In a recent post I laid out the various areas that we need to account for in the overall environmental footprint of a product. One thing you'll notice is the the product travels at least twice (once from the manufacturer to the customer and once from the customer to the recycler), but the bulk of the product may travel more times than that. For example, parts may flow through a supply chain such that the heavy parts take two or three hops before the manufacturer, and may take an additional hop after being initially sorted for recycling.
While the number of hops isn't important, its important to know they exist. You may think you're buying a product from someone in California, but if all of the subcomponents originated in China, then all of that weight started there, even if they weren't assembled yet.
As noted a year or so ago, the environmental cost of shipping varies wildly depending on the method used (per "Let My People Go Surfing"):
- Rail or boat: 400 BTUs per ton per mile
- Truck: 3,300 BTUs per ton per mile
- Air cargo: 21,760 BTUs per ton per mile
So lets make up a scenario and see what the impact is. First, assume a 250W server which will run all year long (roughly 9000 hours/year) for 3 years. That makes a total of 6,750 kWh. Second, assume that the parts start in China, end up as a product in New York, and meet their final resting place in a recycling facility in Oregon, for a total of approximately 13,000 miles. Finally, lets assume that the server weighs 50 pounds.
If we use only one type of transportation, the three options above would check out as follows:
- Rail or boat: 130,000 BTUs or 38kWh
- Truck: 1,072,000 BTUs or 314kWh
- Air cargo: 7,072,000 BTUs or 2,072kWh
So in this case, if we use either of the less costly ways, the overall product impact is not overly affected. However, if we fly the parts around for each hop, the environmental cost is the same as using the product for a whole additional year!