# ncasi

NATIONAL COUNCIL FOR AIR AND STREAM IMPROVEMENT, IN C. P.O. Box 13318, Research Triangle Park, NC 27709-3 318 Phone (919) 941-6400 Fax (919) 941-640 1 Reid A. Miner Vice President - Sustainable Manufacturing Phone (919) 941-6407 Fax (919) 9 41-6401 e-mail RMiner@ncasi.org

Environmental research for the forest products industry May 21, 2008

TO: Ms. Becky Nicholson, RTI International

CC: Brad Upton, Ron Yeske, Al Lucier, Jay Unwin – NCASI Rhea Hale, Jerry Schwartz – AF&PA

FROM: Reid Miner

SUBJECT: Calculations documenting the greenhouse gas emissions from the pulp and paper industry

In your email of May 13, you asked a number of questions rel ated to greenhouse gas emissions from pulp and paper mills. Herein, I attempt to address some of t hose questions. The material below is drawn largely from analyses done by others on our staff, especially Jay Unwin and Brad Upton.

TOTAL INDUSTRY EMISSIONS

We have been assisting AF&PA in estimating CO 2 emissions related to fossil-fuel consumption at AF&PA member companies as part of the industry’s commitme nt in the Climate VISION program. Rhea Hale will send you a copy of the latest VISION report whi ch is now undergoing review.

In a separate effort, we have been working with the U.S . Forest Service to develop a carbon and greenhouse gas profile of the U.S. forest products industry. Although that analysis is not complete, Brad Upton has finished his calculation of total industry emiss ions related to fossil fuel consumption (CO 2 , CH 4 and N 2 O) and biomass fuel consumption (CH 4 and N 2 O). The following text is copied from the draft report containing the full profile.

“Almost all direct GHG emissions from forest products ind ustry manufacturing facilities are the result of fossil fuel combustion. The industry satisfies much of its energy requirements by also burning large quantities of biomass fuels, but the CO 2 released from biomass combustion is not included in GHG totals because it contains biogenic carbon.... S mall amounts of nitrous oxide (N 2 O) and methane (CH 4 ) are also released during combustion of biomass fuels and fo ssil fuels. [Note: These biomass-related emissions of CH 4 and N 2 O are added to fossil fuel-derived greenhouse gas emissions below.]

... Pulp and paper sector energy consumption during 1990 and 2004 were det ermined from data obtained from the American Forest and Paper Association (A F&PA). GHG emission factors from IPCC (1997) were used in conjunction with this data to ca lculate direct emissions from fuel

combustion. The IPCC Tier 1 CH 4 and N 2 O emission factors were used with the exception of

CH 4 and N 2 O from biomass fuel combustion, which were estimated using e mission factors from the International Council of Forest and Paper Associations and NCASI (ICFPA/NCASI) [reference omitted]. Emission factors are shown in Ta ble 2.1 [table omitted]. GHG emission estimates are expressed as CO 2 equivalents (CO 2 eq.) and include CO 2 , CH 4 , and N 2 O, including- 2 -

CH 4 and N 2 O from combustion of biomass fuels. Global warming potentia ls (GWPs) of 21 and

310 were used for CH 4 and N 2 O, respectively.

... Available fuel consumption data for 2004... was obtained from [AF&PA] survey responses representing 84,660,000 metric tons of production. Total US pulp an d paper sector production in 2004 (including paper, paperboard, and market pulp production) was est imated to be 102,340,000 metric tons based on data published by AF&PA (reference omi tted). Therefore, in order to arrive at a representation of the total US pulp and paper industry the emission estimates based on 2004 AF&PA energy data were multiplied by a factor of 1.21 (= 102,340,000 ÷ 84,660,000).

Pulp and paper industry manufacturing direct emissions from fu el consumption were ... 57.7 [million metric tons] CO 2 eq. in 2004...“

We have not estimated biomass-derived CO 2 emissions because they are not included in greenhouse gas emission totals in any of the protocols with which we ar e familiar. Furthermore, in our experience,

estimates of biomass-derived CO 2 emissions are never used.

GREENHOUSE GAS EMISSIONS BY EMISSION SOURCE

Our estimates of greenhouse gas emissions from combustion ar e based on corporate-wide reporting of fuel consumption preventing many of the disaggregated estima tes you seek. We have, however, generated estimates for some of the non-combustion operations you liste d and these are discussed below.

On-site landfills

Summary: NCASI’s analysis indicates that these emissions could reasonably be excluded from EPA’s registry because they are small (on the order of 1% of the industry’s direct emissions) and estimated only with great uncertainty. Additional information is provided below.

When the ICFPA/NCASI calculation tools for pulp and paper mills were first developed, the intent was to be as comprehensive as possible because (a) the tools would serve a range of purposes and (b) the experience at that point was inadequate to know whether certa in emissions were so small that they could be ignored. At the time, there were no data on the methane e missions from mill landfills, so in the interest of being as comprehensive as possible, NCASI included calc ulation methods that were based largely on estimation methods for MSW landfills. Several years ago, NCASI began work to develop estimation

methods better tailored to mill landfills.

Wastewater treatment plant (WWTP) residuals (i.e. slu dges) and ash comprise most of the material being placed in pulp and paper mill landfills (see Solid Waste Management Practices in the U.S. Paper Industry

- 1995 . NCASI Technical Bulletin No. 793, 1999). Because the ash is almost completely inert, any greenhouse gas emissions from mill landfills are likely at tributable to WWTP residuals. Therefore, to

better understand the contribution of mill landfills to metha ne emissions and carbon sequestration, NCASI conducted laboratory and field tests on several W WTP residuals. The work was only recently completed, but we can share some preliminary findings that help characterize the role of landfills.

NCASI conducted laboratory studies using the methods of Dr. Morton Barlaz at North Carolina State University. These methods are the same as those used in U SEPA studies to characterize landfill degradation of municipal solid waste, most of which have a lso been conducted by Dr. Barlaz. The laboratory studies indicate the ultimate methane yield of t he WWTP residuals and, conversely, the

fraction of the carbon in the WWTP residuals that is ess entially non-degradable under anaerobic conditions. This non-degradable fraction of the organic carbon remains stored in landfills for very long- 3 -

periods, sequestering the carbon. The laboratory studies yi eld data to calculate values for the parameter

L

o , which is the “ultimate” cubic meters of methane generate d per dry metric ton of waste.

To calculate methane generation over time using EPA’s methods, you also need to know the first order rate parameter, k. NCASI constructed field test cells and operated them for over 5 years to generate data

that could be used to estimate k. Below we summarize t he findings of both the laboratory and field

studies.

The normal method to estimate methane emissions from la ndfills assumes that the generation process occurs according to first order kinetics. The rate of gene ration is defined by two parameters, a rate parameter, k (yr- 1 ), and an ultimate yield parameter, L

o (m 3 /Mg). There are two primary ways to estimate these parameters from laboratory and field data.

1. You can let the laboratory studies define L

o and then use this value with the field data to estimate

k.

2. You can rely entirely on the field data to determine L

o and k, using regression techniques to find the values for these parameters that best fit the field data and first order kinetics.

NCASI found that the field data gave very different val ues for L

o than obtained from the laboratory tests. The reasons for this remain unclear although they may i nclude (a) a lag period in the degradation process or (b) the inability of first order kinetics to describe the field data. Because of the large uncertainty in the

estimates for L

o obtained using method 2 above, NCASI decided to rely on method 1. The results are shown below. A much larger variation in k is seen than fo r L

o , but this may be because k is based, in part, on field data that showed much more variability than t he laboratory data. To date, NCASI has been unable to explain the variability between the results for samples from different mills.

Table 1. Methane generation parameters from laboratory and fi eld data*

Residual Description k, yr - 1 L

o , m 3 /Mg

A Bleached Kraft , combined 0.0034 69.9

B Deinked, combined 0.020 73.0

C Deinked, primary 0.014 101

D Nonintegrated, primary 0.016 78.1

Average 0.013 80. 5

* L

o was obtained from laboratory tests and then used in combin ation with the field data in a regression analysis to estim ate k.

To calculate industry methane emissions over time, the avera ge values for Lo and k were used, together with data on the historical rates of placement of mill WWTP residuals in landfills back to 1970. The calculation method was the same as used by EPA and IPCC. A global warming potential of 21 was used

to convert methane to CO 2 equivalents. Methane releases in 2005 are estimated to h ave been approximately 1.2 million metric tons CO 2 equivalents. These emissions are offset, to a signifi cant degree, by carbon storage in these same landfills, discus sed below.

To understand the net impact of mill landfills, one needs to examine the potential significance of landfill sequestration as an offset to methane emissions from mi ll landfills. The carbon not degraded in the landfill, and remaining in long-term storage, can be estim ated directly from L

o by assuming that (a) the gas generated from decomposing biomass is a 50/50 mix of methane and carbon dioxide and (b) material not degraded to gas remains stored in the landfill. Using this approach, one finds that on a long-term basis- 4 -

approximately 2/3 of the carbon remains sequestered in the landfill representing a net removal of carbon from the atmosphere. Considering global warming potentials, t his is adequate to offset approximately one-half of the long-term methane emissions from these same landfills.

Consequently, while the estimates shown above for methane emissions from mill landfills are small (1.2

million metric tons CO 2 equivalents in 2005), the net emissions associated with mills landfills are smaller still. With the true net impact of mill landfills being clos er to 0.6 million tons CO 2 equivalents per year, these emissions are barely 1% of emissions related to bur ning fossil fuels at all U.S. pulp and paper mills, estimated by NCASI to be 57.7 million metric tons CO 2 equivalents in 2004.

Therefore, it appears reasonable not to include mill land fill emissions in a mandatory greenhouse gas reporting program. Not only are the emissions very small, their estimation is subject to large uncertainty associated with (a) uncertainty in the proper form of the equation describing the decay process, and (b) the unexplained variability among WWTP residuals, especially evident in the field testing.

On-site wastewater treatment

Summary: NCASI’s recent measurements of methane emissions from mill wastewater treatment plants indicate that these emissions can reasonably be excluded fr om reporting in EPA’s registry because they are small (less than 1% of the industry’s direct emission) and are estimated only with great uncertainty. Information explaining these observations follows.

As noted above, when the ICFPA/NCASI calculation tools for pulp and paper mills were first developed, the intent was to be as comprehensive as possible. At the t ime, the only recommendations from IPCC for estimating emissions from wastewater treatment were fo r methane emissions from systems that were designed to accomplish removal of organic matter under anae robic conditions. The IPCC methods for such systems, therefore, were included in the ICFPA/NC ASI tools, although it was known that there were, and still are, very few such systems in the indust ry, especially in the U.S.

In its annual inventory, however, EPA had been estimating methane emissions from a range of types of treatment plants in the pulp and paper industry. These esti mates were not based on data generated at mill treatment plants so NCASI undertook a sampling program (in conjunction with a program to measure releases of sulfur compounds) to generate data that would improve the ability to estimate these emissions. The data have been gathered and the report will be publishe d soon. The data reveal several important findings.

NCASI studies have confirmed that mechanical clarifiers and aerobic biological treatment systems with high-intensity mixing, such as activated sludge treatment systems, do not generate significant amounts of methane. Anaerobic treatment systems are known to generat e methane, but there are very few biological treatment systems in the U.S. forest products industry t hat are designed to provide treatment via the anaerobic decomposition of organic matter. There are, howe ver, a number of operations that can have zones within them that become anaerobic; namely, aerated s tabilization basins (ASBs), primary settling basins, and post-aeration basins. These emissions are est imated below.

ASB Emissions: NCASI measurements suggest that, although t here is great unexplained variability between the few systems for which emissions have been me asured, on average about 1 percent of removed BOD is converted to methane by ASBs. Several sourc es of information were used to identify 125 U.S. mills operating ASBs in the U.S. and the final e ffluent BOD loads from these ASBs. The sum of

annual final effluent BOD for all mills with ASBs wa s used to derive an estimate on incoming BOD loads by assuming a treatment efficiency of 90% across the ASB s. Using these data, the annual mass of methane emitted from ASBs was calculated to be 6,563 metr ic tons, or approximately 0.14 million metric

tons CO 2 equivalents.- 5 -

Settling Pond Emissions: In lieu of mechanical clarifier s, some mills use earthen primary settling ponds to remove suspended solids from the wastewater prior to entering an ASB or activated sludge treatment system. Temporary storage of solids in these ponds can r esult in anaerobic conditions and the subsequent release of methane. NCASI measured the methane generation rate at one primary settling pond. These data were used to generate an industry-wide estimate using statistics presented in EPA’s 1993 Technical Development Document wherein it was noted that approxima tely 10 % of U.S. pulp and paper production

is associated with treatment of wastewaters in such ponds. Using the same production data as described above, the annual mass of methane emitted from settling ponds was calculated to be 5,094 metric tons, or approximately 0.11 million metric tons CO 2 equivalents.

Post-Aeration Basins: Many mills that operate ASBs use a post-ASB (quiescent) basin to allow suspended solids to settle out. In situations where mills do not have a separate quiescent basin, they often use a non-aerated tail-end portion of the ASB to settle s olids. In either arrangement, the mixing energy is low enough that some of the solids settle to the bottom of these basins. The storage of solids in these ponds can result in anaerobic conditions and the subsequent rele ase of methane. Methane emission measurements from post-aeration basins are limited to one study by NCASI conducted at a southern Kraft mill that utilizes a quiescent basin to settle solids pr ior to final discharge. Using annual methane emission rates for this quiescent basin and the annual production for the mill, the methane emitted on a per metric ton basis was calculated. This emission rate was multipl ied by the sum of the production for all mills operating ASBs. The resulting sum of methane produced by solids in quiescent basins was 9,538 metric tons methane in 2004, equal to approximately 0.2 million metric tons CO 2 equivalents per year.

Total on-site wastewater management-related emissions: Based on the estimates above, it appears that the combined emissions of methane from industry wastewater mana gement systems were approximately 0.45

million metric tons CO 2 equivalents 2004, which is less than 1% of the emissions associated with burning fossil fuels at pulp and paper mills, according to NCASI e stimates.

It is important to emphasize that the factors used by NCASI to estimate methane releases from the industry’s wastewater treatment plants are not appropriate for use at individual mills. In some cases, for instance, NCASI scaled up from a single treatment plant t o the entire industry based only on production. Clearly, there are many mill-specific factors that th is does not consider. We know, for instance that methane emissions should be related in some way to organi c load from the mill, the degree of aeration, the basin area, the amount of settled solids in a bas in, how frequently solids are removed and perhaps other factors. All of these would be expected to affec t the methane emissions from a pulp and paper mill wastewater treatment plant but currently there is inadequat e knowledge of the mechanisms for methane generation and release to include these factors in predicti ve equations or emission factors. Consequently, there is a significant risk of unintended consequences if a reporting program is based on emission factors normalized to only one of these factors. For instance, if an emission factor is based on raw waste load, a mill that reduced methane emissions by improving mixing int ensity would not be able to show this and would actually be required to report increased methane emissions if raw waste load increased.

Accordingly, because the emissions from wastewater treatme nt plants are so small and because the uncertainty associated with estimating these emissions at individual mills is so large, it is reasonable omit them from a mandatory GHG reporting program.

On-site mobile sources and machinery

Because the estimates we make are usually based on corporate -wide fuel use data, these emissions, to the extent they are direct emissions for the company, are usuall y included in the emissions totals that we calculate. Of course, in some cases, these emissions ar e not direct emissions for the reporting company. We have been told by several companies that have examined t hese emissions that they represent around- 6 -

one percent (give or take) of a pulp and paper mill’s direct emissions, but this will of course vary depending on how large the mill’s direct emissions are.

Make up chemicals

Summary: Information from a variety of sources provide a bas is for excluding from reporting requirements the CO 2 emissions associated with purchased make-up carbonates at Kraft mills because these emissions are very small (certainly less than 0.7% of the industry’s direct emissions) and are offset, to at least some degree, by the sequestration of carbonat es in Kraft recovery system wastes in landfills. Explanatory material follows.

When companies first began estimating mill emissions of CO 2 , questions arose about how to handle the

emissions from Kraft mill lime kilns. These kilns are ve ry different from cement kilns or other types of lime kilns in that essentially all of the CaCO 3 fed to Kraft mill lime kilns contains carbon that ori ginated in the tree and is therefore biogenic. This biogenic carbon is not included in greenhouse gas totals (although the CO 2 released from burning fossil fuels in Kraft mill lime ki lns is included). To be comprehensive, the ICFPA/NCASI calculation tools included met hods to estimate the CO 2 emissions

formed via the disassociation of that small fraction o f the CaCO 3 that contains carbon not of biogenic origin. This small amount of CaCO 3 is added to the process at some mills to make up for small amounts of chemical that are lost on a routine basis. The potential significance of these make-up carbonates was examined in a paper by Miner and Upton ( Methods for estimating greenhouse gas emissions from lime kilns at Kraft pulp mills . Energy, Volume 27 No. 8, Sept. 2002). In that paper the follow ing assessment

was described.

“At some Kraft mills, a small portion of the CaCO 3 , fed to the kiln contains carbon of fossil and mineral origin. These small amounts originate in purchase d calcium carbonate and sodium carbonate that some mills use to make up normal losses of sodium and calcium from the recovery system. In most cases, the carbon in these purchased car bonates is fossil (or mineral) in origin. For several reasons, however, it is clear that these amoun ts are so small that they can be ignored in developing estimates of overall industry greenhouse gas em issions. First of all, at many mills, sodium and calcium are added to the recovery system in fo rms that do not contain carbon, such as sodium sulfate, sodium hydroxide, and calcium oxide [referen ce omitted]. Furthermore, even in

those cases where sodium- and/or calcium carbonate are use d, the amounts of make-up chemical are small. Calcium make-up, required to compensate for l osses in the recovery cycle, normally amounts to only 2 to 5% of the kiln throughput [references om itted]. As far as sodium carbonate is concerned, the United States Geological Survey (USGS) e stimates that, in 1999, the pulp and paper industry used 121,000 metric tons of sodium carbonate for all purposes [reference omitted].”

The paper goes on to indicate that “US Kraft mills release d about 9.6 million metric tons of calcium carbonate-derived CO, in 1995.” If 3.5% of this was derived f rom make-up chemicals (the mid-point of the range noted above) it would amount to 340,000 metric tons CO 2 potentially associated with the use of make-up calcium carbonate. If the 121,000 metric tons of sodium c arbonate, noted above, are converted

to CO 2 , it amounts to 50,000 tons CO 2 per year. Together, therefore, emissions related to make -up calcium carbonate and sodium carbonate are less than 390,000 tons CO 2 per year, or less than 0.7% of the industry’s direct emissions. One can be confident that the emissions are less than this, mostly because many mills compensate for calcium and sodium losses by usi ng make-up chemicals that do not contain carbon (e.g. CaO and NaOH). In addition, since the wri ting of the paper discussed above, it has been

realized that some of the calcium carbonate and sodium ca rbonate that is lost on a routine basis from the Kraft recovery system is contained in solids that are se nt to landfills where the carbon is, for all intents and purposes, permanently sequestered, representing an offs et to the small amounts of CO 2 released from- 7 -

make-up chemicals. It is evident, therefore, that the emis sions associated with make-up carbonates are very small and it is reasonable to exclude them from EPA’s reporting requirements.

Flue gas desulphurization (FGD) systems

Methods for estimating emissions from FGD systems were a dded to the ICFPA/NCASI calculation tools to address the potential that such systems are used in the pulp and paper industry. This is not, however, a process that is unique to the pulp and paper industry. Indeed, w e have never given this aspect of the tools much attention because there are very few such systems used in the U.S. pulp and paper industry.

EMISSIONS DISTRIBUTION CURVES

This is a question we have forwarded to AF&PA and I expec t that you (or EPA) will be hearing from

them.

We hope you find this information helpful.