Paul Vixie wrote:
>
> aside from the corrosive nature of the salt and other minerals, there is an
> unbelievable maze of permits from various layers of government since there's
> a protected marshland as well as habitat restoration within a few miles.  i
> think it's safe to say that Sun Quentin could not be built under current
> rules.
>

The ones I have are MDPE (Medium Density Polyethylene) and I haven't
understood that the plastic would have corrosive features. Obviously it
can come down to regulation depending on what you use as a cooling agent
but water is very effective if there is no fear of freezing (I use
ethanol for that reason). The whole system is closed circuit, I'm not
pumping water out of the ground but circulating the ethanol in the
vertical ground piping of approximately 360 meters. The amount of slurry
that came out of the hole was in order of 5-6 cubic meters. Cannot
remember exactly what the individual parts cost but the total investment
was less than $10k. (drilling, piping, circulation, air chiller, fluids,
etc.) for a system with somewhat over 4kW of cooling capacity. (I'm
limited by the airflow, not by the ground hole if the calculations prove
correct)

Pete