The tool for the reduction and assessment of chemical and other environmental impacts (TRACI) is described along with its history, the research and methodologies it incorporates, and the insights it provides within individual impact categories.
TRACI, a stand‐alone computer program developed by the US Environmental Protection Agency (USEPA), facilitates the characterization of environmental stressors that have potential effects, including ozone depletion, global warming, acidification, eutrophication, tropospheric ozone (smog) formation, ecotoxicity, human health criteria–related effects, human health cancer effects, human health noncancer effects, fossil fuel depletion, and land‐use effects. TRACI was originally designed for use with LCA, but it is expected to find wider application in the future (Bare 2003; UNEP‐SETAC 2000).
The categories of odor, noise, radiation, waste heat, and accidents are outside of the USEPA’s purview and are usually not included within case studies in the United States for various reasons, including, perhaps, because the perceived threat from these categories is often considered minimal, local, or difficult to predict. The resource depletion categories are recognized as being of significance in the United States, especially for fossil fuel, land, and water use.
For the development of TRACI, each of the above impact categories was considered and its current state of development and perceived societal value were assessed. The traditional pollution categories of ozone depletion, global warming, human toxicology, ecotoxicology, smog formation, acidification, and eutrophication were included within TRACI because various programs and regulations within the USEPA recognize the value of minimizing effects from these categories. The category of human health was further subdivided into cancer, noncancer, and criteria pollutants (with an initial focus on particulates) to better reflect the focus of renewable fuels, and purchased electricity used. Emissions from wastewater treatment plant and other biological processes are not included. In Washington State, 60% energy used in the pulp and paper mills are generated from renewable sources (almost all from hydro) and 40% from purchased electricity generated from natural gas, coal, and oil. The CO2 emissions from renewable energy sources assumed zero. Typical values of 70% combustion efficiency and 60% electricity transmission efficiency were assumed. For an overall efficiency factor of 42% in calculating CO2 emissions from nonrenewable sources, power‐generating plants to pulp mills were used.
USEPA regulations and to allow methodology development consistent with US regulations, handbooks, and guidelines (USEPA 1989b, c). Smog‐formation effects were kept independent and not further aggregated with other human health impacts because environmental effects related to smog formation would have become masked and/or lost in the process of aggregation. Criteria pollutants were maintained as a separate human health impact category, allowing a modeling approach that can take advantage of the extensive epidemiological data associated with these well‐studied impacts.
Model Input and Output
It is important to note that data quality is fundamental to LCA and its interpretation. Some of the data quality issues such as reliability and consistency can be overcome by using standardized database, which are starting to emerge after years of data compilation and their incorporation into publicly and commercially available databases. Table 6.7 presents some chemical release data that are used in TRACI. Table 6.8 presents the overall environmental and human health impacts, including global warming, smog formation, human health criteria pollutants, acidification, eutrophication, and ecotoxicity. The results indicate that biopulping has a lower environmental impact than that of the TMP process because of its reduced energy consumption. Biopulping also has a lower impact than that of chemical pulping in all the measures except global warming. One should note that the total CO2 production per ton was the highest for chemical pulping, but because kraft recovery furnaces are fired with lignin derived from the wood, a renewable resource, this contribution to GHGs was assumed to be net zero. Figure 6.10 shows global warming characterization results predicted by TRACI.
These results likely indicate that biopulping is the preferred process when the electrical supply is dominated by renewable energy sources. In cases where the fuel mix for producing electricity is largely fossil fuels, chemical pulping provides a process powered by renewable energy but at a cost of higher hazardous waste emissions.
In conclusion, this streamlined LCA clearly indicates that biopulping in the papermaking process has several advantages over chemical and mechanical processes as follows:
Table 6.7 Emissions from chemical‐, mechanical‐, and bio‐pulping and papermaking processes, 1000 T OD per day.
| Pollutant | Chemical | Mechanical | Bio (TMP) |
| Acetone (lb) | 1.5 × 103 | — | — |
| BOD (lb) | 4.4 × 103 | 1.76 × 103 | 1.76 × 103 |
| CO2,a (lb) CO (lb) | 3.5 × 106 5.5 × 104 | 8.0 × 106 5.5 × 103 | 5.5 × 106 5.5 × 103 |
| Chloroform (lb) | 8.5 × 102 | 7.5 × 102 | 7.5 × 102 |
| COD (lb) | 6.0 × 103 | 1.0 × 103 | 5.0 × 102 |
| Ethanol (lb) | 5.0 × 102 | 5.0 × 101 | — |
| H2S (lb) Isoprene (lb) | 2.35 × 103 1.0 × 103 | — 1.0 × 103 | — 1.0 × 103 |
| Methane (lb) | 8.2 × 103 | 2.7 × 103 | 2.7 × 103 |
| Methanol (lb) | 2.3 × 103 | 6.0 × 102 | 6.0 × 102 |
| Nitrogen (lb) | 7.5 × 102 | — | — |
| NO2 (lb) NO (lb) | 3.5 × 104 3.5 × 104 | 1.0 × 103 1.0 × 103 | 5.0 × 102 5.0 × 102 |
| SO2 (lb) | 1.75 × 104 | — | — |
a CO2 emissions would depend on actual nonrenewable energy sources.
Table 6.8 Environmental and human health impacts characterization results in percentage for chemical‐, mechanical‐, and bio‐pulping processes using TRACI.
| Impacts % | Chemical | Mechanical (TMP) | Bio‐pulping (TMP) |
| Global warming | 21 | 47 | 32 |
| Photochemical smog | 44 | 28 | 28 |
| Acidification | 97 | 2 | 1 |
| Ecotoxicity | 36 | 32 | 32 |
| Human health cancer | 36 | 32 | 32 |
| Human health noncancer | 36 | 32 | 32 |
- Reduced electrical energy consumption (at least 30%) over mechanical pulping
- Potential 30% increase in mill throughput for mechanical pulping
- Improve paper strength properties
- The TRACI model indicates a significant reduction in environmental and human health impacts
- The biopulping process proves to be more sustainable in terms of not only economic advantage but also environmental and human health benefits
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