Zin Eddine Dadach

Higher Colleges of Technology, UAE

CO2 Capture & Storage

A Solution To Global Warming

I. Is the world getting warmer?

II. Are The Actions Of Mankind To Blame For Earth‟s Temperature Increases?

III. What Can/Should Be Done About These Issues?

IV. Carbon Capture & Storage ?

V. CO2-Capture Strategies

VI. Strategies For the Compression of CO2

VII. Strategies For The Transport Of CO2

VIII. VIII: CO2 Storage In Suitable Geological Formations VIII.1: Sequestration In Saline Aquifers

VIII.2: CO2 Injection For Enhanced Oil Recovery

IX. Getting Green is Expensive

X. Safety And Legal Issues

XI. Conclusion

Is the world getting warmer?

If so, are the actions of mankind to

blame for earth‟s temperature

increases?

What can/should be done about these

issues?

Carbon dioxide (26%) is not as strong a greenhouse gas as water vapor (58%), but it absorbs energy in wavelengths (12-15 micrometers) that water vapor does not, partially closing the “water vapor window” through which heat radiated by the surface would normally escape to space.

Carbon dioxide and the greenhouse effect are necessary for Earth to survive. In fact, if we had no greenhouse effect, our planet would have an average temperature of –300C [source: UNEP]. However, human inventions like power plants and transportation vehicles, which burn fossil fuels, release extra CO2 into the air.

Power generation

industry plays a major

role in the economic

growth of any country.

About 80% of total

electricity in the world

is produced from

fossil fuels fired

thermal power plants.

Combustion Reactions

CH4 + Air (O2 +N2) → CO2 + H2O +N2

C5H10+ Air(O2 +N2) → 5CO2 + H2O +N2

Oil

Coal

NG

Nuclear

Renewables Qu

ad

(1

0 1

5)

BTU

16

as energy consumption continues to rise

Climate change is probably the biggest challenge the

world is facing, but it‟s not too late to fix it, however

Carbon Capture and Storage has the potential to provide a

critical near-term solution for reducing the concentration of

carbon dioxide in the atmosphere.

17

CCS alone could provide up to 20% of the CO2 emission reductions

we need to make by 2050.

Carbon capture and storage is mostly used to describe methods for removing CO2 emissions from large stationary sources, such as electricity generation and some industrial processes, and storing it away from the atmosphere.

STEP I Capturing and concentrating CO2 from industrial sources. STEP II Compression of CO2 until pressure of injection (20 MPa) STEP III Transport of CO2 from Compression units until injection sites. STEP IV CO2 will be stored underground or in Oil and Gas fields.

The high capital cost of CO2 capture technologies is

often cited as a key barrier by the potential CCS

developers and investors.

More Impurities with Heavier Fuels Global Warming Effects of

Impurities

Involves the removal of CO2 from the flue gas produced by combustion of fossil fuel.

Nearly pure oxygen is used for combustion instead of air. The flue gas that is mainly CO2 and H2O.

Involves reaction of a fuel with air and/or steam to give mainly a gas composed of carbon monoxide and hydrogen. The carbon monoxide reacts with steam to give CO2 and more hydrogen

Solvents – aqueous amines and salts

Membranes – polymeric

Solid sorbents – Lime, zeolite, activated carbon

Cryogenic processes – Liquefaction/distillation

The advantage of Post-combustion is that it can be

fully integrated with existing plants.

The main issue is the low concentration of CO2 in the flue gases (3-

10%) that makes the process very costly (70-80% of CCS Cost)

CH4 + (2O2 + 7.52 N2) → CO2 + 2H2O +7.52 N2

STEP I: Isolate CO2 from the other gases (10%) (CO2 reacts with amine in the absorber)

STEP II: Concentrate CO2 from 10% until 90-95% (CO2 is separated from amine in the desorber)

INCONVENIENT: With the classical amine MEA, 70-80 % of CCS cost is due to the heat for its regeneration in the reboiler.

The Classical MEA Consumes a lot of heat during regeneration.

The principal question is how to select a competitive solvent which

is capable of rapid rate of absorption. At the same time, the

solvent should have low regeneration energy consumption

ADVANCED AMINE SOLVENT (blend of low concentration of primary

amine MEA mixed with high concentration of tertiary amine MDEA

(slow reaction but needs less heat for regeneration).

The Piperazine (PZ) activated MDEA process was patented by BASF

in the early 80‟s

The hindered amine 2-Amino-2-Methyl-1-Propanol (AMP) is also

used by some companies (Mitsubishi) instead of MDEA.

Some authors ranked the regeneration performance in the

following order AMP>MDEA>DETA>DEA>MEA

Recently Ionic liquids are introduced as new family of solvents to be tested for CO2 Capture

Ionic liquids need less energy in the desorber than classical amines (CO2 physically absorbed)

Inconvenient: Very viscous and have lower rates of absorption than amines

Post Combustion by absorption: Adding Ionic Liquids To amine mixture :An aqueous amine solution mixed with ionic liquid was proposed and the results are the following:

The energy consumption of the mixed (Ionic liquid + MEA

amine) solution in the desorber was 37.2% lower than that of aqueous MEA amine solution alone.

Publication Date: January 2014; American Chemical Society

VI : Compression of CO2

It requires significant power to boost the pressure of CO2 from the atmospheric pressure

(0.1MPa) of the capture plant up to a pressure suitable for injection of 15 MPa because

storage of CO2 is more efficient if it is in supercritical conditions (P > 7.4 MPa and T> 300 K.).

Compression of “captured CO2” performed by multi-

stage reciprocating or turbo compressors with

intercooling from atmospheric pressure (0.1 MPa) to

injection pressure of about 15 MPa.

A reciprocating compressor with three stages and intercooling until critical pressure of CO2 (7.38 MPa).

The critical pressure of CO2 is often cited as the “cut-off” pressure for switching from a compressor to a pump).

Liquefaction of CO2

Triplex diaphragm pump

17% energy saving from traditional compression with compressors.

VII: Transport of CO2

Many point sources of captured CO2 would not be close to

geological or oceanic storage facilities. In these cases,

transportation would be required. The main forms of

transportation are pipeline & shipping

The effectiveness of geological

storage for safe and long storage of

CO2 depends on a combination of

physical and geochemical trapping

mechanisms (Depth of 800 m, Seal,

Porosity, Permeability, Brine water)

Storage Capacity Injectivity

Perfect sealing

Depth: 800 m

Geological

sequestration of carbon

dioxide is a means of its

injection in a suitable

geological formation

Saline aquifers,

Oil and gas reservoirs

(EOR),

Depleted oil and gas

reservoirs,

Coal beds

Ocean

Impacts

o pH change

o Mortality of ocean organisms

o Ecosystem consequences

o Chronic effects unknown

Change of bacteria, nanobenthos and meiobenthos abundace after exposure to 20,000 and 5,000 ppm for 77-375 hrs during experiments carried out at 2000 m depth in NW Pacific

100%

80%

60%

40%

20%

0%

-20%

-40%

-60%

-80%

-100% <10 mm 10-30 mm

Meibenthos Nanobenthos Bacteria

Chan

ge po

pulat

ion

20,000 ppm

5000 ppm

VIII.1: Sequestration In Geological Formations

Deep saline formations are very similar to oil and gas reservoirs in that they are deep, porous rocks that may contain a fluid trapped by cap-rock for many millions of years

Injecting CO2 in these formations would see the CO2 at first added to the salty brine, eventually dissolving and finally mineralizing to become part of the rock

Another potential storage medium is unminable coal. CO2 can be injected into suitable coal seams where it will be adsorbed onto the coal, locking it up permanently.

This is the most dominant trapping mechanism. The injected supercritical CO2 (more buoyant than other liquids) will percolate up through the porous rocks until it reaches the top of the formation where it meets (and is trapped by) an impermeable layer of cap-rock.

Structural traps are formed as a result of changes in the structure (domes, anticlines, and folds).

Stratigraphic traps lateral and vertical variations in the thickness, texture, porosity or lithology of the reservoir rock.

Concern: it does not immobilize CO2 itself.

This phase of trapping

happens very quickly as the

porous rock acts like a tight,

rigid sponge.

As the supercritical CO2 is

injected into the formation it

displaces fluid as it moves

through the porous rock.

Concern: some of the CO2

will be left behind as

disconnected - or residual

CO2 dissolves in other fluids in its gaseous and supercritical state.

This phase in the trapping process involves the CO2 dissolving into the salt water (or brine) already present in the porous rock.

Concern: Aqueous CO2 can still migrate due to ground water flow and any drop in pressure can lead to the liberation of CO2.

Final phase of trapping, CO2 dissolves in water to form a weak carbonic acid

This process can be rapid or very slow (depending on the chemistry of the rock and water in a specific storage site) but it effectively binds CO2 to the rock.

Over a long time, this weak acid can react with the minerals in the surrounding rock to form solid carbonate minerals,

The carbonation and calcination loop can be used to capture the CO2 from the flue gases of combustion chambers

In carbonate looping, calcium oxide is put into contact with the combustion gas containing CO2 to produce calcium carbonate.

The calcium oxide is regenerated by calcination, giving a CO2 off-gas

Carbonation technology is not yet sufficiently developed to enable CO2 capture.

It may theoretically be possible to combine a power plant and a cement plant, with the clinker burning process utilizing the degraded CaO from the looping process

VIII. 2: CO2 Injection For Enhanced Oil Recovery

By definition, oil reservoirs are

proven natural traps of liquids

and gas, and the injected CO2

would fill the pores in the rock

that were previously filled by

them..

Oil displacement by CO2

injection relies on the phase

behavior and dependent on

reservoir temperature,

pressure and oil composition.

Sandstone/Carbonate

formations suitable for CO2EOR

MMP is the minimum pressure required to achieve multi-contact miscibility between CO2 and the reservoir oil at a given temperature and composition.

First, CO2-Oil MMP (Rising Bubble method) need to be determined for the specific candidate oil field based on the reservoir pressure, temperature, and oil composition.

There are two main types of CO2-EOR processes called Miscible and Immiscible CO2-EOR

Immiscible Flooding: At pressures below MMP, injected CO2 does not mix with the oil within the reservoir, but causes the swelling of the oil, reducing its density, improving mobility and increasing oil recovery.

Miscible Flooding : At pressures above the MMP, the injected CO2 does mix completely with the oil into the reservoir to form a low viscosity fluid that can be easily displaced and produced. Some concerns about asphaltene precipitation and well plugging.

Miscible enhanced oil recovery processes have estimated additional 10-15% recovery of OOIP (Original oil in place), compared to immiscible displacement processes that with 5-10%. 1)

Recommended Range of current projects

Crude Oil

Gravity (0API) >22 27-44

Viscosity (cp) < 10 0.3 to 6

Composition High percentage of C5 to C12

Reservoir

Oil saturation

( % PORE VOLUME)

> 20 15 to 70

Type of formation Sandstone or carbonate and relatively thin unless dipping.

Average permeability

,md

Not critical if sufficient injection rates can be maintained

Depth and

temperature

Depth should be enough to allow injection pressures greater than

MMP which increases with temperature and for heavier oils.

Type of CO2 flooding Oil Gravity (0API) Depth must be greater than (ft.)

Miscible > 40 2500

32-39.9 2800

28-31.9 3300

22 to 27.9 4000

< 22 Fails for miscibility

Immiscible 13 to 21.9 1800

< 13 All reservoirs fail at any depth

At < 1800 ft., all reservoirs fail screening for either miscible or immiscible flooding with supercritical CO2

Three CO2 injection strategies commonly used in commercial

miscible-flooding applications:

Slug injection involves continuous injection of approximately 0.2 to

0.4 hydrocarbon pore volumes (HCPV) of CO2 that, in turn, is

displaced by water or dry solvent

Water-alternating-gas (WAG) injection involves alternately injecting

small volumes (0.01–0.04 HCPV) of water and solvent. The total

amount of CO2 injected usually ranges from 0.2 to 0.6 HCPV. The final

drive fluid is usually water or dry solvent.

Gravity-stable injection is used for some pinnacle reefs and steeply

dipping reservoirs with high vertical communication, it is

advantageous to inject less-dense CO2 at the top of the reservoir in a

gravity-stable displacement process

Traditionally, CO2-EOR projects have been designed only to enhance crude oil production. Amount of CO2 injected minimized (Cost).

New CO2-EOR Strategies need to use a larger amount of CO2 in order to optimize between CO2 storage and increasing crude oil production.

These increased CO2 volumes need to be “managed and controlled” to assure that they contact, displace, and recover additional residual oil, rather than merely circulate through a high permeability zone of the reservoir.

“State of the Art” CO2-EOR : The injection of much larger volumes of CO2

at 1.0 HCPV (hydrocarbon pore volume) rather than the smaller (on the

order of 0.4 HCPV) volumes used in the past.

“New Generation” CO2-EOR: After using the “State of the Art” CO2 EOR,

the “New Generation” miscible CO2-EOR technique will Increase Oil

Recovery Efficiency and expanding CO2 Storage Capacity by increasing

the volume of CO2 injected into the oil reservoir from 1.0 to 1.5 HCPV

“Second Generation” CO2-EOR: After the “Next generation” technologies,

It will target both the main pay zone plus an the underlying residual oil

zones (ROZs), with continued CO2 injection into and storage in an

underlying saline aquifer, including injecting continuous CO2 after

completion of oil recovery operations.

NEXT GENERATION SECOND GENERATION

CO2-EOR CO2-EOR CO2-STORAGE TOTAL

CO2 STORAGE

(Million Metric

Tons)

32 76 33 109

Storage Capacity

Utilization

22% 53% 23% 76%

Oil Recovery

(million barrels)

92 180 180

It takes a large amount of energy to capture CO2 from stacks at

power plants, cement kilns, refineries, etc. It takes more energy to

compress it to the point of injection

► Cost of CCS makes electricity power stations more expensive to

build and electricity more expensive to buy.

Actual cost of CCS range from 50 to 100 USD/CO2

Capture & Compression: 25-50 USD/ tonne CO2.:

Transportation: 1-5 USD/ tonne CO2 &100 km.

Storage :1-2 USD/ tonne CO2

OBJECTIVE 2030:

Cutting the cost of CCS to 25-50 USD per tonne of CO2

A cost for CO2 emissions (Carbon Tax) could provide the

economic rationale for CCS projects

CCS economic viability could also be based on an

business agreement to sell its captured carbon to

another company for Enhanced Oil Recovery (EOR)

(It is estimated that some 300–400 million tons of CO2 will be

required for every billion barrels of incremental oil to be

recovered).

EOR: A Vital Tool In A Low-Carbon Future

Revenues from the extra production of crude oil could be invested in CCS projects

To ensure public support, the

technology must be shown to be

safe, which involves predicting the

fate of the CO2 over thousands of

years. The risks due to storage of

CO2 in geological reservoirs fall into

two broad categories:

Global risks involve the release of

stored CO2 to the atmosphere that

may contribute significantly to

climate change if some fraction

leaks from the storage formation.

Local risks include hazards for

humans, ecosystems and

groundwater.

The engineered bio-mineralization process produces biofilm and mineral deposits that

1) Reduce the permeability of geologic media

2) Modify the geochemistry of brines to enhance CO2 solubility and mineral precipitation.

• Fraction retained in appropriately selected and

managed geological reservoirs is

– very likely to exceed 99% over 100 years, and

– is likely to exceed 99% over 1,000 years. "Likely" is a probability between 66 and 90%, "very likely" of 90 to 99%

• Release of CO2 from ocean storage would be

gradual over hundreds of years

A rigorous regulatory process that has

broad public and political support will be

required if CO2 is to be sequestered

underground on a large scale

Some sort of international monitoring

system will be needed if countries or

companies are going to engage in

international trading of credits related to

sequestration of CO2

Issues related to prohibition by

international conventions of dumping of

industrial waste in the ocean will need

to be resolved (would fossil fuel CO2

qualify as an „industrial waste‟?)

CAPTURE

The economic viability of CCS on a global

scale largely depends on the value and

price that governments and people put

on environmental and ecosystem

viability.

STORAGE

Unless it can be proven that CO2 can

be permanently and safely stored

over the long term, the option will be

untenable, whatever its additional

benefits.

Cost Effective Strategies to Reduce CO2 Emissions in the UAE: A Literature Review,

Faisal Al Wahedi & Zin Eddine Dadach (Higher Colleges of Technology);

Industrial Engineering and Management, 2-4, 1-9, 2013

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