With food and other products, we are often concerned with the number of miles the food has travelled to get to our tables. Locavorism encourages people to consume foods produced within 100 miles of home.
But is the number of miles travelled really all there is to measuring a product’s carbon footprint?
The answer is an emphatic no. The analysis of a product’s carbon footprint is in fact extremely complex and needs to take in to account every step of that product’s lifecycle from cradle to grave.
Life-cycle assessment, or cradle-to-grave analysis, must account for everything that went in to making that product (including the extraction or manufacture of “sub” products, e.g., the materials required to build a computer), everything it took to get that product to the consumer, and then everything it takes to dispose of that product.
Take a classic example from the economics literature (economists are often the spreadsheet-happy types who perform this sort of meticulous bookkeeping). There are several variations on this study, but the basic question asked is this: Is it “cheaper” (i.e., is the total energy usage lower) to bring fresh-cut roses to a London flower market from the Netherlands or from Kenya?
A typical first response is, the Netherlands, of course. Much less fuel is involved in moving flowers to London from Holland (which could be done by truck) than from Kenya (where air freight would be needed).
However, there are many other considerations than just the transportation energy needed to move roses from Point A (Holland or Kenya) to Point B (London). An easy one to grasp is heating costs. In Kenya, rose bushes can be grown outdoors: it’s warm and sunny there, so no additional energy is required to keep the plants happy and flourishing. In the Netherlands, though, rose bushes need to be grown in greenhouses. So the energy costs of building a greenhouse (as well as all the energy that went in to manufacturing and transporting the greenhouse building materials) have to be factored in to the Netherlands scenario. Add to that the cost of heating the greenhouse, and you can see the energy bill from Dutch roses really starts to add up.
Other factors include soil and plant nutrition. If roses are planted in potting soil in Dutch greenhouses, there might be a positive credit in the energy balance because of things like compost (which recycles the carbon from food waste into food for plants), the easy access to relatively abundant water, and so on. In Kenya, maintaining soil health and productivity might be a much more energy-intensive job, perhaps requiring nitrogen fertilizer, which will almost inevitably have been produced from petroleum and probably transported (as ammonia) a long distance via ship (a notoriously high-carbon method of transportation).
All of the materials, labor and energy used in the production and transportation of roses have to be factored in. Even then, it’s still just a partial picture of the true cost of a red rose purchased in a London flower stall.
Let’s switch products and think about diamonds for a moment. Add up all the factors a mining company, such as De Beers, has to account for in getting that tiny bit of bling into a Seattle jewelry store. Don’t forget the social costs of producing a product?
Some diamonds (as well as some gold and other minerals, often called conflict minerals, used in cell phones and other devices we now take for granted) are mined in areas torn by war or in countries with serious human rights abuse issues. The mining itself can cause enormous environmental damage, thus hindering local populations from farming or conducting other life-necessary tasks. The sale of such diamonds may be used to finance the purchase of weapons, escalating and perpetuating hostilities and abuses in the mining region.
The life-cycle assessor must somehow factor these human and environmental costs into their calculations. De Beers, among many other companies, have pledged to not do business in places where conflict and human rights are at issue. For a dramatization of the issue, check out the Leonardo DiCaprio film, Blood Diamond.
Scientists working on the NARA project looked hard at, according to the NARA website, the “‘cradle to grave’ impacts of creating biofuels and co-products from woody biomass.” The assessment compares petroleum and forest residuals-based fuels along a variety of environmental attributes, including energy use, greenhouse gas emissions, and other environmental measures. It includes a variety of harvesting options, the bio-jet fuel conversion process, and the impact from integrating biojet fuel manufacturing into the existing forest product industry infrastructure.
For a bio-based economy to really take off, we also have to understand what consumers are willing to accept. There, too, NARA, through its Environmentally Preferred Products Team, has taken steps to assess “attitudes, perceptions, and current understanding of biofuel-based products by the public and policymakers.”
And, of course, nothing is going to be made from plants if it is unprofitable. Here, too, NARA has stepped in to shed some light. Through another sort of analysis called techno-economic analysis, NARA researchers have figured out the relative cost of producing fuels and co-products using a wide variety of variations on a basic scenario. The basic scenario is simple: take the residuals left over from lumber harvesting (currently, NARA has looked at this practice on private land only, as it is generally assumed that the public would not accept such a practice on public lands), transport those residuals to a biorefinery, and then make stuff. It’s that last bit, “make stuff,” that is complicated and subject to a lot of different chemical engineering approaches—and the bit that has to be precisely understood and mapped put in order to be attractive to investors and the companies into which they put their money. For the details, check out this NARA report.