UK DEFRA: Comparative life-cycle assessment of food commodities

This is a “for reference” post on a study of the life cycle environmental footprint of UK-consumed food. The study was funded by the UK Department for Environment, Food and Rural Affairs.

The scope of the study was limited to seven products that are produced in the UK in more than trivial quantities. No effort was invested in attempts to identify the most environmentally friendly international supplier. Instead representative sources were analyzed – e.g., NZ lamb, Spanish strawberries. Nevertheless, it seems to be a credible study.  

(…) A life cycle inventory (LCI) was first produced for each commodity and then a life cycle analysis (LCA) associating inventory data with specific environmental impacts. Each included established LCA criteria including: primary energy use (PEU); global warming potential (GWP); acidification; eutrophication; abiotic resource use; pesticide use; land requirement. Comparative inventories were produced from the first point of pre-production to the Retail Distribution Centre (RDC) in the UK for all seven commodities. The system boundary was through to the RDC, rather than the consumer, as all steps post RDC will be common to UK and non-UK food. The functional units are weight based (e.g. per tonne at the RDC). The study then progressed to a life cycle impact assessment, i.e. associating inventory data with specific environmental impacts. Estimates of the comparative effects on wider eco-services have also been made.

The Fallacy of Locally Grown Produce

Too often, environmentalists are satisfied with the mere appearance and accoutrements of environmentalism, without regard for the underlying facts. Apply some mathematics and some economics, and you’ll find that a smaller environmental footprint is the natural result of improved efficiency.

Brian Dunning, proprietor of Skepticblog, posted a May 2009 debunking the “food miles” myth and other environmental convictions advanced to justify the buy-local meme. A  well-written piece, excerpts:

Many years ago I did some consulting for a company that was then called Henry’s Marketplace, a produce retailer built on the founding principles of locally grown food. They had grown from a single family fruit stand into a chain of stores throughout southern California and Arizona that stuck to its guns and sold produce from small, local farmers. It’s a business beloved by its customers for its image of wholesome family goodness, community, and healthful products. (Henry’s has since gone through several acquisitions and is now called Henry’s Farmers Markets.)

Part of what I helped them with was the management of product at distribution centers. This sparked a question: I had assumed that their “locally grown produce” model meant that they used no distribution centers. What followed was a fascinating conversation where I learned part of the economics of locally grown produce. It was an eye-opening experience.

In their early days, they did indeed follow a true farmers’ market model. Farmers would either deliver their product directly to the store, or they would send a truck out to each farmer. As they added store locations, they continued practicing direct delivery between farmer and store. Adding a store in a new town meant finding a new local farmer for each type of produce in that town. Usually this was impossible: Customers don’t live in the same places where farms are found. Farms are usually located between towns. So Henry’s ended up sending a number of trucks from different stores to the same farm. Soon, Henry’s found that the model of minimal driving distance between each farm and each store resulted in a rat’s nest of redundant driving routes crisscrossing everywhere. What was intended to be efficient, local, and friendly, turned out to be not just inefficient, but grossly inefficient. Henry’s was burning huge amounts of diesel that they didn’t need to burn.

You can guess what happened. They began combining routes. This meant fewer, larger trucks, and less diesel burned. They experimented with a distribution center to serve some of their closely clustered stores. The distribution center added a certain amount of time and labor to the process, but it (a) still accomplished same-day morning delivery from farm to store, and (b) cut down on mileage tremendously. Henry’s added larger distribution centers, and realized even better efficiency. Today their model of distributing locally grown produce, on the same day it comes from the farm, is hardly distinguishable from the models of Wal-Mart or any other large retailer.

Here’s where it seems counterintuitive: If you look at the path traveled by any one given box of produce, it’s much longer than it used to be. It no longer travels in a single straight line from farm to store; it now travels the two long sides of the triangle in its path from farm to distribution center to store. But quite obviously, this narrow view omits the overall picture, where the stores are all stocked with produce that got there much more efficiently.

Locally grown produce is rarely efficient. Apply a little mathematics to the problem, and you’ll find that the ugly alternative of giant suburban distribution centers accomplishes the same thing – fresh produce into stores on the same day it’s picked – but with much less fuel burned.

(…)

 Don’t get me wrong, I love farmers’ markets. We go to our local one sometimes and it’s a fun family event for us. We love the giant, wonderful tomatoes and strawberries that you can’t get at the supermarket. I’d hate to see the experience replaced by the efficient alternative I just described, but then, I understand that farmers’ markets are more of a premium boutique community experience than an efficient (or “green”) way to buy food. The real reasons to enjoy your farmers’ market have nothing to do with it being somehow magically environmentally friendly. It’s the opposite.