Energy -II

1. Energy -II

2. Assuming no action is taken to reduce these emissions, the U.S. will emit approximately 8,000 million metric tons (8,800 million tons) of CO2 by 2030, increasing 2005 emission levels by more than 33 percent 86% of the emission will be for power generation

3. Clean Coal • Scrubbers and electrostatic precipitaors • Low Nox burners • Crushing and washing coal • Fluidized bed • Capture and sequester CO2

4. Reducing emissions • Soot: Electrostatic precipitators, along with baghouses (which work like large industrial-scale vacuum cleaners to capture ash and dust particles in felt or woven fabric bags), have been able to reduce the release of soot-forming particulate matter by 99 percent or more. Today, all coal burning power plants employ one, or in some cases, both of these devices • SO2: Scrubbers can reduce sulfur emissions by 90 percent or more. They are essentially large towers in which aqueous mixtures of lime or limestone “sorbents” are sprayed through the flue gases exiting a coal boiler. The lime/limestone absorbs the sulfur from the flue gas. • NOx: Exhaust gases, prior to going up the smokestack, pass through the system where anhydrous ammonia reacts with the NOx and converts it to harmless nitrogen and water. • Mercury: activated carbon – a powdery substance commonly used to remove odors and contaminants in drinking water systems – has also been shown to be effective in absorbing mercury from the flue gases of coal plants • Fluidized-bed combustors

5. Fluidized bed combustion • Blowing pulverized particles of coal into a super-hot (approx. 3,000 degrees F) combustion chamber – fluidized-bed combustors suspend larger chunks of coal (about the size of your fingernail) on upward-blowing jets of air.  • The bed material consists of a coal-water fuel paste, coal ash, and a dolomite or limestone sorbent. • Dolomite or limestone in the bed reacts with sulfur to form calcium sulfate, a dry, granular bed-ash material, which is easily disposed of or is usable as a by-product. • A low bed-temperature of about 1,600°F limits NOx formation. •  effective in reducing SO2 and Nox by more than 90% • eliminate the need for a post-combustion scrubber, and they can burn almost any grade of coal.

6. More than 170 fluidized-bed combustion units now operate in the United States. • From 1980 to 2003, • the amount of coal used to generate electricity in the United States increased by 75 percent; • sulfur dioxide, nitrogen oxide and mercury emissions declined by 40 percent

7. CO2 sequestration • Carbon sequestration encompasses the processes of capture and storage of CO2 that would otherwise reside in the atmosphere for long periods of time. • Geologic sequestration • Terrestrial sequestration

8. Geologic sequestration • is defined as the placement of CO2 into an underground repository in such a way that it will remain permanently stored. • (1) mature oil and natural gas reservoirs, • (2) deep unmineable coal seams, • (3) deep saline formations, • (4) oil- and gas-rich organic shales, and • (5) basalt formations.

9. Deep unmineable coalseams Deep Saline Formations Mature oil and natural gas fields

10. Terrestrial sequestration involves the net removal of CO2 from the atmosphere by plants and microorganisms and its storage in vegetative biomass and in soils. • Also provides ancillary benefits such as habitat and water quality improvements • increasing carbon uptake through reforestation and amendment of minelands and other damaged soils. • through various land management techniques including no-till farming and wetland restoration.

11. The Coal Plant of the Future Coal gasification (Synthetic Natural Gas – SNG) •  reacting coal with steam and oxygen under high pressures – produces a gas • can be cleaned of more than 99% of its sulfur and nitrogen and remove Mercury and other potential pollutants • the coal gas can be cleaned to purity levels approaching, or, surpassing those of natural gas. • Integrated gasification combined-cycle: like natural gas, cleaned, the coal gases are burned in a gas turbine-generator to produce electricity.  • Exhaust gases exiting the turbine are hot enough to boil water, creating steam that drives a steam turbine-generator, producing a second source of electricity. • Integrated gasification combined-cycle power plants are one of the cleanest and most efficient coal-fueled power stations. • eliminate virtually all of coal's pollutants, • generate considerably more power from a given quantity of coal. 60% against 33-35% of today's power plants • Higher coal-to-electricity efficiencies mean that less coal is used to generate power hence less carbon dioxide is emitted.

12. SNG: problems • Require 50% more coal • Produces 50% more CO2 • Costlier

13. Natural Gas • US proven reserve: 164 trillion cubic feet • Supplies 25% of all energy consumed in US • Consumption: 22 trillion cubic feet /year • World reserve: <5000 trillion cubic feet • Former USSR and Iran account for more than 60% of world reserve • Cleanest Fossil Fuel: Emits 30% less CO2 than oil and 43% less than coal, mostly free of sulfur and NO.

14. Enhanced Recovery • Any dramatic rise in reserves unlikely • Typically about 2/3rd of all oil deposits are left in the ground because of difficulty of recovery • Methods used for Enhanced recovery include: • Water and CO2 under high pressure and explosives to increase permeability • Hot water and detergents to decrease viscosity • Can increase yield by an additional 40% • Can be used for old and new fields • Increases risks of pollution and ground subsidence • Adds to the cost

15. Alternate Gas sources • Geopressurizedgas: At very great depths oil breaks down to natural gases which dissolves in pore waters and can be recovered by drilling. Est. Reserve: 150 to 2000 trillion cu. ft • Gas Hydrates: In arctic regions and in marine sediments crystalline solids of gas and water called hydrates occur in commercial quantities. Estimated reserve: 10,000 trillion cubic feet (2 X Fossil Fuel reserve) • Potential greenhouse effect of methane • Enhanced recovery by fracturing of ‘tight’ sandstones and gas bearing shale in the Appalachians

16. Oil shale • Sedimentary rocks containing kerogen: a waxy substance formed from the remains of plant, algae and bacteria. • Oil Shale has to be powdered and distilled to recover “oil” • US reserve=2 to 5 trillion barrels = 2/3rd of World supply. • Enough oil to supply USA for 110 years • Found in Green River Formation of CO,WY and UT • World supply = 240X crude oil • 1 ton of oil = 3 tons of rock and 3 barrels of water, • Problem of water, waste disposal and land reclamation

18. Retorting is the process by which oil is recovered from oil shale by application of heat

19. Tar Sand • Sedimentary rocks containing semi-solid tar-like petroleum (Bitumen) • Either early stage of oil formation or residues after lighter fraction has migrated away • Too thick to be pumped out • Athabasca Tar Sands of Canada may contain 280-300 billion barrels of recoverable oil (total reserve may be more than 2000 billion barrels). Canada hopes to meet 1/3rd of their oil needs from the tar sands. • 15% of world’s oil supply, second only to Saudi Arabia. Venezuela other major country with huge tar sand deposit • Uses natural gas and water, produces 80 kg of greenhouse gas each barrel of oil, destroys boreal forests, bogs, rivers • Same processing and disposal problem as oil shale • 1 barrel of oil uses up 0.7 barrels of energy

20. Athabasca tar sand