SAVING WATER: Food Waste Is More Than Wasting Food
Much, if not most, of the conversation around food waste and the need to reduce it, focuses on its impact on the environment, particularly as it relates to climate change. That is, perhaps, as it should be given that as much as 97% of wasted food ends up in landfills, where it decomposes into carbon dioxide and methane, a greenhouse gas as much as 28 times more powerful than CO2. And, of course, many engaged in the fight against hunger point to the fact that cutting global food waste by just 15% would be enough to feed 25 million hungry people. Either of these benefits, drawing down on heat-trapping greenhouse gases or eliminating food insecurity, is sufficient as a raison d’etre for the movement to curtail food waste. However, food waste is about more than just food.
The Color of Water
Getting food from the field to the table accounts for 10% of the country’s energy budget, including 80% of the water consumed –evaporated or otherwise removed from the watershed. (The Water Footprint of Food, n.d.) Calculating the total amount of so-called virtual water inputs for agriculture, industrial or otherwise, involves accounting for all the water, expressed in cubic meters per tons, per hectare or unit of currency, from all potential sources, used in the production of a crop and/or its byproducts (Hoekstra, 2011). The water footprint of goods and services as originally postulated by Arjen Hoekstra, Professor in Water Management at the University of Twente, the Netherlands, has three components, water:
Green Water – Water from precipitation stored in the root zone, the area of soil and oxygen surrounding the roots of a plant, assimilated by plants, or returned to the atmosphere via evapotranspiration.
Blue Water – Water culled from the surface, including ponds and lakes, or groundwater, e.g. aquifers, absorbed by plants, transported from one source to another, including by irrigation, or returned to the atmosphere via evapotranspiration.
Grey Water -. Water required to assimilate pollutants, including herbicides and pesticides, sufficiently to comply with applicable water quality regulations
The table below shows the amount of water needed to produce some common foods. Even a cursory examination of the data begins to shed some light on why throwing away food -oftentimes perfectly edible food- is tantamount to shedding water. For instance, the large order of fries you ordered with your Grand Mac™ required just over 11 gallons of water to grow. The patties appropriated approximately 614 gallons of H2O; the buns, weighing in at 9 ounces, sopped up 88 gallons, while the two slices of cheese swallowed up almost 56 gallons, for a total, excluding the lettuce and pickles, of 768 gallons of precious sky juice.
Table 1. Source: Arjen Y. Hoekstra, Twente Water Centre, University of Twente, the Netherlands, The Water Footprint of Food Table 1 Water footprint of different food items.
And even that is not quite the whole story, in part, because it does not include the additional water used to turn a pound of beef into 2 double quarter pounders, including that consumed in the production of the power used to grill, deep fry, toast, keep warm, etc.
But for all of water’s prowess as a solvent, the importance of its function as a coolant, both for our bodies and the body corporate, in its guise as the thermoelectric power industry, cannot be overstated.
The Power and the (Water) There is not one living system that does not require water, in part because of its role as a solvent. In fact, water dissolves more substances than any other liquid. Wherever “the universal solvent” flows in our bodies, it carries minerals, nutrients, and waste to the appropriate organ systems (USGS, 2016). But for all of water’s prowess as a solvent, the importance of its function as a coolant, both for our bodies and the body corporate, in its guise as the thermoelectric power industry, cannot be overstated.
From slick water (water mixed with clay) use to “frack” the natural gas used to fuel turbine engines, in natural-gas-based power plants, to the water withdrawn from nearby sources, by nuclear power facilities to be used as an energy store and/or as a coolant to prevent their reactors from overheating, the relationship between water and energy is both intimate and enduring. In fact, the thermoelectric power industry accounted for 45% of total freshwater, aka blue water, withdrawal in the U.S., exceeding even agriculture (Dodder, 2014). Just how much water is used at any given facility depends on the fuel type, cooling technology, and the prime mover, the type of engine used to rotate an electrical generator. Of these, cooling technology is by far the most important factor governing water use in thermoelectric power plants (Sanders, 2016).
…the more than 773 gallons of water used to produce the entire, aforementioned quick-serve spread is enough to generate enough electricity to power the average American household for almost 6 months! Once and Again As indicated below in Figure 1, wet recirculating tower systems and once-through systems are the two most popular among plant operators in the US, accounting for 54.37% and 28.57% respectively, of the more than four trillion kilowatt hours generated in the US, in 2014. Initially, once through systems, because of their simplicity, and low cost, were the preferred method of cooling. Choosing once-through systems also offers up the possibility of locating facilities close to primary water sources -rivers, lakes, aquifers, from which water is withdrawn and circulated through the pipes of the system, absorbing heat from its condensers. The warm water is then discharged back into the original source, disrupting the local ecosystem, the implication of which is the subject of a future post (How It Works: Water for Power Plant, n.d.). Suffice it to say that notwithstanding lower consumption (See Figure 2), the environmental impacts of once-through systems were severe enough to warrant a switch to more eco-friendly, sustainable technologies.
On the other hand, simply stated, recirculating cooling systems, as the name implies, reuse water drawn from a primary water source, into an on-site pond. Towers are used to expose the heated water to ambient temperatures, resulting in a loss of water in the form of evaporation. The remaining water is sent back to a condenser; an amount equal to what is lost to evaporation is withdrawn from the pond and the cycle starts once again (How It Works: Water for Power Plant, n.d.). As a consequence, although recirculating tower cooling systems withdraw less water from the watershed than once-through systems, they typically consume more.
Figure 2. Once-through systems use withdraw more water but consume less than recirculating cooling towers
The exception occurs when fuel type, tower technology and prime mover is included in the equation. Note for example, in Figure 3; a natural gas combined cycle facility, one that uses both gas and steam to turn the turbines that power the generator, and then uses a once-through cooling system, without an on-site pond, consumes over 1200 gallons of water to produce 1 MWh of electricity. An identically configured plant using a recirculating pond cooling system generates the same amount of power, while consuming just 158 gallons of water or less than 26% of what was required to produce the beef patties for the aforementioned fast food feast. Seen from another perspective, if, as is estimated by the Energy Information Administration, the average residential utility customer consumes, on average, 897 KWh of electricity per month, then the more than 773 gallons of water used to produce the entire, aforementioned quick-serve spread is enough to generate enough generate enough electricity to power the average American household for almost 6 months!
Figure 3. Plants where steam is the prime mover use significantly more water, regardless of fuel type.
Does that mean the thermoelectric power industry is less water intensive than industrial agriculture? No. Indeed, in 2010, irrigation accounted for 32% or 11.5 trillion gallons of the daily demand on fresh and saline water resources, while meeting the needs of the country’s power grid required 16.1 trillion gallons per day or as indicated above, 45% of the total. Taken together, these two sectors exceeded the demand of all other categories, including, public supply, self-supplied private and industrial, combined (Water Use in the United States , 2016). However, it should be noted that the vast majority of the water withdrawn from the watershed, by the thermoelectric power industry is returned, albeit sometimes significantly warmer. It is also true that while that water is being used in boilers and cooling systems, it is unavailable to you or your local fire department.
The geometry of the water footprint of industrial agriculture is different from that of the thermoelectric power industry, although there is confluence, i.e. bioethanol and biodiesel. Its imprint is expansive and indelible. Despite being, on average, 90% water, only about 3% of the water absorbed from its root zone is used for growth by a plant, permanently removed from the watershed, which begs the question, What happens to the remaining 97%?
Cowboys, Cacti, CO2 and Feedback Loops If, like the author, you grew up watching westerns, then you know that it was not uncommon to find the hero stranded in the desert, canteen empty, skin seared and blistered by the merciless heat of a relentless, desert sun, his tongue swollen in his dry, muted mouth. It was an ordeal he had to endure to earn his street cred. Sometimes our parched protagonist was spared as a result of an incidental encounter with a member of some indigenous tribe who knew the secrets of what appeared, at least to the uninitiated, to be a waterless wasteland. On other occasions he was rescued by a member of a family of succulent plants named Cactaceae, aka cacti.
Luckily, for our cotton-mouth cowboy, cactus, more than any other plant, has evolved many adaptations to survive in the most arid, desolate, drought-prone places on the planet, including a particular way of performing photosynthesis called crassulacean acid metabolism (CAM). Simply stated, CAM photosynthesis is a process by which a succulent plant takes in and stores CO2 as malic acid, during the night, which means during the day, its stoma, the pores on the surface of its leaves, remain closed, to preclude the loss of excess water, keeping it conveniently on tap so that our dehydrated drover could wet his dry. And yet, while in this instance the plant’s response to changes in its environment is conservative, both for it and our marooned wrangler, there is at least one other circumstance when such a biological rejoinder is anything but, for the rest of us yahoos. Left untreated hypercapnia leads to carbon dioxide narcosis and, ultimately, death, paradoxically, from oxygen starvation.
Oxygen and CO2: Elixirs of Life or Virulent Vapors? Feedback loops abound in nature; among the simplest is the way ethylene gas ripens apples while still on the tree. Far more complex are biological response modifiers that activate/modulate our immune system’s response to so-called xenomolecules.
Feedback loops are a response to the constancy of change in natural systems. If the response bring the system back to normal, the feedback is positive. If, however, the response augments the change, the feedback is considered negative.
For example, when exposed to high concentrations of oxygen, the body adapts, initially, by slowing down its heart rate and cutting the production of red blood cells. If oxygen levels remained unchanged, pulmonary alveoli in the lung parenchyma collapse, impeding the exchange for carbon dioxide (CO2) for oxygen (O2). If that sounds familiar, it is because it mirrors the response of plant leaf stoma, to excessive heat, observed in the spines of the saintly succulent, set out in the scenario above.
Continued exposure, between 4 and 22 hours, to such hyperoxic conditions results in, among other things, tracheobronchitis (inflammation of the upper airway), and an increase in plasma level carbon dioxide, also known as hypercapnia. Left untreated hypercapnia leads to carbon dioxide narcosis and, ultimately, death, paradoxically, from oxygen starvation. CO2 is to plants what oxygen is to humans, an Elixir of Life. Is it also a virulent vapor?
In the presence of too much of its indispensable inhalant, a plant’s stomata, like its mammalian, functional counterpart, the alveolus, closes, shutting down, not only the O2/CO2 exchange, but just as importantly, at least for the sake of the instant narrative, the release of the remaining 97% of the water it absorbs from its root zone, interrupting the process known as evapotranspiration (sweating) that cools the plant in the same way perspiration cools our own bodies.
The implications for the plant are mixed, including improved drought resistance (de Boer, Lammertsma, Wagner-Cremer, Dilger, & Wassen, 2011) and increased biomass, at least for some types of plants, offset by a diminished capacity to acquire nitrogen and thereby inhibiting photosynthesis, despite being awash in CO2. This is especially true for, albeit certainly not limited to, temperate and/or cropland plants. Nor is nitrogen fertilizing a palliative. (Feng, et al., 2015). What these adaptations augurs for the planet is far more foreboding. “…even absent its role as a heat-trapping gas, whether you subscribe to the notion of human-induced climate change or not, that CO2 is a significant, long-lived climate forcer is irrefutable.” One Big Fucking Air Conditioner Fortunately, plants do not die as a consequence of prolonged exposure to superfluous CO2. However, along with becoming less nutritious, as mentioned above, they also adapt by presenting a kind of selective anhidrosis, the inability, or should I say unwillingness, to sweat. Consider for a moment that, on a hot day a single tree can release tens of gallons of water into the air, acting as natural air conditioner for its surroundings (CO2 Effects On Plants Increase Global Warming, 2010). Now consider that 31% or almost 10 billion acres of the planet’s surface is covered by forest. Add to that another 3.7 billion acres of cropland, and let’s face it; That is one big fucking air conditioner!!! Recklessly fertilizing the air with copious amounts of CO2 is equivalent to turning up the thermostat, raising surface temperatures by as much as 25%. Moreover, when plants do not sweat, that water is no longer available for cloud formation, altering rainfall patterns (Bonan, 2008). In other words, even absent its role as a heat-trapping gas, whether you subscribe to the notion of human-induced climate change or not, that CO2 is a significant, long-lived climate forcer is irrefutable (CO2 Effects On Plants Increase Global Warming, 2010).
To put a finer point on it, that is …32% of the 11 trillion gallons of water…California needed in 2014, to recover from what was then a three-year long drought.
Every Year in America: The Loop We’re In Every year in America, on average, food crops and their derived products remove over 218 trillion gallons of water from the watershed cf. water cycle (Hoekstra, 2011). Every year in America, on average, crop cultivation alone accounts for nearly 285 million metric tons of CO2 equivalents emissions (Greenhouse Gas Inventory Data Explorer, 2019). Every year in America 133 billion pounds of food, and the more than 3.5 trillion gallons of water embedded therein, is wasted and/or thrown away. To put a finer point on it, that is 12,000 per capita or 32% of the 11 trillion gallons of water scientist, from NASA’s Jet Propulsion Laboratory, estimated California needed in 2014, to recover from what was then a three-year long drought (Needed: 11 Trillion Gallons to Replenish California Drought, 2014). Every year in America food waste is responsible for life-cycle -from the land to the landfill- greenhouse gas emissions totaling 113 million metric tons of CO2e, accounting for 2% of all national emissions (Venkat, 2012). That is the loop we are in. Succinctly stated, the way we grow food and, moreover, live, on the planet is threatening our ability to grow food and, as such, live on the planet. It is the quintessential enantiodromia.
The success, the economies of scale achieved by Big Ag and Food Manufacturers produced excess of relatively low-cost food, or food-like products, an apparent attendant ambiguity about what food is as well as a, seemingly, concomitant, cavalier attitude about throwing it away. This is especially true in in first-world countries like America, where food waste and food loss occurs much later in the supply chain and, necessarily, involves the squandering of many more inputs, including water, the indispensable input.
As chefs and restaurateurs, because of our near end-of-life interaction with food, we are especially well positioned to minimize the loss of the water, and other ecosystem products and services, embedded therein. In a previous post, we offered some effective ways to reduce food waste in the food service industry. The benefit-cost ratio, we reported, was as high as 614:1. In other words, every $1 dollar invested in food waste reduction potentially returns as much as $614 in value. Click on the links below to discover some direct measures you can adopt to plug the leaks in your restaurant more directly. Doing so can result in, approximately, an 11% reduction in operating cost as well as a decline in energy and water use by 10% and 15% respectively (McGraw Hill Construction, 2009), proving once again that the assertion that we have to choose between the economy and the environment is, at best, spurious. The biosphere is the bottom line. Saving food saves water. Saving water saves food. Saving water saves food. Saving food saves water. Saving food and water saves the environment. Saving the environment saves our asses. And, at the end of the day, that is what it is really about. Isn’t it?
 1 kilogram equals 2.2 lb.
 1 litre equals approx. 34 oz. or .26 gal.
Bonan, G. (2008). Forests and Climate Change: Forcings, Feedbacks, and the Climate Benefits of Forests. Science Magazine, 1444-1449.
CO2 Effects On Plants Increase Global Warming. (2010, May 2). Retrieved from Carnigie Science: https://carnegiescience.edu/news/co2-effects-plants-increase-global-warming-0
de Boer, H. J., Lammertsma, E. I., Wagner-Cremer, F., Dilger, D. L., & Wassen, M. J. (2011). Climate Forcing Due to Optimization of Maximal Leaf Conductance in Subtropical Vegetation Under Rising CO2. Journal of Natural Sciences, 4041 - 4046.
Dodder, R. S. (2014, May 7). Digital Commons@University of Nebraska-Lincoln. Retrieved from https://digitalcommons.unl.edu: https://digitalcommons.unl.edu/usepapapers/index.html#year_2014
Feng, Z., Rutting, T., Pleijel, H., Wallin, G., Reich, P. B., Kammann, C., . . . Kazuhiko, K. I. (2015). Constraints to nitrogen acquisition of terrestrial plants under elevated CO2 . Global Change Biology, 3152-3168.
Greenhouse Gas Inventory Data Explorer. (2019). Retrieved from EPA: https://www3.epa.gov/climatechange/ghgemissions/inventoryexplorer/#agriculture/allgas/source/all
Hoekstra, M. M. (2011, May 5). The Water Footprint of Crops and Derived Crop Products. Hydrology And Earth System Sciences, pp. 1577 - 1600.
How It Works: Water for Power Plant. (n.d.). Retrieved from Union of Concerned Scientists: https://www.ucsusa.org/clean-energy/energy-and-water-use/water-energy-electricity/
McGraw Hill Construction. (2009). Water Use in Buildings SmartMarket Report. Bedford: McGraw-Hill.
Needed: 11 Trillion Gallons to Replenish California Drought. (2014, December 16). Retrieved from Nasa: Science Beta: https://science.nasa.gov/science-news/science-at-nasa/2014/16dec_drought/
Sanders, R. A. (2016, December 23). Environmental Letters. Retrieved from IOP Science: http://iopscience.iop.org/article/10.1088/1748-9326/aa51d8/meta
The Water Footprint of Food. (n.d.). Retrieved from Grace Communications Foundation: https://gracelinks.org
USGS. (2016, December 2). The USGS Water ScienceSchool. Retrieved from USGS: https://water.usgs.gov/edu/qa-solvent.html
Venkat, K. (2012). The Climate Change and Economic Impacts of Food Waste in the United States. International Journal On Food System Dynamics, 431-446 .
Water Use in the United States . (2016, December 9). Retrieved from USGS: Science For A Changing World: https://water.usgs.gov/watuse/wuto.html