# Is there an "energy returned on materials invested" index for energy sources?

We already try to measure how much energy is invested (EROEI) in the production of energy, but I have a hard time finding numbers on the materials invested.

For example: What is the total energy a wind turbine produces in it's lifetime divided by the total mass of all the materials consumed in its construction, operation and and maintenance?

Of course it would be even more interesting to know the kind of materials invested.

• For materials, do you mean something like table 2 and 3 in this paper? (click on the view button on the right of the loaded page to see contents)
– THelper
May 5 '15 at 11:26
• Related: energy out divided by energy in, for a wind turbine, is asked and answered here May 5 '15 at 12:00
• @THelper I guess the tables in the paper you mention ( pdf link without signup ) could be used to calculate the energy returned on materials invested. May 5 '15 at 12:05

# Measuring impact

I've yet to see a meaningful metric that relates directly to materials, other than the EROEI (Energy Returned On Energy Invested); and there's discussion about whether or not EROEI is at all a useful measure: its probably not that useful, since once it's over 1.0, it's completely subsumed into the economics. The same would be true of a more explicitly materials-based index: it's completely subsumed into the economics.

As THelper hints at in the comments, calculations of energy inputs, and other lifecycle cost analyses (LCAs), do usually work from a quantified list of materials that are used in construction, operations and decommissioning. So most detailed LCAs will contain such a list.

It will vary depending on whether the turbine has a permanent (neodymium) magnet or not; whether it's onshore or offshore; and if offshore, what sort of foundation / tethering is used.

Energy out per unit kilogram (kg) mass input seems like a strange measure, as it equates a kg of water, a kg of oxygen, a kg of steel, a kg of platinum: I can't really see how that's at all a useful measure.

# Materials for one wind farm

Here are the two tables identified by THelper, from "Energy performances and life cycle assessment of an Italian wind farm" by Ardente et al (2006):

Materials per 660kW-capacity turbine:

Additional Materials for the whole 11-turbine farm:

To get total energy generated, you could assume a 20-year life and something like a 25% capacity factor, to get:

20y x 25% x 11 x 660kW x 8766 h/y