A network-based view of the U.S. energy sector

We describe portions of the U.S input-output tables through the tools of networks analysis - focusing on either energy intensive industries or those that are part of the separate and distinct energy sector. We first represent both energy intensive and energy sector industries visually through network diagrams for the years 1997, 2002, and 2007. Next, we show that the energy sector is generally more densely connected than either energy intensive industries or all industries over those years, and is more likely to have groups of three sub-sectors all linked as well. We then move to the level of individual industries within the broad sectors and find that energy intensive industries have the most in-coming connections on average for these tables. Energy sector ones have fewer, but the number grows over time, as do outgoing connections. Other measures of centrality - closeness and betweenness - vary over time for both the energy sector and energy intensive industries. Specifically, petroleum refining and electricity generation stand out for their centrality, drilling oil and gas wells for its lack of centrality.