CO2 Capture and Fossil Energy

Christopher W. Jones

Georgia Institute of TechnologySchool of Chemical & Biomolecular Engineering

Atlanta, GA 30332

Thursday, March 29, 2012

– The earth is warming (about 0.6 ˚C in last 100 years).

– Intergovernmental Panel on Climate Change (IPCC): 90% probability that increase in CO2 concentration in the air is main culprit.

– Major source of CO2 concentration increase is fossil fuel combustion.

– Future increases could have catastrophic consequences… or not.

– Need carbon mitigation options.

Climate and Fossil Fuel Use:

A Problem Created by Chemists & Chemical Engineers:

A chemist and chemical reaction engineer who produced the most important scientific discovery1 of the 20th century?

Who are these people?What was the discovery?

1. V. Smil Nature 1999, 400, 415.

A Problem Created by Chemists & Chemical Engineers:

A chemist and chemical reaction engineer who produced the most important scientific discovery1 of the 20th century?

Who are these people?What was the discovery?

Fritz HaberNobel Prize, Chemistry, 1918

Carl Bosch Nobel Prize, Chemistry, 1931

1. V. Smil Nature 1999, 400, 415.

N2 + 3 H2 -> 2 NH3.

Nitrate minerals for fertilizer (Chile): $45/tonne in 1925$19/tonne in 1937

Energy Demand Growth Dominated by Developing Countries:

Source: ExxonMobil

Energy Demand Growth Dominated by Developing Countries:

Source: ExxonMobil

Year Population1650 0.5 Billion1900 1.6 Billion2011 7.0 Billion

• Population growth in (relatively) poor zones will drive increased use of cheap (fossil) energy.

How the Energy Demand Will be Met:

Source: ExxonMobil

Message: Advances in windand solar energyare desperately needed, but evenwith tremendous growth…..

How the Energy Demand Will be Met:

Source: ExxonMobil

Message: Advances in windand solar energyare desperately needed, but evenwith tremendous growth, society will continue to rely heavily on fossil energy for the next several decades.

Continued use of fossil fuel in a carbon constrained world will require all of the following:

• Moderating demand (e.g., by improving energy efficiency).

• Developing low/no-carbon energy sources.

• Implementing large scale CO2 capture and sequestration?

Energy Outlook and CO2 Capture:

Envisioning Widespread Carbon Capture and Sequestration:

Source: IPCC, 2005

• Separation and concentration require work (energy).

• Capture and sequestration will cost us energy and money.

• What is the best we can do? The thermodynamic limit.

Base Case Scenario of Energy Cost:

Dilute CO2 mixed in N2

Separated CO2 at 1 atm

Pressurized CO2 at 140 atm

Pipeline ready

~9kJ/mol~5% of the output

~13kJ/mol~7% of the output

~2kJ/mol~1% of the output

Pumping underground and

water displacement

House et al., Energy Env. Sci. 2009, 2, 193.

Post-Combustion Capture from Power Plant Flue Gas:

The Bruce Mansfield Power Plant:

• 2360 MW electric power generation capacity.

• 7 million tons coal burned/year.

• ~41% efficiency.

• 17.5 million tonnes CO2 generated per year.

• 47,800 tonnes/day CO2 formed (at ~15% vol concentration).

• 220,000 tonnes flue gas processed per day.

• The yearly output fits in a 400m cube at sequestration pressures (140 atm).

Slide courtesy of Prof. John Kitchin, Carnegie Mellon University.

Post-Combustion Capture Conditions Separation of CO2:

• Flue gas composition after sulfur scrubbing

– 13-16% CO2

– 4-5% O2

– 6-7% H2O

– Minor impurities

– Balance N2

• Flue gas conditions – 60-80°C– 10-15 psi

• Flue gas production rate

– A 2500 MW coal plant produces ~550 kg CO2/s

– ~240,000 tons/day of flue gas must be treated• Capture goal

– 1200-2000 psi, dry CO2 for pipeline ready transport

CO2 emission sources in the US:

1750 1800 1850 1900 1950 2000 20500

5

10

15

20

25

30

35

Year

CO

2 e

mis

sio

ns

(G

t)

TotalLiquidsSolidsGasCementGas Flaring

http://cdiac.ornl.gov/ftp/ndp030/global.1751_2004.ems

http://cdiac.ornl.gov/ftp/ndp030/CSV-FILES/nation.1751_2003.csv

Global CO2 emissions

Slide courtesy of Prof. John Kitchin, Carnegie Mellon University.

• The US has 1493 coal-fired units (400+ plants)– 336,000 MW of power generation

capacity.– Burn 930 million tonnes of coal/year.– ~50% of total US electricity

production.

– Produced ~2Gt of CO2 emissions.

– Power generation is ~1/3 of the total

CO2 emissions

--Transportation ~1/3,

-- Industrial sources ~1/3.

What Would Capture and Sequestration Cost?

• ~$300 billion dollars/year in electricity sold from coal.

• At 2 Gt CO2/year, if we can manage CO2 at $30/tonne ~ $60 billion/year in the US.

– The $30/tonne has to include all the operating and capital costs associated with CCS.

• ~$1 trillion/year globally to deal with 30 Gt/year (1-2% GDP).

• Replacing power capacity with CO2-free energy also very $$$.

Envisioning Widespread Carbon Capture and Sequestration:

Source: IPCC, 2005

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

Schematic of a CO2 Capture Process

75˚C

Schematic of a CO2 Capture Process

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

Exhaust with 90%CO2 removed

Schematic of a CO2 Capture Process

75˚C

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

Schematic of a CO2 Capture Process

Exhaust with 90%CO2 removed

75˚C

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

Schematic of a CO2 Capture Process

125˚C

Exhaust with 90%CO2 removed

75˚C

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

125˚C

CO2 for sequestrationor conversion

Schematic of a CO2 Capture Process

Exhaust with 90%CO2 removed

75˚C

Exhaust fromcombustion.

Key: Amine adsorbent

Non-CO2 flue gas

CO2

Questions for Discussion:

1. If CCS costs 1-4% of GDP? Will we do this? Should we do this? What would you do as a policy-maker?

2. Why can’t we simply turn the CO2 into something useful, on a practical scale?

3. What country should take the lead in implementing CCS? What country do you think is most likely to take the lead in using this technology?

Point Source Capture vs. “Air Capture”:

CO2 Source Properties: Air/Flue

Property Air Flue

Amount of CO2 3 teratonnes 20 gigatonnes/yr

Distribution 400 ppm - “infinite”

mostly uniform source

10-15% point sources

Temperature 10-30 °C

Low T

45-65 °C

High T – heat integration!

Contaminants Low levels of

contaminants

High levels of SOx

NOx , particulates

Movement wind, fans fans

Two motivations: (i) environmental and (ii) CO2 source

• What is the best we can do? The thermodynamic limit.

Base Case Scenario of Energy Cost:

Dilute CO2 mixed in N2

Separated CO2 at 1 atm

Pressurized CO2 at 140 atm

Pipeline ready

~9kJ/mol~5% of the output

~13kJ/mol~7% of the output

~2kJ/mol~1% of the output

Pumping underground and

water displacement

House et al., Energy Env. Sci. 2009, 2, 193.

Post-Combustion Capture from Power Plant Flue Gas:

CO2 Capture from Ambient Air:

-- first step is thermodynamically more expensive, the rest is the same.-- for 25-90% CO2 capture from air, the minimum energy required is 2.6 – 2.9 times more expensive than flue gas capture at 90% capture.-- actual cost = how close to perfect thermodynamic efficiency can be achieved.

M. Ranjan, M.S. Thesis, MIT 2010

• A review of approaches to extract CO2 from the ambient air has been written.

• Supported amine adsorbents are promising materials for the extraction of CO2 from the ambient air; IF it can be done economically:

-- air capture may allow for a “carbon-negative technology”-- account for CO2 from all emissions sources, including cars,

planes-- economics for “environmental applications” currently unknown-- may allow for on-site generation of CO2 – business

development

• Supported amines offer the advantage of high capacities (1.5-2.5 mol CO2/kg sorbent) and operation in all humidity levels.

Air Capture Conclusions:

C. W. Jones Ann. Rev. Chem. Biomol. Eng. 2011, 2, 31-52.

• Air capture may allow for feeding CO2 to biomass for biofuel production (low concentration) or eventually, CO2 production for sale (EOR) or sequestration.

• Air capture should NOT be considered as an alternative to CO2 capture from flue gas – these are complimentary approaches.

Air Capture Conclusions:

Photo: NY Times

Global Thermostat:

Conflict-of-Interest Statement:Georgia Tech receives research funding from Global Thermostat, LLC, and Jones has a financial interest in Global Thermostat Operations, LLC.

Questions for Discussion:

1. If post-combustion CCS costs ½ of what “air capture” costs, should we pursue CCS? Or air capture? Or both? At what cost should priorities shift to air capture?