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Project History and Evolution

The NYC Department of Environmental Protection is the City agency responsible for handling the City's wastewater treatment, and the vast amount of sewage biosolids it generates.  For several years, I've been in touch with the DEP's biosolids manager, who prefers not to be named. She is able to tell me some things, with other information remaining confidential.  As DEP gradually moves forward with its plans for handling biosolids, what she is able to share has changed. 

I've also been in correspondence with staff at Aries Energy, which is building a biosolids gasification plant in Linden, NJ, who has been as forthcoming as he can.  Between the two, I've been able to connect some dots.


During some long conversations with Albert Bates, author of The Biochar Solution, I learned that an important way to promote carbon sequestration through biochar in NYC would be by advocating for better processing of its sewage sludge.  A year later, I had a clearer idea of what that would look like. 


In spring of 2018, I got in touch with the DEP's biochar manager.  The City and DEP have a mandate to move away from landfilling treated sewage sludge, called biosolids in the waste treatment world.  While my contact was supportive, all I could get from her was the official position from DEP that it would continue to study all disposal methods: landfilling, composting, gasification / pyrolysis, and incineration.   


What if incineration turned out to be the least costly option, and DEP went for that over gasification / pyrolysis? It would be a lost opportunity for NYC to advocate for a new technology that would not just lower carbon emissions, but would permanently store carbon in solid form, keeping it out of the atmosphere.

Discussions with my sometimes candid, sometimes cryptic DEP source led me to believe that DEP still might support incineration if it was less costly.  It seemed like NYC Council could pull this information into the public realm and pressure them to choose the most carbon-sequestering choice. 

It seemed reasonable to ask the Chair of the NYC Council's Environmental Committee, Costas Constantinides,
to hold a hearing or request a briefing on DEP's research.  I got a number of NYC environmental and climate groups to sign on to a letter to him, see below. 


However, Costa got busy.  In the winter and spring of early 2020, Costa was immersed in a campaign for Queens Borough President, which I also volunteered with.  Then in March, the pandemic hit and the City locked down.  Costa later resigned from the Council.  This project, like many other things, was put on hold. 


In early spring, with Costa and his likely support in Council no longer available, and the Mayoral primary race overshadowing all City affairs, it seemed it might be useful to contact the policy staff of candidates. 

After much consultation with my patient contact at Aries, I went back to my DEP contact with more pointed questions.  To my surprise, it became clear that gasification / pyrolysis by private partners had very quietly become DEP's default preference for how to manage biosolids!

However, G/P faces huge obstacles.  Because it's a new technology, very few people know about G/P outside the industry know about it.  Many environmentalists and environmental justice advocates automatically assume it's greenwashing, a fancy name for highly polluting incineration, which it is not.  Thus, they will fight tooth and nail to block G/P plants. Aries was moving forward with a plan to build a state of the art G/P plant in Newark, which was killed by local environmental justice advocates. 

NYC DEP does not seem at all inclined to help potential private partners set up G/P plants with a public education effort.  Also, a big piece of NY State's climate response plan is now being hammered out by the advisory committees set up under the NY State Climate Leadership and Community Protection Act.  They too too seem to be unaware of the benefits of G/P, and how G/P is different from incineration.

So, as the political landscape has evolved, the points to intervene in support of biosolids G/P have moved, and the pitches have changed.  At first, it was lobbying the NYC Council.  Then, to lobbying NYC Mayoral candidates.  Now, it's lobbying the members of the NYS CLCPA advisory committees.  The journey continues.

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2018:  Environmental and civic groups are invited to sign onto this letter requesting that NYC Council hold a hearing
on sewage biosolids disposal planning.

Groups signed on: 
350NYC, 350 Brooklyn, Drawdown Project NYC, Forest Hills Green Team
Jackson Heights Beautification Group, West 80s Neighborhood Association, New Yorkers for Clean Power, Jewish Climate Action Network - Massachusetts.

For more information, and to sign on, contact

- - - - - - - 

Councilmember Costa Constantinides
Chair, Environmental Committee
NYC Council

Chairman Constantinides, 

We are writing to request the NYC Council Environmental Committee hold a hearing on the City’s plans to dispose of its sewage sludge, and the climate, financial, and pollution impacts of alternatives. 

The City has many initiatives underway responding to the climate emergency, mostly by reducing carbon emissions through lower energy use.  Scientists report that in addition to reducing carbon emissions, we must also draw carbon down, out of the atmosphere.  Pyrolysis of sewage biosolids would enable NYC to start drawing down carbon - a new type of climate emergency response it is not using so far. 

NYC now produces 1,400 tons per day of sewage sludge biosolids, which are shipped to distant landfills at a cost of $55 million a year.  Since landfill space is shrinking and fees are rising, NYC Department of Environmental Protection (DEP) is looking into new ways of handling this waste stream. Two leading alternatives are both forms of thermal treatment that sharply reduce the volume of the waste.  One method yields solid, stable carbon, and would have a positive climate impact.  

With incineration, organic waste is burned, and its carbon is released into the atmosphere as carbon dioxide gas.  With pyrolysis, organic waste is heated in a low-oxygen environment, leaving behind a combination of ash and solid carbon, sometimes called biochar. Production of biochar has been recognized by scientists with Project Drawdown as one of the top 100 policy responses to the climate crisis.

There are industrial uses for high-carbon residue from this and other organic wastes.  Pyrolysis of large quantities of organic waste, especially wet waste, is still very new.  A facility to pyrolyze sewage biosolids is opening soon in New Jersey. Results from this facility should guide further NYC DEP research. Adoption of this method of sewage biosolids disposal by NYC would encourage other governments to follow, having a much greater climate impact.

Considering that NYC has declared a climate emergency, DEP should consider the financial costs, pollution and climate impacts of each disposal method. The City should prioritize the method with the greatest climate benefit. DEP should report to the NYC Council Environmental Committee regularly on the progress of its research.

For more information, see this summary article, or the biochar pages at


Dan Miner



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Background: carbon emission reduction and carbon drawdown


When fossil fuels or organic solids are burned, or as they decompose, the carbon in them escapes into the atmosphere as carbon dioxide. Physically capturing and storing carbon long term so it can’t return to the atmosphere as carbon dioxide gas (CO2) is called drawdown or carbon sequestration.  The IPCC reported that carbon sequestration will be essential to bring CO2 levels down to 1.5C, citing several negative emission approaches. 


There are a few high tech methods to capture and store CO2 from the exhaust gases of burning fuels, but they’re still experimental, and might be both very costly and very difficult to scale up fully. 

The other carbon storage methods studied by the IPCC were planting forestsagriculture practices that increase soil carbon, and making biochar. These are safe, proven, and highly effective, and would have many indirect ecological benefits.  Of the three, only the last one can be applied directly in urban environments – and can be put into practice by NYC officials and other progressive municipal governments.   


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