US Energy Flow

While I’m on the subject of flow charts, I thought this visual from the Lawrence Livermore National Laboratory brings into relief the changes we are facing in terms of energy supply.

First, there is the sheer inefficiency of the overall system — of 105,000 petajoules (PJ) of energy consumed, some 57,943 PJ are wasted. Second, despite all the debate about nuclear, wind and solar, together they amount for very little of our energy supply. It is a world of coal, natural gas and oil. According to the analysis:

The national energy balance sheet reveals a number of pertinent facts. First, coal-fired power plants generate almost half of our electricity and are responsible for nearly 2 billion metric tons of greenhouse gas emissions per year—equivalent to the emissions of the entire transportation industry. Greenhouse gas emissions from coal, and to a lesser extent natural gas and oil, explain why the electric power industry is the single largest contributor to U.S. greenhouse gas emissions. Second, although there has been explosive growth in solar, wind and biomass power in recent years, renewable generation still provides a small amount of our generating capacity. Third, the current electricity system, from generation to end-user, wastes vast sums of energy; for example, a light bulb receives less than half of the energy contained in a piece of coal. Finally, the U.S. transportation sector is almost wholly reliant on oil, more than half of which is imported.

United State Energy Flow (Petajoules, 2007)
United State Energy Flow (Petajoules, 2007)

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