Use of FGD Byproducts in Agriculture: DOE Perspective Workshop on Research and Demonstration of Agricultural Uses of Gypsum and Other FGD Materials St

Use of FGD Byproducts in Agriculture: DOE Perspective

Workshop on Research and Demonstration of Agricultural Uses of Gypsum and Other FGD Materials

St. Louis, MO

September 13, 2006

William W. Aljoe, Project ManagerU.S. Department of Energy, National Energy Technology Laboratory

OARDC FGD Workshop, September 12-14, 2006

DOE Terminology: CUBs

Coal Utilization By-products Includes Fly ash, Bottom ash, Boiler slag, FGD solids Other acronyms: CCBs, CCPs, CCW, FFCW, CCR ...

Utilization includes: Combustion Gasification & Hybrid systems

By-products because: $ from electricity sales >> $ from CUB sales Become “Products” when sold or beneficially used Become “Wastes” when sent to a permanent disposal site

Can still become “products” after disposal


Outline

Types of FGD Systems & By-products Wet FGD Systems Dry FGD Systems Fluidized Bed Combustion (FBC)

FGD By-product Characteristics FGD Gypsum vs. “Mixtures” (wet & dry)

Production and Use Recent and future trends Effect of SO2 and Hg regulations


Byproducts from Wet FGD Systems

Pulverized Coal

Bottom Ash or Boiler Slag

Boiler

ESP or Fabric Filter

Fly Ash

Wet FGD Absorber

Wet FGD By-product

Lime or Limestone Slurry

Flue Gas

Stack Emissions


Wet FGD System Alternatives

Reagent Limestone or Lime Sodium-based (rare)

Oxidation method Inhibited or Natural In-situ External

2 major classes of By-products Older systems: Sulfite sludge (CaSO3 · ½ H2O)

Must be “stabilized” or “fixated” before disposal or use Newer systems: Gypsum (CaSO4 · 2H20)

No stabilization needed


FGD Byproduct Formation: Sulfite Sludge Basic Chemical Reaction (Limestone Reagent)

SO2 + CaCO3 → CaSO3·½ H2O (s) + CO2 (g)↑

Source: http://www.worldbank.org/html/fpd/em

/power/EA/mitigatn/aqsowet.stmUnstabilized

FGD Byproduct(CaSO3 · ½H2O)Stabilized (Fixated)Stabilized (Fixated)

FGD ByproductFGD Byproduct


FGD Gypsum Formation Basic Chemical Reaction (Limestone Reagent)

SO2 + CaCO3 → CaSO3 · ½ H2O + CO2 (g)

Source: http://www.worldbank.org/html/fpd/em/power/EA/mitigatn/aqsowet.stm

+ O2 → CaSO4 ·2H20 (Gypsum)

Forced Oxidation (In-Situ)

Air

FGD GypsumFGD Gypsum

Forced Oxidation (External)

Air

Slurry


Byproducts from Dry FGD Systems(Spray Dryers)

Pulverized Coal

Bottom Ash or Boiler Slag

Boiler

Spray Dryer

Absorber


Dry FGD Byproduct =Fly Ash + CaSO3 + CaSO4 + Ca(OH)2

Lime Slurry

Flue Gas

Stack Emissions


Byproducts from Fluidized Bed Combustion (FBC)

Coal, Refuse, or other Fuel

Limestone

FBC Boiler

Bottom Ash + CaSO4 + CaSO3 +CaO


Fly Ash + CaSO4 + CaSO3 +CaO

Flue Gas

Stack Emissions


U.S. CUB Production and Use – 2004(Data from American Coal Ash Association)

2004 Fly Ash Bottom AshFGD

GypsumOther Wet

FGD Boiler Slag Dry FGD FBC Ash Total

Production (million tons) 70.8 17.2 12.0 17.5 2.2 1.8 0.9 122.5Total Use (million tons) 28.1 8.2 9.0 1.2 2.0 0.2 0.5 49.1

Percent of production utilized 39.6% 47.4% 75.7% 6.8% 89.6% 9.7% 54.6% 40.1%

0

10

20

30

40

50

60

70

80

Fly Ash BottomAsh

FGDGypsum

OtherWet FGD

BoilerSlag

Dry FGD FBC Ash

Production (million tons)

Total Use (million tons)


U.S. FGD Byproduct Production and Use – 2004(Data from American Coal Ash Association)

2004FGD

GypsumOther Wet

FGD Dry FGD FBC Ash

Production (million tons) 12.0 17.5 1.8 0.9Total Use (million tons) 9.0 1.2 0.2 0.5

Percent of production utilized 75.7% 6.8% 9.7% 54.6%

FGD Gypsum

Other Wet FGD Dry FGD

FBC Ash

(54%)

(37%)

(6%)

(3%)


Fate of FGD Gypsum – 2004(Data from American Coal Ash Association)

FGD Gypsum

Cement, concrete, grout

Raw feed for cement clinker

Wallboard

Agriculture

Other

Disposal


Fate of “Other” (Sulfite) Wet FGD Byproducts – 2004(Data from American Coal Ash Association)

Other Wet FGD

Raw feed for cement clinker

Structural fill

Mining applications

Agriculture

Other

Disposal


FBC Ash Structural fill

Soil modification

Mining applications

Waste stabilization

Other

Disposal

Fate of Dry FGD and FBC Byproducts – 2004(Data from American Coal Ash Association)

Dry FGD Cement, concrete, grout

Flowable fill

Mining applications

Agriculture

Aggregate

Disposal


Recent Trends in FGD Byproduct Production & Use

0

2

4

6

8

10

12

14

16

18

20

2002 2003 2004

Mill

ion

To

ns

FGD Gypsum Production FGD Gypsum Use

Other Wet FGD Production Other Wet FGD Use


Effect of CAIR on FGD Byproducts

CAIR Requirements 44% reduction in SO2 emissions by 2010

56% reduction in SO2 emissions by 2015

Total volume of FGD byproducts will increase Most “new” wet FGD systems will produce gypsum Many “old” (sulfite-producing) FGD systems will continue to

operate More dry FGD systems will be added

Less efficient for SO2 removal than wet FGD Dry: 70-90%; Wet: 95%+ (BACT considerations)

Will be used mostly for for low-S coals, where water is scarce


Future Trends in FGD Byproduct Production

FGD Byproduct Production (All Types)

0

10

20

30

40

50

60

1996 1998 2000 2002 2004 2006 2008 2010 2012 2014

Mill

ion

To

ns

CAIR Phase II

CAIR Phase I


Potential Impact of Power Plant Mercury Emission Regulations (CAMR) on CUBs

Fly Ash Loss of all reuse applications

~ $908 M/yr impact

FGD Solids Loss of all reuse applications

~ $213 M/yr impact

Hazardous designation of all CUBs could cost more than $11 billion/year

Fly Ash FGD Byproduct

Mercury


Mercury Partitioning Across Coal Power Plants(Annual Nationwide Estimates based on 1999 EPA ICR Data)

Sorbent Injection

EnhancedScrubbing

Typical Control Technologies

In 2018: ~94T Hg

~6T Hg ~73 T Hg

15T Hg CAMR Phase II

After CoalCleaning

BoilerParticulate

ControlFGD

System

48T Hg

StackBottom Ash~5T Hg

Pre-CAMR: ~75T Hg

Fly Ash FGD Byproduct

~22T Hg


Effects of CAMR on Hg in Wet FGD Byproducts Points to consider

1. Wet FGD systems already remove oxidized Hg

Byproducts already contain 70-90% of initial Hg2+


Flue gas from boiler Hg2+

Hg0

Wet FGD Absorber Stack Emissions

Hg2+ Hg2+

Hg0 Hg0

Fly Ash Wet FGD By-product



2. Hg concentration in wet FGD byproducts will be slightly higher if SCR is added or if “oxidation enhancement additives” are used

SCR+additives+scrubber won’t be chosen ($$) if incoming Hg is primarily Hg0

Flue gasfrom boiler

SCR ESP or Fabric FilterHg2+

Hg0

Hg2+ Hg2+

Hg0 Hg0


Hg2+

Hg0

Oxidation Enhancement Additive



3. Hg concentration in wet FGD byproducts may be lower if powdered Hg sorbents are used for Hg control

Hg Sorbent


Flue gasfrom boiler or SCR

Hg2+

Hg0

Hg2+ Hg2+

Hg0 Hg0


More Hg in fly ash = less in FGD byproduct


Effects of CAMR on Hg in Dry FGD Byproducts

Powdered sorbents will probably be the Hg control method of choice

FGD byproduct will have some more Hg but much more carbon than before

Flue gas from boiler

Stack

Spray Dryer

Hg Sorbent

FGD Sorbent

ESPor FF

Fly ash +

FGD byproduct +

Sorbent


Environmental Release of Hg from FGD Byproducts R&D Must “Check all the Boxes”

FGD Source

Landfill ImpoundmentUtilization

Hg (g)

Hg (aq)

Hg (g)

Hg (aq)

+ +

LandfillHg (g)

Hg (aq)

+

Manufactured Products

Roads/Fills/Land Application

Hg (aq)

Hg (g)Hg (g)

Hg (aq)

+

Hg (p)

Hg (g) = VolatilizationHg (aq) = LeachingHg (p) = Dust+ = Microbial activity/methylation


Near-Term R&D Goals Hg Release from FGD Byproducts

Determine the stability of Hg and other metals under simulated end-use environments Disposal and re-use

Explain the chemistry underlying metal stability

Drywall ready for landfill

FGD solids ready for disposal


Where Does the Hg Go upon Capture ?

Hg in Zimmer WFGD ProductsND set to 0.0

0

2

4

6

8

10

12

14

16

18

Hg

, p

pm

(dry

)

Zimmer-Fines

Zimmer-Slurry

Zimmer-Gypsum

“… the mercury compound formed in the wet scrubber is associated with the fines and is not tied to the larger gypsum crystals.”

Source: “FULL-SCALE TESTING OF ENHANCED MERCURY CONTROL TECHNOLOGIES FOR WET FGD SYSTEMS” Final Report, DE-FC26-00NT41006, BABCOCK & WILCOX CO. and McDERMOTT TECHNOLOGY, INC. May 7, 2003


Leaching of FGD Byproducts Using Continuous Stirred Tank Reactor (CSTX)

FGD Gypsum Gypsum totally dissolved

Leachate: No Hg Residue

< 1% of original material Fe, Al, and all Hg

Wallboard Gypsum totally dissolved

Leachate: ~1% of Hg Residue

~ 2% of original material Fe, Al, and majority HgContinuous stirred tank

reactor


CSTX Results Summary

An iron-containing phase, probably introduced with limestone, is responsible for sorption of mercury

Hg content of FGD gypsum appears to correlate with Fe content

Rapid Hg leaching is unlikely in typical disposal and land-application (agricultural) environments


FGD Byproducts in Agriculture and Land Applications Relevant CBRC Projects

Website: http://wvwri.nrcce.wvu.edu/CBRC/

Project Title Performer Total Project Value

Start Date End Date

Environmental Effects of Large-Volume FGD Fill GAI Consultants, Inc. $206,800 4/15/2001 12/31/2004Power Plant Combustion Byproducts for Improved Crop Productivity of Agricultural Soils

New Mexico State University Agricultural Science Center at Farmington

$119,008 9/1/2004 8/31/2005

Flue Gas Desulfurization Byproducts Provide Sulfur and Trace Mineral Nutrition for Alfalfa and Soybean Ohio State University $97,300 1/3/2000 8/31/2003

Boron Transport from Coal Combustion Product Utilization and Disposal Sites Southern Illinois University $118,241 11/1/1999 8/31/2003

The Impact of Adsorption on the Mobility of Arsenic and Selenium Leached from Coal Combustion Products

Southern Illinois University $138,412 9/1/2002 12/31/2004

Qualifying CCBs for Agricultural Land ApplicationUniversity of North Dakota $105,613 9/1/2002 7/31/2005

Field Testing of Arsenic and Mercury Bioavailability Model from Land-Applied CCBs Tennessee Valley Authority $142,300 7/1/2006

National Network of Research and Demonstration Sites for Agricultural and Other Land Application Uses of FGD Products

Ohio State University $575,677 7/1/2006

Community-based Social Marketing: the tool to get target audiences to use CCBs University of Tennessee $275,193 7/1/2006


FGD Byproduct Reuse: Economics 101

Producer (Utility) Perspective: Recycling occurs when cost of reuse < Cost of disposal

In theory: new technology reduces cost of reuse In practice: reuse becomes “economical” when disposal costs

rise

User Perspective: Recycling occurs when cost of reuse < cost of alternative

materials Need specifications for reuse (not always available) Need consistent supply and quality of material Need support from material supplier


How Can FGD Byproduct Use in Agriculture Be Increased?

Education

Communication Finding “Win-Wins”

Diligence Don’t quit ‘til you get it right


For More Information

DOE-NETL CUB Website http://www.netl.doe.gov/technologies/coalpower/ewr/co

al_utilization_byproducts/

Documents

Use of FGD Byproducts in Agriculture: DOE Perspective Workshop on Research and Demonstration of Agricultural Uses of Gypsum and Other FGD Materials St