Bad professors, BAD. The truth about “Eat the Dog”October 23, 2009
I am told humans are smart, but sometimes I wonder. I was born back in ’02, and I have learned a trick or two in my 49 years. But this old dog will never play the kind of trick that Brenda and Robert Vale are playing. They are off by a factor of 20 when comparing the energy to power an SUV with the energy to power a dog.
Brenda and Robert Vale are professors at Victoria University in Wellington, New Zealand. They are either complete mathematical boneheads, or they have simply realized that in today’s world there is no limit to the outrageous claims that they can peddle to other completely credulous humans. They claim in their book “Time to Eat the Dog: The real guide to sustainable living” that I am an energy hdogs – worse than a gas guzzling SUV. Here is their (il)logic, as reported in the New Zealand Dominion Post…
The couple have assessed the carbon emissions created by popular pets, taking into account the ingredients of pet food and the land needed to create them.
“A lot of people worry about having SUVs but they don’t worry about having Alsatians and what we are saying is, well, maybe you should be because the environmental impact … is comparable.”
In a study published in New Scientist, they calculated a medium dog eats 164 kilograms of meat and 95kg of cereals every year. It takes 43.3 square metres of land to produce 1kg of chicken a year. This means it takes 0.84 hectares to feed Fido.
They compared this with the footprint of a Toyota Land Cruiser, driven 10,000 kilometers a year, which uses 55.1 gigajoules (the energy used to build and fuel it). One hectare of land can produce 135 gigajoules a year, which means the vehicle’s eco-footprint is 0.41ha – less than half of the dog’s.
Let me help my two-legged friends with their calculations.
Let’s compare the amount of land needed to generate enough biofuel to drive a Toyota Land Cruiser 10,000 km, to the amount of land required to feed a dog. Let’s compare kibbles to kibbles. In the case of the Land Cruiser grain may be converted to ethanol to power the vehicle. Similarly, grain can be fed to animals to yield meat, which can be fed to the dog.
My farm animal friends tell me that corn is the best grain for making ethanol. In the US, where they grow a lot of corn, they got 371 bushels of corn per hectare in 2007.* Each bushel of corn gives about 2.7 gallons of ethanol according to the USDA. So that means each hectare of corn yields about 1000 gallons of ethanol.**
The humans at Toyota say that the Land Cruiser gets 13 miles (20.8 kilometers) per gallon in the city and 18 miles (28.8 kilometers) per gallon on the highway. But that is when it runs on gasoline. The energy content of gasoline is 115,000 BTU/gallon. But for ethanol it is only 75,700 BTU/gallon. So it takes about 50% more ethanol to get the same energy.*** That is, the Land Cruiser would only get 8.6 miles (13.8 kilometers) per gallon of ethanol in the city and 11.8 miles (18.9 kilometers) per gallon of ethanol on the highway.**** Let’s average it and call it 10.2 miles (16.3 kilometers) per gallon of ethanol for the Land Cruiser.
So it takes 613 gallons of ethanol to drive the Land Cruiser 10,000 kilometers. That translates into 0.61 hectares of corn land. *****
Feeding a dog
Remember, a hectare of corn gave 371 bushels of corn in 2007. A bushel of corn weighs 56 pounds (25.5 kilograms). That is 20,776 pounds (9,441 kilograms) of corn per hectare.+
If you want to convert that corn into chicken meat, as the professors suggest, then according to the Agricultural branch of the Australia’s Department of Primary Industries, the conversion factor is about two kilograms of chicken feed to one kilogram of chicken liveweight. That means that a hectare of corn would give about 10,388 pounds (4,722 kilograms) of chicken liveweight. Dogs are not as fussy as humans, but even we don’t eat the feathers. We would only eat about 2/3 of the bird liveweight. That fetches 6925 pounds (3147 kilograms) of edible meat per hectare.++
According to the boneheaded professors, a typical dog eats 164 kilograms of meat per year. (I have a pretty good life – but I can tell you I don’t eat nearly that much. But I’ll play along anyway.) That would require 0.052 hectares to produce.+++ They say that we also eat another 95 kilograms of cereals each year – or another 0.01 hectares worth of corn.++++ That sniffs out to 0.062 hectares worth of land to feed an overfed dog.
0.61 hectares to feed the soulless Toyota Land Cruiser.
0.062 hectares to feed your best friend.
That’s 10 times as much for the Land Cruiser than for me. I could have sworn the professors said the dog required twice as much land as the Land Cruiser. They were only off by a factor of 20.
Bad professors, BAD. Don’t make me rub your nose in it.
* (151.1 bushels / hectare) x (2.46 acres / hectare) = 371 bushels per hectare.
** (371 bushels) x (2.7 gallons/bushel) = 1006 gallons
*** 115,000 BTU / 75,700 BTU = 1.52
**** (13 miles / gallon) / 1.52 = 8.6 miles / gallon = 13.8 kilometers / gallon
**** (18 miles / gallon) / 1.52 = 11.8 miles / gallon = 18.9 kilometers / gallon
***** 10,000 kilometers / (16.3 kilometers / gallon) / (1002 gallons/ hectare) = 0.61 hectares
+ (371 bushels/hectare) x (56 pounds/bushel) = (20,776 pounds/hectare) = (9443 kilograms/hectare)
++ (20,776 pounds/hectare) x (1/2) x (2/3) = (6925 pounds/hectare) = (3147 kilograms/hectare)
+++ (164 kg of meat/dog) / (3147 kg of meat/hectare) = (0.052 hectares/dog)
++++ (95 kg of corn/dog) / (9,441 kg of corn/hectare) = (0.01 hectares/dog)