Posted on december 21 2016 by gail tverberg.
Eroei solar panels.
That is use the same rules for evaluating the eroei of fossil fuels and of renewable energy.
That is to say the eroi of solar panels being made in 2013 is quite a bit higher than of solar panels made in 2000.
Studies have given figures for the eroi of solar energy as low as 3 9 and as high as 45 45.
Energy has played a critical role throughout human society s demographic economic and social development.
If we do that we find that for instance photovoltaics has an eroei around 10.
Abstract a recent paper by ferroni and hopkirk 2016 asserts that the eroei also referred to as eroi of photovoltaic pv systems is so low that they actually act as net energy sinks rather than delivering energy to society.
The availability and quality of various energy and material resources to a society is linked to the general trend of the settlement growth and eventual decline experienced by each civilization white 1959 tainter 1988 a society must have an energy surplus for there.
A related measure energy stored on energy invested is used to analyse storage systems.
Actually solar energy has superb energy return on energy investment eroei 1 to 4 years according to the us national renewable energy lab or 1 to 2 5 years in europe.
If the amount of energy produced relative to the amount of energy utilized in producing that energy tends to decline at some point as the ratio approaches 1 0 or perhaps even becomes a fraction less than 1 0 there is little if any return on the energy invested and society will collapse.
Eroei usable acquired energy energy expended it seems so simple.
To be considered viable as a prominent fuel or energy source a fuel or energy must have an eroei ratio of at least 3 1.
In fact many readers seem to think of course eroei is what we should be looking at when comparing different types of energy.
Wind energy does better than that with an average eroei around 20.
That s why we should compare what s comparable.
The concept was originally derived in ecology and has been transferred to analyse human industrial society.
When the eroei of a source of energy is less than or equal to one that energy source becomes a net energy sink and can no longer be used as a source of energy but depending on the system might be useful for energy storage.
Not bad but not as large as crude oil in the good old days.
In today s energy mix hydroelectric power nuclear power have values 50.
Such claim if accurate would call into question many energy investment decisions.
That should be obvious increasing efficiency and lower energy costs per watt make it so.
The energy return on energy invested eroei or eroi of any energy gathering system is a measure of that system s efficiency.
If we used only the estimates from 2010 on we d find an eroi for poly si solar of around 15.
