‘Mayor Adams has taken on the admirable challenge of promoting plant-based diets because of their health benefits to individuals. In many ways, composting and healthy eating go hand-in-hand, improving human health and the well-being of the environment around us. To be successful, both also require a shift in our thinking.’

Adi Talwar

Composting at a Harlem community garden in 2017.

Mayor Eric Adams’ proposed budget chops the city’s residential composting program. The reason he gave is that the effort is broken. While he’s correct that it has not lived up to its potential, advocates of the program are also right that New York City needs to divert organic materials from landfills. This moment presents us with a unique opportunity to re-imagine, if not completely overhaul the program. 

While many things have changed since New York City’s residential composting program was first introduced, a lot has also stayed the same. For one thing, the program remains voluntary. This has hindered participation rates, leading to higher collection costs when compared to traditional recycling (paper and metal, glass and plastic) and trash that is landfilled. In recent years the city diverted around 1.4 percent of its waste from landfills to organics collection. In 2019, the program cost $32.2 million. Such costs vs. benefits have made the program an easy target of budget cuts.

To reduce these costs, there have been a number of calls to make participation in the program mandatory and/or charge people for the amount of waste they dispose of, referred to as “pay-as-you-throw (PAYT).” For example, State Sen. Brad Hoylman recently proposed statewide mandatory residential composting that would include all buildings in New York City.

Currently, traditional residential recycling is mandatory in the city, but still hovers at around 50 percent capture rates for most materials (28 percent for non-rigid plastics). One question to consider is whether making composting mandatory will substantially improve organic waste diversion rates. Another issue is the broader financial implications, including program implementation, and not putting unreasonable burdens on building owners covered by the potential rule.

Proponents of making composting mandatory in New York City often cite successful efforts of other cities. Particularly in the U.S., San Francisco diverts around 80 percent of its organic waste and has implemented both mandatory requirements and PAYT. A number of differences between New York and San Francisco make that comparison somewhat oversimplified and hard to extrapolate. As one example, San Francisco has been more effective at creating a system that not just collects the waste, but also processes it efficiently.

To increase processing capacity, New York City needs more land and/or access to facilities that can process organics in less space, within a reasonable distance. Large-scale anaerobic digesters, which achieve this goal in the absence of oxygen and produce biogas that can be substituted for natural gas, have been the technology of choice to date. Such equipment usually has high capital costs and is located on farms or at wastewater treatment centers.

To various degrees, all of these options aim to incrementally improve the current composting program. However, with politics swinging back and forth over funding and, more recently, pulling the program’s  expansion (in part due to challenges presented by COVID-19), now may be the time to ask how much potential we really have to make it work in its current configuration? Is there a better way?

Disposing of items in a landfill or separating them for recycling logistically and economically benefit from centralized infrastructure. Composting doesn’t have to work that way. In fact, localizing composting, where the material is broken down closer to where it is produced, offers a lot of advantages. Going one step further, it creates an opportunity to reduce the role of the Department of Sanitation (DSNY) and its corresponding costs from the equation.

A few years ago, such a statement might have seemed highly implausible. Since then, times and technology have changed. Instead of comparing New York City to other composting programs in different cities that were built decades ago, we should look at our city’s unique set of circumstances. This will allow us to create a plan that works not only now, but is also flexible enough to uptake new technology and policy modifications in the decades to come.

In terms of technology, a notable advancement has come in the form of small-scale aerobic digesters (SSADs). They effectively break down organic waste using enzymes, allowing the process to occur relatively rapidly with respect to conventional composting. Using such machines avoids the formation of methane, a potent greenhouse gas, in the landfill breakdown process. Being small enough to fit onsite, users can keep the equipment running continually, reducing additional methane generated as the organic waste likely would have otherwise decayed in trash bags.

Additionally, SSADs give New York City more flexibility. The product is comparable, but not exactly analogous to compost. It is reduced in volume compared to the input material and is non-toxic. It is also odorless, helping to reduce insects and rodents. These qualities allow it to be more easily stored onsite. Uses for the material include: a soil additive, fertilizer, input to an anaerobic digester or conversion to pellets to serve as a biomass fuel. In another advancement, small-scale anaerobic digesters are starting to appear, which would allow buildings to produce and use biogas onsite to heat their boilers.

The cost of SSADs varies based on processing capacity, but are not that different from a traditional compactor. The challenge, of course, is how to finance and site such equipment in buildings. The city could help offset the purchase costs with incentives, and require space for them in new construction. Another path may be to allow the emissions reductions associated with such equipment to count toward requirements under Local Law 97 and/or Local Law 87. Funding sources could include the New York State Energy and Research Development Authority (NYSERDA) energy upgrade programs and the NYC Property Assessed Clean Energy (PACE) financing program.

While not sending waste to large-scale anaerobic digesters eliminates the ability to bring in more revenue from biogas, the trend away from natural gas and investment to scale up anaerobic infrastructure across New York City make it a strategy with an uncertain outlook. In fact, the plans for anaerobic co-digestion of food scraps at the Newtown Creek Wastewater Treatment Plant were announced in 2013, but have yet to provide biogas for residential use.

Mayor Adams has taken on the admirable challenge of promoting plant-based diets because of their health benefits to individuals. In many ways, composting and healthy eating go hand-in-hand, improving human health and the well-being of the environment around us. To be successful, both also require a shift in our thinking. Let’s be open to a world of local possibilities.

Nancy Holt leads Science for New York (Sci4NY), an effort to have policymakers and scientists in NYC work more closely together through project-based interaction. She holds a PhD in Physical Chemistry and formerly worked on climate change issues at the U.S. Department of State. On Twitter @Sci4NY

Calder Orr is a research scientist with the City of New York. He holds an MPA in Environmental Science and Policy from Columbia University.