Another (unsustainable) Initiative

See p. 11 of the 2015 National Western Center Regeneration Framework  authored by ME Engineers:

9.4 Adding Renewable Energy – Waste to Energy

Instead of hauling off non-recyclable municipal solid waste (MSW) to landfills, there are several options to convert it to energy. NWC can incinerate it on-site. The waste heat can be used to generate steam. One option is to use steam turbines to produce electricity. The exhaust fumes of the incinerator must be controlled so it’s not contributing to local air pollution.

The other option: ‘gasification’ is a unique process that transforms any carbon-based material, such as MSW, into energy without burning it. Instead, gasification converts the materials into a gas by creating a chemical reaction. This reaction combines those carbon-based materials (known as feedstocks) with small amounts of air or oxygen, breaking them down into simple molecules, primarily a mixture of carbon monoxide and hydrogen, and removing pollutants and impurities. What’s left is a clean ‘synthesis gas’ (syngas) that can be converted into electricity and valuable products. With gasification, MSW and other types of wastes are no longer useless, but feedstocks for a gasifier. Instead of paying to dispose of and manage the waste for years in a landfill, using it as a feedstock for gasification reduces disposal costs and landfill space, and converts those wastes to electricity and fuels.


Response to the Denver Post

We recently read The Denver Post’s poorly thought out editorial titled “Let Denver Zoo convert animal waste to fuel.” The editorial is just that, an opinion piece that ignores facts regarding the Denver Zoo’s waste to energy machine. Below we dismantle select statements from The Post‘s opinion piece:

  • Let Denver Zoo convert animal waste to fuel.”

First, the title of the editorial indicates the authors show a weak understanding of the environmental regulatory process. “Let” implies allow. If the EPA and state regulators find the machine is not in compliance with environmental laws and regulations, the Zoo will not be granted final operating permits. All permits to date are draft.

Secondly, the Zoo’s proposed waste stream is not only animal waste. In fact, according to the Zoo’s own document, the waste stream is comprised of 90-92% organics (woodchips, all animal waste, cardboard, food waste, yard trimmings, alfalfa, hay, waste paper, paperboard) and 8-10% (PLA plastic, PET plastic, HDPE/LDPE plastic).

This “plant” would “convert” paper products (possibly chlorinated and containing formaldehyde),  PLA (compostable) plastics, and HDPHE/LDPHE plastics to pellets to make syngas. This process would possibly release toxic chemicals such as dioxin, considered a persistent organic pollutant. Through the Stockholm Convention, the international community is working towards a ban of these chemicals (Annex C).

  • The Denver Zoo has suddenly run into a buzz saw of ill-advised opposition over its endeavor to install a waste-to-fuel plant that would convert animal poop and other waste into a power source.

We are not sure what constitutes “a buzz-saw of ill-advised opposition.” In a representative democracy, citizens have a right and obligation to investigate and ask questions of their government, especially on matters that directly affect them.

The Post opinion piece ignores the fact there was opposition to the Zoo’s machine by a major neighborhood organization and citizens. There was also lack of public comment, which was recognized in an October 2014 memo to Councilman Christopher Herndon written by former Department of Environmental Health (DEH) Executive Director Doug Linkhart.

As we have pointed out, while we recognize the Zoo advertised the project, it did not educate. In fact, the Zoo appears to not understand the basic principles of risk communication.

We recommend The Post Editorial Board spend an afternoon, maybe two or three, reading the official documents we have provided at our expense to educate the public and City officials.

  • The inventive $3.3 million biomass gasification process would shred and dry the material into pellets that would be heated at temperatures up to 1,470 degrees in an oxygen-starved environment, creating a gas that would power generators.

The Post is correct the Zoo’s project is “inventive.” The machine is invented by two Zoo officials, who we speculate, may have something to gain from the adoption of this machine in settings besides the Denver Zoo. One need only read the patent to question this experimental technology projected for operation in a neighborhood setting. In July, 2014, the Zoo asked CDPHE for a waiver for reporting a “detailed engineering description of the incinerator” including air pollution control equipment.

  • The zoo expects the plant would eliminate 1.5 million pounds of waste it trucks every year to the landfill and cut the amount of electricity it pulls from the grid by 20 percent.

We have not completed a comprehensive review, but from our perspective, the Zoo could increase its composting by diverting PLA compostable plastics from the incinerator; it could also increase its composting of dung (the Zoo sends out about 20 yards of manure twice a week for composting). Currently, the Zoo includes PLA plastics in its waste stream for the OSWI (Other Than Solid Waste Incinerator). These plastics are designed for composting, not used as potentially toxic fuel.

Solar, wind, and net zero building principles might have been employed by the Zoo, as well as true zero waste principles, which emphasize “designing and managing products and processes to systematically avoid and eliminate the volume and toxicity of waste and materials, conserve and recover all resources, and not burn or bury them” (Zero Waste Alliance, 2009).  In addition, it is not clear why the Zoo ceased production of Zoop fertilizer, a partnership with A1 organics.

But the biggest elephant in the room, no pun intended, is the Zoo’s waste to energy project is completely disconnected from the City and County of Denver’s municipal solid waste plan. This is even more a source of concern for Denver citizens.

  • The main source of agitation is over potential air quality problems in the park and surrounding neighborhoods.

Agitation? We suggest that what The Post Editorial Team views as “agitation” is public participation and citizen oversight, both essential to the democratic process and necessary for government accountability.

  • The zoo has been open about its plans since 2009. An article about the plant was included in a zoo publication that went to 65,000 people and information about the plant has been featured on the zoo’s website, e-newsletter and through large scale public events. Zoo officials met with council members, held open houses and tours of the building, presented plans to neighborhood groups and the parks advisory board and even held its own public hearing.

To repeat, The Post ignores the facts. There was opposition to the Zoo’s machine. There was also lack of public comment and relatively low public attendance at the Zoo’s presentations. But the most disturbing fact that remains is that public officials did not fully question the environmental impact on the Denver neighborhoods that surround Denver Zoo, the Natural History Museum,  and City Park.

  • A 51-page engineering design and operations plan explained the project’s technical aspects.

We assume the editorial board refers to the Engineering Design and Operations Plan? If so, we have pointed out many deficiencies of this document and other official documents posted here at our blog.

In addition, we have not located any documents that explain how the Zoo’s machine escaped scrutiny on the matter of zoning. Perhaps The Post might concentrate – as the fourth estate – on investigative journalism to unearth how the waste-to-energy system was zoned in a densely populated urban setting.

  • The only way the council can officially withdraw its support is if something has gone wrong. And that hasn’t happened. The project should move forward. We hope that it will become a model for how institutions can deal with waste and generate energy without endangering the health of the public.

In our opinion, the entire process has “gone wrong.” Important questions remain as to

_ adequate health risk assessments;

_ a completed waste management plan that fully informs the public and regulators as to operations, waste streams, and possible risk;

_ concerted efforts to deal with waste in a truly sustainable way that avoids the release of toxic air pollutants and ash;

_ effect of Zoo’s system on property values;

_ funding of the project;

_ who benefits financially.

The Post Editorial Board is profoundly uniformed, and as such, its recommendations to “move forward” are simply based in opinion, not the facts and questions that would assist the public in understanding anything significant about the Zoo’s project and its impact on their neighborhood and quality of life.

This “editorial” could have just as well been written by one of the Zoo’s several paid public relations staff persons rather than by what should be a group of studied and experienced journalists.

Denver Zoo, Zero Waste Program (Biomass Gasification)

Here’s the description of the gasifier from the Rocky Mountain Chapter, ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) 2015 conference:

Denver Zoo’s Waste to Energy Program will convert 90% of the Zoo’s waste (from trash to animal waste) to clean, sustainable energy by using a biomass gasification system. The process of becoming a zero waste facility by 2025 starts with reducing the waste stream and promoting recycling and ends with converting remaining waste to energy. The biomass gasification project will chemically convert zoo waste in a high temperature, low oxygen process into a usable combustible gas. The resulting energy generated is expected to meet 20% of the zoo’s energy needs while managing the expectations of the owner and design team.

But does the use of the gasifier really reflect zero waste principles?

Vote (of no confidence) for Denver Zoo’s Gasifier

Via youtube, a video circa 2010 illustrating the potential waste stream for the Zoo’s gasifier. Materials – including park trash consisting of what appears to be cholorinated paper products and PLA plastics (which could be composted)  – are shredded, “pelletized,” then utilized to manufacture “syngas” or synthetic gas.

The video doesn’t mention potential pollution to surrounding City Park neighborhoods, any air scheduled monitoring, toxic emissions from the gasifier, and ash that is generated and most likely treated as a hazardous waste. So where are the “energy” savings from cradle to grave? Adhering to true zero waste principles?



Deconstruction of the CD

A  certificate of designation (CD) is

a document issued by the local governing body authorizing the use of land for a solid waste disposal site or facility. The CD is issued if it has been determined that the technical standards set out in regulation are met and after local issues are considered and satisfied. Anyone operating a facility for solid waste disposal where processing, treatment, or final disposal of solid waste is performed must obtain a certificate of designation (6 CCR 1007-2 Section 1.3.3).  Examples of such facilities include municipal solid waste landfills, certain private solid waste landfills, composting facilities, and solid waste incinerators.


The Zoo’s undated Executive Summary – Certificate of Designation Application — Denver Zoo Waste-to-Energy System  (submitted by Denver Zoological Foundation, Inc., as Applicant) is an interesting public document for several reasons.

First, the Denver Zoo describes the “machine” as “part of an innovative waste to energy system.”

Secondly, the Zoo’s CD acknowledges an existing incinerator housed at the Denver International Airport (DIA), permitted by an 8/28/2000 Denver City Council Bill 0652, Ordinance 2000-0696);  the Zoo’s Executive Summary states “the last CD application that was reviewed and approved by Denver City Council was Denver International Airport CD September 5, 2000. Ordinance #696 Council Bill 652.”  By mentioning the DIA incinerator in its Executive Summary, are we to take the Zoo is justifying the use of a polluting technology?

Third, the Zoo’s public outreach process has failed.  We find there is a distinction between between advertising /marketing and public education on pollutants and potential harm to individuals and nature from the “waste to energy system.”  While the Zoo is correct in its CD that it “has been sharing the story of the planned waste to energy system publicly for several years” and probably utilized “used far-reaching communication channels including a member publication reaching $65,000 area,” we pose that if a poll was done of residents who live in the Zoo-City Park vicinity, would they be aware of the Zoo’s plans? How upset conditions (when the flare or gasifier malfunctions) would impact residential neighborhoods?

Furthermore, the Zoo is mistaken about Inter-Neighborhood Cooperation’s (INC) support of the project, including its actions that “formally voted to support the project.” INC did not support the waste to energy project. In fact, on its Web site, INC states “we did not have enough information to make an informed decision.”

Lastly, the CD is interesting for its list of appendices to the Engineering Design and Operations Plan (EDOP). Some of the Appendices are available at the City Council’s site. Some are not. None of the “appendices” are labeled as appendices to the EDOP, making learning about the Zoo’s project increasingly difficult.


Also see draft bill CB 14-0941 dated December 10, 2014 Ordinance granting a certificate of designation for the “waste to energy system,” which is unsigned; the Zoo created a handout (no date) describing the certificate of designation process to the Denver City Council. In this “process” document, the Zoo states the project is  “planned for no effects on nearby surroundings.”