Green Metrics, Clean Metrics

What is the carbon footprint of a bee?

That is not a trick question! So many of the fruits, nuts and vegetables we eat are a direct result of commercial bee pollination. Natural pollinators thrive in environments where diverse crops are grown on small scales. With large monocultures -- even those that are "organic" -- the only way to keep production up is to truck commercial bee hives from long distances at specific times of the year to pollinate the crops. Joe Hansen, a commercial beekeeper and writer, describes this beautifully in the Oregonian. He goes on to say that consumers would be surprised at the size of the carbon footprint involved in commercial pollination. So what is the carbon footprint of a bee?

For example, California's central valley produces 1.9 billion pounds of Almonds each year, and requires about a million (that's right!) beehives to be shipped from all over the country. Each beehive travels an average of 1500 miles each way on a semitrailer truck for this gig. And the beehive is fed about 75 pounds of sugar annually to replenish the carbohydrates the bees burn in the hard work of pollination. Putting all this together into CarbonScope, I see that the bees increase a typical Almond crop's carbon footprint by about 10%. Not huge, but it is also not trivial, and it easily exceeds the typical impact of transporting the product to market.

Kumar Venkat

LCIs must focus on systems, not products

We can use life-cycle inventories to compare the environmental performance of two systems performing identical functions, but comparing two products or materials is risky business. Here is more on this subject from a report by Boustead for Plastics Europe:

All life cycle inventories are concerned with describing the behaviour of industrial systems, not products; a product is simply one materials flow within the system. The system itself is identified in terms of its function. Consequently if any comparisons are to be attempted, then they must be confined to comparing systems that perform identical functions. This is the basis of all life cycle assessments. Despite this requirement, which has been stated many times, there are still some users of life cycle inventories who continue to compare materials on the basis of 1 kg of polyurethane versus 1 kg of some other material. Such comparisons are meaningless.

 

Also, when comparing systems, which perform equivalent functions, it is important to compare the data for the whole life cycle and not just data for those elements of the life cycle that differ. Comparison of parts of systems can lead to misleading conclusions. For example, if polyurethane foam is used to insulate a house, the value of the exercise is demonstrated by a comparison of the system describing the un-insulated house with that describing the insulated house. Essentially the investment of a small amount of energy and feedstock in the production of the foam insulant leads to a saving of at least 100 times this initial investment in heating fuels over the lifetime of the house. The investment of 1 unit of energy results in a saving of 99 units. If a different type of insulant is used with a production energy that is 25% greater than the polyurethane, the net energy saving will be 98.75 units for every 1.25 units of initial investment.

 

Such a comparison indicates that the important feature is to install insulation materials of any type to achieve the saving of energy. Comparing the insulation materials on the basis of their production energies is a marginal exercise of little value since the difference in production energies of different materials is trivial compared with the ultimate saving.

 

Kumar Venkat

The sun rises again?

A fascinating article in the Economist suggests that the shift in economic power from the West to the East may be a bit exaggerated. Asia's 31% share of world exports last year was only slightly higher than its 28% share in 1995. China's share has grown, of course, offsetting Japan's declining share. More interestingly, Asia accounted for over half of the world output for 18 of the past 20 centuries, and is projected to get close to the 50% point once again by 2025.

Kumar Venkat

Global Trade

A few years ago, I was playing around with the idea that global trade could be constrained by the environmental costs of transportation. Crank up the transportation cost, and trade becomes more and more local (see our simulation study in InterJournal). So it was interesting to see Paul Krugman talk about the same thing from a comparative advantage perspective. His analysis suggests that global trade would expand over time if technological progress in transport consistently exceeds improvements in manufacturing. But if productivity increases across board (so that transport costs about the same in relative terms), then technological progress does not necessarily imply increased global trade as a share of world domestic product.

Kumar Venkat