X-Message-Number: 16512 From: "Tim Freeman" <> Date: Sun, 10 Jun 2001 21:03:21 -0700 References: <> Cryomessage #16435 From: Driven FromThePack <> >Eugene Leitl on the Extropain list recently said that >cryonics may become much more difficult because of >changes in manufacturing methods. Anyone have comments >on this? The message was dated Wed May 16 2001 - 18:18:46 MDT and the relevant part reads: >...Current cheapness of LN is largely artefacted of it being a >side product of liquid air fractionation (to obtain oxygen for steel >production). Most developed countries no longer use that process (they use vacuum >electrosteel processes and since recently hydrogen reduction and sintering, >or enrich oxygen by air by means of molecular sieves if they have to), if >they haven't completely outsourced steel production to cheap, environmentally >unregulated places. So LN prices will go up, requiring a switchover to some other >cryogenics method. Both the heat lossage through walls and value of >Joule-Thompson coefficient would indicate that you'd want to stick around >-150 deg C tops, which is still perfectly fine for vitrified tissue. Of >course, you lose the advantage of phase change enthalpy, so you're in >deep shit once the power goes out. Not only have you to use expensive >cryogenics aggregates, and massive air conditioning to keep these happy, >you also have to install failsafe power generators, and rapid contingency >plans, as your safety window is only a few hours (instead of a couple of >weeks) wide. Suddenly, things are becoming expensive, complex, and brittle. >This is certainly going to have an impact on prices, reliability, or both. I don't know anything about the price of liquid nitrogen, but even if it goes up, IMO it won't make much of a difference in the long term because: a) For vitrified patients it's probably better to go to higher temperature storage anyway. b) If you have a big enough storage space for your patients, and you store them together and fill in the unused portion of the space with buckets of water (because water is cheap and it takes a lot of heat to change its temperature a small amount), you can make the safety window for coping with power failures as long as you like. A few years ago on the cryonics mailing list, there was a fascinating conversation about cold rooms and using water ballast in them. As I recall, the design would give the maintenance people a week or so to reestablish refridgeration if it failed. If you have enough ballast, you don't need any tricks with phase changes to have adequately controlled temperature. Vacuum failures in the dewars are another source of brittleness to pay attention to. The cold room strawman design just used styrofoam. No vacuum, hence no vacuum failures. -- Tim Freeman ; formerly Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=16512