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Sunday, July 15, 2018

Green House Gases from Food Waste

Link for this post:

Sunnyvale "Food Cycle" Program


Of all the options potentially available the Sunnyvale Food Recycling program is one of the least effective ways to reduce Green House gas emissions due to food waste.  This to some extent because of the processing energy and transportation of the food waste.  That is not to say other potential options were available at the time the Food Cycle program was chosen, but it does say we need to re-examine the issue when possible.


In an earlier post I put what I could find on Sunnyvale's Food Recycling program.  That post is here:

I decided to revisit the issue because of all the discussion on Sunnyvale's Food Recycle program.  I looked at what percentage of Green House Gases come from food waste at the home and how much of a difference the "FoodCycle" program might make.

The non-profit organization ReFED has calculated the impact of different ways to reduce food waste in terms of environment and GHG reduction.  They have a number of options to look at the issues of food waste.  One of them is GHG emissions which you select from a box-tab on their web site at: as seen below:

This will produce a number of solutions to the problem such as the example for Composting seen below: (click image to enlarge)

Their calculations cover a lot of options.  I selected those that the city could implement (at least in theory) and plotted the numbers they gave:

The last bar (in the red box) - "Animal Feed" - is the "FoodCycle" program.  It is the least effective of all the alternatives mentioned by ReFED saving 34 tons of CO2 equivalent (t CO2e) GHGs.  The top one, "Community Composting", was rated at 2,605 tCO2e or 77 times more GHGs removed.  The next one, "Anaerobic Digestion", was rated at 1,179 tCO2e or 35 times more GHGs removed.

This to some extent because of the processing energy and transportation of the food waste as mentioned below from

That doesn't mean that the other options are available to Sunnyvale right now, but it does suggest we should re-examine the issue when possible, and look for better ways of addressing GHG reduction.

The University of California notes that food waste contributes 6.7% of global GHG emissions.

This 6.7% is not all just due to the actual food spoiling and being thrown out.  The transport, processing, refrigeration, etc. of food emits GHGs.

If the food that went through that processing, transport , etc. is wasted, then those GHG emissions from the tractors, trucks, refrigerators, etc. are wasted GHG emissions as well.

Worldwide, about one third of all food is wasted in the shipping or processing before it even reaches the consumer.  (From the UN's Food and Agriculture Organization, ).  So of that 6.7%, 2.2% is wasted before you or I even see it.  Now we're down to 4.4% of CO2 emissions from food waste directly due to the average consumer.

If tractors, trucks, food processing, etc., all run off of electricity from 100% non-GHG emitting sources like solar panels and wind turbines, then much of that 6.7% of GHG emissions attributed to food waste could be eliminated.  That 4.4% would shrink even further to perhaps 3%.

Cutting Food GHG Emissions

The main sources for GHGs world-wide are actually grains as noted in the UC web site above:
"Overall, because of the scale of their production, grains produce both the most waste and the most greenhouse gas emissions. Relatively little meat is wasted worldwide, but even small amounts of meat waste produce large amounts of greenhouse gases. Even among meats and dairy products, there is quite a bit of variation in levels of impact: Emissions are highest for beef and lamb, but much lower for pork, chicken, eggs and dairy."
We can see the impact of different diets.  Beef and lamb are the big GHG emitting food animals as seen below.  At 15.8 pounds of CO2e per day, eating a lot of meat emits about 250% of the CO2e compared to a vegan diet and over 180% of a "pescatarian" diet (vegetarian plus fish) - which latter is almost the same as the pure vegetarian diet.

46% lower CO2 emissions from switching from meat to fish. Almost the same as pure vegetarian
60% lower CO2 footprint by going all out vegan.
Another way of looking at the same thing below with a little more detail. Vegans and vegetarians need to substitute more of other foods to get the necessary protein.
So if the average diet comprises no beef (or lamb) then we have cut our CO2 footprint by nearly half and along with it the CO2 emissions due to our own food waste - from the 3% we got to earlier to about half of 3% or 1.5% (we can round up to 2%) of GHG emissions due to our wastage of food.

The next question is how serious about cutting GHG emissions is the government that wants us to recycle food?  The Sunnyvale Climate Action Plan tells us that most of our GHG emissions come from commercial buildings (39%), followed by transport (35%), then residential (16%) as seen below.
From Sunnyvale "Climate Action Plan", page 15 of the PDF
So what about the industrial or residential sector which combined come to 55% of Sunnyvale's GHG emissions?  Solar panels are now a cheaper way to generate electricity than coal.  Has California, Santa Clara County, or the City of Sunnyvale mandated that new construction have solar panels as San Francisco did?


About 52% of GHG emissions from residences in California come from natural gas to heat living spaces and hot water for bathing.  Natural gas is a huge source of methane which is about 24 times more potent a GHG than CO2.  Electric heat pumps can substitute for other forms of heating at less cost overall.  C.f.  (see diagram below) 
Space Heating + Water Heating = 52% of CA Home Energy Use
Has California, Santa Clara County, or the City of Sunnyvale mandated that no new construction have natural gas to heat water or living spaces?


One has to ask why these governments which all claim to be on the side of the environment have not addressed the areas where they can have the most impact.  It would make many people feel a little better about the inconvenience of Food Recycling if they knew that all the billionaire developers putting up office buildings and apartments were being asked to do their part.