Trash incinerators are the dirtiest way to make electricity by most air pollution measures. Even with air pollution control equipment, trash incinerators emit more pollution than (less controlled) coal power plants per unit of energy produced. Coal power plants are widely understood as the most air-polluting energy source, but few realize how much worse trash incinerators are for air quality.
This is not a radical conclusion. The New York State Department of Environmental Conservation proved, in a 2011 analysis, that the state’s 10 trash incinerators are dirtier than the 8 coal-burning power plants that were still operating at the time (all of the coal power plants have since closed, but the 10 incinerators remain). Except for sulfur dioxide, trash incinerators are dirtier than coal on the six other pollutants the state compared (nitrogen oxides, carbon monoxide, hydrochloric acid, mercury, lead, and cadmium).[1] See the chart at the bottom of this page for the summarized New York data.
Dioxins/furans: Trash incinerators are well known to be the largest source of the most toxic man-made chemicals known to science – dioxins. The latest national inventory of dioxin emissions – by the U.S. Environmental Protection Agency in 2006, looking at data from 1987, 1995, and 2000 – shows that trash incineration has gone from the largest source of dioxin emissions in 1987 and 1995 to the 4th largest source in 2000. However, if one accounts for the lack of continuous monitoring and the consequent massive underestimation of dioxin emissions from incineration, trash incineration is still the largest source of dioxins, despite the cleanup or closure of some of the dirtiest incinerators.[2]
Between 2000 and 2005, new dioxin emissions limits were implemented for trash incinerators, requiring the worst dioxin polluting incinerators to clean up or shut down. EPA and the trash incinerator industry tout that dioxin emissions from trash incinerators have been reduced by over 99% between 1990 and 2005. Even with this large reduction, and without even accounting for the aforementioned underestimation from lack of continuous monitoring, trash incinerators release 28 times as much dioxin than coal power plants do to produce the same amount of energy.[2][3][4]
Mercury is another notoriously toxic pollutant released from incinerators. It is a potent neurotoxin that accumulates in the fatty tissue of fish once in the environment. Mercury emissions from trash incineration were a close second to coal power plants in the early 1990s, which is rather incredible given the much larger size of coal power plants and the fact that there are about five times as many coal plants as incinerators. Pollution controls required on trash incinerators reduced the industry’s mercury emissions 96% by 2005.[5] However, even with this dramatic industry-wide reduction, trash incineration still put out 5.3 times as much mercury as coal plants do to produce the same amount of energy, according to the latest available national data from 2018.[5] A state-wide analysis by the New York State Department of Environmental Conservation found that, in 2009, the state’s 10 trash incinerators released 14 times as much mercury per unit of energy than the state’s 8 coal power plants – high enough that the total amount of mercury coming from the incinerators was higher than the emissions from the coal plants, even without adjusting for size (coal plants are far larger facilities).[1]
Lead is another well-known toxic chemical that diminishes intelligence and – by lowering dopamine levels in the brain – may even be tied to increases in violent behavior and cocaine addiction.[6][7][8] Trash incineration releases more than six times as much lead as coal to produce the same amount of energy.[5]
Nitrogen oxide (NOx) pollution primarily contributes to eye, nose, throat, and lung irritation and respiratory problems like shortness of breath that can trigger asthma. Trash incineration releases 3.3 times as much NOx as coal does to produce the same amount of energy.[9]
Carbon monoxide (CO) is also released from trash incinerators at rates comparable coal power plants per 1 MWh of energy produced.[5] Both NOx (directly) and CO (indirectly) contribute to the formation of ground-level ozone pollution, aggravating asthma.[11][12]
Sulfur dioxide (SO2) – famous as a cause of acid rain – is also bad for lungs, with even short exposures to ambient levels causing “bronchoconstriction and increased asthma symptoms.”[13] SO2 is one of the rare pollutants where coal plants are worse. Coal plants release two times more SO2 as trash incinerationbsp;to produce the same amount of energy.[5][9]
Hydrochloric Acid (HCl) is linked to acute bronchitis and lung cancer.[14] Trash incineration releases a whopping 27 times more HCl than coal plants to produce the same amount of energy.[5]
Carbon dioxide (CO2) – the prime global warming pollutant – is released at a rate 1.65 times that of coal power plants.[15][16][17]. By analyzing 2018 data from EPA’s Greenhouse Gas Reporting Program (GHGRP), we were able to compare data from continuous emissions monitoring systems (CEMS) on both incinerators and coal plants. Other data sources (such as EPA’s eGRID database) estimate incinerator emissions with emissions factors. However, according to EPA, “for heterogeneous fuels such as municipal solid waste, CEMS are generally considered the most accurate emissions estimation method.”[18]
While comparing incinerators and coal plants, we ruled out facilities that burn more than 5% of another fuel (to ensure a fair comparison of fuel types) and facilities that weren’t generating any energy. We also excluded facilities that aren’t primarily making electricity. This was done to ensure that we can make comparisons in terms of pollution per amount of electricity produced without overestimating pollution levels by failing to account for significant amounts of energy produced in the form of steam heat instead of electricity.
CO2 emissions from incinerators and coal plants have not changed much over time. In 2012, trash incinerators also emitted 65% more CO2 than coal plants.[15][17]
CEMS technology tracks the total CO2 coming out of the smokestack and doesn’t discriminate between the biogenic and anthropogenic fractions of carbon dioxide emissions.
The industry argues that the “biogenic” portion of CO2 emissions (that from burning paper and other organic material) should not count because trees will regrow and take the CO2 back out of the air.[19] However, studies of the alleged “carbon neutrality” of biomass incineration have shown that biomass is not truly carbon neutral, as it can take many decades for trees to reabsorb the pulse of CO2 emitted by incineration – meanwhile, the climate is heating up at a higher rate.[20] This also presumes that somewhere, trees are being replanted in sufficient numbers to eventually take up this extra carbon pollution (and that those trees aren’t being counted toward offsetting some other climate damage… and that the trees will not be cut back down as soon as it’s profitable to use them). Trash incinerators are not causing any additional tree and plant growth, so in comparison to landfills or to other energy producers, no credit deserves to be applied to zero out biogenic carbon emissions.
Comparision of pollutants with the strongest data
Using 2018 interim NEI data[5], we conducted a robust analysis of over 73 pollutants tracked by NEI that were emitted and tracked across many different types of power plants (biomass burners, gas plants, oil plants, etc.). From there, we eliminated pollutants that had fewer than 25 facilities reporting emissions (since an outlier could significantly change data) and pollutants based on modeled data. Using reliability scores (with a reliability score of 1 representing a verified measurement and a score of 5 representing the lowest data quality) from EPA’s peer-reviewed StEWI software[21], we further restricted the pollutants to those with reliability scores of 1, 2, 3 ensuring that we were only comparing pollutants with verified measurements and calculations.
| Pollutant | Coal emissions (lbs/MWh) | Coal Data Points | Incinerator emissions (lbs/MWh) | Incinerator Data Points | x times worse than coal |
|---|---|---|---|---|---|
| Lead | 4.0E-05 | 186 | 2.5E-04 | 42 | 6.2 |
| Mercury | 7.8E-06 | 188 | 4.0E-05 | 41 | 5.2 |
| Benzene | 3.2E-04 | 159 | 1.1E-03 | 30 | 3.3 |
| Nitrogen oxides | 1.5E+00 | 220 | 4.9E+00 | 51 | 3.3 |
| Toluene | 7.1E-05 | 148 | 2.0E-04 | 30 | 2.8 |
| Cadmium | 1.0E-05 | 189 | 2.4E-05 | 40 | 2.4 |
| Carbon Monoxide | 7.0E-01 | 189 | 7.1E-01 | 42 | 1.0 |
| PM2.5 Primary | 3.1E-01 | 189 | 1.6E-01 | 42 | 0.5 |
| Nickel | 6.3E-05 | 188 | 2.5E-05 | 32 | 0.4 |
| Sulfur dioxide | 2.1E+00 | 220 | 7.6E-01 | 51 | 0.4 |
- New York State Department of Environmental Conservation, “Matter of the Application of Covanta Energy Corporation for Inclusion of Energy from Waste Facilities as an Eligible Technology in the Main Tier of the Renewable Portfolio Standard Program. Case No. 03-E-0188,” Aug. 19, 2011. http://documents.dps.ny.gov/public/Common/ViewDoc.aspx?DocRefId={DEEA097E-A9A6-4E53-898C-0BC2F4C60CC4}
- “An Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States for the Years 1987, 1995, and 2000,” U.S. EPA, November 2006, Table ES‑2. http://cfpub.epa.gov/ncea/CFM/recordisplay.cfm?deid=159286 The largest sources in 2000 are considered to be backyard burn barrels (498.5 grams), followed by medical waste incineration (378 g), sewage sludge applied to land and emissions from sludge incineration (89.7 g) and trash incineration (83.8 g). The backyard burn barrel estimate is not subject to drastic differences based on test methods. 95% of medical waste incinerators have closed between 2000 and 2009. Most of the sewage sludge dioxin emissions are from land application rather than sludge incineration (since far more is dumped on farm fields than is burned). EPA admits in their inventory report (p 3–23): “Because all tests were conducted under normal operating conditions, some uncertainty exists about the magnitude of emissions that may have occurred during other conditions (e.g., upset conditions, start up, and shut down).” If the medical waste, sludge incineration and trash incineration numbers are adjusted upwards by 30–50 times to account for the fact that a 6‑hour stack test each year underestimates dioxin emissions by this amount, compared to using continuous monitoring (and if the aforementioned differences in the medical waste and sludge incineration data are accounted for), trash incineration would still be the largest dioxin pollution source by far. A newer study from the Netherlands (data from 2015 to 2017) found that actual dioxin emissions are 460–1,290 times higher than stack tests indicate. See Arkenbout, A, Olie K, Esbensen, KH. “Emission regimes of POPs of a Dutch incinerator: regulated, measured and hidden issues” http://docs.wixstatic.com/ugd/8b2c54_8842250015574805aeb13a18479226fc.pdf
- U.S. Environmental Protection Agency, Emissions & Generation Resource Integrated Database, eGRID2002 and eGRID2007 (for 2000 and 2005 electric generation data). http://www.epa.gov/egrid/
- “Emissions from Large and Small MWC Units at MACT Compliance,” U.S. Environmental Protection Agency memorandum, August 10, 2007. https://energyrecoverycouncil.org/wp-content/uploads/2016/03/ERC-070810_Stevenson_MWC_memo.pdf
- United States Environmental Protection Agency (EPA). 2018. “National Emissions Inventory (NEI)” Interim 2018 data accessed from the Emissions Inventory System (EIS)
