Primary and Secondary Data

Example data collected:

• Raw material use
• Energy use
• Transportation distances
• Chemical use
• Waste treatment information
• Process yields
• Life time
• Water use
• Product and co-product flows
• Other flows in or out of the system that are within the defined cut-of-criteria 

 Tracking the material flows into and out of the defined system is the first step of LCI. After the materials flows have been determined through interviews, literature searches, and measurement, LCA software can be used to track the material process’s elementary flows to and from the environment. Elementary flows originate in the environment and are mined or retrieved for use in a process or flows that are released from processes to the environment and are not used by other processes. These elementary flows are the actual materials used and materials released to the environment as a result of the studied product system. In Figure 1.1

, the two types of LCI data can be seen. On the top half of the figure, process flows such as products, services and other goods are listed. The lower half lists elementary flows such as chemicals released to soil or air.

Figure 1.1  System boundary diagram of a cradle-to-grave biofuels process.