Thursday, June 14, 2012
I recently came across several studies that answer a long-running question of mine: what is the carbon footprint of goods traveling from China to that big box store down the road? The answer also planted a more perplexing question: could it be possible that the carbon footprint of goods in China, if built and assembled in China (or some other distant country) and shipped in a particular eco-sensitive way, could be less than goods "made in the USA"?
The issue of goods transportation and carbon footprints seems to me one of the most important, but potentially counter-intuitive, aspects of land use policy. Independent of economic concerns, which of course is a huge issue of its own, we might presume that a consumer good "made in the USA" has a lower carbon footprint than one made in China. But what if the "American" good is made from parts manufacturers around the world and simply assembled in the United States? For instance, just 40% of the Ford Focus in made in the USA, and just 15% of that car is made in Mexico, with the remainder coming from non-North American parts suppliers. Most "American" cars are really smorgasbords of parts suppliers shipped from the world over to a factory in the US. At the very least, that provides factory assemply jobs for US workers. But if we just consider the environmental impact for a minute, would the carbon footprints of those cars be lower if all the parts were made in one place in China, assembled in China, and then those cars were shipped to their US destinations?
While I can't answer that question directly, a really interesting November, 2011 paper, Moving Containers Efficiently with Less Impact: Modeling and Decision-Support Architecture for Clean Port Technologies, by Josh Newell and Mansour Rahimi at USC's School of Policy Planning and Development, traces the important steps in answering carbon footprint issues in the supply chain. In particular, Chapter 2 in the report models the emissions from real container shipments of an undisclosed toy manufacturer from manufacturing destinations in China to various retail destinations across the US.
The report noted that there were three main contributors to carbon footprints, each of which were potential variables:
The first is the land contribution, which is partitioned into China and United States segments, and is further partitioned into truck and rail segments. The second contribution comes from the sea, which is portioned into cruising speed, and slow speed segments. The third contribution comes from port operations for loading and unloading containers.
In general, the report concluded:
For the average container shipped from China to various U.S. destination zip codes, a carbon footprint of 2,821 kilograms per container per trip was determined. Transport by container ship is the most efficient in terms of CO2 burned per mile. So it is possible for a container to travel a greater distance, yet have a smaller carbon footprint than one that uses land transportation (train/truck) for a greater portion of the distance.
So there you have it: 2,821 kilograms per container on average. And the further the container goes by ship, the lower the CO2 emissions. A similar NRDC study studying retail apparel shipments from China to Denver compared air to ship transit and concluded:
[T]he truck-air-truck pathway emits over 5 times more soot (particulates) and 35 times more greenhouse gases than rail-ship-rail, sending an additional 99 tonnes [sic] of greenhouse gases into the air. On the ocean leg alone, a retailer would reduce GHG emissions by 99% sending cargo by ship instead of plane. Using this method, a retailer could send 101 full containers by ship and still emit fewer GHGs than one container sent by plane.
So ships are cleaner than air transit, too. And what if we could make ship transit cleaner, with greener fuels and such?
All of this brings me back to my new question. If ship transport is relatively green (and we could likely make it greener), and we can run ships all around the world and ship things in containers for relatively low costs, would it be better from a carbon emissions perspective to build all the parts near an assembly site for a product in China and ship it here, or build parts around the world and assemble it in the US? This presumes, of course, that we cannot convince manufacturers to both build the parts and assemble them in the US, which seems to be an industrial model that has gone the way of the dodo bird for economic reasons.
The implications seem vast to me for our industrial areas, both for how we conceive of them in economic and environmental terms in this global age. If the shipping container has changed the economics of manufacturing (anyone interested in this must read Marc Levinson's excellent The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger), might it also change the environmental aspects of manufacturing, too? And if so, what might this mean for our city's industrial areas, and in particular, how we contemplate their environmental footprints? I'd be curious if anyone has studied this particular issue.
Stephen R. Miller
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