Energy Returned on Energy Invested (EROEI)

 

EROEI is a standard metric for measuring various sources of energy.  Energy invested includes all the energy required to develop and use an energy source.  For example, oil requires geologists to study data, identify sites, drill wells, pump oil, truck, ship, and pipe the oil to refineries.  After refining the finished product needs to then be transported to the end user.  You then calculate the amount of energy returned from your finished product after subtracting the amount invested.  This number is presented in the form of a ratio E_r/E_i.  Obviously an energy source would need to have an EROEI greater than 1 to be of any value.  Approximately 100 years ago US domestic oil had an EROEI that approached 100.  This explains the meteoric rise of the US as a superpower.  Today, US domestic oil has an EROEI closer to 2.  This metric is also very useful in determining that some sources of energy like oil shale and ethanol are not really sources of energy since their EROEI is so close to 1.

 

Although there are many factors involved studies have shown that world wide, oil has an EROEI of 10-20, while Wind has an EROEI of approximately 50.  The Wind Accelerator Dome improves the EROEI by 30% to 100%.  That is, with the WAD the EROEI of wind is approximately 65 to 100.  However, this assumes that the energy involved in building the dome is not counted since the dome is being used as a structure for storage or dwelling.  Domes currently provide the most efficient structure for enclosing space, so using domes would actually save energy over other structures.

 

However, some investors may use other metrics for measuring an investment.  Wind requires a higher percent of up front investment, whereas oil is a more “pay as you go” type of investment.  Other metrics for investments include Return on Investment (ROI) and the ratio of the value of an investment over the lifetime to its cost.  An ROI of 25% or better is considered a very good return on investment, especially for anything that is viewed as a commodity like electricity.  The calculated ROI for the Wind Accelerator Dome is generally 50% or more.  There is a wide variation depending on many factors including how expensive the dome is and the price you will ultimately receive for the electricity generated. 

 

--Stuart Willett

Wind Accelerator Dome, International