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20 Energy from Toxic Organic Waste for Heat and Power Generation

given that the study neglected food waste that occurs at the farm-to-retail
level. However, even this conservative estimate of waste translates to over
130 billion pounds of food, valued at over $US160 billion dollars, and rep-
resents a loss of 1250 kcal/person/day out of available 3800 kcal/person/
day available to Americans. Notably, the majority of food waste in the US
(68%) occurs after consumers had purchased food from a retailer [19].
This pattern is consistent with global analyses indicating more absolute
and per capita loss and waste in the developed world, especially by consum-
ers, as compared to the developing world [1]. For instance, in 2009, food
loss and waste in North America and Oceania was estimated as 1520 kcal/
person/day, which encompasses an estimated 115 kg of food thrown away
that year by each consumer [16]. The same year in South and Southeast Asia,
food loss and waste was estimated at 414 kcal/person/day, encompassing
11 kg of waste by each consumer [1, 16].

3.4 FOOD WASTE WITHIN THE FOOD-ENERGY-WATER
NEXUS: A PROPOSED CONCEPTUAL MODEL

A food-energy-water (FEW) model was proposed by Kibler et al. [1] in
which food waste influences the FEW nexus via two interconnected mech-
anisms, both of which are driven by human behavior and decision-making.
In both production and waste management phases, food waste impacts to
the FEW nexus are driven by individual consumer choices made during
food purchasing, consumption, and disposal, as well as collective decision-
making at the societal level regarding methods of food production and food
loss and waste management (e.g., landfilling versus anaerobic digestion). All
food produced, whether consumed or wasted, demands resources includ-
ing energy, water fertilizers, herbicides/pesticides, land, and labor. Water and
energy are consumed directly in the production of food, for instance, when
water is withdrawn for irrigation, or when energy is used to transport ir-
rigation water, process and ship food, or to create chemical fertilizers and
pesticides/herbicides.
Indirectly, water is contaminated by agricultural runoff or used in en-
ergy production. Similarly, management of wasted food entails costs within
energy and water sectors. Energy is consumed during food waste collection
and transportation and to treat or assimilate contaminated effluents gener-
ated during waste management. Biogas produced by degradation or heat
generated during combustion of food loss and waste are potential energy
sources. When less food is wasted, more food is available without the need