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Clean Coal


Clean Coal Oxymoron or Key to Energy Independence? Michelle Chesebro Current Coal Usage 50% of the energy in the U.S. is generated from coal ... – PowerPoint PPT presentation

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Title: Clean Coal

Clean Coal
  • Oxymoron or Key to Energy Independence?
  • Michelle Chesebro

Current Coal Usage
  • 50 of the energy in the U.S. is generated from
  • More than 500 coal-fired power plants in U.S.
    with average age of 35 years
  • U.S. supplies of coal projected to last from 164
    -250 years

Economics and Security of Supply
  • Coal is plentiful and cheap
  • Coal is found in abundance in countries with
    stable governments
  • United States, India, China
  • MIT concluded that coal will continue to be used
    to meet the worlds energy needs in significant

Greenhouse Gases
  • Among fossil fuels, coal is the most
    carbon-intensive so electricity generated by coal
    produces high CO2 emissions
  • U.S. coal-burning power plants contribute 1.5
    billion tons per year of CO2
  • Globally, coal is responsible for 40 of CO2


Chinas Contribution to Greenhouse Gases from CO2
  • International Energy Agency now predicts China
    will surpass the U.S. in CO2 emissions by 2009,
    10 years earlier than previous projections
  • China uses more coal than the U.S., the E.U. and
    Japan combined
  • China is bringing new coal-fired power plants
    online almost every week

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Proposed Solution
  • Carbon Capture Sequestration (CCS) can reduce
    CO2 emissions significantly while using coal to
    meet energy needs
  • Components

Initial Step Coal Gasification
  • Coal put in gasifier with oxygen and steam where
    heat and pressure are used to form a synthetic
    gas, known as syngas
  • CO2 can then be captured
  • Before combustion (IGCC)
  • After combustion (Pulverized Coal plants)

Product Syngas
  • Composition Carbon Monoxide and Hydrogen
  • Potential Uses
  • Power Generation (IGCC)
  • Fertilizers Methanol
  • Natural Gas
  • Gasoline Diesel Fuels (Fischer-Tropsch)

Post-Combustion Capture
  • Used in conventional pulverized coal-fired power
    (PC) plants that produce flue gases
  • CO2 separated out from flue gas
  • 80-95 captured (but low concentrations to begin
    with in flue gas)

Post-Combustion Process
  • Flue gas is passed through an absorber where a
    solvent removes most of the CO2
  • CO2-containing solvent goes to stripper and is
    heated to release the CO2
  • New process being used by American Electric
    Power chilled ammonia used as solvent can
    process larger amounts of CO2, but requires less

Post Combustion
Pre-Combustion Capture
  • Integrated Gasification Combined-Cycle (IGCC)
  • Used in new power plants and well suited for high
    grade bituminous coal
  • 90 of CO2 removed

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IGCC Process
  • Coal gasification to produce syngas
  • Syngas cooled and cleaned to remove particulates
    and other emissions
  • Electricity generation
  • Syngas then combusted with air or oxygen to drive
    gas turbine
  • Exhaust gases are heat exchanged with water/steam
    to drive steam turbine
  • By introducing steam between cooler and gas
    clean-up, CO converted to CO2 which can be
    captured and stored before combustion

IGCC Process
  • Coal burned to produce syngas
  • Syngas burned in combustor
  • Hot gas drives gas turbines
  • Cooling gas heats water
  • Steam drives steam turbines

Competing Technologies
  • Because of the differences in coal type, a wide
    range of technologies will need to be deployed.
    We should not jump on the IGCC bandwagon too
    quickly for research development , but
    continue to fund a variety of options
  • Clear preference for IGCC or SCPC (Super Critical
    Pulverized Coal) cannot be justified at this time

Comparison of IGCC and SCPC
  • Reasons to prefer IGCC
  • Potential tightening of air quality standards for
    other pollutants reduced by IGCC, such as SO2,
    NOx and mercury
  • Likelihood of a future carbon charge
  • Possible federal or state financial assistance
    for IGCC
  • Reasons to prefer SCPC
  • Near-term opportunity for higher efficiency
  • Capability to use lower cost coals
  • Ability to cycle the power plant more readily in
    response to grid conditions
  • Confidence in reaching capacity factor/efficiency
    performance goals

Retrofitting Costs
  • Major technical modifications required regardless
    of which technology is used
  • Based on todays engineering estimates, cost of
    retrofitting for IGCC appears to be cheaper than
    retrofitting for SCPC
  • Variables
  • Timing and size of carbon charge
  • Difference in retrofit cost
  • Very possible that old plants will just have to
    be bulldozed because retrofitting will prove to
    be cost-prohibitive

Another Option UCG
  • Underground Coal Gasification
  • Addresses other environmental concerns associated
    with coal mining

Other Technologies
  • Oxygen fired pulverized coal combustion (more
    promising for lower quality coals)
  • Burning coal in oxygen-rich atmosphere to produce
    a pure stream of CO2
  • Chemical looping combustion
  • Continually looping two stage reaction process
    that provides two waste streams from coal
  • The first contains carbon dioxide and water, and
    the CO2 can be compressed for storage

Transport of Captured CO2
  • Compressed to supercritical fluid
  • Dense as liquid
  • Gas-like viscosity
  • Transported through pipelines
  • Or further cooled and transported in marine
    tankers like LNG

Storage of Captured CO2
  • Deep geologic formations such as saline aquifers
  • Depleted oil and natural gas fields
  • Ocean
  • Dissolving CO2 deeper than ½ mile
  • Depositing liquefied CO2 on sea floor 2 miles down

Carbon Options
  • CO2 pumped into disused coal fields displaces
    methane which can be used as fuel
  • CO2 can be pumped into and stored safely in
    saline aquifers
  • CO2 pumped into oil fields helps maintain
    pressure, making extraction easier

Storage Concerns
  • Leakage presents an immediate hazard to humans
    and ecosystems (CO2 is an asphyxiant)
  • Possibilities
  • Blow-out at injection well
  • Slow leak through faulty well or ground fractures
  • Even slow leaks negate the benefit of burying the
    CO2 in the first place

Regulatory Framework for Storage
  • Must include
  • Site selection
  • Injection and surveillance
  • Eventual transfer of liability to the government
  • The goal of energy independence cannot be allowed
    to trump global warming concerns. Even if a
    regulatory framework is developed for the U.S.,
    who will be the global carbon police?

Status of CCS Projects
  • Current IGCC Projects used primarily for
    enhanced oil gas recovery, not CO2 storage
  • Sleipner in Norway
  • Weyburn in Canada
  • In Salah in Algeria
  • Need large-scale demonstration before this can be
    considered a viable proposal
  • Large-scale electricity generation proposed
  • FutureGen in the U.S.
  • ZeroGen in Australia
  • A number of proposals in Europe and Canada

Price of Coal
  • Coal is plentiful and currently cheap because the
    health and environmental costs are borne by the
    public, not the industry
  • But price will increase
  • Charge for CO2 emissions to account for health
    and environmental costs
  • Deploying carbon capture and storage will
    increase price of coal-fired power by at least
    50, with some estimating twice that amount

Grandfathering Loophole
  • Utilities may be tempted to invest in new power
    plants without capture in the hope that these
    plants will be grandfathered in
  • Expectation of free CO2 allowances under future
    carbon emissions regulations
  • Benefit when electricity prices increase as a
    result of a carbon control regime
  • Congress needs to close the loophole

Coal to Liquid
  • The bigger hurdle for energy independence is
    finding a replacement for gasoline. Other
    countries have used a process for turning coal
    into gasoline (Nazi Germany and the apartheid
    government of South Africa).
  • Coal ? Gasifier ? Syngas
  • Fischer-Tropsch Process
  • Syngas ? Reactor ? Hydrocarbons
  • Hydrocarbons cooled liquid fuel
  • Concern Coal to Liquid (CTL) development has no
    near-term plan to capture any of the CO2 it
    produces. Until it does, using the label clean
    coal is inaccurate.

Liquid Fuel from Coal
  • Second approach direct coal liquefaction ? coal
    is pulverized and mixed with oil and hydrogen in
    a pressurized environment

  • CTL with carbon capture
  • Will be incredibly expensive and will require
    government subsidies
  • If 85 of the CO2 is captured, the liquid fuel
    that is produced will have the same emissions as
    a gallon of regular diesel
  • CTL without carbon capture
  • May be economically viable without government
  • Will be a disaster in terms of global warming

  • Technological issues for both capture and
    sequestration are not trivial and we are still at
    least five to ten years away
  • Any sequestration method still has the potential
    for leaks
  • Impact to human health high concentrations of
    CO2 causes loss of consciousness
  • CO2 makes water in aquifers acidic enough to
    dissolve certain types of rocks releasing toxins
    that seep into drinking water
  • Any leak at all reduces the benefits of carbon
    capture technology, because there is no way to
    recapture the leaked CO2 and store it again

Big Picture
  • Federal funding should continue so that we can
    learn more about the costs and risks of burying
  • However, coal is the fuel of the past, not the
    future. (Jeff Goodell) Clean coal technology is
    not a long-term solution to Americas (or the
    worlds) energy problems.