Don Bowen wrote:
> What is the current payback for the cells? That is how much energy do they
> have to produce to equal the amount of energy needed to make them in the
> first place. This embedded energy is a value that is never
> considered.
>
> I am looking for a mail list that will cover these issues in technical
> terms rather than emotional.
Check out the pv users list at: [EMAIL PROTECTED] (pvusers).
There are plenty of people there that are capable of discussing the
technical side of pv.
The subject of embodied energy and payback period for photovoltaic
cells has been considered in detail and papers have been written
about it. It was covered thoroughly on the pv users list a couple
months ago, and we also discussed it a bit on this list. It turns
out that the payback period is not as long as one might think, from
less than one to a few years in the best cases. There are a lot of
factors involved in calculating the payback, such as sources of
silicon, manufacturing processes, available sunlight at point of
use, etc., so a definite answer is not possible. But the "bottom
line" is that they can generate more energy during their useful life
than their production required. Quite a bit more, in fact.
Finally, payback period isn't everything. I know you're talking
about energy, but many people will consider payback only in terms of
money. In that case, what's the payback for a new SUV? So many of
our purchasing decisions are not based upon "payback" but rather
upon what we think we need to live a satisfying life or some other
factor that has little to do with payback in money.
Doug
