[ExI] Small scale solar payback time (was Re: Planetary defense)

[Kelly Anderson]

On Sat, May 21, 2011 at 3:13 PM, Damien Sullivan
<phoenix at ugcs.caltech.edu> wrote:
> On Sat, May 21, 2011 at 01:59:09PM -0700, Damien Sullivan wrote:
>
>> > If you had a polymer PV that had an energy payback time of a couple of
>> > months and lasted 2 years, that would be possible to grow energy on
>>
>> If you had that you'd have EROEI of 48 months / 2 months = 24, pretty
>> good.
>
> I'm apparently too sleep-deprived.  That'd be 24 months / 2 months = 12,
> of course.
>
> Which raises the question: is it better to have fast growth but high
> maintenance costs, or slower growth but cheaper equilibrium?  If you
> have 2 month payback, EROEI 12, vs. 2 year payback, EROEI 24 (48 year
> lifetime), which is better?  The first lets you transform faster, but
> has twice the 'maintenance and replenishment tax', not counting labor
> costs.

The main problem with alternative energy is the high capital cost of
getting into it. So I would say that if you could get something cheap
fast, that would be the preferable tradeoff. It allows people to get
into it. In all likelihood, the law of accelerating returns will make
replacing the cheap stuff even cheaper in a few years. So I'm all for
low capital solar, even if it isn't as long term as alternatives. It
does have to be competitive with grid electricity over the life term
for most people to look at it.

The energy used to make the stuff is largely irrelevant to the public
at large, though I do understand the issue. The folks who shop at
Walmart (virtually everyone) don't think about the global consequences
very often, they think about the cost of the toaster oven they are
trying to buy.

-Kelly