SHP Columbia University
(King?) Coal Diego Villarreal SHP Columbia University October 17th, 2015 COAL FACTS What is the role of coal Coal is the most widespread fuel in electricity generation Over 40% of worlds 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) How is coal used (world)
Source: IEA Key World Energy Statistics 2014 Electricity Production by Fuel/Region
Source: IEA Key World Energy Statistics 2014 TPES in the US US EIA Annual Review Supplies in quadrillion BTUs. How is coal used in the US?
Source: EIA Monthly Energy Review September 2014 Coal by the numbers (Production)
Source: IEA Key World Energy Statistics 2014 Coal by the numbers (Consumption)
Consumption by region (million tons of oil equivalent) Consumption per-capita (toe)
BP Statistical Review of World Energy 2013 BP 2013 Thinking about reserves
Resources in the lower right corner of the grid have highly speculative existence and would be very expensive to mine even if they did exist. Resources in the upper left corner are proven to exist (for example, an as-yet-unmined area in an existing mine) and can be mined at lower cost than the price they can be sold for, under existing market prices and technologies. These resources are known as reserves. As the price of coal increases, some of the demonstrated subeconomic resources will become economic, and shift into the reserves box. As more resources are proven or hypothesized, they will shift to the left in the grid. The entire resource base has the potential to become reserves, but only if we can find everything (and know conclusively that it is everything) and it can all be extracted profitably. The outline of this diagram can be used to understand the risk of future coal and gas availability. Fossil Fuel Reserves Ultimately recoverable resources, the measure of long-term fossil fuel production potential, are considerably higher than proven reserves. As market conditions change and technology advances, some of these resources are set to move into the proven category, providing further reassurance that the resource base will not constrain production for many decades to come. Source: IEA WEO 2012 Distribution of proved coal reserves in 1992, 2002 and 2012 (percentage)
BP Statistical Review of World Energy 2013 BP 2013 Recent trends world in supply/demand
Coals share in the global primary fuel mix has increased by five percentage points over the past decade to reach 29% in 2013. Coal strengthened its position as the second-largest primary energy source, behind oil. China continues to be the engine of coal demand growth. As the most carbon-intensive fossil fuel, coal is the leading source of carbon-dioxide (CO2) emissions, as well as a major contributor to local air pollution. In the absence of rapid and widespread adoption of high-efficiency coal-fired generation technologies and, in the longer term, of CCS, the increased use of coal will be incompatible with climate goals. IEA WEO 2014 Recent Trends supply/demand (US)
In short/medium term coal losing market share in electricity generation to natural gas and renewables. New EPA rules and Mercury and Air Toxic Standards (2016) will lead to a wave to coal-fired capacity retirements. Future GHG policies will directly affect coal. Recent Trends supply/demand (US) TECHNICAL CONSIDERATIONS Types of coal Coal is classified into four main types:
Lignite -Lowest rank of coal and used almost exclusively as fuel for electric power generation % Subbituminous Used primarily as fuel for steam-electric power generation and is an important source of light aromatics for chemical industry % carbon content 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% 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. Coal extraction methods
Dragline Longwall Typical coal-fired power plant
SO2, NOx and CO/CO2 emissions Reduced if Natural gas or hybrid coal-gas is used 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 F (540 C) 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. 20 IGCC Typical pulverized coal power plants 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. IGCC Wikipedia Coal plant example A 500 MW power plant burns Bituminous coal. The heat rate of this Bituminous coal is found to be ~ 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 = kJ Molar mass C = 12 g/mol; M.M O = 16 g/mol; M.M S = 32 g/mol. 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. Price of coal Coal in the US (2) EIA projects total coal consumption of 941 MMst in 2014, an increase of 1.7% from last year. Total coal consumption is projected to fall by 2.0% in 2015, as retirements of coal power plants rise in response to the implementation of the Mercury and Air Toxics Standards, electricity sales growth slows to 0.6%, and natural gas prices fall relative to coal prices. 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. Electricity Production in the US COAL AND THE ENVIRONMENT 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. 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). External costs of coal Provides 40% of worlds 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 Full cost accounting for the life cycle of coal
This graph shows the best estimates of the externalities due to coal, along with low and high estimates, normalized to per kWh of electricity produced. (In color in Annals online.) This slide is made available for non-commercial use only. Please note that permission may be required for re-use of images in which the copyright is owned by a third party. Annals of the New York Academy of Sciences Volume 1219, Issue 1, pages 73-98, 17 FEB 2011 DOI: /j x Coal-Burning Factories in Shanhi Province, China, 2006 images
Gu Dian steel plant Beijing, Jan 10, 2013 Beijing January 12, 2013. Pollution times higher than safe levels Tiananmen Square in Beijing Sunday, Jan. 13, 2013 Visitors gather near an entrance to the Forbidden city during a very hazy day in Beijing Sunday, Jan. 13, 2013 Beijing, Jan 13, 2013 Beijing,January 14 West Virginia 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. 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 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 FFs) is key to curbing climate change. DATOS NECESARIOS: Calores de combustin: Calor_Combustion_C_Antracita = MJ/kg Calor_Combustion_CH4 = MJ/kg. Masa molecular: C ~ 12 g/mol CH4 ~ 16 g/mol Para simplificar el problema, asumamos que tanto en el caso del carbn como en el caso del metano tenemos comubstiones completas: C + O2 --> CO2 (1) CH4 + 2O2 --> CO2 + 2H2O (2) Energa liberada por mol de carbn: 32.50 MJ/kg * 12 g/molC * 1kg/1000g= 0.39 MJ/molC Energa liberada por mol de CH4: 55.5 MJ/kg * 16 g/molCH4 * 1 kg/1000g = 0.88 MJ/molCH4 Las ecuaciones (1) y (2) nos demuestran que por cada mol de carbon = 1 mol CO2 y que cada mol CH4 = 1 mol CO2. Emissiones de CO2 por MJ (carbon): 1 molC/0.39MJ * 1 molCO2/molC = mol CO2/MJ Emisiones de CO2 por MJ (CH4): 1 molCH4/0.88MJ * 1molCO2/molCH4 = mol CO2/MJ Factor de emisiones de CO2 entre Carbon y CH4 (C/CH4) = molCO2/MJ /(2.56molCO2/MJ) = 0.443 Source: IEA WEO 2012 END 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 ~ 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/yr Mass of Sulfur coming in = 1.5% of Coal = 1.5*107 Kg/yr C+O2 -> CO2 => =44or CO2/C mass = 44/12=2.46 Mass 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 48 SO2 produced = 3*107 Kg/yr if all S is converted
S+O2 -> SO2 SO2 produced = 3*107 Kg/yr if all S is converted SO2/Energy input = 3*107 / 2.85*1013 = g/MJ Acid Rain Clean Air Act Emission standard of g/MJ Flyash = 80% of AshBottom 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 49