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PostPosted: Mon Aug 27, 2012 2:49 pm 
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Joined: Tue Apr 18, 2006 2:09 pm
Posts: 1649
Location: Regina, Saskatchewan, Canada
I posted part of this in a different thread but thought it deserves it's own thread

Using 2008 data (population and world energy creation) I come up with:
77.4 GJ/person-yr
Using the low end of recommended calorie intake and converting the units:
3.36 GJ/person-yr
Two estimates of the portion of energy used directly and indirectly to get food on our table (in USA and in UK) were both in the mid 70s of percent so to be conservative I will use 70%
77.4 x 0.7 = 54.2
how much energy does it take to make food energy?
54.2 / 3.36 = 16.13 (note I kept full numbers in the calculator)
It takes 16 times as much energy to make your food then the energy in your food. This is also a global number so it includes the low energy use of the poorest parts of the world but assumes they eat the recommended calories.

I did a calculation based on several sources so might be wrong but one GJ of natural gas produces 55.1 tons of CO2 (coal and other fuels would be more) so:
55.1 x 54.2 = 2987
Growing your own food could save 3000 tons of CO2 per year per person

In the UK, it is estimated their cars produce 5.6 tonnes of CO2 per car annually so growing your own food would be the equivalent of taking over 500 cars off the road ... per person growing their own food!


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PostPosted: Sun Sep 02, 2012 3:23 pm 
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Joined: Tue Aug 07, 2012 1:54 pm
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Location: Hamilton, Canada
For my own part, my family's carbon footprint used to be quite large when we lived in a suburb...better defined as an ex-urb, since it was a 2 mile drive into town. I had to drive 50 miles/80 km to get to work each day, so we always had to have two cars in running condition. Since we were still paying a mortgage and my wife had to stop working for health reasons, the shear costs of suburban life were more than I could afford. So, although I didn't really want to live in the city where I work, we moved to an older neighbourhood where I could ride my bike or run the 3 miles to and from work. So, our one remaining car gets a tank-full every two or three weeks.

If I had my way, I wouldn't even keep one car! I know a lot of people...especially younger people, are in love with their cars and would sacrifice almost everything to keep them, but car culture has to be phased out if we are ever going to have a sustainable future. It's not just a matter of switching to battery-powered electric cars; we are running out of the resources that are needed to keep building millions of new cars every year, and then there is the huge carbon footprint of building and maintaining roads and highways. When I was young, the vision of the future (back then the year 2000) was that we would be traveling from city to city on high-speed rail, but the special interests behind subsidizing car culture has made sure that rail continued to decline -- even for transporting freight! If it wasn't for the special interests involved, it would be easy to make the conversion to a post-auto era. And it should be done now, before civilization itself collapses, and we are back to an age when people rarely, if ever left their own villages where they grew up!


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