2012 was a remarkable year for energy in the US, with domestic output of oil, gas, wind and solar energy all advancing strongly. This was the result of an unfolding revolution in unconventional oil and gas, along with federal, state and local incentives and regulations promoting renewable energy. Yet despite extensive media coverage and vocal constituencies for each of these energy sources, I haven’t seen any recent efforts to compare their respective contributions to US energy supplies.
That may be due in part to the confusing array of energy units involved. It’s daunting to match up oil in 42-gallon barrels (bbl), gas in cubic feet or British Thermal Units (BTUs), and wind and solar in kilowatts (kW) or Megawatts (MW) of capacity, or kilowatt-hours (kWh) or Megawatt-hours (MWh) of actual generation. Conversion factors among these various units are easy to find on the internet. However, meaningful equivalencies are complicated by important distinctions between liquid or gaseous fuels and grid electricity, and the fact that these energy sources compete with each other only in specific situations.