Clean Coal

1. Clean Coal Oxymoron or Key to Energy Independence?

2. Bellringer Explain in complete sentences what are pros and cons of tidal energy use.

3. Homework What is the world consumption and demand of organic products?

4. Current Coal Usage • 50% of the energy in the U.S. is generated from coal • 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

5. 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 world’s energy needs in significant quantities.

6. 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 emissions

8. China’s 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

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

11. 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)

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

13. 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)

14. 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 energy

15. Post Combustion

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

18. 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

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

20. 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

21. 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

22. Retrofitting Costs • Major technical modifications required regardless of which technology is used • Based on today’s 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

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

24. 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 combustion • The first contains carbon dioxide and water, and the CO2 can be compressed for storage

25. 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

26. Sequestration

27. 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

28. 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

29. 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

30. 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?

31. 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 projects: • FutureGen in the U.S. • ZeroGen in Australia • A number of proposals in Europe and Canada

32. 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

33. 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

34. 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.

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

36. CTL • 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 subsidies • Will be a disaster in terms of global warming

37. Concerns • 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

38. Big Picture • Federal funding should continue so that we can learn more about the costs and risks of burying CO2 • However, “coal is the fuel of the past, not the future.” (Jeff Goodell) Clean coal technology is not a long-term solution to America’s (or the world’s) energy problems.