Parasitic Power for Carbon
Capture
Doug Carter
Consultant
[email protected]
We are about to discuss
• A brief history of the future
• How to retrofit a power plant for carbon
capture and storage (CCS)
• What is parasitic power?
• How does parasitic power impact a utility’s
decision making?
The future: how and when will the sky fall
• The legislative track:
– Expect climate change legislation to be enacted in 2-3
years, and be at least as stringent as the S.1766
(Bingaman), which requires about a 33% reduction in
emissions in 2030 v 1990. Reductions begin ~2012.
• The regulatory track:
– Endangerment finding and mobile source CO2 limits
by EPA in 2008.
– Immediate requirements for NSR/BACT on new fossil
fueled power plants, without any new Stationary
Source regulations.
– Possible regulation under NSPS, including existing
power plants under 111(d), without any new
legislation.
Compliance options are not entirely
appealing
• Under a cap&trade – may be able to pay for
reductions elsewhere, until cheaper technology
(hopefully) is developed.
• Under performance standards, will need to
control locally: Efficiency, low carbon fuel, CCS.
• Difficult choices may emerge as reserve margins
fall in the face of limited supply.
Carbon Capture and Storage
(or Sequestration)
• “CCS” represents the technologies to capture
and store CO2 through the following process:
1. Separate and capture CO2 from power plant “fuel gas”
or the “flue gas”
2. Compress the CO2 into a liquid form
3. Move the CO2 via a pipeline to the location where it will
be stored.
4. Inject the CO2 a deep geological formation for longterm storage
• There are currently several technologies under
development to capture CO2.
Pulverized Coal Plant with Carbon Capture
Drying &
Boiler
Coal
Air
Comp.
NOx
Removal
PM removal
(FF or ESP)
(SCR)
Flyash
Recycle
Sulfur
removal
(FGD)
Sequestration
Ready CO2
CO2 Capture
CO2 AH2
Scrubbers
Stack
Sulfur
By Products
Steam Turbine
Generator
Condenser
NETL study found that 4 acres of space needed for
additional hardware, @ 433MW generator.
Electric
Power
Oxy-Coal Combustion Plant
With Carbon Capture
Flue Gas Recycling
Boiler
NOx
Removal
PM removal
(FF or ESP)
Sulfur
(FGD)
(SCR)
Drying &
Comp
Coal
Sequestration
Ready CO2
AH2
CO2 Capture
Air
O2
Flyash
Recycle
Sulfur
By Products
Air
Separation
Plant
Steam Turbine
Generator
Electric
Power
Solid
By Products
Condenser
CO2 Storage – Main Focus Is Injection into
Geological Formations
• Saline reservoirs
– 100’s of years
capacity
– Little experience
• Economical, but lesser
capacity options
– Depleted oil & gas
reservoirs/enhanced
oil recovery
– Unmineable coal
beds/enhanced coalbed methane
recovery
Courtesy of Peter Cook, CO2CRC
Timing for CCS Deployment Requires
Aggressive Federal RD&D
ENDGAME
NOW
Complete larger scale
capture demos
“Small” demos
(5MW Ammonia, etc.)
2005
Bench-scale – postcombustion capture
2010
Start larger scale
demos – capture &
storage
2015
Commercial
availability
CCS
2020
Start multiple full
scale demos
Efficiency improvements at existing plants can be implemented now
Needs: Multiple large-scale CAPTURE & STORAGE demos
Timing: 2020 endgame è start today, parallel paths
Realistic? A challenge – technical, policy, funding
Source: DOE-NETL Carbon Sequestration R&D Roadmap Modified to add Chilled Ammonia example
Let’s talk about parasitic
power ….
Parasitic power is like income tax
• You have to pay it
• You may not like how it is used
• Parasitic power is used to run the emission
mitigation machinery
– Regeneration of CO2 capture sorbents
– Compression of captured CO2 for transport &
injection
– Additional tower to minimize SO2 emissions (from 94
to 99% removal)
– Production of oxygen in oxy-fuel systems
DOE/NETL evaluated a range of
CO2 control levels
• Based on AEP Conesville
#5, 434MW PC
• Capacity dropped to
303MW @ 90% capture
via MEA.
• Heat rate increased from
9750 to 13980 Btu/kwh
(35 -> 24%)
• ~ 30% parasitic power
need
• Lower %-removal had
linear effect on parasitic
power needs
Sorbent regeneration requires
substantial energy
• In NETL study, 50% of steam to LP turbine was needed
for stripping CO2 from MEA.
• Study design included a new “letdown” turbine to extract
some useful energy prior to using LP steam for stripping.
• Modified arrangement reduced power output by 16% (or
about ½ of total parasitic power need).
• 3-stage compression of captured CO2 to 194 psia is
followed by liquefaction via propane refrigeration system,
followed by more compression to 2000 psia.
Similar results from studies of
greenfield capture systems
• DOE/NETL “Baseline”
study of SCPC (39%) and
SubCPC (37%) found the
same absolute energy
penalty (12%).
• Higher output of SCPC
meant slightly less
replacement power by
capacity (MW).
Consider the components of cost
Cost of Electricity - New units
PLEASE DO NOT TAKE
THESE NUMBERS
TOO
100 LITERALLY. THEY VARY WITH INPUT
ASSUMPTIONS.
- CO2 trans, injn, mon
Capt.
90
- Fuel
- VO&M
- FO&M
- Capital
COE, Levelized $/MW-hr
80
70
No
Capt.
Variable Costs
60
50
40
30
20
10
IGCC
IGCC
SCPC
Bit Coal: $1.58/mmBtu
SCPC
NGCC
NGCC
NatGas: $5.93/mmBtu
Source: DOE/NETL “Baseline” report, May 2007; EIA AEO-07 fuel costs for 2020.
Retrofit CCS will cost more, unless capital
cost of unit is largely depreciated
CCS Retrofit Options
180
160
THESE FIGURES ALL ARE BASED ON
EIA’S FORECAST PRICE FOR NATURAL
GAS IN 2020: $5.93/mmBtu.
140
Replacement Power
- Repl pwr, fix
- Repl pwr, var
COE, $/MW-hr
120
- CO2 trans, injn, mon
- Fuel
100
Variable Costs
- VO&M
- FO&M
80
- Capital
60
40
20
-
IGCC
SCPC
NGCC
Multiple dynamics control dispatching of
CCS-retrofit systems
Dispatching Cost for Fossil Generating Options
140
Variable costs, $/MWhr
120
100
Must balance: Price of Natural Gas,
source of replacement power,
current/anticipated C-tax, efficiency –
all of which are uncertain.
80
60
40
20
0
10
20
30
40
50
60
70
80
90
100
Carbon Tax, $/metric ton CO2
Conventional PC, no capture, no tax
PC, no capture but paying tax
PC, w/50% capture *
PC, w/90% capture
NGCC, no capture but paying tax
NG-steam, no capture, pay tax
NGCC w/90% capture
NGCT, no capture, pay tax
Replacement power costs can be
treated several ways
• At a new unit, the unit is simply oversized
• At an existing unit
– Can purchase “clean” power (all costs become
variable and impact dispatching)
– Can build within your system (fixed costs do not
impact dispatching)
• In this case, coal versus natural gas matters, due to high
variable cost of gas
– Other ?
Don’t miss the abyss
• NSR can bite from 2 directions
– If an environmental project leads to significant net increases in
other pollutants (like PM) then you become a major modification
for those pollutants. The problem now exists for CAIR and
CAMR and could be much greater for CO2 retrofits
• You will likely need squeaky clean SO2 and NOx for the C-capture
technology to work properly, but other pollutants may increase due
to the need to burn more coal to meet the same power demand (at
reduced load periods). Unclear how the rules will be interpreted.
– If the cost of the “change” exceeds 50% of the replacement cost
of the unit, then you are a “reconstructed” source – subject to
NSR & NSPS
• NETL study shows cost increase of 80% to install CCS
• With a 40% “retrofit factor”, that grows to about 115%
• Either way, you greatly exceed the 50% tripwire.
• Costs of complying w/ NSR are not included in systems
studies
CCS: Cautious optimism for the future
is justified
• IF we have time and sufficient resources, ongoing RD&D
may produce much more efficient CCS systems, at lower
costs.
• E.g. – Chilled ammonia sorbents may have much lower
parasitic energy requirements than Amines.
• We also need near-term experience with existing
technology (i.e., we need subsidies) to facilitate longterm storage practices.
• And we need a pragmatic system to oversee the pioneer
CCS plants to ensure safe operation and acceptable
liability requirements.
BUT recognize that there is an
approaching train wreck
• Power demand continues to grow with the economy, and
may spurt if PHEV’s become practical
• It is becoming increasingly difficult to permit anything but
NGCC
• Future natural gas pricing depends on how much more
LNG we can import
• Existing coal units may flip from being an assumed
liability to being a critical asset
• In that case, parasitic power for CCS may become a
100GW issue
Have a nice day.
Questions ??