Material Flow Analysis of Nitrogen Around Industries in Japan from 2005 to 2015

Abstract

Nitrogen used for economic activities initially takes the form of ammonia, and is ever-present in our daily lives, not only as fertilizers, but through its role in chemical products such as synthetic chemical fibers, resins, semiconductors, and more. The purpose of this study is to understand the changes in demand accompanying future economic change by organizing trends in, and characteristics of the demand for reactive nitrogen (Nr), especially nitrogen fixed as ammonia (NH₃-N), demand in Japan. Material flow analysis (MFA) was used to quantify and simultaneously analyze changes over time of the flow of Nr and NH₃-N in Japan. The results showed that, in 2005 and 2015, the Nr flows from food & feed to house hold use were 898 kt-N and 775 kt-N; the flows from the chemical industry to fertilizers were 632 kt-N and 500 kt-N; and the recoveries from sewage sludge to fertilizer were 28.6 kt-N and 68.3 kt-N, respectively. The Nr (or NH₃-N) flows related to food & feed, the chemical industry, and fertilizers decreased from 2005 to 2015 (food & feed: 13%, chemical industry: 26%, fertilizer: 7%). In spite of the downturn in Nr demand in the chemical industry, industrial usage (e.g., chemical products) still accounts for more than 50% of the NH₃-N demand (623 to 884 kt-N) in Japan, much higher than its global share (20%). Interestingly, the NH₃-N flow to the semiconductor industry accounted for 0.21%, 0.57% and 1.03% of the industrial use in 2005, 2011 and 2015 respectively. In the future, management and conservation of NH₃-N will be even more essential in controlling Nr and NH₃-N flow.