Energy Flow Diagrams from LLNL

2010 Energy Flows

At the beginning of December, the Lawrence Livermore National Laboratory (LLNL) publishes it’s now famous energy flow charts, also known as “Spaghetti” diagrams. These diagrams are commonly used to track the flow of money, people or material goods through a process common in operations management analysis. LLNL adapted this methodology to the flow of energy through the US, going from Primary energy used all the way to final use, dividing it into useful and wasteful energy.

There are several striking things about this graph. Obviously, it is expressed in Quads, or quadrillion British Thermal Units (BTUs). The thickness of the lines corresponds to the amount of flow.

1. The striking part isthe amount of wasted energy, more than half of total primary energy – most of which comes from electricity generation and petroleum use in transportation. Due to Carnot limits and other costly engine design problems, petroleum engines waste about 75% of the energy content in petroleum. Similarly, fossil-fuel burning (not turbine) power plants waste 50% – 60% of the energy content in their fuel.
2. On the consumer side, once we get past the production of electricity, energy usage is remarkably efficient, with all three sectors estimated to waste about 20% of incoming energy flow.
3. A growing amount, now 40% of primary energy is being used to make electricity, from just 20% in the 1970s.
4. Finally, it shows the carbon intensity of the economy, with full 83% of our energy from fossil-fuels. Only about 8% of the energy comes from renewable sources (not counting nuclear), and of that most is hydropower (majority over 50 years old) and biomass, largely used industrially. Wind and solar together represented less than 1% of total energy use in 2010.

Changes since 2009

Now, 2009 was the first year after the recession, but it would be interesting to see how things changed since. The following is the energy flow diagram from 2009, also from LLNL.

Now, mostly due to somewhat recovering economy, energy use grew 4% between 2009 and 2010. The following table illustrates the growth in each area, again as in before the quantity is in quadrillion BTU:

One might notice a sizable drop in Geothermal generation, and part of this has to do with changes in how geothermal is classified, but the rest is in a drop of actual interest in Geothermal when compared to the growth in wind generation (currently driven by federal tax incentives). Additionally, the hydrology of 2010 resulted in less water available in dams, reducing the power generation capability. However, the overall growth rate emphasizes a rebound in demand, which saw a 5% drop from 2008 to 2009.