Food waste diversion
It’s time to pursue disposal alternatives that make environmental and economic sense
According to the U.S. EPA, 15.1 percent of total municipal solid waste (MSW) generation in the U.S. is food waste. That statistic is derived from a variety of sources – residential, commercial and institutional – but does not include food waste diversion to feed people and animals or waste generated by entities outside of the official MSW arena, like industry and agriculture.
The EPA’s July 2018 numbers on MSW food waste (based on 2015 statistics) estimated 2.1 million tons were composted in 2015 or 5.3 percent of the 39.73 million tons of food waste generated.
Compared to the approximately 2 percent of the 30,700,000 tons of food waste that were composted in 2000, that was good news. Even better, in the ensuing 15 years, composting tonnages more than tripled while the total food waste stream grew by only 29.3 percent.
But with the percent of food waste diverted to composting stuck in the single digits, there’s still a long row to hoe. In 2015, more than 37 million tons went to non-sustainable end use or disposal: 7.4 million tons to combustion with energy recovery, and the bulk – 30.3 million tons – to landfill burial. Not-so-good news.
There are several versions of a food recovery/food waste management hierarchy floating around on the web. Some place industrial composting above or on par with bioenergy production; some don’t. But all of them agree that reducing food waste at the source is best and burying/burning food waste is the worst. What lies between these extremes are opportunities for diversion.
Cutting food waste as a frontline objective
Most folks understand that the best way to reduce the negative economic and environmental impacts of food waste is to not generate the stuff in the first place.
Fortunately, all along the route from farm to table to garbage are opportunities to reduce or eliminate wasteful practices.
As an example, let’s look at the humble potato, No. 6 on a list of the world’s most nutrient-dense foods. Sadly, it’s also one of the most wasted foods in the western world where, in some countries, as much as half the crop is destined for the garbage can.
In the U.S., 2017 potato production was estimated at 441.41 million cwt (hundredweight). Since 1 cwt equals 100 pounds, that’s 44.141 billion pounds of potatoes – more than 135 pounds for each of the 325.7 million people in the U.S.
If half of that crop goes to waste, about 22 billion pounds or 11 million tons of that crop was wasted – about 68 pounds per person. That’s more than double what the average American eats in French fries in a year.
From not buying more than one intends to chew to embracing the quirkiness of “ugly” fruits and veggies, if all 126.22 million households in the U.S. tried to reduce potato waste by just a half-pound or so next year – about 1 medium-sized Russet – potato waste in America could become a non-issue.
The moral of this tale is that it doesn’t take much individual effort to make a big difference in food waste tonnage if enough people embrace change and take action.
2nd best food waste option — feeding people and livestock: But is it practical?
Once upon a time, kitchen waste went from the table to a bucket, then out the back door and over the fence into the pig pen. But with the majority of the U.S. population now living in cities, the hog trough as a food recycling option is pretty much a thing of the past.
More than 60 percent of the U.S. population lives in incorporated areas; the majority of the world’s human inhabitants are urbanites, as well. Within the next 30 years or so, urban dwellers are expected to approach 70 percent.
That means the only likely candidates for table scrap feeding at the household level are pets, a practice discouraged by many veterinarians.
There are still some farmers who take the time and trouble to collect food waste from places like grocery stores. But gathering enough volume to make the trip worthwhile, plus the cooking or other preparations required to meet regulatory requirements for converting waste to animal feed, can make such ventures impractical, as well as uneconomical.
There’s also the fact that farmers who raise livestock for big meat companies are often prohibited from using any food/feed not sanctioned by the integrator.
Food waste diversion to feed people is not without its problems, either. Donated people–food has to be edible. This stuffs some food bank sacks with cans and other packaged foods, not fresh.
Most perishable foods on a downhill slide from peak, including meats and dairy, still wind up in a dumpster bound for disposal. Historically, whether from laziness or lack of storage space or skittishness over trusting Good Samaritan laws, processors and grocers have been reluctant to embrace the concept of fresh food donation.
That may be slowly changing thanks to the leadership of a handful of national chains, some of which not only donate food, but also send inedible food to composting. In the long run, donating food to feed people may prove to be more practical than moving food waste out to distant livestock operations.
But for now, neither seems to be making an appreciable dent in the volumes of food waste making up the disposal stream.
3rd choice – food waste diversion for industrial use: are all options sustainable?
While energy generation using a sustainable feedstock like trash may be considered a positive step in some circles, including food waste in that stream is not.
Waste may be considered a “sustainable” resource, but waste-to-energy (WTE) systems that destroy or bury organic matter fail to meet the definition of sustainable for biodegradables. Destruction of organics is a short-sighted, convenience-driven waste management strategy that threatens food and water supplies for existing and future generations. This includes landfill gas systems, as well as combustive/thermal WTE technologies.
Why? Because they do nothing to return nutrients and organic matter to the soil. They do not close the recycling loop. Technologies producing a residual known as biochar may prove to be the exception. But the jury is still out on biochar derived from MSW due to concerns related to toxic constituents in the feedstock stream.
Anaerobic digestion (AD) is a biologically-based energy technology that offers the possibility of food waste diversion and other organics reclamation if the resulting waste stream – digestate – is further processed as a feedstock in the production of quality compost products.
Digestate, in its raw state, really isn’t suitable for much except low-value agricultural use or landfilling. However, energy extraction does nothing to lower its value as a compost feedstock. When composted, value is added, converting digestate into a high-value revenue stream for the AD operation.
Unfortunately, generating energy from biomass is still among the most expensive renewable energy technologies and is not widely adopted in the U.S. where other options tend to be more cost-effective.
As for landfilling, landfill gas capture systems are only marginally better than a do-nothing approach. Active landfill cells are often open for long periods of time before they are filled and capped. Much of the damaging methane gas generated during anaerobic decomposition of the organic material has already escaped to the atmosphere before a cell can be sealed and the gas capture technology installed … assuming such a system is in use in the first place.
There are an estimated 1,500 to 2,000 operational landfills in the U.S. Fewer than 600 landfills are equipped with gas recovery systems.
Looking at dollars and common sense
Wet material doesn’t burn unless moisture is removed. Food waste and other high-moisture biomass can introduce an expensive complication for combustion technologies. Dewatered sludge, for example, cannot be incinerated auto thermally (reach temperatures above 850 degrees C or 1562 F) without using an auxiliary fuel or further drying the sludge to increase the percent of dry solids.
Either option will add to the cost while resulting in a disappointing energy balance. Using biomass for waste-to-energy feedstocks is among the most expensive ways to generate electricity, even more expensive than advanced nuclear and second only to a conventional natural gas-fired combustion turbine.
Not including wet material in the feedstock stream for landfills and combustion technologies is only common sense.
The economics for waste generators looking at disposal options tell the same story.
Nationwide, the average U.S. tipping fee for MSW landfills is $55.11 per ton (August 2018). In 2010, the national average for waste-to-energy tipping fees was $74.79 per ton or $86.74 in 2018 dollars when adjusted for inflation.
A national sampling suggests gate fees at composting/AD facilities can offer food waste diversion at significant savings over destruction or burial of organic resources:
- Southern California – 30 percent less than local landfill tipping fees
- Vermont – landfills cost 2-3 times more than composting
- South Carolina – landfilling at $66/ton; composting at $25/ton
- Minnesota — $0 for composting vs. $45.28 for other waste
- Central New York — $40/ton for source-separated organics bound for anaerobic digestion vs. $62/ton for MSW (new program, expected operation beginning Q1 2019)
To make food waste diversion and recycling happen …
Systems that burn or bury organics fail to meet the definition of true sustainability, since they don’t complete the recycling loop for soil organic matter. In addition, these lesser technologies require expensive add-on systems to deal with the negative impacts of managing organic materials inefficiently and contrary to nature’s recycling methods.
To stop the madness, all organics — food waste included — must be diverted to composting, with or without anaerobic digestion.
To make that happen, communities need to stop using “lack of infrastructure” as an excuse and recognize lack of interest/intent as the real reason behind that missing infrastructure. Inadequate infrastructure is a symptom, not a cause.
This is especially true when considering municipalities and other government entities do not need to invest taxpayer dollars to provide professionally-managed, industrial-scale, composting services. Food waste diversion is possible without capital expenditures on the part of public partners/collaborators.
Mandates, coupled with an enticing RFP and a good site, will bring major companies with time-tested technologies to the table, ready, willing, and able to finance and operate successful organics recycling operations to serve the region.