Monday, March 29, 2010

How buying “local” produce can have a very high carbon footprint….

.....and other such thoughts.

Buying “local” food and supporting local farmers and their local produce is one bullet point mantra often touted to be far more sustainable than buying food at a supermarket that belongs to a big company. The main claim for this is that local produce has very low transport costs (from the farm near by to the market), so the carbon footprint for this produce is extremely low. This then would mean that it is far less energy consuming and in the long term far more sustainable.

For a while I thought this was a compelling argument, and sometimes pondered over how guilty I should feel for not heading out to the local farmer’s market to buy “local” produce. But then, ever the skeptic, I decided to actually see if this was true.

First of all, at least in most of the US, local food now means food grown not necessarily 10 miles from the city, but within the state. Obviously, there are many cities near which there is no significant farming/agricultural land growing wheat, corn, fruit and vegetables. While Dallas does have farms a hundred miles or so from it, “local” predominantly means within the state of Texas. But since Texas is almost three times the size of France with most of the population in the four large urban centers (Dallas-Fortworth, Houston, San Antonio and Austin) it is very likely that a significant portion of the “local” food is being trucked across hundreds of miles from various rural, agricultural parts of the state to the cities. So that immediately weakens the distance and high energy consumption argument.

But could it still be possible for me to be more energy efficient (and our food more sustainable) if I shopped at a farmers market and not at a supermarket chain? Here is what some simple but rigorous calculations suggest:

Dallas has a lovely farmers market as well as other stores that sell local produce extensively. All of them are located around 8-10 miles from home. So a return trip is about 20 miles by car, through significant traffic. In addition, these stores only sell produce, so if I need a toothbrush or soap or any other daily use produce, I need to head out to a pharmacy or a general store to buy it. So if I get my food from a farmers market my gas consumption will be about gallon of gas a week (or over 50 gallons of gas a year). It also is a significant investment of my time.

In contrast, we live about 500 yards from a supermarket owned by Safeway/Tom Thumb, which is at the end of the street our house is in. It is the typical big American supermarket which sells everything from food and produce to kitchen towels and brooms. In our case, shopping is done on the way back from work without any detour, and on occasion I walk down to the store to pick up stuff. The total extra annual gas consumption for our shopping is zero gallons. In addition, it also saves a lot of time during the week since there is no need to make additional shopping trips for items of daily use that is not food or produce.

All of this only considers individual energy consumption (which can be quite significant), and does not go into the significant energy efficiencies brought about by economies of scale achieved by larger supermarket chains.

There is tremendous value in local food and local crops, and there should be a significant space for it. But even a simple hard look suggests that it is not necessarily a more “sustainable” and energy efficient method of food production. The more I research these issues (and those around “slow food”), the more it seems like they are largely seductive rants against corporations and globalization. Where there remains much value in these ideas, and they should be encouraged, they will not meet any rigorous analysis of sustainability and energy efficiency unless one uses similar eyewash metrics that large, inefficient corporations use.

(For a fascinating and rigorous information on a host of these issues, Just Food is an excellent read).


sameer said...

Its not about how much you drive, but how much the produce travels! The produce could travel to Walmart/wherever you buy stuff from closerby and that'll help. And its not just fuel, there's refrigeration, preservatives, water etc etc saved.

Even better, try being not just a consumer, but in whatever limited way possible, a producer as well. Even in our little balcony in Bangalore, we grow basil, chillies, the odd tomato. You can use solar panels to make electricity, and harvest rainwater.

Its not so much the hair-splitting calculations, but more the consciousness and attitude that'll help since those determine the goals. The paths to these will be then experimented with, and the right ones found sooner or later.

For instance, your in-between-the-lines goal of reducing the miles done in your car is spot on. And one way or the other, you'll get there now that you've thought of it :)

Big Foot said...

I have rather limited knowledge on this issue but even from a layman perspective I would say that your argument is about a very specific case.

While supermarkets are good for the consumer (everything under one roof) there is a tremendous amount of wastage involved simply because of the massive quantities in which they deal. On the other hand if you chop down that amount into say a 100 small vendors (not necessarily farmers but say small retailers) the amount of wastage goes down.

Nevertheless, a good read :)

Sunil said...

sameer....I understand that the general issue is about how much the food travels to reach the store. But after years of thinking/reading about this, I think the "local" movement has been too glib in their efforts to portray everything local as good, and everything in stores as bad. I used this one simple example to show that it is not as simple as that, and that there are significant inefficiencies in local food, and some efficiencies in supermarket produce. I haven't thought of this just now :-)

Big foot....yes, it is a specific case, but with significant broad implications. Again, I'm trying to point out a large gray area that is outside the vision of both the "local" movements and the corporations.

central texas said...

It seems to me that you need to provide some basis for your assertions regarding "local" being defined as anywhere up to 700 miles away, (based on your somewhat singular example of the second largest state). Does your hypothesis hold as well for, say, Rhode Island? As a counter-example, the farmer's markets in Austin are limited to those growing or producing within a 100 mile radius and at least three of the farms selling at the market I patronize are within the city limits.

No doubt "the corporations" are appreciative of any efforts to blur the distinction among providers and their sources. I doubt the "local movements" are as grateful.

Sunil said...

central're pretty quick off the gun aren't you? Yes, my example is worthless in Rhode Island. I also say that there is plenty of value in very local produce and farmers markets (and I still continue to support them in as many ways as possible). But the point here is that very often buying local is not necessarily more energy efficient or sustainable. As far as other issues go (supporting "communities" etc) there remains much value in local food etc. But there is a need for introspection and analysis within local food movements and slow food movements, which I find singularly lacking. I am not an ideologue, so I really don't care about corporations or movements. But I do care about sustainability, and am just looking hard at all options.

Sudip said...

I live about 0.2 mile to a Big Chain supermarket and about 0.5 mile to a farmers market - so for me, it does not make much difference in terms of driving, or walking time. So yes, different people have different experiences depending upon where they live.
As one of the comments earlier, it also depends on how much the food had to travel to get to the store. Remember that the least amount of innovation has been done in the area of large-truck automotives, in terms of making them fuel efficient. They are still big cuboids with no thoughts put to aerodynamics. Then consider the amount of energy that is spent in keeping these perishable items at a low temperature - both in those trucks as well as the supermarkets. The last I heard, 10% of the energy used annually in the US was consumed by the food industry. [Heller, Martin C., and Gregory A. Keoleian. Life Cycle-Based Sustainability Indicators for Assessment of the U.S. Food System. Ann Arbor, MI: Center for Sustainable Systems, University of Michigan, 2000: 42.]

hk said...

Sunil, I'm not sure this suggests that the local produce mantra is flawed. It only implies that consumers should exert even greater effort in convincing ALL stores (including the supermarket 500 yards away) to stock local produce, whenever feasible. Further, stores need to prioritize same county first, then same state. Consume local seems to make sense.