First among the short list of climate actions that will work is electrify everything, but why? Why not insulation or renewable natural gas or wind turbines? To answer that, we’ll have to take a bit of a detour into Sankey diagrams and rejected energy.
The Lawrence Livermore National Laboratory Sankey diagram, a visual masterpiece in its own right, doesn’t just chart U.S. energy flows — it paints a stark picture of all of our economies’ inefficiencies. On the left of the diagram, all of the primary energy that flows into our system of electrical generation, buildings, industry and transportation. In the middle, how it gets used. On the right, two big boxes.
Primary energy is all of the coal, oil, gas, geothermal, hydroelectric, wind and solar energy that starts out as a raw source of energy. The hydroelectric, wind and solar are grossed up from their actual megawatt hours so that they are “equivalent” to coal, oil and gas based on the low average efficiency levels of those fuels, under 40%.
The big box on the bottom right is the energy that we actually use, energy services. That’s energy that heats our water, toasts our bread and gets us through our commutes and to our shopping. You’ll note that it’s about a third of the primary energy that comes in on the left, about 32 of the roughly 97 quads — a quad is a quadrillion BTU, otherwise known as an awful lot of energy — we started with.
It’s the big box on the upper right that’s our focus. It’s rejected energy. It’s the energy that doesn’t do us any good. Of all the primary energy that enters our economies globally, we throw away about two-thirds of it. Almost all of that is waste heat from burning fossil fuels. Most countries have some version or versions of this diagram, but the US one is particularly good at highlighting wasted energy. Shrinking rejected energy as compared to energy…
