Coal: An Old Source Facing New Challenges Daniel Cohan Rice University October 4, 2014

Outline Overview of coal and its use Emissions from coal Controlling emissions from coal Other impacts of coal Costs of coal 2

Overview of Coal and its Use

4 How Coal Forms Plants die in swamp forests and are buried by sediment as peat Heat and pressure expel water and gases Coal becomes more carbon and energy rich over millions of years Graphic from Univ of Kentucky

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6 Western coals becoming increasingly prevalent Thick seams in West for large-scale mining Appalachian coals heavily utilized before, most accessible reserves already tapped Western coals have lower sulfur content, lower price –Transportation costs, bottlenecks are issue US EIA, AEO 2012

Powder River Basin Coal supplies many TX power plants 7

8 U.S. uses 1,045,878,000 tons of coal for electric generation each year 3.5 tons/person/year (~50 times our weight) 100 tons 1 ton 360 tons 12 tons

9 U.S. Coal Use Trends Historically, large use by industry, homes, transportation Now power plants predominate US EIA, AEO 2006

Coal supplies 34% of electricity for the Texas ERCOT grid 10

Coal is big share of US electricity capacity, but most growth is natural gas & renewables 11

Most U.S. coal-fired electricity is from decades-old power plants 12 Cohan and Douglass, 2011

Emissions from Coal

14 IPCC

Projected climate change depends on CO 2 emissions 15 IPCC, WGI SPM, 2013

Electricity Generation: Biggest source of greenhouse gases in U.S. 16

Highest CO 2 emissions from coal (This is life cycle CO 2 equivalent basis, so includes CH 4 leaks, etc) 17 Greenhouse gas impact per kWh: Coal >> Natural gas >> Solar, biomass, wind, nuclear Weisser, “A guide to life-cycle greenhouse gas emissions from electric supply technologies.” Energy, 2007

Old coal plants emit far more NO x than other options in Texas 18 Cohan, 2013 Emissions from Texas power plants

NO x contributes to excess ozone in Texas cities (standard is 75 ppb) 19 Cohan, 2013

20 Ground-level Ozone Impacts Health effects –Strong oxidant, irritates lungs –Linked to asthma and other respiratory illnesses –Recently linked to mortality Damage to vegetation & crops Greenhouse gas Non-attainment of EPA standards

Old coal plants emit far more SO 2 than other options in Texas 21 Cohan, 2013 Emissions from Texas power plants

22 SO 2 contributes to fine particulate matter Particulate matter: airborne particles composed of a variety of chemical compounds Particulate matter is likely the leading cause of illness and mortality from air pollution

Controlling emissions from coal-fired electricity

Timeline of US cap-and-trade policies for air pollutants

25 U.S. Power Plant Emissions Trends NO x Emissions SO 2 Emissions

US EPA Policies for CO 2 from Power Plants Historically, CO 2 was not regulated 2007: Supreme Court in Massachusetts v. EPA ruled Clean Air Act can cover CO : Proposed New Source Performance Standards of lb CO 2 /MWh –Attained by new natural gas plants –Would require partial capture of CO 2 from coal 2014: Proposed Clean Power Plan, with CO 2 targets for each state –For Texas: 39% reduction by

Clean Power Plan CO 2 Reduction Targets 27

US Power Plant CO 2 Trends 28

29 Power Plant NO x Control: Selective Catalytic Reduction (SCR) Ammonia is injected after boiler to convert NO x to N 2 and water –Requires catalyst –Specific temperature range ~85% NO x reduction 29

Flue Gas Desulfurization (“Wet Scrubber”) for SO 2 US DOE National Energy Technology Laboratory

Rainfall Acidity, 1994

Rainfall Acidity, 2009 (Note the reductions in acidity in regions where coal is heavily used for electricity; results from SO2 & NOx controls under Acid Rain Program)

Post-combustion carbon capture 33 FIGURE 12.1 Flowsheet of the monoethanolamine (MEA) process for CO 2 capture. Fay & Golomb textbook Reaction of liquid solvent MEA with CO 2 C 2 H 4 OHNH 2 (“MEA”) + H 2 O + CO 2 ↔ C 2 H 4 OHNH HCO 3 - Need 1 mole MEA per mole CO 2 captured Huge material flows: 400 kg/s MEA for 500MW plant Forward 40-65°C (flue gas must be cooled) Reverse °C (needs steam; hurts efficiency)

34 CO 2 Transport Pipelines –Some CO 2 pipelines already exist for enhanced oilfield recovery –Similar impacts as other hydrocarbon pipelines Ships –CO 2 could be liquefied for ship transport Road or rail –Probably not cost-effective

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37 Geological Storage Capacity For comparison, global anthropogenic emissions are about 28 GtCO 2 /year IPCC, 2005

Cost of CCS vs. other CO 2 control options 38

Coal Impacts beyond Air and Climate

40 Mountaintop Removal Mining In much of Appalachia, coal seams may be hundreds of feet beneath surface 500 feet or more of a mountain summit may be removed to access coal

Coal Ash Pond Spill, Kingston (TN) Power Plant, December 2008 Associated Press 41

Ash from Coal Power Plants 42

Coal Ash Ash from coal combustion: 10% of original volume of coal (U.S. EPA)U.S. EPA –Fly ash (74%): Mixed with exhaust gas; captured by various technologies –Bottom ash (20%): Large, settles to bottom –Boiler slag (6%): Ash that melts by heat 1,300 coal ash dumps in U.S. –Mercury, lead, arsenic, and selenium in ash –Lack of federal regulation –$5-11 billion/year estimated clean-up costs N.Y. Times, “Hundreds of Coal Ash Dumps Lack Regulation,” 1/6/

Solid Wastes from Coal Power Plants Coal combustion generates ~129 million tons/year of wastes in US; ~35% reused US EPA Coal Combustion Products Partnership 44

Cost of Coal Electricity

New coal costs more than gas, wind, or geothermal; with carbon capture, it costs more than solar

Alternatives to coal in Texas 47 Cohan, 2013 Costs per MWh generated

Externality costs of coal (National Research Council, 2009) 3.2 cents/kWh due to health and other impacts of air pollution –1.7 cents/kWh by 2030 as emissions are cut –Natural gas impacts are ~0.2 cents/kWh –Other studies estimate much higher impacts from coal Wide uncertainty on climate impacts (up to 10 cents/kWh) Additional impacts from coal mines and transport 48

Projections of coal use depend on climate policy 49 GHG15 scenario: US sets CO 2 emission price, rising to $44/ton by 2035 US EIA Annual Energy Outlook 2012

Summary of challenges to coal Old coal plants provide affordable electricity, but: –Need to control NO x, SO 2, and mercury –Retrofit carbon capture is very expensive –EPA Clean Power Plan will require CO 2 cuts New coal plants aren’t cost competitive with natural gas or some renewables –Need carbon capture to meet EPA’s proposed New Source Performance Standards Impacts to air, climate, land, and water 50