In my last column, I introduced the concept of lifecycle analysis, which is an emerging method of evaluating the energy efficiency of agriculture. National retailers, led by Wal-Mart, are requiring all suppliers to document how energy and carbon efficient their products are. I know of at least two commodity groups in North Dakota that are striving to evaluate their energy and carbon footprints.
What is lifecycle analysis? Essentially, energy scientists have adopted a new, integrated tool worldwide as the standard method for making energy and carbon assessments. A unique aspect of the analysis is that it evaluates all resources coming from nature that are used to produce goods or a service and then proceeds to track where that resource ends up (air, soil, water or as human products) at each process stage.
Some of the common resources tracked include the amount of fossil energy utilized, electricity, carbon dioxide and other gas emissions. Such analyses become fairly complex to diagram and track because of all the relationships involved.
I have a diagram that shows just part of the lifecycle for energy beet production in North Dakota (amount of energy consumed to produce the crop). From this, I will develop a second diagram showing where all the energy ends up. In essence, the final diagram will look like an inverted tree placed directly above the existing graph.
Each line in the energy beet production graph represents the amount of fossil energy needed at that stage. The widest line on the left side of the figure is the amount of diesel fuel consumed for field operations. The next widest line is on the right side of the graph, representing the fuel needed to transport the beets from the field to the plant. The stages in between show the amount of fuel needed for seeding, nitrogen, glyphosate, other herbicides and electricity (from left to right, respectively).
As we move down the diagram, the amount of fuel needed for each input is quantified. Here is where it gets complex because obtaining diesel fuel from a refinery requires additional trucking, electricity, natural gas and even some diesel fuel. Hence, we have a large number of horizontal lines going back and forth. It isn’t shown because of space limitations, but one could track the amount of energy used to produce the tires on the tractor used in field operations.
In total, it takes 2,820 ounces or 22 gallons of fossil oil to produce an acre of energy beets and deliver them to a processing plant in North Dakota. This can be compared with the total amount of biofuel produced per acre of nearly 800 gallons. To evaluate overall energy efficiency though, we will have to determine energy consumption at the biofuel plant and in delivery to retail customers.
A similar diagram could show the amount of natural gas consumed in each stage of production. In this case, the widest line would be directly under nitrogen fertilizer because the production of nitrogen fertilizer requires large amounts of natural gas. However, there would be just as many smaller lines as well because natural gas is used to produce tractors, herbicides and other inputs for energy beet production.