A Q&A with Paul Sellew on the past, present and future of organic waste.
Paul Sellew is the founder and CEO of Harvest Power, an organic waste handling firm based in Waltham, Mass. The company operates the largest permitted food and yard waste composting facility in North America, builds renewable energy facilities powered by organic waste and helps establish source separation programs. Sellew recently shared his thoughts on the organic waste sector with Waste Age.
What is organic waste management?
Organic waste is generated as part of our society. It's generated from municipal solid waste, industry and agriculture. Our initial target is organics generated from municipal solid waste, and our focus is around source-separated organics, so that would be leaves, grass and brush — collectively yard waste — and also food waste. And then in industry, food processing organics, and then lastly agriculture — both crop residues and animal waste products.
What technologies does organic waste management require?
Number one, composting. We have what we think is some excellent composting technology and also product marketing at the back end. We also have some renewable energy technologies, one being high solids anaerobic digestion. Anaerobic digestion, obviously, is a well-known, well-understood robust technology and is quite common in wastewater treatment plants.
Our technology works with high-solids materials, materials that are stackable that can be moved with, for instance, a wheel loader. That includes leaves, grass, brush, pre-consumer, post-consumer, food waste.
Lastly, gasification, which deals more with the cellulosic and ligneous materials that are more difficult to biodegrade through anaerobic digestion and composting. That's a thermal process to produce syngas, which can be turned into electricity or thermal energy.
Is there a rough percentage breakdown of those three technologies in terms of what handles the greatest portion of the organic waste stream?
Well, if you look at the pie chart that the [U.S. Environmental Protection Agency] puts out on municipal solid waste, yard waste and food waste are almost 30 percent of MSW. The drier woody materials are excellent for biomass gasification. I would say [gasification handles] roughly a third to a half of what's available. The remaining [technologies] are excellent for the wetter materials where there's higher moisture content.
What are some of the challenges and benefits associated with organic waste management?
When I got started [25 years ago], there was a relatively small handful of commercial composters in the United States. Now, if you count the municipal sites and private operations, there are 4,500 to 5,000 composting operations. So I was part of seeing the composting infrastructure and industry develop in the United States.
I think now what we're looking at is food waste is going to be the next organic material that's going to be removed from the MSW stream. So the challenges are still going to be there, [although] not the way they were back 20 or 25 years ago when there were just no sites and all of that infrastructure had to be built from scratch. Now you have an infrastructure, you have the ability to amend those permits and put in higher-level technologies that you are oftentimes going to need to have in place to manage food waste because of potential odor issues.
But the benefits, I think, are enormous. You have the ability to produce renewable energy, and then return that organic matter back into the region where that organic waste was generated. I think it's just a better and more sustainable use of those organic feedstocks.
What are the biggest stumbling blocks to widespread adoption of organics recycling in the home? Are the obstacles different for businesses? How do you foster greater participation?
Clearly, we're a proponent of source separation. That means, by definition, that you're going to have to do it at the source, at the home and at the business level. So I think those are two different sets of challenges.
I think there are examples, more in the western United States, where large municipalities — San Francisco and the Seattle area are notable examples — where you basically have three bins: you've got the organics bin, you've got the single-stream bin and you've got the garbage bin. What can happen is that with single-stream recycling and with organics diversion and recycling, the garbage bin is by far the smallest of the three and you end up having a weekly collection for the recyclables and the organics, and the garbage every other week.
That's the model that's worked successfully in Europe and is working successfully here in parts of the United States. Still, those are the exceptions to the rule. But I think that's what we're a believer in as far as what it's going to take, and that's going to be a long-term trend.
On the commercial side, there are a number of examples of large companies, from WalMart down to owner-operated restaurants, that are doing a great job of separating out the organics from their facilities. Again, you have to have a separate collection bin in the store where that material can be separated and collected as a source-separated organic. Then it's a function of being able to offer savings over it going to a waste-to-energy plant or a landfill. There are a number of models in place that are working along those lines right now. So I think it will start with the commercial [sector], and I think it will eventually roll into the homeowner.
Specifically looking at curbside collection, do you think it's more resistance on the part of residents in terms of the "ick factor," or do you think it's a logistical issue of not having infrastructure in place to handle that material?
I think there's a lack of [permitted infrastructure]. Despite the 4,500 to 5,000 composting sites, most of those are for leaves, grass and brush. So oftentimes you need to get a different permit to manage food organics. As a result, then, I would say that despite the physical infrastructure, you don't have the permitted infrastructure to handle all of these food organics.
I think that is going to be the principal challenge. Because clearly if you are going to go to the effort of separating that [material] out of the MSW stream and go to curbside collection in a separate container, you are going to need a place to bring those organics to beneficially reuse them.
What's your vision for the future of organic waste management?
I think now renewable energy is going to help drive the growth of it. Through technologies that Harvest Power and other companies have, we can extract the renewable energy out of these organic wastes in the form of high-quality biogas that can be turned into electricity and thermal energy back in the same community where the organics are generated. Then, ultimately, the compost product coming out of that can be used locally as well. I just think you're extracting more value out of the organics. It's just a higher and better use.
As we continue to create incentives around renewable energy in our country, I think that's going to be an important driver that was not in place until recently. If you look at the yard waste bins, that was all just public policy because they didn't want to let these organics fill up our landfills and burn up in waste-to-energy plants. So now I think it's going to be a combination of renewable energy [and] returning organics in the form of high-quality compost back to the regions where it is generated. Ultimately, I think that's what's going to help propel the growth of the organics business over the next 25 years.