U.S. patent application number 12/124864 was filed with the patent office on 2008-11-27 for system and method for removing carbon dioxide from an atmosphere and global thermostat using the same.
Invention is credited to Graciela Chichilnisky, Peter Eisenberger.
Application Number | 20080289495 12/124864 |
Document ID | / |
Family ID | 40071181 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080289495 |
Kind Code |
A1 |
Eisenberger; Peter ; et
al. |
November 27, 2008 |
System and Method for Removing Carbon Dioxide From an Atmosphere
and Global Thermostat Using the Same
Abstract
A system for removing carbon dioxide from an atmosphere to
reduce global warming including an air extraction system that
collects carbon dioxide from the atmosphere through a medium and
removes carbon dioxide from the medium; a sequestration system that
isolates the removed carbon dioxide to a location for at least one
of storage and which can increase availability of renewable energy
or non-fuel products such as fertilizers and construction
materials; and one or more energy sources that supply process heat
to the air extraction system to remove the carbon dioxide from the
medium and which can regenerate it for continued use.
Inventors: |
Eisenberger; Peter;
(Princeton, NJ) ; Chichilnisky; Graciela; (New
York, NY) |
Correspondence
Address: |
LAWRENCE R. OREMLAND, P.C.
5055 E. BROADWAY BLVD., SUITE C-214
TUCSON
AZ
85711
US
|
Family ID: |
40071181 |
Appl. No.: |
12/124864 |
Filed: |
May 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11825468 |
Jul 6, 2007 |
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12124864 |
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11805477 |
May 22, 2007 |
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11825468 |
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11805271 |
May 21, 2007 |
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11805477 |
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Current U.S.
Class: |
95/107 ; 95/139;
95/148; 95/227; 95/236; 96/146; 96/242 |
Current CPC
Class: |
Y02C 10/08 20130101;
Y02C 10/06 20130101; B01D 53/62 20130101; B01D 53/1418 20130101;
B01D 2258/0233 20130101; B01D 53/04 20130101; B01D 53/1425
20130101; Y02A 50/20 20180101; Y02C 10/04 20130101; B01D 2257/504
20130101; Y02E 20/32 20130101; B01D 53/1475 20130101; F23J 15/02
20130101; Y02C 20/40 20200801; B01D 2251/604 20130101; B01D
2251/304 20130101; Y02A 50/2342 20180101; Y02E 20/326 20130101 |
Class at
Publication: |
95/107 ; 96/146;
95/148; 96/242; 95/227; 95/236; 95/139 |
International
Class: |
B01D 53/62 20060101
B01D053/62; B01D 53/14 20060101 B01D053/14; B01D 53/18 20060101
B01D053/18 |
Claims
1. A system for removing carbon dioxide from an atmosphere to
reduce global warming which can increase availability of renewable
energy or non-fuel products such as fertilizers and construction
materials, comprising: an air extraction system that collects
carbon dioxide from the atmosphere through a medium and removes
carbon dioxide from the medium; a collection system that isolates
the removed carbon dioxide to a location for at least one of
sequestration, storage and generation of a renewable carbon fuel or
non-fuel products such as fertilizers and construction materials;
and one or more energy sources that supply process heat to the air
extraction system to remove the carbon dioxide from the medium and
which can regenerate it for continued use.
2. The system of claim 1, wherein the one or more energy sources
are selected from the group of primary energy sources consisting
of: fossil fuel, geothermal, nuclear, solar, biomass and other
renewable energy sources and exothermic chemical processes whose
use can result in a supply of process heat.
3. The system of claim 1, wherein the air extraction system
comprises an air contactor that includes the medium to absorb
carbon dioxide from the atmosphere.
4. The system of claim 3, wherein the air contactor is selected
from the group of air contactors consisting of: convection towers,
absorption pools, packed scrubbing towers, and separation systems
in which the medium is carried by a pancake shaped substrate.
5. The system of claim 3, wherein the medium is selected from the
group of mediums consisting of: a liquid, a porous solid, a gas and
mixtures thereof.
6. The system of claim 5, wherein the medium is an NaOH
solution.
7. The system of claim 5, wherein the medium comprises an amine
attached to the surface of a substrate.
8. The system of claim 1, wherein the air extraction system
collects carbon dioxide and the sequestration system isolates the
removed carbon dioxide using the process heat supplied by the one
or more energy sources.
9. The system of claim 1, wherein the location is underground.
10. The system of claim 1, wherein the location is at a remote site
upwind from one or more other components of the system.
11. A method for removing carbon dioxide from an atmosphere to
reduce global warming and increase availability of renewable
energy, comprising: collecting air from the atmosphere; removing
carbon dioxide from the collected air; isolating the removed carbon
dioxide for at least one of sequestration, storage and generation
of a renewable carbon fuel or non-fuel products such as fertilizers
and construction materials, wherein at least one of the collecting,
removing and isolating steps is performed using an energy source
that comprises process heat.
12. The method of claim 11, wherein the step of removing comprises
absorbing the carbon dioxide using an absorber.
13. The method of claim 12, wherein the absorber is an NaOH
solution.
14. The method of claim 12, wherein the absorber comprises an
amine.
15. The method of claim 11, wherein the step of isolating comprises
at least one of mineral sequestration and injection into geologic
formations.
16. A system for producing a negative carbon dioxide effect on a
planet's atmosphere, comprising: a system that provides a medium
for extracting carbon dioxide from the atmosphere and uses process
heat for extracting carbon dioxide from the medium and to
regenerate it so it can be reused.
17. The system of claim 16, wherein process heat is obtained from a
primary energy source selected from the group of energy sources
consisting of: fossil fuel, geothermal, nuclear, solar, biomass and
other renewable energy sources and exothermic chemical processes
whose use can result in a supply of process heat.
18. The system of claim 16, including a collection system that
isolates the removed carbon dioxide to a location for at least one
of sequestration, storage and generation of a renewable carbon fuel
or a non-fuel product such as fertilizer and construction
materials.
19. The system of claim 18, wherein the air extraction system
comprises an air contactor that includes the medium extracts carbon
dioxide from the atmosphere.
20. The system of claim 19, wherein the air contactor is selected
from the group of air contactors consisting of: convection towers,
absorption pools, packed scrubbing towers and separation systems
with pancake shaped substrates.
21. The system of claim 18, wherein the medium is selected from the
group of mediums consisting of: a liquid, a porous solid, a gas and
mixtures thereof.
22. The system of claim 18, wherein the medium is an NaOH
solution.
23. The system of claim 18, wherein the medium comprises an
amine.
24. The system of claim 18, wherein the air extraction system
collects carbon dioxide and the collection system isolates the
removed carbon dioxide using the heat supplied by the energy
source.
25. The system of claim 18, wherein the location is
underground.
26. The system of claim 18, wherein the location is at a remote
site upwind from one or more other components of the system.
27. The method of claim 11, wherein a medium for extracting carbon
dioxide from the air is provided on a porous relatively large area
pancake shaped substrate, and wherein the step of removing carbon
dioxide from the air comprises directing the air at the substrate,
and removing carbon dioxide from the medium by directing process
heat at the substrate and providing a flow of carbon dioxide away
from the substrate.
28. The method of claim 27, wherein the substrate is in a
substantially vertical orientation during the steps of removing
carbon dioxide from the air and removing carbon dioxide from the
medium.
29. The method of claim 27, wherein the substrate is in a
substantially horizontal orientation during the steps of removing
carbon dioxide from the air and removing carbon dioxide from the
medium.
30. The method of claim 27, wherein the substrate is moveable in a
substantially continuous path during the steps of removing carbon
dioxide from the air and removing carbon dioxide from the
medium.
31. The method of any of claims 11-15 and 27-30, wherein removing
carbon dioxide from the air is at least partially performed under
non equilibrium conditions.
32. The method of any of claims 11-15 and 27-30, wherein removing
carbon dioxide from the air includes the step of using fluid from a
solar heating tower as an energy source for directing the air at a
medium that is used to remove carbon dioxide from the air.
33. A global thermostat for controlling average temperature of a
planet's atmosphere, comprising a plurality of systems, each of
which is capable of producing a negative carbon dioxide effect on a
planet's atmosphere by extracting carbon dioxide from the
atmosphere and uses process heat for extracting carbon dioxide from
the medium, so that the plurality of systems together can
effectively extract carbon dioxide from the atmosphere at a rate
that is faster than the rate at which the carbon dioxide is
increasing in the atmosphere.
Description
RELATED APPLICATIONS/CLAIM OF PRIORITY
[0001] This application is a continuation-in-part of, and claims
priority from, each of the following US patent applications: (a)
U.S. patent application Ser. No. 11/825,468 (Attorney Docket No.
6236.104US), filed on Jul. 6, 2007, which in turn is a
continuation-in-part of U.S. patent application Ser. No. 11/805,477
(Attorney Docket No. 6236.103US), filed on May 22, 2007, which in
turn is a continuation-in-part of U.S. patent application Ser. No.
11/805,271 (Attorney Docket No. 6236.102US), filed on May 21, 2007,
(b) U.S. patent application Ser. No. 11/805,477 (Attorney Docket
No. 6236.103US), filed on May 22, 2007, which is a
continuation-in-part of U.S. patent application Ser. No. 11/805,271
(Attorney Docket No. 6236.102US), filed on May 21, 2007, and (c)
U.S. patent application Ser. No. 11/805,271 (Attorney Docket No.
6236.102US), filed on May 21, 2007, all of which are entitled
"System and Method For Removing Carbon Dioxide From An Atmosphere
and Global Thermostat Using The Same". The contents of each of the
foregoing applications are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to systems and methods for
removing greenhouse gases from an atmosphere, and in particular to
systems and methods for removing carbon dioxide from an
atmosphere.
BACKGROUND OF THE INVENTION
[0003] There is much attention currently focused on trying to
achieve three energy related and somewhat conflicting energy
related objectives: 1) provide affordable energy for economic
development; 2) achieve energy security; and 3) avoid the
destructive climate change caused by global warming. Many different
approaches are being considered to address climate change,
including increasing the use of clean, non polluting renewable
energy sources such as biofuels, solar, wind and nuclear,
attempting to capture and sequester the carbon dioxide emissions
from fossil fuel plants, as well as increased conservation efforts.
Some of these approaches, such as solar power, have had their large
scale implementation blocked due to their current high costs as
compared to the cost of fossil based electricity, and other
approaches, such as nuclear, are restrained by their environmental
and security risks. In fact, the infrastructure and supply for
renewable energy is so underdeveloped (e.g., only about 0.01% of
our energy is provided by solar) that there is no feasible way to
avoid using fossil fuels during the rest of this century if we are
to have the energy needed for economic prosperity and avoid energy
shortfalls that could lead to conflict.
[0004] The climate change threat caused by global warming and the
more general recognition of our need to use renewable resources
that do not harm our planet has grown steadily since the first
Earth Day in 1972. It is mostly undisputed that an increase in the
amount of so-called greenhouse gases like carbon dioxide (methane
and water vapor are the other major greenhouse gases) will increase
the temperature of the planet. These greenhouse gases help reduce
the amount of heat that escapes from our planet into the
atmosphere. The higher the concentrations of greenhouse gases in
the atmosphere the warmer the planet will be. There are complicated
feedbacks that cause the amount of carbon dioxide and other
greenhouse gases to change naturally even in the absence of human
impact. Climate change throughout geological history has caused
many extinctions. The concern about the threat of human induced
climate change (i.e., global warming) resulted in the Kyoto
Protocol that has been approved by over 165 countries and is an
international agreement that commits the developed countries to
reduce their carbon emissions.
[0005] One reason global warming is thought by the
Intergovernmental Panel on Climate Change (IPCC) to be a threat is
because of the sea level rise resulting from the melting of
glaciers and the expansion of the ocean as our planet becomes
hotter. Hundreds of millions of people who live just above sea
level on islands or on the coasts are threatened by destructive
flooding requiring relocation or the building of sea walls if the
sea level rises even a meter. There is also a threat to other
species from climate change which will destroy ecosystems that
cannot adjust to the fast rate of human caused climate change.
Additional threats include increased infectious diseases and more
extreme weather as well as direct threats from extreme heat.
[0006] We can demonstrate the challenge of dealing with global
warming using a simple model. Let C.sub.CA (Y.sub.N) represent the
carbon dioxide added to the atmosphere in year Y.sub.N in
gigatonnes per year. Similarly, let C.sub.EX (Y.sub.N) equal the
amount extracted, C.sub.EM (Y.sub.N) the amount emitted by humans
and C.sub.N(Y.sub.N) be the amount either added or removed due to
natural variations in the carbon cycle. Today, the land stores each
year approximately 1.8 gigatonnes (10.sup.9 tonnes) of carbon
dioxide and the ocean approximately 10.5 gigatonnes (note carbon
dioxide is 3.66 times heavier than carbon), while the amount humans
add by emissions is about 24 gigatonnes of carbon dioxide. More
generally, we have:
C.sub.CA(Y.sub.N)=-C.sub.EX(Y.sub.N)+C.sub.EM(Y.sub.N)+C.sub.N(Y.sub.N)
(1)
C.sub.A(Y.sub.N+1)=C.sub.A(Y.sub.N)+C.sub.CA(Y.sub.N) (2)
where C.sub.A(Y.sub.N) is the amount of carbon in the atmosphere in
year Y.sub.N, 2780 gigatonnes of carbon dioxide today. Other forms
of carbon contribute to global warming, most notably methane,
although by weight they represent a small component
[0007] If C.sub.EX (Y.sub.N) is set to zero than the only way one
could possibly stop adding carbon dioxide to the atmosphere would
be to reduce our emissions to be equal to the natural uptake.
However, C.sub.N(Y.sub.N) itself varies greatly and can be a net
addition to the atmosphere from the much larger natural carbon
cycle which adds and subtracts carbon at about 750 gigatonnes of
carbon per year. It is the shifts in this natural balance that has
caused climate change before our species existed and will also
continue to do so in the future. Thus, it is clear that there is no
solution that only reduces human contributions to carbon dioxide
emissions that can remove the risk of climate change. With air
extraction and the capability to increase or decrease the amount of
carbon dioxide in the atmosphere one can in principle compensate
for other greenhouse gases like methane that can change their
concentrations and cause climate change.
[0008] Accordingly, there is a broadly recognized need for a system
and method for reducing the amount of carbon dioxide in the
atmosphere created by burning of fossil fuels and for providing a
low cost, non-polluting renewable energy source as a substitute for
fossil fuels.
SUMMARY OF THE INVENTION
[0009] A system for removing carbon dioxide from an atmosphere to
reduce global warming and which can increase availability of
renewable energy or non-fuel products such as fertilizers and
construction materials according to an exemplary embodiment of the
present invention comprises an air extraction system that collects
carbon dioxide from the atmosphere through a medium and removes
carbon dioxide from the medium by using process heat to heat the
medium, a collection system that isolates the removed carbon
dioxide to a location for at least one of sequestration, storage
and generation of a renewable carbon fuel, and one or more energy
sources that provides a supply of process heat to the air
extraction system to remove the carbon dioxide from the medium.
[0010] In at least one embodiment, the one or more energy sources
are selected from the group of energy sources consisting of: fossil
fuel, geothermal, nuclear, solar, biomass and other renewable
energy sources.
[0011] In at least one embodiment, the air extraction system
comprises an air contactor that includes the medium to absorb
carbon dioxide from the atmosphere.
[0012] In at least one embodiment, the air contactor is selected
from the group of air contactors consisting of: convection towers,
absorption pools, packed scrubbing towers, and gaseous separation
systems, some having pancake shaped area substrates with a medium
that extracts carbon dioxide from the air. In its broadest context,
the present invention contemplates structures in which the air is
passed into contact with the medium that extracts the CO2.
Currently, in the most likely embodiment the structure would have a
large area perpendicular to the air flow and be very thin in the
direction of air flow with the medium being a porous substrate on
to the surface of which the amine or alternative that binds the CO2
is attached--that medium would also have a large cross-section and
be very thin like the contactor structure that houses it).
[0013] In at least one embodiment, the medium is selected from the
group of mediums consisting of: a liquid, a porous solid, a gas and
mixtures thereof.
[0014] In at least one embodiment, the medium is an NaOH
solution.
[0015] In at least one embodiment, the medium comprises an
amine.
[0016] In at least one embodiment, the air extraction system
collects carbon dioxide and the sequestration system isolates the
removed carbon dioxide.
[0017] In at least one embodiment, the location is underground.
[0018] In at least one embodiment, the location is at a remote site
upwind from one or more other components of the system.
[0019] A method for removing carbon dioxide from an atmosphere to
reduce global warming and increase availability of renewable energy
according to an exemplary embodiment of the present invention
comprises the steps of: collecting air from the atmosphere;
removing carbon dioxide from the collected air by using process
heat to heat the medium that removes the carbon dioxide from the
collected air; and isolating the removed carbon dioxide to a
location for at least one of sequestration, storage and generation
of a renewable carbon fuel, wherein at least one of the collecting,
removing and isolating steps is performed using one or more
renewable energy sources.
[0020] In at least one embodiment, the step of removing comprises
absorbing the carbon dioxide using an absorber, preferably an
absorber in the form of a medium carried by a large surface area
substrate.
[0021] In at least one embodiment, the absorber is an NaOH
solution.
[0022] In at least one embodiment, the absorber comprises an amine,
preferably an amine bound to the surface of (carried by) a large
surface area porous substrate.
[0023] In at least one embodiment, the step of isolating comprises
at least one of mineral sequestration or injection as a pressurized
gas into geologic formations.
[0024] The principles of the present invention can be used to
provide a global thermostat for controlling average temperature of
a planet's atmosphere, through the use of a plurality of systems
according to the principles of the present invention, each of which
is capable of producing a negative carbon dioxide effect on a
planet's atmosphere by extracting carbon dioxide from the
atmosphere and using process heat for extracting carbon dioxide
from the medium and to regenerate the sorbent (medium) for another
cycle of adsorption. Thus, the plurality of systems together can
effectively extract carbon dioxide from the atmosphere at a rate
that is faster than the rate at which the carbon dioxide is
increasing in the atmosphere (and can generate a renewable carbon
fuel using the extracted gases).
[0025] Applicants' preferred concept of extracting carbon dioxide
from the atmosphere and using process heat to separate carbon
dioxide from the collection medium is a significant way of
addressing the global warming problem, and goes against the
conventional wisdom in the art (and is counterintuitive to those in
the art). Specifically, the use of process heat to solve the global
warming problem by extracting carbon dioxide (CO2) from the low
concentration ambient air is very attractive compared to both the
conventional approach of extracting CO2 from high concentration
flue gas sources and other schemes known in the art for extracting
CO2 from the ambient atmosphere. In the former case it goes
directly against conventional wisdom that 300 times lower
concentration of the CO2 in ambient atmosphere would expect it to
be 300 times more expensive since separation costs are thought to
generally scale inversely with the concentration. Thus federally
funded efforts have been directed at extracting CO2 from the flue
gas emissions of power plants (e.g. clean coal) and experts have
publicly claimed that the use of ambient air as opposed to flue gas
makes no sense. However, the large infinite size of the ambient air
source compared to the finite flue gas source and sources generally
is one feature that enables applicants' approach to be effective in
spite of conventional wisdom and practice. In the flue gas case the
emissions containing the CO2 are at a higher temperature (65-70
degrees centigrade) and therefore regeneration uses higher
temperature heat which is more costly than is needed for the cool
ambient air (approximately 25-30 degrees centigrade). There are
other benefits of applicants' approach including the ability to use
very thin separation devices that also provide further process
improvements. Thus, it could be less costly to remove CO2 by piping
the process heat to a global thermostat facility that operates on
the principles of applicants' invention, rather than cleaning up
directly its flue emissions. In addition, the applicants' approach
would produce negative carbon, actually reducing the amount of CO2
in the atmosphere, while cleaning up the flue gas would only
prevent the CO2 content in the air from increasing.
[0026] Further analysis shows that one cannot solve the global
warming problem in a timely manner to reduce the great risk it
poses by simply cleaning up large stationary fossil fuel sources
like coal plants or for that matter by conservation or use of
renewables. One needs to actually be able, as is the case in this
invention, to extract CO2 from the atmosphere ("negative carbon")
thus reducing the ambient concentration and reducing the thereat of
global warming. Other published schemes for extracting CO2 from the
ambient atmosphere have used higher temperature heat generally and
not process heat specifically and therefore have not been seriously
considered because of their high energy costs.
[0027] Additionally, it should be noted that applicants' preferred
concept for extracting carbon dioxide from the atmosphere comprises
using a large area substrate perpendicular to the air flow, which
could be porous with a high surface area, with a medium (e.g. an
amine) that removes carbon dioxide from the atmosphere and using
process heat to remove carbon dioxide from the medium. Using a
relatively large area substrate perpendicular to the direction of
air flow is particularly useful, because of the relatively low
concentration of carbon dioxide in the atmosphere (as opposed to
the relatively high concentration that would normally be found in
flue gases, for example).
[0028] These and other features of this invention are described in,
or are apparent from, the following detailed description (and
accompanying drawings) of various exemplary embodiments of this
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Various exemplary embodiments of this invention will be
described in detail, with reference to the following figures,
wherein:
[0030] FIG. 1 is a generalized block diagram of a system for
removing carbon dioxide from an atmosphere according to an
exemplary embodiment of the present invention;
[0031] FIG. 2 is a block diagram of a system for removing carbon
dioxide from an atmosphere according to an exemplary embodiment of
the present invention;
[0032] FIG. 3 is a block diagram of an air extraction system
according to an exemplary embodiment of the present invention;
[0033] FIG. 4 is a map illustrating a global thermostat according
to an exemplary embodiment of the present invention; and
[0034] FIG. 5 is a block diagram of a system for removing carbon
dioxide from an atmosphere according to an exemplary embodiment of
the present invention;
[0035] FIG. 6 is a schematic illustration of one version of a
medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention;
[0036] FIG. 7 is a schematic illustration of another version of a
medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention;
[0037] FIG. 8 is a schematic illustration of still another version
of a medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention; and
[0038] FIG. 9 is a schematic illustration of yet another version of
a medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0039] FIG. 1 is a generalized block diagram of a system, generally
designated by reference number 1, for removing carbon dioxide from
an atmosphere according to an exemplary embodiment of the present
invention. The system 1 includes an air extraction system 40 and a
collection system 50, that isolates the removed carbon dioxide to a
location for at least one of sequestration, storage and generation
of a renewable carbon fuel or the generation of a non-fuel product
such as fertilizer and construction materials. The air extraction
system 40 preferably incorporates any known or later-discovered
CO.sub.2 extraction method, including methods which use a medium to
absorb and/or bind CO.sub.2 from the atmospheric air by exposing
the medium to chemical, electrical and/or physical interaction with
the CO.sub.2 in the captured air. The medium may be liquid, gaseous
or solid, or a combination of liquid, gaseous and solid substances,
where in the case of solids, the substance is preferably porous.
The medium is preferably recyclable so that after the CO.sub.2 is
captured by the medium and separated from the medium for
sequestration, the medium can be reused for absorption/binding of
additional CO.sub.2. However, in other embodiments the medium may
be sequestered along with the captured CO.sub.2. As shown in FIG.
1, the separation of the CO.sub.2 from the medium, as well as other
processes such as the absorption/binding of CO.sub.2 and the
sequestration of the CO.sub.2 performed by the sequestration system
50, may be made more efficient by the addition of heat to the air
extraction system 40. In the present invention, the heat is process
heat generated e.g. by a solar energy generator, such as a solar
collector, to be described in further detail below. In other
embodiments, process heat may be provided by other types of energy
sources, such as, for example, fossil fuel, geothermal, nuclear,
biomass, and other renewable energy sources. The term "process
heat" as used herein refers to the lower temperature heat remaining
after the higher temperature heat has been used to generate
electricity. More generally, the term "process heat" refers to any
low temperature heat remaining after a primary process or that is
added by the process itself, such as, for example, exothermic
carbonation reactions in which carbon dioxide is stored as a
mineral or in fact when it binds to the medium and is captured.
Moreover, "process heat" may be provided from the use of sources of
energy to produce products other than power or electrical
generation. For example, primary processing such as chemical
processing, production of cement, steel or aluminum, production of
energy products like coal to liquid energy products, refining, may
use heat to drive the primary processing, and the unused heat
remaining after the primary processing or created during the
primary processing would be the process heat of such processing,
and can be used in a system or method according to the principles
of the present invention.
[0040] Applicants' preferred concept of extracting carbon dioxide
from the atmosphere and using process heat to separate carbon
dioxide from the collection medium is a significant way of
addressing the global warming problem, and goes against the
conventional wisdom in the art (and is counterintuitive to those in
the art). Specifically, the use of process heat to solve the global
warming problem by extracting carbon dioxide (CO2) from the low
concentration ambient air is very attractive compared to both the
conventional approach of extracting CO2 from high concentration
flue gas sources and other schemes known in the art for extracting
CO2 from the ambient atmosphere. In the former case it goes
directly against conventional wisdom that 300 times lower
concentration of the CO2 in ambient atmosphere would expect it to
be 300 times more expensive since separation costs are thought to
generally scale inversely with the concentration. Thus federally
funded efforts have been directed at extracting CO2 from the flue
gas emissions of power plants (e.g. clean coal) and experts have
publicly claimed that the use of ambient air as opposed to flue gas
makes no sense. However, the large infinite size of the ambient air
source compared to the finite flue gas source and sources generally
is one feature that enables applicants' approach to be effective in
spite of conventional wisdom and practice. In the flue gas case the
emissions containing the CO2 are at a higher temperature (65-70
degrees centigrade) and therefore regeneration uses higher
temperature heat which is more costly than is needed for the cool
ambient air (approximately 25-30 degrees centigrade). There are
other benefits of applicants' approach including the ability to use
very thin separation devices that also provide further process
improvements. Thus, it could be less costly to remove CO2 by piping
the process heat to a global thermostat facility that operates on
the principles of applicants' invention, rather than cleaning up
directly its flue emissions. In addition, the applicants' approach
would produce negative carbon, actually reducing the amount of CO2
in the atmosphere, while cleaning up the flue gas would only
prevent the CO2 content in the air from increasing.
[0041] Further analysis shows that one cannot solve the global
warming problem in a timely manner to reduce the great risk it
poses by simply cleaning up large stationary fossil fuel sources
like coal plants or for that matter by conservation or use of
renewables. One needs to actually be able, as is the case in this
invention, to extract CO2 from the atmosphere ("negative carbon")
thus reducing the ambient concentration and reducing the threat of
global warming. Other published schemes for extracting CO2 from the
ambient atmosphere have used higher temperature heat generally and
not process heat specifically and therefore have not been seriously
considered because of their high energy costs.
[0042] FIG. 2 is a block diagram of a system, generally designated
by reference number 2, for removing carbon dioxide from an
atmosphere according to an exemplary embodiment of the present
invention. The system 2 includes a solar collector 10, an optional
supplemental energy source 20, a power generator 30, an air
extraction system 42 and a collection system 50. Each of these
components of the system 1 are explained in detail below.
[0043] The solar collector 10 may be any known or future-discovered
solar energy collection system, which may include solar energy
collection units, such as, for example, concentrated solar power
parabolic mirrors, and concentrated solar power towers. As is known
in the art, the solar collector 10 converts solar energy to thermal
energy, which may be used to drive the power generator 30. Residual
thermal energy (i.e., process heat) may be used to drive the air
extraction system 42 and/or the collection system 50. For example,
the process heat may be used to improve the efficiency of chemical
and/or physical reactions used in the air extraction system 42 to
absorb CO.sub.2 from the air and/or to drive off the CO.sub.2 from
the medium. In addition, in other exemplary embodiments, as shown
by the dashed arrows in FIG. 2, direct heat from the solar
collector 10 may be used to drive the air extraction system 42
and/or the collection system 50.
[0044] The power generator 30 may be, for example, a thermal power
generator that converts the thermal energy provided by the solar
collector to electricity. As is known in the art, the suns heat may
be focused on a medium, such as molten salts, that is then used to
generate high temperature, high pressure steam that drives a
turbine to generate electricity. The generated electricity may then
be used to power the other components of the system 2, in addition
to providing power to the general population as part of a power
grid. In this regard, the thermal energy provided by the solar
collector 10 may be supplemented by energy generated by the
supplemental energy source 20. For example, the supplemental energy
source 20 may be a waste incineration plant, which provides
additional thermal energy to drive the power generator 30. Also, it
should be appreciated that any other type of renewable energy
source may be used in addition to solar energy, and preferably a
renewable energy source that produces heat as a precursor to the
generation of electricity. Other potential renewable energy sources
to be used in addition to solar energy include, for example,
nuclear, biomass, and geothermal energy sources.
[0045] Alternatively, the power generator 30 may be any known or
later discovered fossil fuel facility (plant) that relies on the
burning of fossil fuels, such as, for example, coal, fuel oil,
natural gas and oil shale, for the generation of electricity. The
power generator may also be for a purpose other than generating
electricity (for example the power generator could be for chemical
processing, or various other purposes like producing aluminum). The
thermal energy produced by the fossil fuel power plant 30 is used
to produce electricity and the residual thermal energy (i.e.,
process heat) may be used to drive the air extraction system 42
and/or the sequestration system 50. For example, the process heat
from the fossil fuel power plant 30 may be used to improve the
efficiency of chemical and/or physical reactions used in the air
extraction system 42 to absorb CO.sub.2 from the air and/or to
drive off the CO.sub.2 from the medium. The residual heat provided
by the fossil fuel power plant 30 may be supplemented by energy
generated by a supplemental energy source. For example, the
supplemental energy source may be a waste incineration plant or a
renewable energy source, such as, for example, solar, nuclear,
biomass, and geothermal energy sources, which provides additional
thermal energy to drive the air extraction system 42 and/or the
collection system 50. Process heat from the supplemental energy
source may also be used to drive the air extraction system 42
and/or the collection system 50.
[0046] Moreover, as described above, "process heat" may be provided
from the use of sources of energy to produce products other than
power or electrical generation. For example, primary processing
such as chemical processing, production of cement, steel or
aluminum, refining, production of energy products like coal and
liquid energy products, may use heat to drive the primary
processing, and the unused heat remaining after the primary
processing or created during the primary processing would be the
process heat of such processing, and can be used in a system or
method according to the principles of the present invention.
[0047] FIG. 3 is a block diagram of the air extractor system 42
useable with the system 2 according to an exemplary embodiment of
the present invention. The air extractor system 42 includes an air
contactor 41, a causticizer 43, a slaker 45, a calciner 47 and a
capture unit 49. The air contactor 41 may use a sorbent material to
selectively capture CO.sub.2 from the air, and may be composed of
any known or later-discovered contactor structures, such as, for
example, large convection towers, open, stagnant pools, and packed
scrubbing towers. In the present embodiment, the sorbent material
may be sodium hydroxide (NaOH), which readily absorbs CO.sub.2 from
the air. It should be appreciated that other known or
future-discovered capture methods may be used, such as, for
example, chemical absorption, physical and chemical adsorption,
low-temperature distillation, gas-separation membranes,
mineralization/biomineralization and vegetation. As a further
example, as known in the art, aqueous amine solutions or amine
enriched solid sorbents may be used to absorb CO.sub.2. Preferably,
the sorbent material is regenerated and the capture method requires
less than about 100-120.degree. C. heat to regenerate the sorbent
material.
[0048] In this embodiment, at the air contactor 41, CO.sub.2 may be
absorbed into an NaOH solution forming sodium carbonate
(Na.sub.2CO.sub.3), e.g. in the manner described by Stolaroff et
all in an article entitled "A pilot-scale prototype contactor for
CO2 capture from ambient air: cost and energy requirements", which
article can be found at
www.ucalgary.ca/.about.keith/papers/84.Stolaroff.AirCaptureGHGT--
8p.pdf, and is incorporated herein by reference. Of course, other
known or future-developed absorbers may also be used as an
alternative or in addition to an NaOH solution. The generated
Na.sub.2CO.sub.3 is then sent to the causticizer 43, where the NaOH
is regenerated by addition of lime (CaO) in a batch process. The
resulting CaCO.sub.3 solid is sent to the calciner 47 where it is
heated in a kiln to regenerate the CaO, driving off the CO.sub.2 in
a process known as calcination. The regenerated CaO is then sent
through the slaker 45, which produces slaked lime Ca(OH).sub.2 for
use in the causticizer 43.
[0049] The capture unit 49 captures the CO.sub.2 driven off at the
calciner 47 using any know or later-discovered CO.sub.2 capturing
method that is effective in the low concentrations in which
CO.sub.2 is present in the atmosphere and that needs only low
temperature heat for regeneration. For example, the capture unit 49
may use an amine based capture system, such as the system described
in Gray et al U.S. Pat. No. 6,547,854, dated Apr. 15, 2003, and
also Sirwardane U.S. Pat. No. 6,908,497, dated Jun. 21, 2005, both
of which are incorporated herein by reference. The capture unit 49
may also compress the captured CO.sub.2 to liquid form so that the
CO.sub.2 may be more easily sequestered.
[0050] The collection system 50 isolates the removed carbon dioxide
to a location for at least one of sequestration, storage and
generation of a renewable carbon fuel or the generation of a
non-fuel product such as fertilizer and construction materials. The
collection system 50 may use any known or future-discovered carbon,
sequestration and/or storing techniques, such as, for example,
injection into geologic formations or mineral sequestration. In the
case of injection, the captured CO.sub.2 may be sequestered in
geologic formations such as, for example, oil and gas reservoirs,
unmineable coal seams and deep saline reservoirs. In this regard,
in many cases, injection of CO.sub.2 into a geologic formation may
enhance the recovery of hydrocarbons, providing the value-added
byproducts that can offset the cost of CO.sub.2 capture and
collection. For example, injection of CO.sub.2 into an oil or
natural gas reservoir pushes out the product in a process known as
enhanced oil recovery. The captured CO.sub.2 may be sequestered
underground, and according to at least one embodiment of the
invention at a remote site upwind from the other components of the
system 2 so that any leakage from the site is re-captured by the
system 2.
[0051] In regards to mineral sequestration, CO.sub.2 may be
sequestered by a carbonation reaction with calcium and magnesium
silicates, which occur naturally as mineral deposits. For example,
as shown in reactions (1) and (2) below, CO.sub.2 may be reacted
with forsterite and serpentine, which produces solid calcium and
magnesium carbonates in an exothermic reaction.
1/2Mg.sub.2SiO.sub.4+CO.sub.2.dbd.MgCO.sub.3+1/2SiO.sub.2+95
kJ/mole (1)
1/3Mg.sub.3Si.sub.2O.sub.5(OH).sub.4+CO.sub.2=MgCO.sub.3+2/3SiO.sub.2+2/-
3H.sub.2O+64 kJ/mole (2)
[0052] Both of these reactions are favored at low temperatures. In
this regard, both the air capture and air sequestration processes
described herein may use electricity and/or thermal energy
generated by the solar collector 10 (or other renewable energy
source) to drive the necessary reactions and power the appropriate
system components. In an exemplary embodiment of the present
invention, a high temperature carrier may be heated up to a
temperature in a range of about 400.degree. C. to about 500.degree.
C. to generate steam to run a generator for electricity, and the
lower temperature steam that exits from the electrical generating
turbines can be used to drive off the CO.sub.2 and regenerate the
sorbent (e.g., NaOH). The temperature of the high temperature heat,
the generated electricity and the temperature of the lower
temperature process heat remaining after electricity production can
be adjusted to produce the mix of electricity production and
CO.sub.2 removal that is considered optimal for a given
application. In addition, in exemplary embodiments, still lower
temperature process heat that emerges out of the capture and
sequestration steps may be used to cool equipment used in these
steps.
[0053] One or more systems for removing carbon dioxide from an
atmosphere may be used as part of a global thermostat according to
an exemplary embodiment of the present invention. By regulating the
amount of carbon dioxide in the atmosphere and hence the greenhouse
effect caused by carbon dioxide and other gas emissions, the system
described herein may be used to alter the global average
temperature. According to at least one exemplary embodiment of the
present invention, several carbon dioxide capture and sequestration
systems may be located at different locations across the globe so
that operation of the multiple systems may be used to alter the
CO.sub.2 concentration in the atmosphere and thus change the
greenhouse gas heating of the planet. Locations may be chosen so as
to have the most effect on areas such as large industrial centers
and highly populated cities, or natural point sources of CO.sub.2
each of which could create locally higher concentrations of
CO.sub.2 that would enable more cost efficient capture. For
example, as shown in FIG. 4, multiple systems 1 may be scattered
across the globe, and international cooperation, including, for
example, international funding and agreements, may be used to
regulate the construction and control of the systems 1. In this
regard, greenhouse gases concentration can be changed to alter the
average global temperature of the planet to avoid cooling and
warming periods, which can be destructive to human and ecological
systems. During the past history of our planet, for example, there
have been many periods of glaciation and rapid temperature swings
that have caused destruction and even mass extinctions. Such
temperature swings in the future could be a direct cause of massive
damage and destabilization of human society from conflicts
resulting from potential diminished resources. The global
thermostat described herein may be the key to preventing such
disasters in the decades to come.
[0054] FIG. 5 is a block diagram of a system, generally designated
by reference number 100, for removing carbon dioxide from an
atmosphere according to another exemplary embodiment of the present
invention. The system 100 includes a renewable energy source 110,
an optional supplemental energy source 120, a power generator 130,
an air extraction system 142 and a collection system 150. The
present embodiment differs from the embodiment of FIG. 2 in that
the renewable energy source 110 may be any known or
future-discovered energy source besides solar, such as, for
example, nuclear, geothermal, and biomass energy sources.
Preferably, the renewal energy source produces thermal energy,
which can be used to produce electricity and to improve the
efficiency of the various chemical and/or physical reactions that
take place within the air extraction system 142 and the collection
system 150. In this regard, the air extraction system 142 and the
collection system 150 may be the same as described with reference
to the previous embodiment, or may include components according to
any other known or future-discovered air extraction and collection
systems. In addition, as shown in FIG. 4 with reference to the
previous embodiment, a plurality of systems 100 may be
strategically placed across the globe, and control of the systems
100 may be coordinated so as to collectively function as a global
thermostat.
[0055] FIGS. 6-9 are schematic illustrations of several ways that
carbon dioxide can be removed from an atmosphere, according to the
principles of the present invention.
[0056] Specifically, in FIG. 6, a pair of substrate 600, 602 are
illustrated, each of which has a medium (e.g. NAOH, an amine) that
can be brought into contact with an atmosphere to remove carbon
dioxide from the atmosphere. The substrates 600, 602 are pancake
shaped (in the sense that they are relatively large area compared
to their thickness) oriented vertically, and can each be relatively
large (in surface area) and relatively thin (e.g. on the order of a
few millimeters, and preferably not thicker than a meter). Each
substrate can move (e.g. by a pulley system (not shown) between an
upper position in which carbon dioxide laden air is brought into
contact with the medium carried by the substrate to remove carbon
dioxide from the air, and a lower position in which process heat is
directed at the substrate to remove carbon dioxide from the medium.
The substrates 600, 602 are porous with large surface areas, so
that air directed at a substrate can flow through the substrate.
When a substrate is in an upper position (e.g. the position of
substrate 600), carbon dioxide laden air is directed at the
substrate (e.g. by a fan 604 shown in dashed lines), so that as the
air flows through the substrate, the carbon dioxide contacts the
medium and is substantially removed from the air. Thus, carbon
dioxide laden air is directed at and through the substrate so that
carbon dioxide comes into contact with the medium, carbon dioxide
is substantially removed from the air by the medium, and air from
which the carbon dioxide has been substantially removed is directed
away from the substrate. When a substrate is moved to the lower
position (e.g. the position of substrate 602), process heat is
directed at the substrate (e.g. via a fluid conduit 606), and
carbon dioxide is removed (drawn off) by a source of fluid that is
directed at the substrate (in the direction shown by arrow 608) and
a source of suction 610 by which carbon dioxide that has been
removed from the medium is drawn away from the substrate. The
substrates 600, 602 can alternatively move between the upper and
lower positions, so that the substrate in the upper position is
removing carbon dioxide from the air and carbon dioxide is being
removed from the substrate in the lower position. It should be
noted that rather than the fan, if there are strong winds available
natural wind flows can be used to drive the air through the
substrate. In addition, as described below, the fan can be replaced
with a solar driven source (or by either wind or thermally-driven
air currents), in which case the efficiency and cost reduction of
extraction of carbon dioxide from atmospheric air can be further
improved. Moreover, rather than switching the positions of the
substrates, the means for generating the air flows, the flow of
process heat, and the flow of carbon dioxide away from the
substrate can be switched as carbon dioxide is captured from the
air and then extracted from the medium, as will be readily apparent
to those in the art.
[0057] FIG. 7 is a schematic illustration of another version of a
medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention. Specifically, in FIG. 7, a
pair of substrates 700, 702 are illustrated, each of which has a
medium (e.g. NAOH, an amine) that can be brought into contact with
an atmosphere to remove carbon dioxide from the atmosphere. The
substrates 700, 702 are oriented horizontally, and can each be
relatively large (in surface area) and relatively thin (e.g. on the
order of millimeters or centimeters). Each substrate can move
horizontally (e.g. by a pulley system (not shown) between an air
extraction position in which carbon dioxide laden air is brought
into contact with the medium carried by the substrate to remove
carbon dioxide from the air, and a carbon extraction position in
which process heat is directed at the substrate to remove carbon
dioxide from the medium. The substrates 700, 702 are porous, so
that air directed at a substrate can flow through the substrate.
When a substrate is in an air extraction position (e.g. the
position of substrate 700), carbon dioxide laden air is directed at
the substrate (e.g. by a fan 704 shown in dashed lines), so that as
the air flows through the substrate, the carbon dioxide contacts
the medium and is substantially removed from the air. Thus, carbon
dioxide laden air is directed at and through the substrate so that
carbon dioxide comes into contact with the medium, carbon dioxide
is substantially removed from the air by the medium, and air from
which the carbon dioxide has been substantially removed is directed
away from the substrate. When a substrate is moved to the carbon
extraction position (e.g. the position of substrate 702), process
heat is directed at the substrate (e.g. via a fluid conduit 706),
and carbon dioxide is removed (drawn off) by a source of fluid that
is directed at the substrate (in the direction shown by arrow 708)
and a source of suction 710 by which carbon dioxide that has been
removed from the medium is drawn away from the substrate. The
substrates 700, 702 can alternatively move between the air
extraction and carbon extraction positions, so that the substrate
in the air extraction position is removing carbon dioxide from the
air and carbon dioxide is being removed from the substrate in the
carbon extraction position It should be noted that rather than the
fan, if there are strong winds available natural wind flows can be
used to drive the air through the substrate. In addition, as
described below, the fan can be replaced with a solar driven source
(or by either wind or thermally-driven air currents), in which case
the efficiency and cost reduction of extraction of carbon dioxide
from atmospheric air can be further improved. Moreover, rather than
switching the positions of the substrates, the means for generating
the air flows, the flow of process heat, and the flow of carbon
dioxide away from the substrate can be switched as carbon dioxide
is captured from the air and then extracted from the medium, as
will be readily apparent to those in the art.
[0058] The version of the invention shown in FIG. 9 is generally
similar to the horizontally oriented version of FIG. 7, but in the
version of FIG. 9, rather than a fan being the source that moves
the carbon laden air through the substrate in the air extraction
position (e.g. substrate 900), there is a source of gas flow that
is generated from a solar heating tower or chimney (shown
schematically at 912 in FIG. 9). A solar chimney can be generated
by heating an air mass with the sun. The solar chimney would have a
"skirt" (shown in dashed lines 913 in FIG. 9) that enables the
solar heated air to be concentrated in the chimney. Thus, a solar
field with a solar chimney can be associated with a system and
structure that removes carbon dioxide from the atmosphere and
removes carbon dioxide from a medium in the manner shown and
described in connection with FIG. 7. However, rather than a fan 704
as the primary driver of carbon dioxide laden air at the substrate,
the carbon dioxide laden air is heated by solar energy and that air
is allowed to rise in the solar funnel or tower 912. Because of the
tendency for the hot air to rise, an upward draft is generated,
that would carry with it carbon dioxide laden air, and the
substrate 900 would be positioned in the way of that upward draft.
Thus, the carbon dioxide laden air would be directed through the
substrate 900 in the air extraction position, and carbon dioxide
would be removed from the substrate 902 in the carbon extraction
position in the same way as shown and described in connection with
FIG. 7. By driving the extraction of carbon dioxide from air by
solar energy, the costs of extraction are further reduced, and the
overall operation is highly renewable. Of course, provision would
need to be made for those periods when the sun didn't shine, and
some form of driver similar to the fan 704 (FIG. 7) would be
needed. But in any case, having periods in which, instead of the
fan, replacing the fan with a solar driven source (or by either
wind or thermally-driven air currents), the efficiency and cost
reduction of extraction of carbon dioxide from atmospheric air can
be further improved.
[0059] FIG. 8 is a schematic illustration of yet another version of
a medium for removing carbon dioxide from an atmosphere and for
removing carbon dioxide from the medium, according to the
principles of the present invention. In FIG. 8, the medium from
which carbon dioxide is removed from atmospheric air and from which
carbon dioxide is removed from the medium is disposed on a
continuously moving substrate 800. The substrate moves through an
air extraction zone 814, where carbon dioxide laden air is directed
at and through the substrate (which is also porous as with the
prior embodiments) so that carbon dioxide is removed from the air.
The substrate 800 then moves to a carbon extraction zone 816, where
process heat is directed at the substrate and carbon is drawn away
from the substrate in the manner described above in connection with
FIGS. 6, 7. Then, the substrate 800 moves to and through a heat
exchange zone 818 where the temperature of the substrate is lowered
(e.g. by the air that flowed through the substrate in the air
extraction zone, and by any additional cooling device that may be
useful in reducing the temperature of the substrate to a level that
enables it to efficiently remove carbon dioxide from the air when
the substrate moves back through the extraction zone 814. In
addition, the system of FIG. 8 may have another carbon extraction
zone 816, where process heat is directed at the substrate and
carbon is drawn away from the substrate in the manner described
above in connection with FIGS. 6, 7.
[0060] It should also be noted that in all of the versions of the
invention described above, the removal of carbon dioxide from the
air can be at least partially performed under non equilibrium
conditions. Additionally, it should be noted that applicants'
preferred concept for extracting carbon dioxide from the atmosphere
comprises using a relatively thin, large surface area substrate
with a medium (e.g. an amine) that removes carbon dioxide from the
atmosphere and using process heat to remove carbon dioxide from the
medium. Using a relatively large area substrate perpendicular to
the direction of air flow is particularly useful, because of the
relatively low concentration of carbon dioxide in the atmosphere
(as opposed to the relatively high concentration that would
normally be found, e.g. in flue gases).
[0061] While this invention has been described in conjunction with
the exemplary embodiments outlined above, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, the exemplary embodiments of
the invention, as set forth above, are intended to be illustrative,
not limiting. Various changes may be made without departing from
the spirit and scope of the invention.
* * * * *
References