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Waste digestion gains momentum in CT

If Connecticut is going to reach its goal of diverting 60 percent of its municipal waste away from incinerators and landfills, a technology known as anaerobic digestion is likely to play an important role. Anaerobic digestion, which is relatively new to Connecticut, is a biological process that breaks down food waste and other materials into combustible methane gas. Quantum Biopower's 1.2-megawatt plant is now up and running and another (1.4-megawatt plant developed by Turning Earth) is under construction. Both are in Southington.

This Q&A asks Department of Energy and Environmental Protection Commissioner Rob Klee about the future of anaerobic digestion in the state.

Q: Quantum and Turning Earth together will be able to process approximately 90,000 tons of organics per year, which is about 18 percent of the total food waste generated in Connecticut annually. How many more anaerobic digestion plants does the state need to reach its environmental goals?

A: Connecticut's 2016 Comprehensive Materials Management Strategy estimates that the state needs a minimum of 300,000 tons per year of new capacity for organics (including food waste). That's the equivalent of five to 10 anaerobic digestion facilities around the state, depending on their size. It's important to note that anaerobic digestion is not the only option. Food-waste reduction and composting, which recycles organic materials into soil, are preferred options.

Q: It took about three years for Quantum Biopower to develop and build its Southington plant, which opened this spring. A new law, Public Act 17-218, seeks to make the permitting process easier for future plants. How does it ease the process?

A: Quantum was the first facility of its kind to be developed in the state, and thus, there was a learning curve for both our permitting staff and the project developers. It may have taken longer than some had hoped, but we are thrilled with the outcome.

The new law opens up a new pathway for the permitting of waste conversion technologies. In the past, the only realistic way for an anaerobic digestion project to get a permit was if a facility could qualify as a composting facility (like Quantum was able to), which processes organic materials (like food waste) into compost. If a facility couldn't prove it could generate a usable compost at the end of its process, we had to treat it like a combustion waste-to-energy facility, which has a much longer and more expensive process to get a permit.
The law provides a new option for facilities that take a mix of feedstocks. Even if DEEP can't allow the residual material to be used as a compost, the anaerobic digestion process may still be beneficial in extracting the maximum energy value from the material prior to it being incinerated or going to a landfill.
This change also opens up possibilities for waste to fuel and other emerging technologies.

Q: Do you see anaerobic digestion as a viable replacement to burning waste? What does an ideal mix look like?

A: Our ideal mix would follow the waste hierarchy. It's a set of preferences we've established that seeks to minimize the environmental impact of waste.
Thus, our first focus is on waste reduction, reuse and recycling. Connecticut has a well-established recycling infrastructure that could actually handle more recyclables than are currently being collected at the curbside. So our focus there is on helping residents recycle more — and recycle right. We recently launched RecycleCT.com to provide information about how to become a better recycler.
With respect to food scraps, composting is recycling, and we support both home composting and the development of commercial facilities.
Next on the list, for material that is not reduced, recycled or composted, we want to see technologies that extract the maximum energy value, or convert waste into usable materials. Waste combustion recovers energy, but there are newer promising technologies that should phase in over time.
The worst option is landfilling, because it tends to have the greatest negative impact on our air, soil and water.

Q: Another bill that made it through the legislature this year provides incentives for farmers to build anaerobic digestion facilities to process cow manure. Why is that significant?

A: On-farm management of manures has always been an essential component of farming. Public Act 17-218 provides new incentives for anaerobic digestion facilities to get up and running. This has both environmental and economic benefits. It can support proper management of farm waste to avoid nutrient loading of soils and waterways, as well as providing new economic opportunities for farmers looking to harness the value of "cow power."