102 to charging station 109 such that energy source 102 is coupled to power
gird 106. Similarly, an operator of energy source 104 may couple energy source 104
and or battery 1 1 1 to generator 1 10 and/or to power grid 106 such that energy source
104 is coupled to power grid 106. A signal representative of energy source 102 being
coupled to power grid 106 is transmitted from energy source 102 to respective
computing device 112 via communication module 113. Similarly, a signal
representative of energy source 104 being coupled to power grid 106 is transmitted
from energy source 104 to respective computing device 112 via communication
module 114. Each computing device 112 may then prompt each operator with an
option to receive energy data, such as, for example, a plurality of energy prices and/or
a quantity of energy, from each utility 115. The operator who elects to receive such
information confirms receiving the energy data, and computing device 112 presents
the energy data to the operator. By receiving the energy data, the operator may
identify when to purchase energy from each utility 115 and/or when to sell energy to
each utility 1 15.
In the exemplary embodiment, each operator chooses to sell
energy to each utility 115 and inputs such information into the respective computing
device 1 12. Each computing device 112 transmits a signal to each utility 115.
Energy from energy source 102 is transmitted to charging station 109 and to power
grid 106. Similarly, energy from energy source 104 is transmitted to generator 1 10
and to power grid 106. This additional energy supplied to power grid 106 can later be
sold by each utility 115 to others. Alternatively, the operator, such as the operator of
energy source 102 may decide to purchase energy from each utility 115, via
respective computing device 1 12. In such a case, energy from power grid 106 may be
transmitted to energy source 102 and/or energy source 104.
Fig. 2 is a block diagram of one computing device 112 used
with power system 100 (shown in Fig. 1). In the exemplary embodiment, computing
device 112 includes a user interface 204 that receives at least one input from a user,
such as an operator and/or owner of an energy source, such as energy source 102
(shown in Fig.1) and energy source 104 (shown in Fig. 1). In the exemplary
embodiment, user interface 204 includes a keyboard 206 that enables a user to input
pertinent information. Alternatively, user interface 204 may include, for example, a
pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch
screen), a gyroscope, an accelerometer, a position detector, and/or an audio input
interface (e.g., including a microphone).
Moreover, in the exemplary embodiment, computing device
112 includes a presentation interface 207 that presents information, such as input
events andlor validation results, to the user. In the exemplary embodiment,
presentation interface 207 includes a display adapter 208 that is coupled to at least one
display device 210. More specifically, in the exemplary embodiment, display device
210 is a visual display device, such as a cathode ray tube (CRT), a liquid crystal
display (LCD), an organic LED (OLED) display, and/or an "electronic ink" display.
Alternatively, presentation interface 207 may include an audio output device (e.g., an
audio adapter andor a speaker) andor a printer.
Computing device 112 also includes a processor 214 and a
memory device 218. In the exemplary embodiment, processor 214 is coupled to user
interface 204, presentation interface 207, and to memory device 218 via a system bus
220. In the exemplary embodiment, processor 2 14 communicates with the user, such
as by prompting the user via presentation interface 207 and/or by receiving user
inputs via user interface 204. Moreover, in the exemplary embodiment, processor 2 14
is programmed by encoding an operation using one or more executable instructions
and providing the executable instructions in memory device 218. For example,
processor is programmed to generate at least one offer to purchase energy from an
operator of an energy source, such as energy source 102 and/or energy source 104.
The offer to purchase energy is based on the energy data that computing device 112
receives from each utility 115 (shown in Fig. 1). ~rocessor' 214 is further
programmed to generate at least one offer for sale of energy to the operator of energy
source 102 and/or energy source 104. The offer for sale of energy is also based on the
energy data received from utility 1 15.
In the exemplary embodiment, processor 214 may also be
programmed to organize the energy data in a hierarchy. In the exemplary
embodiment, processor 214 may be programmed to organize a plurality of energy
prices and/or a plurality of quantities of energy received from each utility 115 in a
hierarchy. For example, processor 214 may be programmed to organize a highest
energy price of the plurality of energy prices in a first tier within the hierarchy and a
lowest energy price of the plurality of energy prices in a last tier within the hierarchy.
Similarly, processor 214 may be programmed to organize a highest quantity of energy
in a first tier within the hierarchy and a lowest quantity of energy in a last tier within
the hierarchy. Alterantively, processor 214 may be programmed to organize the
energy data using any criteria that may be programmed to processor. Such criteria,
for example, may be established by the operator.
The term "processor" refers generally to any programmable
system including systems and microcontrollers, reduced instruction set circuits
(RISC), application specific integrated circuits (ASIC), programmable logic circuits
(PLC), and any other circuit or processor capable of executing the functions described
herein. The above examples are exemplary only, and thus are not intended to limit in
any way the definition andor meaning of the term "processor."
In the exemplary embodiment, memory device 218 includes
one or more devices that enable information, such as executable instructions andlor
other data, to be stored and retrieved. Moreover, in the exemplary embodiment,
memory device 21 8 includes one or more computer readable media, such as, without
limitation, dynamic random access memory (DRAM), static random access memory
(SRAM), a solid state disk, andor a hard disk. In the exemplary embodiment,
memory device 218 stores, without limitation, application source code, application
object code, configuration data, additional input events, application states, assertion
statements, validation results, and/or any other type of data. More specifically, in the
exemplary embodiment, memory device 2 18 stores input data received by an operator
via user interface 204 andor information received from other components of power
system 100, such as from utility 1 15.
Computing device 112, in the exemplary embodiment, also
includes a communication interface 230 that is coupled to processor 214 via system
bus 220. Moreover, in the exemplary embodiment, communication interface 230 is
communicatively coupled to utility 115 via network 118 (shown in Fig. 1) and
communicatively coupled to communication module 113 (shown in Fig. 1) and
communication module 114 (shown in Fig. 1). In the exemplary embodiment,
communication interface 230 may communicate with utility 115, energy source 102,
energy source 104, andlor other components within power system 100.
During operation, an operator of an energy source, such as
energy source 102 and/or energy source 104, couples each energy source 102 and 104
to power grid 106. For example, an operator of energy source 102 may couple energy
source 102 to charging station 109 such that energy source 102 is coupled to power
gird 106. Similarly, an operator of energy source 104 may couple energy source 104
and/or battery 11 1 to generator 1 10 and/or to power grid 106 such that energy source
104 is coupled to power grid 106.
A signal representative of energy source 102 being coupled to
power grid 106 is transmitted from energy source 102 to respective computing device
112 via communication module 113. Similarly, a signal representative of energy
source 104 being coupled to power grid 106 is transmitted from energy source 104 to
respective computing device 1 12 via communication module 1 14. Communication
interface 230 in each computing device 112 receives the signal and the signal is
transmitted to processor 214 in each computing device 112. Presentation interface
207 in each computing device 112 then prompts each operator with an option to
receive the energy data from each utility 115. In the exemplary embodiment, each
operator provides an input, via user interface 204 in each computing device 112, to
receive the energy data.
Processor 214 then transmits a signal to communication
interface 230 to retrieve the information from each utility 115. Each utility 115
transmits the energy data to each computing device 112 via network 118. When
communication interface 230 receives the information, the energy data is transmitted
to processor 214. In the exemplary embodiment, processor 214 rank orders the
energy data. For example, processor 214 may organize a plurality of energy prices
and/or a plurality of quantities of energy received from each utility 115 in a hierarchy.
Processor 214 may also organize a highest energy price of the plurality of energy
prices in a first tier within the hierarchy and a lowest energy price of the plurality of
energy prices in a last tier within the hierarchy.
Computing device 112 presents the energy data to each
operator via presentation interface 207 for each computing device 112. By receiving
the energy data from each utility 115, each operator is enabled to identify when to
purchase energy from each utility 115 and when to sell energy to each utility 115. For
example, each operator may identify a time range when energy prices are low and a
time range when energy prices are high. Moreover, an operator may want to sell
energy to utility 115 during the time range when energy prices are high and purchase
energy from utility 1 15 when energy prices are low.
When each operator has been presented with the energy data,
processor 214 in each computing device 112 generates at least one offer to purchase
energy from each operator and/or generates at least one offer for sale of energy to
each utility 115. Computing device 112 then presents each operator, via presentation
interface 207, with the offer to purchase energy and/or with the offer for sale of
energy. In the exemplary embodiment, each operator inputs a response to accept the
offer to purchase energy such that each utility 115 is enabled to purchase energy from
each operator. Computing device 112 transmits a signal representative of each
operators' response to each utility 1 15 notifying each utility 1 15 of the acceptance.
Alternatively, based on the energy data of each utility 115
that is presented to each operator, each operator may also input to sell energy to only
one utility 115. For example, if the energy prices in the energy data for one utility
115 are higher than the energy prices in the energy data for another utility 115, the
operator may decide to sell only to the utility 11 5 with the higher energy prices. Such
a selection by the operator may be transmitted from computing device 112 to each
utility 1 15. When each utility 115 receives the operator's selection, the utility 115 not
selected due to, for example, a lower price, may be willing to increase their price and
transmit the new price to computing device 112. Computing device 112 may then
present the new price to each operator enabling the operator to change his or her
selection by an input via user interface 204.
In the exemplary embodiment, when an input is made that
each operator is selling energy to each utility 115, communication module 113 then
transmits the amount of energy contained within energy source 102 to respective
computing device 112. Similarly, communication module 114 transmits the amount
of energy contained within energy source 104 and/or production level or continuous
supply level of energy source 104 to respective computing device 1 12. When
computing device 112 receives the amount of energy in each energy source 102 and
104, computing device 112 prompts, via presentation interface 207, each operator to
provide a duration of time for which energy will be transmitted from each energy
source 102 and energy source 104 to power grid 106. Alternatively, computing
device 112 may prompt each operator to provide an amount of energy that will be
transmitted from each energy source 102 and 104 to power grid 106. Each operator
then inputs, via user interface 204, for example, the duration of time for which energy
will be transferred from each energy source 102 and energy source 104. Energy is
then transmitted from each energy source 102 and 104 to power grid 106.
Moreover, in the exemplary embodiment, when each operator
is presented with the offer to purchase energy andlor with the offer for sale of energy,
each operator may input a response to accept the offer for sale of energy such that
each utility 115 is enabled to sell energy to each operator. For example, the operator
of energy source 102 may input a response to accept the offer for sale of energy. In
the exemplary embodiment, the operator may select and purchase energy from utility
115 providing the lowest energy prices. Alternatively, the operator may select and
purchase energy from utility 115 providing the greatest quantity of energy.
Further, in the exemplary embodiment, when the operator
chooses the best rate andlor any other parameter that the operator establishes for the
purchase of energy from one of the utilities 115, computing device 112 will prompt
the operator, via presentation interface 207, to provide, for example, a duration of
time for which each energy source 102 will receive energy from power grid 106.
Alternatively, computing device 112 may prompt the operator to provide a quantity of
energy that will be transmitted from power grid 106 to energy source 102. The
operator then inputs, via user interface 204, the duration of time for which energy will
be transferred from power grid 106 to energy source 102. Energy is then transmitted
to energy source 102 from power grid 1 06.
As compared to known apparatus, systems, and methods that
are used to enable communication between utilities and consumers, the exemplary
apparatus, systems, and methods described herein facilitate a platform for operators
and/or owners of energy sources to negotiate and sell power, at a relatively
competitive rate, fiom their energy sources back to a grid and/or the utility. More
specifically, the embodiments described herein provide a computing device for use
with a power system. The computing device includes a communication interface that
is configured to receive energy data from at least one utility, wherein the energy data
includes at least one of at least one quantity of energy and at least one energy price.
A processor is coupled to the communication interface and programmed to generate at
least one offer to purchase energy based on the energy data. A user interface is
coupled to the processor and configured to enable at least one operator of at least one
energy source to sell energy to the utility by responding to the offer to purchase
energy.
Exemplary embodiments of the apparatus, systems, and
methods are described above in detail. The apparatus, systems, and methods are not
limited to the specific embodiments described herein, but rather, components of the
apparatus, systems and/or steps of the methods may be utilized independently and
separately from other components and/or steps described herein. For example, the
system may also be used in combination with other apparatus, systems, and methods,
and is not limited to practice with only the system as described herein. Rather, the
exemplary embodiment can be implemented and utilized in connection with many
other applications.
Although specific features of various embodiments of the
invention may be shown in some drawings and not in others, this is for convenience
only. In accordance with the principles of the invention, any feature of a drawing
may be referenced and/or claimed in combination with any feature of any other
drawing.
This written description uses examples to disclose the
invention, including the best mode, and also to enable any person skilled in the art to
practice the invention, including making and using any devices or systems and
performing any incorporated methods. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to those skilled in
the art. Such other examples are intended to be within the scope of the claims if they
have structural elements that do not differ from the literal language of the claims, or if
they include equivalent structural elements with insubstantial differences from the
literal language of the claims.

We Claim
1. A computing device (1 12) for use with a power system (loo),
said computing device comprising:
a communication interface (230) configured to receive energy data
from at least one utility (1 15), wherein the energy data includes at least one of at least
one quantity of energy and at least one energy price;
a processor (214) coupled to said communication interface and
programmed to generate at least one offer to purchase energy based on the energy
data; and
a user interface (204) coupled to said processor and configured to
enable at least one operator of at least one energy source to sell energy to the at least
one utility by responding to the at least one offer to purchase energy.
2. A computing device (1 12) in accordance with Claim 1, wherein
said processor (214) is further programmed to generate at least one offer for sale of
energy based on the energy data, the at least one offer for sale enables the at least one
operator to selectively purchase energy from the at least one utility (1 15).
3. A computing device (1 12) in accordance with Claim 2, wherein
said processor (214) is programmed to prompt the at least one operator to input a
duration of time for the at least one operator to receive energy when the at least one
operator accepts the at least one offer for sale of energy.
4. A computing device (1 12) in accordance with Claim 2, wherein
said processor (214) is programmed to receive a response to the at least one offer for
sale of energy from a plurality of operators to enable each of the operators to provide
a bid on the at least one offer for sale of energy.
5. A computing device (1 12) in accordance with Claim 1, further
comprising a presentation interface (207) coupled to said processor (214) for use in
presenting the energy data to the at least one operator to enable the at least one
operator to identify at least one of when to purchase energy from the at least one
utility (1 15) and when to sell energy to the at least one utility.
6. A computing device (1 12) in accordance with Claim 1, wherein
the at least one quantity of energy includes a plurality of quantities of energy and said
processor (2 14) is programmed to rank order the plurality of quantities of energy.
7. A computing device (1 12) in accordance with Claim 1, wherein
the at least one energy price includes a plurality of energy prices and said processor
(214) is programmed to rank order the plurality of energy prices.
8. A power system (100) comprising:
at least one energy source (102) for supplying energy to a power grid
(106);
at least one computing device (1 12) coupled to said at least one energy
source, said at least one computing device comprising:
a communication interface (230) configured to receive energy
data from at least one utility (1 15), wherein the energy data includes at least one of at
least one quantity of energy and at least one energy price;
a processor (2 14) coupled to said communication interface and
programmed to generate at least one offer to purchase energy based on the energy
data; and
a user interface (204) coupled to said processor and configured
to enable at least one operator of at least one energy source to sell energy to the at
least one utility by responding to the at least one offer to purchase energy.
9. A power system (100) in accordance with Claim 8, wherein
said at least one energy source (102) comprises at least one of an energy storage
device and an energy generating device.
10. A power system (100) in accordance with Claim 9, wherein
said energy storage device is a battery and said energy generating device is at least
one of a wind turbine, a solar panel, a generator, and a fuel cell.