Global Insight has an interesting perspective on energy use and efficiency in production and industry (particularly energy production). Interestingly:

It is important to note, though, that in generating $691 billion worth of energy output, the [United States] energy sector itself used $495 billion worth of energy inputs, resulting in a value-added contribution of only $196 billion (28.4% of total). Thus, energy use as an intermediate input is nearly eight times as large as its use in final consumption.