Transcript Advanced Coal and the Environment

Integrated Coal Gasification Combined
Cycle (IGCC) Power Plants and
Geologic Carbon Sequestration
Joe Chaisson
April 21, 2004
www.catf.us
IGCC: What is it?
• “Integrated coal Gasification Combined Cycle” or
IGCC
• Chemical conversion of coal to synthetic gas for
combustion in a modified gas turbine
• Inherently cleaner process because coal is not
combusted and the relatively small volumes of
syngas are easier to clean up than the much larger
volumes of flue gases at a coal combustion plant.
Coal IGCC Process1
Feeds
Gasification
Gas
Cleanup
Oxygen
End
Products
Combined Cycle
Power Block
Alternatives:
Gas & Steam
Turbines
Coal
Electricity
Steam
Heavy Oil
Alternatives:
Petroleum Coke
Refinery
Residues
Orimulsion
SULFUR
REMOVAL
SULFUR
RECOVERY
Clean Syngas
Hydrogen
Ammonia
F-T Liquids
Marketable
Byproducts:
Natural Gas
Solid Sulfur
Slag (ash)
1
Texaco Gasification Power Systems (TGPS)
Tampa Electric – Polk Power Station
.
250 MW – operating since 1996
IGCC Environmental Impacts - Air Pollution
•
Commercially available IGCC power plant technologies can have much lower air
pollution emissions than new conventional coal plants.
•
Actual air emissions performance will likely depend, at least in in part, on what
control technology and performance levels are required by regulators .
•
Mercury capture at IGCC plants is quite feasible and much less costly than at
conventional coal plants and the potential exists to indefinitely sequester
mercury captured at IGCC facilities.
•
Commercially available IGCC power plant technologies produce substantially
smaller volumes (about one half) of solid wastes than do new conventional coal
plants using the same coal
•
IGCC solid wastes are less likely to cause environmental damage than fly ash
from conventional coal plants because IGCC ash melts in the gasification
process, resulting in an ash much less subject to leaching pollutants than is
conventional coal combustion fly ash.
Comparative SO2 Emissions
2.00
1.85
1.80
1.60
Emissions in Pounds per MWH
1.40
1.20
1.00
0.80
0.60
0.40
0.16
0.20
0.00
0.00
New Coal
Current IGCC
New Natural gas
Comparative NOx Emissions
1.200
1.11
Emissions in Pounds per MWH
1.000
0.800
0.600
0.400
0.200
0.16
0.07
0.000
New Coal
Current IGCC
New Natural gas
Coal Gasification and Mercury Management
•
Proven, low cost mercury controls can remove most of the mercury
from coal “syngas” produced (14 years experience at Eastman
Chemical).
•
Mercury is captured in a small volume activated carbon bed (see next
slide). Bed contents are currently managed as hazardous wastes (due
to other toxics captured), but could be sequestered in a long-term
mercury storage facility or the mercury contained could be
economically recycled.
•
Thus coal IGCC with a carbon bed plant mercury control is today the
only technology that can convert coal to power and capture nearly
much of the coal mercury in a form and volume suitable for permanent
sequestration.
IGCC Carbon Emissions
• IGCC plants are more efficient in converting coal to electricity
than conventional coal plants and thus produce less CO2 per
unit of electricity generated.
– Near-term IGCC plants would produce about 20% less CO2 - per
unit of electricity produced - as would the “average” existing coal
plant.
• The longer term potential could be for IGCC plants to produce
about one-third less CO2 - per unit of electricity produced - as
would the “average” existing coal plant.
• IGCC plants can potentially capture and geologically sequester
up to 90% (or more) of coal fuel carbon content.
Geologic Carbon Sequestration
•
CO2 is today mined, transported and injected into the ground in operations to enhance oil
field recovery.
•
CO2 is also removed at some production fields along with hydrogen sulfide gas from natural
gas prior to injection of the natural gas into pipelines. The removed CO2 and hydrogen
sulfide are then often injected into geologic formations for permanent disposal.
•
These technologies are today in commercial practice and are essentially the same as would
be used to transport and sequester (geologic injection and containment) CO2 captured at an
IGCC plant.
•
Statoil’s Sleipner gas field project, off the coast of Norway, is one example of a climatedriven CO2 sequestration project that injects captured CO2 into a saline aquifer.
•
Domestic carbon sequestration would likely focus initially on sites where CO2 injection
would enhance oil recovery (as a credit would be earned to reduce costs) or possibly to
recover methane form deep coal beds. Costs of purchasing CO2 for these applications are
reported to be about $45/ton of carbon.
•
Longer term sequestration options being explored include binding captured CO2 into a
mineral that would be environmentally stable and that could be readily be disposed.
Sleipner Carbon Sequestration Project
Costs of Carbon Capture and Geologic
Sequestration
•
IGCC carbon capture costs are currently estimated by the Electric Power Research Institute
(EPRI) to be about 1.2 to 1.9 cents/kWh for a range of commercially available IGCC
technologies.
•
Geologic storage costs for captured carbon are likely to vary significantly by power plant
location and type of storage “setting” (storage in deep saline aquifers, active enhanced oil
recovery projects, deep coal beds, etc.).
•
Transport of captured carbon and storage at a typical saline aquifer site is estimated by MIT
to add about 0.2 cents/kWh, for total CCS cost of about 1.4 to 2.1 cents/kWh today.
•
Recent analysis by Carnegie Mellon University researchers suggests that IGCC
“repowerings” with carbon capture and sequestration could enter mid-western power
markets at carbon allowance prices of $50 - $75/metric ton.
•
Commercially available CO2 capture and sequestration technologies have not been
optimized for IGCC power plant carbon capture. Capture costs are projected (by MIT and
others) to drop as commercial applications move forward.
•
Carbon capture and sequestration costs will remain uncertain until operational experience
accumulates with commercial-scale IGCC carbon capture and sequestration demonstration
projects.
Comparative CO2 Emissions
2,000
1897
1,800
1673
1,600
Emissions in Pounds per MWH
1,400
1,200
1,000
842
800
600
400
238
200
0
New Coal
Current IGCC
IGCC With CO2 Capture and
Sequestration
New Natural gas
A Bridge to Hydrogen Fuels
•
Movement of IGCC technology into the power market could facilitate
use of coal to produce valuable products beyond electricity –
–
–
–
FT diesel fuel
Chemical feed stocks
Synthestic natural gas
Hydrogen, or hydrogen-rich liquid fuels for transportation and building
energy
•
Hydrogen is the ultimate fuel cell fuel (current fuels cells often include
equipment to convert other fuels - natural gas, etc. - to hydrogen).
•
IGCC is seen by key experts as being critical to economic deployment
of hydrogen transportation fuels and widespread use of fuel cells.
•
Successful deployment of IGCC technology in the power sector may be
critical to the economic viability of other potential coal-derived products.