September 2015
Volume 6, Issue 9


Incineration, Gasification, and Pyrolysis, Oh My!
(September 2015)

Questions Linger Over Denver Zoo Incinerator

- by Josh Schlossberg, Glendale Cherry Creek Chronicle

The Denver Zoo is more than halfway through the construction of a first-of-its-kind energy facility to be fueled by elephant manure and trash -- including plastic and food scraps -- that would provide twenty percent of the Zoo's electricity, and heat its elephant exhibit.

The self-described "greenest zoo in the country" is framing its plan to convert millions of pounds of annual waste into an alternative fuel source as an environmental leap forward that will help it achieve its goal of Zero Waste by 2025.

Critics, however, including local residents, the Rocky Mountain Chapter of the Sierra Club, the former director of the American Environmental Health Studies Project, and a U.S. Environmental Protection Agency (EPA) scientist, voice concerns ranging from air pollution, undermining of recycling and composting efforts, and environmental justice issues.


The Denver Zoo gasifier will source its fuel from 750,000 pounds of elephant dung per year, along with 3 million pounds of waste from the zoo and outside sources, including: wood chips, food waste, waste paper, biodegradable plastic, non-biodegradable plastic, aluminum and other metals, according to a June 20, 2013 email exchange between EPA and CDPHE.Denver Zoological Foundation minutes state that fuel will be "87-89% biomass depending on the season."

The materials will be shredded, dried, and converted into pellets and exposed to high temperatures in a low-oxygen environment to create a combustible synthetic gas (syngas), that will be mixed with natural gas to power generators, supplying 20% of the Zoo's electricity. The leftover heat will run through pipes to heat the Toyota Elephant Passage Exhibit.

The facility is permitted as a controlled partial combustion system, with some aspects of the technology kept from the public as trade secrets. Trash and biomass gasifiers are still in the experimental stages and "not yet proven in commercial applications," according to the National Renewable Energy Labs.



Why Get Trashed When You Can Recycle?

- by Rep. Keith Ellison, MinnPost

A recent Politico article, "Minneapolis Gets Trashed,"lauded the Hennepin Energy Recovery Center (HERC) -- a garbage incinerator that burns 1,000 tons of trash per day just north of downtown Minneapolis -- as a symbol of the city's bright green future. The article was right that Minneapolis's trash policy future is bright, but it was wrong about why.

While the Aug. 20 article detailed some of the benefits of the HERC, it ignored the high costs of burning reusable materials for our health and economy. It also overlooked the far more impressive story of Minneapolis moving to zero waste policies, including composting, recycling, and reusing.

Burning trash is bad for our health. According to the Environmental Protection Agency (EPA), the average municipal solid waste incinerator actually emits more greenhouse gases per megawatt hour of energy than the average coal-fired power plant. The HERC, just like other trash burners, also emits heavy metals and toxic compounds. These toxic materials primarily affect low-income communities and communities of color. The HERC's emissions are most heavily experienced by nearby north Minneapolis -- an area with high poverty, high unemployment, and significant health issues.



Composting vs. Burning Wood in California

- by Alan Kandel, Air Quality Matters

A campaign in the form of state Assembly Bill 590 aims to designate funds from California's cap-and-trade regime as a means to help remaining state biomass facilities to continue to operate. Some may wonder whether allocating cap-and-trade auction proceeds to keep biomass operations running is wise, especially when disposing of the waste in more environmentally sound and viable ways exist.

For example, uprooted orchard trees can either be chipped in a wood chipper or shredded via a shredder; the chipped or shredded material can be returned to the soil in place of it being landfilled or field-burned. In the former application, the wood will decompose and, as it does, soils become enriched with no harmful pollutants being introduced into the air.

But how practical a solution is this? In "Up In Smoke," in the May 2003 Nut Grower Magazine issue, I presented viable ways of disposing of ag waste. In a section sub-headed "Orchard Chipping and Shredding" I wrote:

"Stanislaus County [University of California Cooperative Extension] Farm Advisor Roger Duncan and now-retired Merced County Farm Advisor Lonnie Hendricks presented their findings related to chipping and shredding in Nut Grower Magazine back in November 2001. Their article Turning an Orchard Into a 'No Burn' Zone looked at studies that were undertaken to determine the efficiency of chipping and shredding. One of the conclusions Duncan and Hendricks reached was that each pass with a tractor and shredder costs approximately $10 per acre compared to approximately $7 per acre to push brush out and burn it. They concluded chipping and shredding was initially more expensive, but the added benefit of turning the shredded material into reusable compost and returning the organic matter to the soil would produce a 'long-term agronomic value.'"

As the drought lingers and no revenue is being generated from land taken out of production, will growers take the air into consideration by opting for the most environmentally sound method going in dealing with removal of trees from the orchard -- chipping and shredding with compost being added to the soil; take a more air-unfriendly approach by transporting waste to landfills or to biomass plants (provided sufficient capacity exists to accept it); or push trees into piles and set ablaze?


The Biomass Monitor is the nation's leading publication investigating the whole story on bioenergy, biomass, and biofuels. We accept submissions at thebiomassmonitor AT

Photo: Peter Callaghan, MinnPost

Cartoon: Daryl Cagle


Josh Schlossberg, Mike Ewall, and Samantha Chirillo

Editors, The Biomass Monitor

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Indigo flowers IV.jpg


- by Josh Schlossberg, Editor

Incineration. Gasification. Pyrolysis. The bioenergy industry has many names for similar processes involving heating trash, manure, trees, and other "biomass" to produce air emissions and ash, along with electricity, heat, or liquid fuel.

Gasification and pyrolysis involve turning biomass into a gas, which then can be combusted in an engine to produce power. When employing these technologies, the bioenergy industry goes out of its way to avoid the term "incinerator" and its negative connotations.

For example, the Denver Zoo refers to its upcoming experimental facility to be fueled by manure and trash as a "biomass gasifier." However, the EPA classifies it as an Other Solid Waste Incinerator (OSWI), which are defined as "incinerators that due to their small size or other characteristics are not covered under other incinerator air emissions regulations."

Air emissions and ash are typically incinerator opponents' main concerns, which the bioenergy industry insists are the necessary byproducts of waste disposal.

What if, instead, we created more jobs in the recycling industry? What if all major cities provided free curbside compost pickup? What if we required corporations that manufacture plastic packaging and other non-reusable products to pay the costs of disposal, ultimately forcing them to produce less waste to begin with?

These are the questions that need to be asked, and incineration allows us to avoid addressing any of them.



Top 10 Biomass Stories in the News

Follow The Biomass Monitor on Facebook and Twitter for breaking news on biomass energy.

1. Group Protests Proposed Kentucky Biofuel Facility

2. Columbia, Missouri Coal-Fired Plant May Switch to Biomass

3. Not All Renewable Energy Created Equal

4. Do Liberals Hate Biofuels?

5. Fire at California's Biggest Biomass Incinerator

6. Why Are We Still Addicted to Burning Waste?

7. Residents Upset About Noise From Biomass Project

8. UK Building World's Largest Biomass Facility, Fueled by US Forests

9. Gainesville, FL Regional Utilities Keeps Biomass Facility Off-Line

10. Ethanol, A Love Story



Green or Gross? Denver Zoo to Incinerate Trash and Manure for Energy

The Denver Zoo is building a first-of-its-kind facility that would gasify/incinerate trash and manure, while providing twenty percent of the Zoo's energy, and heat its elephant exhibit.

Join The Biomass Monitor on Thursday, September 17 at 5 pm PT / 8 pm ETwhere we speak with Joan Seeman, Toxics Issue Chair of theRocky Mountain Chapter of the Sierra Club, and Bridget Walsh, founder of Denver Zero Waste, about their concerns with air pollution, zero waste, and environmental justice.

RSVP on Facebook and email thebiomassmonitor [AT] for call in number.

Download the audio file for August's call, "Energy's Water Footprint in the Western Drought."