Jeff writes:

But the spec sheet says "Average current consumption for 12 VDC
systems over 24-hour period." This is the number of interest to most
boaters, and the proper measure is Amp-Hours.

No it isn't. Current is measured in amps. Amp-hours are not a measure
of current. Nothing could be simpler, and nothing more can really be
debated about it. This is not an oversight, it shows the author is a
fraud or a fool.

While R-134a is safer than other refrigerants it is still illegal to
vent and difficult to handle properly. Its toxic and corrosive, and
anyone who has had a larger refrigeration system serviced understands
from the amount of gear the technician hauled down to the boat that
these are not trivial procedures. A CO2 system, on the other hand,
can be vented freely, and recharged with a simple cartridge. No
license or special training is required. If this does not look like a
significant advantage to you, then you should not be posting in a
"cruising" forum.

You are in your typical error about the "simple cartridge" as a
comparative advantage. A cartridge for CO2 at 1000 psi is not "simple"
in comparison to ordinary refrigerants at 100 psi. Whatever
"simplicity" advantage you are imagining, it inheres more in the usual
refrigerants. The fact that it is *harder* to store CO2 in a cartridge,
yet this is claimed as an "advantage", just further shows the stupidity
and/or deceit of the claims.

"Vented freely" is a political, not a technical advantage.

CO2 is lousy refrigerant for all but a few unusual applications, because
of its material properties, such as high saturation pressure, and low
critical temperature. It does not fit ordinary refrigeration
applications, and it cannot be engineered to do so. It only "works" as
a political force-fit, like when Coca-Cola wants PR for the Athens
Olympics.

But you didn't base your argument on weighing pros and cons, you
claimed that CO2 refrigeration was impossible, a hoax, and likened it
to "perpetual motion machines." Thank you for admitting you were
wrong, however obliquely.

No, I said that this "tropikool" gadget amounts to perpetual motion
claims, and that CO2 efficiency was a hoax, that efficiency (relative
to, say, R-134a) was impossible. That politicians let you vent CO2 but
not R-134a says nothing about their respective material properties as a
refrigerant. I never said CO2 refrigeration was impossible in
principle, just impossible that it would be practical in ordinary
applications.

You might as well claim that a steam engine is better than gasoline
internal combustion, because we can fuel it with grass clippings instead
of that expensive petroleum. Yes, it is possible to get steam power
from grass clippings, but it is impossible that it could work better
than a gasoline engine.

Now I will admit I was wrong, in that if a politician holds a gun to my
head and insists that CO2 is all you seem to be claiming, then yes, CO2
is just great. Since we still haven't reached quite that point, I
regret I must maintain that the OP points to a product that is a phony
based on either fraud or foolishness.