According to recent studies by the U.S. Department of Agriculture's Economic Research Service, the value of our wasted food at the retail and consumer levels is $160 billion dollars per year. On a caloric basis, this amounts to 1250 calories per person - 61% as much as we actually eat!
Food waste may be "slop" to most Huffington Post readers, but to an environmental engineer, it is a vast opportunity. Getting there however, is a challenge. The first course of action should be to reduce food waste at the "upstream end" as much as possible. In the U.S., most of our food waste occurs at the retail level (grocery stores) and consumer level (restaurants and homes). For grocery stores and restaurants - industries with very low profit margins - reducing food losses could translate into substantial gains in profit, by not purchasing foods that are not sold or eaten. Personally, as empty nesters, my wife and I eagerly await the availability of half-loaves of bread!
On the "downstream side", after food is discarded, there are additional opportunities. A modest number of cities are now turning toward collection of food wastes, which is then mostly composted. As a gardener, I appreciate that, but if we really start recycling food waste in a large scale, we'll need to look for the highest and best use of various types of food wastes in specific contexts. For example, in our "Waste Not" initiative at the University of Minnesota, my swine nutritionist colleagues have learned that food waste from homes, grocery stores, and dining halls is highly nutritious - for swine, at least. Dried, sterilized feedstocks developed from food waste would be competitive in price with conventional feedstocks like corn and soybean meal. Food waste-derived feedstocks would not be used alone, but blended with other ingredients to create nutritionally optimal animal feeds. We've also used food wastes to create valuable oils and gases that could be used for fuels or raw materials for the chemical industry. Many European cities and a few in the U.S. have built large "anaerobic digesters" to convert food waste to methane gas, which is used as fuel.
As we enter a transition period to close the loop on food waste, many silver bullets will be promoted, but few will succeed. Yes, we can convert food wastes to swine feedstock, but can it be produced economically? Will swine producers accept it? These types of questions need to be answered for each promising food waste conversion process. To do this, we need a vigorous, national research program to provide unbiased results. My sense is that no one technology will prevail; instead a suite of conversion technologies will emerge, each suitable for specific situations.
We also face social barriers in this transition. Many cities now have disorganized waste collection, in which every household selects its own waste hauler (an outcome of the "private sector always does it better" mentality of the 1980s), yet this makes it nearly impossible to segregate and collect food wastes separately. Many folks also resist in-home composting, even where cities do offer separate food waste collection. These and other social and policy questions need to be addressed. Technology alone will not provide the solution.
I predict that most cities will transition to reducing and recycling food waste over the next two decades. It just makes good sense from both an economic and environmental perspective. Our children will cringe at the idea of dumping food waste into landfills (did you really did do that?!), as older adults now cringe when we recall the practice of open dumps that often caught fire, spewing pollution, just 50 years ago. How disgusting!