Off Grid Greenhouse Inquiry [RE-wrenches]

[Lawrence Elliott]

Colin!
If I understand correctly a hydroponic greenhouse uses allot of water.
I would assume that the bulk of the energy needed is in the form of heat
(read : above freezing temps) from fossil fuels with the balance being
to ventilate primarily to keep temps down.
I myself have a greenhouse that uses pex tubing buried in the soil that
is heated by solar collectors.Using the el sid DC pump my power
requirements are almost nil.And ventilation is needed only on a low
level since I use shade cloth and keep the heat out in the first place.

Would it be possible to use the water as both a heating source as well
as a heat sink using active pumping and heat exchangers? Do the roots of
the plants tolerate elevated temps?
This would supply a source of stable heat and would also eliminate allot
of the need to get rid of the heat in an inneficient "pumped air
ventilation system"The water could be pumped into large flat heat
exchangers that would expell the heat outside.

>From my experience in heating in winter months I could not recommend the
Thermomax more highly.


Really never have understood the hydroponic thing though.
Plants love soil. Isn't it  where they live most of their lives anyway.

Larry Elliott
----- Original Message -----
From: "Colin" <colin at positiveenergysolar.com>
To: <RE-wrenches at topica.com>
Sent: Monday, May 20, 2002 1:57 PM
Subject: Re: Off Grid Greenhouse Inquiry [RE-wrenches]


> Wrenches, we need your help!
>
> Here's the situation:  a committed Off-grid client wants to run a home
> hydroponic gardening business.  We have come down hard on the facts of
load
> reduction and urged him to look towards other passive alternatives to
active
> venting, heating and cooling, but sadly the issue is that this
commercial
> greenhouse, which he already owns was designed for a massive infusion
of
> fossil fuel energy.
>
> Our initial load analysis had a first round conservative estimate of
about
> 10 kilowatts of PV array.
>
> What we are looking for is a) good websites for off grid greenhouse
and
> gardening systems, equipment, education, etc.  and b) sources for
efficient
> dc fans, electric seedling warmers, and Thermofor vents.
>
> Any help would be very much appreciated.
>
> Thanks,
>
>
> Colin Mitchell
> Positive Energy
> Santa Fe, NM
>
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