Image Source: Sifu Renka
Dear Pablo: I eat a lot of tofu as part of my vegetarian diet but it seems to me that this may conflict with my concerns for the environment. What is the carbon footprint of tofu?
Tofu is made from soybeans by curdling soy milk much like cheese is made from cow milk. The soybeans require very little, if any, irrigation and they "fix" about 1 pound of nitrogen in the soil per plant because they are legumes. The nitrogen put into the soil by the soybean plants reduces the amount of synthetic nitrogen fertilizer required for the crops, usually corn, that follow in the field's rotation of crops.We all know that the commercial production of food is dependent on oil and the processing, transportation, and combustion of this oil releases a lot of greenhouse gas emissions. But how much?
How Much Do Soybeans Sequester?
A recent study by Omni Tech International, Ltd with LCA modeling by Four Elements Consulting, LLC that was funded by the United Soybean Board came up with some surprising results. Apparently the sequestration of greenhouse gasses by all of the soybean plants grown in the US in 2009 removed enough greenhouse gasses (in carbon dioxide equivalent units) to be equivalent to taking 21 million cars off the road. Of course this is only the greenhouse gas removal side of the equation, what about the emissions from growing soybeans?
How Much Do Soybeans Release?
Growing soybeans requires diesel for farm equipment, electricity for pumping water, and fertilizer. All of these create greenhouse gas emissions and other environmental impacts. Tiffany Plate, a writer from Boulder, Colorado found that farm inputs result in 0.005 and 0.011 pounds of greenhouse gas emissions per pound of organic and non-organic tofu respectively. Tiffany went on to discover that transportation from the field to the soybean processing facility resulting in a further 0.015 pounds of greenhouse gas emissions energy and fuel use at the processing came to 0.002 pounds.
What Is The Impact Of Making Tofu?
By far the greatest source of emissions in the supply chain of tofu comes from the tofu factory itself. Tiffany estimates that fuel and electricity use at the tofu factory results in 0.55 pounds and that transportation to her local store adds another 0.012 pounds of greenhouse gasses to the atmosphere. The total greenhouse gas emissions from making and distributing a pound of tofu is between 0.81 and 0.86 pounds, depending on a variety of factors such as the use of irrigation water, the distance of transportation and organic/non-organic. Compare this to the conclusion of a Scientific American article that claims that the average pound of factory-farmed beef creates almost 15 pounds of greenhouse gas emissions!
What Other Emissions Can Be Attributed To Your Tofu?
One common, yet highly dependent element of life cycle analysis is the use phase. In the case of tofu the additional sources of emissions that can be attributed to it include your trip to the grocery store, refrigeration, and cooking. The making of the packaging as well as its disposal can also be considered. In many cases the use phase of a product's life cycle can far outweigh the impact of its production. This is true for cars, clothing and napkins, as well as tofu. To minimize the impact of the use phase walk to the store or combine errands. Also make sure that you get the tofu home and into your refrigerator quickly so that you don't have to use energy cooling it down again. Of course, the "carbon footprint" of your meal will already be significantly lower since you didn't choose farm-raised beef.
Pablo Päster is a weekly columnist for TreeHugger.com, an experienced greenhouse gas engineer and the Senior Environmental Program Manager at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
More Resource On Tofu:
Tofu's Carbon Footprint
7 Low-Cost Low-Emission Foods
Ten Low-Emission High-Protein Foods
The Tofu Bear: Bean Curd's Best Ambassador