http://www.rmrc.unh.edu/Research/current/project_60/benefits_of_ccp_use_final_rpt.pdf
The report we bring to you in this dispatch, concerning what truly are the "remarkable" economic and environmental "benefits" of utilizing Coal Ash as a basic raw material, in what are lumped together as "construction" applications, does not, we confess, originate entirely from an independent and unimpeachable academic or government source, although it was conducted by a very credible university.
However, it does, in nearly all respects, conform with and confirm similar information impeccably established by the US Government, via the Federal Highways Administration, as in our reports of:
West Virginia Coal Association | FHWA Instructs on the Use of Coal Ash in Road Construction | Research & Development; and:
West Virginia Coal Association | More Coal Fly Ash Facts for Highway Engineers | Research & Development; concerning: "Fly Ash Facts for Highway Engineers; Report Number: FHWA-IF-03-019; 2003";
wherein we're told, in part, that:
"Fly ash utilization, especially in concrete, has significant environmental benefits including: increasing the life of concrete roads and structures by improving concrete durability; net reduction in energy use and greenhouse gas and other adverse air emissions when fly ash is used to replace or displace manufactured cement; reduction in amount of coal combustion products that must be disposed in landfills; (and:) conservation of other natural resources and materials".
As an aside, we want to point out, that, over the years of our reportage, we have seen an evolution in the terminology applied to the materials, the solid residua, that result from our use of Coal in the generation of genuinely economical, truly affordable and dependably abundant electrical power.
We, here, still use the word "Ash" as a label for just about all of it. Aside from it being easier to spell, the word "Ash" does encapsulate the concept. But, it is noted that there are different, e.g., "fly" and "bottom", types of Ash; and, other, i.e., Flue Gas Desulfurization, "FGD", wastes, solid and semi-solid materials generated in a modern Coal-fired power plant.
The general label applied by industry to those materials has evolved during the long course of our research, having started out being called and thought of as "wastes"; then, as their value became a little more apparent, "Coal Combustion By-Products". "CCB's"; and, now, giving them a status comparable to electricity, "Coal Combustion Products", "CCP's".
As another aside - - and, yes, we are compelled to bring it up - - we, here, think that, as seen for only one out of now many examples in:
West Virginia Coal Association | CO2 to Alcohol and Diesel Fuel | Research & Development; concerning:
"United States Patent 8,212,088 - Efficient and Selective Conversion of Carbon Dioxide to Methanol, Dimethyl Ether and Derived Products; July 3, 2012; Inventors: George Olah and G.K. Surya Prakash;
Assignee: University of Southern California; Abstract: An efficient and environmentally beneficial method of recycling and producing methanol from varied sources of carbon dioxide including flue gases of fossil fuel burning powerplants, industrial exhaust gases or the atmosphere itself. Converting carbon dioxide by chemical or electrochemical reduction secondary treatment to produce essentially methanol, dimethyl ether and derived products";
another, falsely-maligned substance is more than worthy of such status, as well.
In any case, herein, we learn that some effort has been applied to figuring out just what specific economic and environmental benefits do accrue to our current use of Coal Ash as a raw material in various aspects of the general field of "construction"; and, what additional benefits might accrue to an increased use of Ash.
There is, however, one rather, to us, startling omission in the study and in the data presented; as we make note of in, and comment on following, excerpts from the initial link in this dispatch to:
"Quantifying the Benefits of Using Coal Combustion Products in Sustainable Construction
Draft Final Report, December 2009
(Note that this report is available on the web from several different sources, but all of them, still nearly three years after this initial publication, are labeled "Draft".)
K. Ladwig, EPRI Project Manager
Electric Power Research Institute; Palo Alto, California
(We have cited the Electric Power Research Institute, EPRI, a few times previously. They are an industry group that represents the entire power generation sector, including those segments which rely on nuclear and environmental sources of energy. It is not a "Coal" trade organization. More can be learned via:
Electric Power Research Institute and EPRI | About EPRI > Overview: "The Electric Power Research Institute, Inc. (EPRI) conducts research and development relating to the generation, delivery and use of electricity for the benefit of the public. An independent, nonprofit organization, EPRI brings together its scientists and engineers as well as experts from academia and industry to help address challenges in electricity, including reliability, efficiency, health, safety and the environment. EPRI also provides technology, policy and economic analyses to drive long-range research and development planning, and supports research in emerging technologies. EPRI's members represent more than 90 percent of the electricity generated and delivered in the United States, and international participation extends to 40 countries.")
This report was prepared by: Recycled Materials Resource Center University of Wisconsin-Madison Madison, Wisconsin; Principal Investigators: C. Benson (and) T. Edil.
(Home - Recycled Material Resource Center - 3G;
Craig H. Benson, Geological Engineering - College of Engineering @ The University of Wisconsin-Madison;
Edil, Tuncer B.)
Acknowledgements: This report was prepared by the Recycled Materials Resource Center using financial support from the Electric Power Research Institute (EPRI). Ken Ladwig was the project manager for EPRI. The following persons provided valuable input to the study: Jeff Daniels and Jessica Sanderson (United Gypsum Company); Jim Johnson and Keith Bargaheiser (Headwaters Resources); Mike MacDonald, Tom Adams, and Dave Goss (American Coal Ash Association); Lyn Luben (U.S. Environmental Protection Agency); Jack Gibbons (CSRI); Tony Fully (National Gypsum Company); John Foster (Boral Material Technologies, Inc.); and Paul Koziar (Koziar Consulting LLC).
Executive Summary: Life cycle analysis programs were used to quantify the benefits of using coal combustion products (CCPs) from electric power production in sustainable construction. The analysis focused on the most ubiquitous CCPs (fly ash, bottom ash, and flue gas desulphurization (FGD) gypsum) and their most common applications (concrete production, wallboard manufacturing, and geotechnical applications) as identified through an analysis of industry CCP use data for 2007.
Comparisons were made between energy consumption, water use, and greenhouse gas (GHG) emissions associated with conventional materials and procedures and those employing CCPs.
The analysis showed remarkable benefits are obtained by using CCPs in sustainable construction:
Energy consumption is reduced by 162 trillion Btu;
water consumption is reduced by 32 billion gallons;
GHG emissions are reduced by 11 million tons CO2e (equivalent); and:
$5-10 billion is saved.
The reduction in energy consumption is commensurate with the energy consumed by 1.7 million homes (a large US city), the water saved is equal to 31% of the annual domestic water use in California, and the reduction in GHG emissions is comparable to removing 2 million automobiles from the roadway.
The financial savings can also provide the average income for approximately 200,000 Americans.
The greatest environmental benefits in sustainable construction are currently being realized by using CCPs (mainly fly ash) in concrete production.
Use of fly ash as a cement substitute annually saves more than 55 trillion Btus of energy ((roughly) equivalent to 600,000 households) and reduces GHG emissions by 9.6 million tons CO2e ((roughly) equivalent to 1.7 million passengers cars).
Using FGD gypsum in wallboard manufacturing results in more energy savings (98.2 trillion Btu annually) and greater reduction in water consumption (31 billion gal, or approximately three times the annual water use in Arizona or Nevada), but a smaller reduction in GHG emissions (0.74 million tons CO2 emitted or 100,000 passenger cars).
Smaller savings in energy consumption, water consumption, and GHG emissions are realized from geotechnical applications at current usage rates.
The greatest financial benefits are obtained by using FGD gypsum in wallboard manufacturing, followed by use of fly ash in concrete, and geotechnical applications. The financial benefits are closely aligned with the reductions in energy consumption and GHG emissions and the total amount of CCPs used.
(Note that the above is applicable only in, and is limited by, the context of this study and report, which did not address, as we indicated in our introductory comments and as explained further on, the potentials for consuming Coal Ash as a raw material in the actual making of Portland-type Cement itself. Such usage, we are convinced, would offer the by far "greatest financial benefits".)
Benefits are also achieved by avoiding disposal; 3.7 trillion Btu of energy is saved (38,600 households) and CO2 equivalent emissions are reduced by 0.3 million tons (46,300 automobiles) by not disposing CCPs in landfills. The financial savings obtained by avoiding disposal ranges between $0.5-5.3 billion/yr depending on the disposal approach (on-site vs. commercial) and the type of disposal facility (Subtitle D vs. Subtitle C).
Introduction: Coal combustion accounts for 42% of all fossil fuel consumed for energy production in the United States, and contributes to 50% of the electrical power generating capacity of the nation (EIA 2009). Use of coal as an energy source has continually increased over time and coal will continue to be an important fuel for the foreseeable future. As a result of increased coal use and new air emissions controls, the production of coal combustion products (CCPs) as a byproduct from pollution control systems is also steadily increasing. In 2007, 131.1 million tons of CCPs were produced in the United States (ACAA 2008). Fly ash (71.7 million tons), bottom ash (18.1 million tons), and gypsum from flue gas desulphurization (FGD) operations (12.3 million tons) constitute the majority (78%) of the CCPs produced annually. Beneficial use in construction applications consumed 47% (48.2 million tons) of the fly ash, bottom ash, and FGD gypsum that was produced in 2007.
The remaining 53% (53.9 million tons) was disposed in impoundments or landfills.
Fly ash is a fine powdery material collected from the exhaust of a coal combustion chamber that is pozzolanic and can be cementitious. The majority of fly ash use is associated with cement and concrete (55% of total used), with partial replacement of Portland cement in concrete the most common use (43% of total used) (ACAA 2008).
Geotechnical applications, which include road base and subbase, soil stabilization, and embankments/fills, are also significant uses of fly ash (28% of total used) (ACAA 2008).
Bottom ash is a coarse granular residue (gravel and/or sand-size particles) from coal combustion that has similar chemical composition as fly ash (EPA 2008, FHWA 2008). Because the particles are larger, bottom ash is used as substitute for conventional aggregates (sands and gravels), primarily in geotechnical applications (55% of total used) (ACAA 2008).
FGD gypsum is a byproduct of flue gas desulphurization at coal-fired power plants that use wet scrubbers and forced oxidation to reduce SO2 emissions. The gypsum produced by the desulphurization process is mineralogically identical to natural gypsum (CaSO4•2H2O), making FGD gypsum an ideal replacement for mined gypsum used to manufacture wallboard.
In 2007, 75% of FGD gypsum produced was used beneficially, 90% of which was used to produce wallboard. Other significant uses of FGD gypsum include agriculture and cement/concrete production (ACAA 2008).
Use of CCPs in construction materials has been steadily increasing, and in some applications (e.g., wallboard, Portland cement concrete) CCPs are now considered as standard or required materials in manufacturing and construction.
The fraction of CCPs used beneficially is increasing due to the desirable attributes of CCPs as construction materials and greater interest in sustainable construction and development. For example, production of Portland cement accounts for 5 to 8% of annual CO2 emissions worldwide. Replacing a portion of the Portland cement with fly ash reduces the CO2 emissions associated with production of Portland cement proportionally.
Energy and water use associated with cement production are also reduced. These savings are accrued because the fly ash is used essentially “as is;” no processing or transformation is required, thereby eliminating emissions and resource consumption associated with creating a construction material.
Although the contribution of CCPs in construction to sustainability is logical, a comprehensive quantitative assessment of beneficial use of CCPs has not been conducted (past studies focused on one material, such as concrete or wallboard). The study described in this report was conducted to quantify the environmental and economic benefits of using CCPs in each of the major construction applications. The focus was on fly ash, bottom ash, and FGD gypsum because of the preponderance of these CCPs relative to other byproducts of coal combustion.
The analysis focused on the benefits of using CCPs in terms of reductions in greenhouse gas (GHG) emissions, consumption of energy and water, and economic savings. Avoidance of landfill disposal costs was also considered in the analysis.
Methodology for Determining Benefits: The environmental and economic benefits of CCP use were quantified by computing differences in energy expenditure, water consumption, and global warming potential between conventional materials and those produced with CCPs ... .
Three major applications were considered: concrete, wallboard, and geotechnical applications using fly ash, geotechnical applications using bottom ash. Total annual benefits were obtained as the product of unit benefits for energy, water, or GHG emissions and the most recent annual beneficial use quantity (in tons) provided by ACAA (2008). Unit financial savings for energy and water were generated using financial data in NPGA (2006). The market price of CO2 was obtained from the Chicago Climate Exchange (CCX) (Chicago Climate Exchange 2009). All financial quantities were adjusted to 2009 US dollars.
Fly Ash Use In Concrete
The analysis assumed that 0.24 ton of cement was required to produce 1 ton of concrete. Conventional concrete was assumed to contain no CCPs. For concrete manufactured with CCPs, 15% of the Portland cement was replaced by fly ash at a 1:1 (by weight) substitution ratio. Discussions with representatives in the ready-mix concrete industry indicated that this replacement rate is conservative (i.e., higher rates are common in practice). FHWA (2003) and PCA (2009) also suggest that 15-30% of the Portland cement in concrete can be replaced by fly ash.
(Note the following statement of gross omission, as we alerted you to in our introductory comments.)
Use of fly ash or other CCPs in manufacturing the cement used in concrete was not incorporated in the analysis.
(Comment concerning the above omission follows additional excerpts.)
FGD Gypsum In Wallboard Manufacturing
Unit benefits of using FGD gypsum as a substitute for conventional gypsum in wallboard manufacturing were obtained from USEPA (2008) analyses ... . The USEPA (2008) analysis considered wallboard manufactured with 100% natural gypsum or 100% FGD gypsum.
All other factors in wallboard manufacturing using natural or FGD gypsum are essentially the same and therefore cancel out in a comparative benefits analysis. For example, calcining of natural gypsum and FGD gypsum consumes the same amount of energy per mass of gypsum that is processed. Transport of natural gypsum can require greater energy and result in greater emissions than FGD gypsum, especially as wallboard manufacturing plants are being constructed adjacent to coal-fired power plants employing wet scrubbers for FGD.
(Tabular data, which we cannot reproduce in our excerpts, seems to indicate that cost savings in excess of three hundred dollars per ton, due to all factors involved, can be achieved when using Coal power plant FGD Gypsum to replace mined natural Gypsum specifically in wallboard manufacturing applications. That does, in fact, seem high to us, for a couple of reasons; but, it is what the tabulated data seem to present.)
The greatest environmental benefits in sustainable construction are currently being accrued through the use of CCPs (mainly fly ash) in concrete production. Use of fly ash as a cement substitute annually saves more than 55 trillion Btus of energy annually (≈equivalent to 600,000 households) and reduces GHG emissions by 9.6 million tons CO2 emitted (roughly equivalent to 1.7 million passengers cars). Using FGD gypsum in wallboard manufacturing results in even more energy savings (98.2 trillion Btu annually) and greater reduction in water consumption (31 billion gal, or approximately three times the annual water use in Arizona or Nevada), but a much smaller reduction in GHG emissions (0.74 million tons CO2 emitted or 100,000 passenger cars). Geotechnical applications of CCPs result in much smaller savings in energy consumption, water consumption, or CO2 emissions at current usage rates. Financially, the greatest benefits are obtained by using FGD gypsum in wallboard manufacturing, followed by use of fly ash in concrete, and geotechnical applications. The financial benefits are closely aligned with benefits associated with reductions in energy consumption and GHG emissions.
The reductions in energy use, water consumption, and GHG emissions are primarily obtained by offsetting production of conventional materials (e.g., use of fly ash in concrete precludes the need to produce some Portland cement). CCPs are byproducts of energy generation and are not produced specifically, as are the construction materials they replace. Consequently, the resources embodied in their production are accounted for in electricity production and are expended regardless of whether CCPs are used beneficially.
Summary and Conclusions: This study has quantified the environmental and economic benefits from each major use of fly ash, bottom ash, and FGD in sustainable construction. Savings associated with reductions in energy and water consumption and lower GHG emissions are primarily accrued by offsetting the need for material production.
CCPs are byproducts of energy generation and are not produced specifically as the construction materials they replace. Consequently, the resources embodied in their production are accounted for in electricity production and are expended regardless of whether CCPs are used beneficially.
The total environmental benefits obtained by replacing conventional construction materials with CCPs are remarkable. Annually, approximately 162 trillion Btu of energy is saved, 11 million tons of CO2 emissions are avoided, and 32 billion gallons of water are not consumed.
These quantities are comparable to the energy use by homeowners in a large US city and the emissions associated with approximately 2 million automobiles. The financial savings are large as well - $5-10 billion is made available for other uses by using CCPs in sustainable construction. These quantities indicate that CCP use in construction contributes significantly to sustainability in the US, and should be nurtured and enhanced if possible."
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And there remains, as the authors confess, and as we noted in the text, one glaring omission:
"Use of fly ash or other CCPs in manufacturing the cement used in concrete was not incorporated in the analysis."
But, as seen in, for one example:
Pittsburgh Converts Coal Ash and Flue Gas into Cement | Research & Development; concerning: "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste; 1998; Assignee: Dravo Lime Company, Pittsburgh; Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide released from the calcium sulfite hemihydrate and calcium sulfate hemihydrate during calcination may be used to produce sulfuric acid, while heat recovered in the process is used to dry the agglomerating feedstock. Claims: A process for producing cement from a flue gas desulfurization process waste product, comprising: providing a moist flue gas desulfurization process waste product containing 80-95 percent by weight of solids of calcium sulfite hemihydrate and 5-20 percent by weight of solids of calcium sulfate hemihydrate; adding a source of aluminum, iron, carbon, and a siliceous material to said flue gas desulfurization process waste product to form a moist mixture thereof; calcining said dry agglomerated kiln feedstock in a rotary kiln to produce a cement clinker; and pulverizing said cement clinker to produce cement. The process for producing cement from a flue gas desulfurization process waste product ... wherein said source of aluminum and iron comprises fly ash";
Coal Ash certainly can be consumed in "manufacturing the cement used in concrete", with additional "remarkable benefits".
As can be learned via:
U.S. Cement Production Flat Following 2009’s Big Decline | ENR: Engineering News Record | McGraw-Hill Construction; Engineering News-Record; "Cement production in the U.S. leveled off in 2010 after steep declines in 2009, says the Portland Cement Association. Total cement production ... in 2010 (even with) production falling (was) 63.75 million tons";
the potential market for Coal Ash in such cement-manufacturing applications is very significant; and, the amount of Coal Ash which could be thus utilized is truly "remarkable".
And, the fact that it is only, at this time, a mostly "potential" market, might be the reason the University of Wisconsin excluded such applications from this study. They were, and it is important to keep in mind, focused on actual current use of Coal Ash, not potential uses, practical and valuable though they might be.
In sum, a rather vast market and business opportunity exists for United States Coal Country, with all of the additional employment and tax revenue "benefits" that implies, through advancing the commercial and industrial usage of the solid byproducts arising from our essential use of Coal in the generation of truly economical and affordable electric power.
As scientists at the University of Wisconsin's Recycled Materials Resource Center herein put it:
Coal Ash "use in construction contributes significantly to sustainability in the US, and should be nurtured and enhanced".
