Words alone cannot tell the full story about America’s energy sector. To understand the energy sector properly, we must know its daily numbers. These have been laid out in the Sources & Uses Map below, so that all readers can have a proper snapshot of where we are today.
Energy Sources are listed on the left-hand side of the map, from top to bottom, and shown in four main categories: Fossil Fuels; Electricity; Liquid Fuel; and Heat.
Energy Uses are listed across the top of the map. Electricity is both a use and a source; it occupies a special place on the map. Not counting electricity, six major Uses are shown: Residential; Commercial; Industrial; Transportation (Gasoline); Transportation (Diesel); and Transportation (Aviation).
Everything has been quantified in watt-hours per day. This isn’t always how we consume energy, of course. When we burn a fuel of any kind, we normally measure its energy content in British thermal units, or Btu, and it has long been the custom in the Department of Energy to state American energy consumption in Btu rather than in watt-hours. Tomorrow’s energy economy, though, will depend more heavily on electricity than today’s, and it is therefore appropriate to use watt-hours as our base unit rather than British thermal units.
Here we will multiply watt hours by a trillion, so that we can deal in terawatt-hours. And we will measure daily average usage, expressed as terawatt-hours per day, or TWH/Day. With terawatt-hours/day as our basic unit of measure, average daily consumption in the American economy turns out to be an easily remembered double digit number. It turns out that end users in our economy consume 56+ terawatt-hours a day worth of energy.
Readers will also note that the totals for Sources and Uses exactly match. 56 terawatt-hours/day of energy are produced; 56 terawatt-hours/day of energy are consumed. The row-by-row total for Sources matches the column-by-column total for Uses.
Begin with the second column on the Sources & Uses Map, the Electricity Generation column. A number of energy Sources play a role in generating the nation’s electricity. Not all the electricity generated, though, ends up being consumed by the nation’s users. It takes energy to move electricity across the grid, and the map reflects this in the row called Losses. On an average day, 0.59 terawatt-hours of electricity are expended getting power to the end users, with 10.27 terawatt-hours a day of Net Electricity supplied to the nation’s end users. Follow the Net Electricity row to the right if you wish to see how much electricity is used in each part of the economy. Residential users consume 3.97 TWH/Day, Commercial users consume 3.64 TWH/Day, Industrial users consume 2.64 TWH/day, and a comparatively tiny amount of electricity is consumed in Transportation.
Coal generates almost half of the nation’s gross electricity total, 5.02 TWH/day. Natural gas generates another 2.46 TWH/Day. Nuclear power generates 2.21 TWH/Day. Hydroelectric dams generate 0.70 TWH/Day. Other sources produce very modest amounts, but the modesty of today’s totals should not obscure the good news. Renewable sources of electricity are growing rapidly. The renewable energy sector may be small at the moment, but this is the sector that captures for us the sun’s energy, and in time we shall see it evolve in into the nation’s primary source of electricity.
The rest of the map is reasonably self-explanatory. One notes several sources of electricity: nuclear energy, hydroelectric power, wind, biomass-wood, biomass-waste, geothermal-E (for electricity from the geothermal steam plants that generate electricity), and Solar/PV, an unfortunate hybrid category that combines solar heat for swimming pools and solar penels for electricity. Other sources will show up on this list as their contributions grow.
One also notes two entries for liquid fuel – ethanol (a fuel based on sugars) and biodiesel (a fuel based on food oils and fats). And three entries for heat – biomass-wood, solar/PV, and geothermal-H. This last category refers to shallow geothermal wells used as thermal boosters for heat pumps.
A careful review of the map yields four major takeaways.
First and most importantly, almost 92% of end use energy is presently derived from fossil fuels, 51.62 TWH/Day out of 56.28.
Second, oil is by far the most important source of end user energy, worth 29.43 terawatt-hours/day, mostly in transportation. Natural gas is the second biggest source of end user energy, at 15.78 terawatt-hours/day. Coal runs a distant third and is in decline. America burns a lot of coal, but only a third of the energy content in coal actually turns into electricity. Measured by its contribution to end user consumption, coal’s share is modest, only 11.4 percent of the total. (6.4 TWH/Day out of 56.3 TWH/Day)
Third, Transportation as a whole is much the largest consumer of end use energy, consuming 21.59 TWH/Day in gasoline, diesel fuel, and aviation fuel. Industry runs a strong second, consuming 18.14 TWH/Day. Residential and Commercial users run a distant third and fourth.
Finally, one must also note that electricity, from an end user perspective, gives us only 10.2 TWH/Day out of a total consumption rate almost six times larger. Electricity is a larger sector when we measure its gross consumption of heat energy at the power plant, but it isn’t nearly so large when we view it from the end user perspective.
9.3 Revision 2011-11-03
[i] Author’s calculations, derived from the Monthly Energy Review September 2011 (2010 full year data), U.S. Department of Energy, Energy Information Administration. (www.eia.gov/mer)