Re: [GBlist] Greenhouses

["malcolm.scott" <malcolm.scott@ntlworld.com>]

----- Original Message -----
From: "Mark Prout" <mprout2@comcast.net>
To: <greenbuilding@crest.org>
Sent: Thursday, April 18, 2002 7:52 PM
Subject: [GBlist] Greenhouses


> Newbie here.
>
> I am considering a career change to escape the cube farm. My passion is
> orchids and I foresee the need to build a greenhouse. Living in Missouri,
I
> am well aware that most orchid vendors surrender all profit to utility
> companies in an effort to heat their glasshouses in the winter, even the
> mild winters of recent years.
>
> What is, where can I find the most up-to-date energy-efficient ideas and
> designs in greenhouses? I have an idea that heatpumps drawing subterranean
> air might be a good way to go (with gas-fired backup ... the new globally
> warmed winters have given us more Arkansas-style winters -- ice storms
> complete with downed power lines). If this is off-topic, just let me know.
>
> Mark Prout
> Kansas City

There are commercial greenhouses burning natural gas in generators to supply
the grid, using the waste heat in the greenhouse. Whether you can negotiate
this kind of deal with an electricity supplier I don't know.
Your heat pump idea I assume draws subterranean heat rather than air.  This
is a way to multiply the heat supply when only electricity is available(It
bumps electrical efficiency up to the level of burning fuels directly).
However I can imagine that if you use an engine to drive the heat pump and
the waste engine heat in the greenhouse as well as the heatpump heat, then
you could well get an extra 50% of heat above that from the fuel itself, but
with a lot of mechanical complication.
There are natural gas burners with catalysts in the exhaust stream. I assume
these could be used directly in the greenhouse without external exhausts and
would bump up the CO2 levels for the plants.


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