October 19, 2013

Diego VillarrealSHP – Columbia University

(King?) Coal

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COAL FACTS

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What is the role of coal

• Coal is the most widespread fuel in electricity generation○ Over 40% of world’s installed base of electricity generating

capacity is coal-fired○ Main source of industrial energy for about 200 years

• Until recently it was also the least expensive○ Today wind and gas (in US) are competitive or perhaps less

costly. Not the case everywhere. ○ Coal produces a lot of CO2 and is sensitive to a price on

carbon & environmental regulations.○ Coal has enormous environmental externalities.

• Coal is also used as a fuel for other energy intensive industries such as steel, cement, and paper.

• In the USA, about 93% of coal is used in the electric sector.

• C(as coal) + O2 CO2 (not including all S, NOx, PPM)

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How is coal used (world)

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Electricity Production by Fuel/Region

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TPES in the US

US EIA Annual Review 2010. Supplies in quadrillion BTUs.

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Coal flows (US)

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Coal by the numbers (Production)

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Coal by the numbers (Consumption)

Consumption by region (million tons of oil equivalent)

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BP Statistical Review of World Energy 2013 © BP 2013

Consumption per-capita (toe)

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Thinking about reserves

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Fossil Fuel Reserves

Ultimately recoverable resources, the measure of long-term fossil fuel production potential, are considerably higher than proven reserves. As market conditionschange and technology advances, some of these resources are set to move into theproven category, providing further reassurance that the resource base will not constrain production for many decades to come.Source: IEA WEO 2012

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Source: Survey of Energy Resources 2010, World Energy Council.BP Statistical Review of World Energy 2013 © BP 2013

Distribution of proved coal reserves in 1992, 2002 and 2012 (percentage)

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TECHNICAL CONSIDERATIONS

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Types of coal• Coal is classified into four main types:

1. Lignite - Lowest rank of coal and used almost exclusively as fuel for electric power generation. 25-35%

2. Subbituminous – Used primarily as fuel for steam-electric power generation and is an important source of light aromatics for chemical industry. 35-45% carbon content

3. Bituminous - Dense sedimentary rock, used primarily as fuel in steam-electric power generation, with substantial quantities used for heat and power applications in manufacturing and to make coke. Carbon content 60-80%

4. Anthracite - Highest rank of coal used primarily for residential and commercial space heating. “Petrified Oil”. Carbon content 92.1%-98%

• Coals with a high heat content are generally higher priced.

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Coal extraction methods

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• Electricity is produced by the process of heating water in a boiler to produce steam. The steam, under tremendous pressure, flows into a turbine, which spins a generator to produce electricity.

• Kingston Fossil Plant near Knoxville, Tennessee (1.7 GW plant)

• Boiler heats the water to about 1,000 ºF (540 ºC) to create steam. Pressure ~ 122 atm.

• Plant generates about 10 billion kilowatt-hours a year, or enough electricity to supply 700,000 homes.

• Burns ~ 14,000 tons of coal a day, an amount that would fill 140 railroad cars.

SO2, NOx and CO/CO2 emissions

Reduced if Natural gas or hybrid coal-gas is used

Typical coal-fired power plant

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IGCC

• Typical pulverized coal power plant’s thermal efficiency ~ 35%

• Can also gasify coal using IGCC technology – Integrated Gasification Combined Cycle○ Turn coal into syngas then burn in

combined cycle power plant – much cleaner than conventional power stations.

○ Greater efficiency & potential ability to capture CO2

○ Only 2 IGCC power plants in the US. Capital costs higher.

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IGCC

Wikipedia

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Coal plant example

• A 500 MW power plant burns Bituminous coal. The heat rate of this Bituminous coal is found to be ~ 28400 kJ/kg. If the plant has a capacity factor of 70% and a thermal efficiency of 38.9%, calculate the following:

○ How much electricity is produced by the power plant in one year?○ How much coal does the power plant use per year?○ How much CO2? (assume complete combustion).

○ What volume would this CO2 occupy?

○ If one railcar holds 100 tons of coal, how many railcars enter the plant each year.

○ If ash is 9.8% of the initial mass of coal, how much ash is produced per year○ The coal that is being used has 1.5% sulfur by mass. How much SO2 does

this power plant produce each year?○ CO2/Fuel energy?

○ SO2/Fuel energy?

• Useful information:○ 1 kWh = 36000 kJ○ Molar mass C = 12 g/mol; M.M O = 16 g/mol; M.M S = 32 g/mol.

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Coal in the USA• Mostly used for power

generation. • Most of the coal comes from WY

and WV.• Wyoming is the largest regional

coal producer, as well as the largest coal-producing state in the nation. Nine of the top ten producing coal mines in the United States are located in Wyoming.

• For many years the dominance of coal in electricity generation was unquestioned. The recent gloat of NG is shifting this dynamic (more on this later).

• However, production is not down as coal displaced by gas in the USA is finding a home in other markets abroad.

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Price of coal

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Coal in the US (2)

• Coal production is expected to increase by 1.0 percent in 2013 as primary and secondary inventory draws, combined with an increase in coal imports, meet most of the growth in consumption. Coal production is forecast to grow by 1.3 percent in 2014.

• Total coal consumption fell by 114 million short tons (MMst) (11.3 percent) in 2012, led by an 11.6-percent decline in coal use for electricity generation.

• EIA expects consumption in the electric power sector to increase over the forecast period as a result of higher electricity demand and higher natural gas prices, but remain below 900 MMst.

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Price of coal vs natural gas

• The recent glut of natural gas has dramatically decreased the cost of natural gas in the US.

• This has an enormous impact on the coal vs. gas competition for power generation.

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Electricity Production in the US

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COAL AND THE ENVIRONMENT

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Environmental Issues With Coal

• Coal abundant, cheap and easy to extract. • However, it is also a very dirty fuel with a lot of environmental

externalities.• When coal is combusted, a series of unwanted and harmful substances

and particulates. Mainly:○ Sulfur dioxide (SO2), which contributes to acid rain and respiratory

illnesses.○ Nitrogen oxides (NOx), which contributes to smog and respiratory

illnesses.○ Particulates, which contribute to smog, haze, and respiratory

illnesses and lung disease.○ Carbon dioxide (CO2), which is the primary greenhouse gas emission

from the burning of fossil fuels.○ Mercury and other heavy metals (Cd, Pb, etc), have been linked

with both neurological and developmental damage in humans and other animals.

○ Fly ash and bottom ash are residues created when coal is burned at power plants. Must be captured by pollution control devices, like scrubbers. In the United States, fly ash is generally stored at coal power plants or placed in landfills. Pollution leaching from ash storage and landfills into groundwater has emerged as a new environmental concern.

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Environmental Issues with Coal (2)

• In 2008 the World Health Organization (WHO) and other organizations calculated that coal particulates pollution cause approximately one million deaths annually across the world, which is approximately one third of all premature deaths related to all air pollution sources.

• There are other environmental (devastating) issues related to the mining of coal.

• In addition coal mining is dangerous and leads to accidents – over 5,000 deaths annually worldwide (most of them in China).

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External costs of coal

• Provides 40% of world’s electric power and >50% of its GHGs

• External costs in US of about $350 billion annually○ Mining accidents○ Pollution impacts on health – 20-50,000

deaths annually in US from particulate pollution

• Charging for these would send cost of power from coal from 7 cents/kWh to 25 cents

• Would radically change inter-fuel competition

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Full cost accounting for the life cycle of coal

Annals of the New York Academy of SciencesVolume 1219, Issue 1, pages 73-98, 17 FEB 2011 DOI: 10.1111/j.1749-6632.2010.05890.xhttp://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2010.05890.x/full#f1

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Coal-Burning Factories in Shanhi Province, China, 2006 images

Gu Dian steel plant

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Beijing, Jan 10, 2013

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Beijing January 12, 2013. Pollution 35-40 times higher than safe levels

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Tiananmen Square in Beijing Sunday, Jan. 13, 2013

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Visitors gather near an entrance to the Forbidden city during a very hazy day in Beijing Sunday, Jan. 13, 2013

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37Beijing, Jan 13, 2013

38Beijing, January 14

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West Virginia

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Satellite image of air pollution spreading out over eastern China and winding a course across the East China Sea, past the Korean Peninsula and northeastwards toward Japan (Image by NASA)

Typical westerly wind flows across the mid-latitudes of the Northern Hemisphere mean air pollution from China is often carried over the Pacific Ocean. If the weather conditions are right, contaminants including mercury, ozone, sulphur and nitrogen oxides, black carbon and desert dust, can reach the west coast of the US within days.

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Is Coal Going Away?• Although global share of coal in power production is

expected to go down, total number of coal-fired power plants expected to increase.

• This is largely driven by demand increases in non-OECD countries (specially China).

• Without CCS, this becomes a real problem for global CO2 emissions

Source: IEA WEO 2012

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Coal & Climate Change

• The burning of fossil fuels is the main driver for the increase in CO2 concentrations in the atmosphere.

• Increases in the concentration of CO2 leads to climate change (more of this in a second!).

• Climate Change raises global average temperatures, disrupt ecosystems, change precipitation patterns, increase sea-level rise.

• Coal is the most carbon intensive fossil fuel fuel.• Moving away from (and other FF’s) is key to

curbing climate change.

Source: IEA WEO 2012

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END

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Example Fossil Fuel Power Plant Energy Conversion and Byproducts• A 500 MW power plant burns bituminous coal. • The Annual Energy input of the plant = 2.847*1013 KJ/yr• Heat rate of bituminous coal ~ 28400 kJ/kg• Mass of Coal used? CO2, SO2, Ash, NOx emission?

Mass of Coal = 2.847*1013/28400 (KJ/Kg) = 109 Kg/yr

Mass of Ash = 9.8% Mass of Coal = 9.82*107 Kg/yrMass of Sulfur coming in = 1.5% of Coal = 1.5*107 Kg/yr

C+O2 -> CO2 => 12 + 32 =44 or CO2/C mass = 44/12=2.46Mass of CO2 = 2.46*109 Kg/yr CO2/Fuel energy = 2.46 kg CO2/Kg Coal /28400 KJ/Kg Coal = 86.5*10-6kg/kJ

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S+O2 -> SO2

SO2 produced = 3*107 Kg/yr if all S is converted

SO2/Energy input = 3*107 / 2.85*1013 = 1.05 g/MJ

Acid Rain Clean Air Act Emission standard of 0.516 g/MJ

Flyash = 80% of Ash Bottom Ash =20%

Flyash/Energy Input = 0.8*9.82*107/ 2.85*1013 = 2.76 g/MJ

Clean Air Act Standard =0.013 g/MJ => 99.53% removal needed