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New Heating Technology Uses Seawater and Carbon Dioxide (csmonitor.com)
Kenneth Stephen writes: While some enterprises have used sea-water for cooling, others are starting to use this for heating. and thereby cut back greatly on the carbon footprint of large facilities. What makes this technique even more fascinating is that a key component of this technology is carbon dioxide — the greenhouse gas that has climate watchers so worried.
An Alaska aquarium recently announced "the first installation of CO2 refrigerant heat pumps to replace oil or electrical boilers in a conventional heating system in the United States" after 7 years of development, and predicts they'll now save up to $15,000 each month on their heating bill.
CO2 is just the refrigerant. It is not consumed by the heating cycle. CO2 has been used for cooling in many places, this is the first I've heart of using it in a heat pump for heating though.
Article is dumb.
The real news is buried. Google "transcritical CO2" to get the real story.
I don't read your sig. Why are you reading mine?
Presumably the energy source is still fossil fuels because they likely want to heat the place on days and nights when the wind isn't blowing (not much solar at 60N in December).
The energy source is the difference between the temperature of the seawater (the heat source) and that of some other heat sink (probably the Alaskan air). Heat is collected from the ocean via a titanium heat exchanger, transferred to a glycol-water mix (i.e. antifreeze-laden water), and moved to a refrigerator operating as a heat engine - which then drives a heat pump to heat air warmer than either the ocean or the heat-sink air (or whatever).
The "news" is that they modified the heat engine to use liquid/gas carbon dioxide as a replacement for its original working fluid - R-134a (the pricey modern refrigerant that replaced the R-12 "freon" of ozone-hole fame).
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
You still need energy to drive the compressor. Maybe that's what he means?
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Traditional refrigerants like R-12 (dichlorodifluoromethane) have massive ozone destruction capability, 1st generation replacements like R-134a (1,1,1,2-tetrafluorethane) has minimal ozone destruction capability but very high global warming potential (thousands of times more potent than CO2, gram for gram), 2nd generation replacements like R-1234yf (2,3,3,3-tetrafluorpropene) while having no ozone destruction capability and minimal global warming potential suffer from being highly flammable, increasing the risk of leaks.
The advantage of CO2 is that it is neither flammable, ozone damaging, high GWP, nor significantly toxicity. The disadvantage is that substantial re-designs of refrigeration systems are required to use it, as well as some changes to operation/maintenance.
The transition from R-12 to R-134a, is near drop-in, with only minimal redesign required for optimal performance. To switch to R-1234yf, the re-design required is relatively modest (pressures are higher, so a different pump is needed), but otherwise the principles and basic system architecture are the same. With CO2, you are dealing with transcritical fluids, and this requires a significant architectural change to the refrigerant circuit (as there is no condensation of the refrigerant, so no liquid refrigerant in the circuit).
CO2 levels need to be above/around 50k ppm, or 5%, before it starts becoming a real danger. You'll know something is up long before that, around 1-2%.
Ammonia, on the other hand, is considered lethal at 500 ppm, or 0.05%
I'm going to go with 'CO2 is at least 1/100th as toxic as Ammonia'. The CO2 displacing the O2 is a bigger concern, but still 'solvable' by getting out of the room.
I don't read AC A human right
The pressure really isn't that big of a deal. 2000PSIG sounds high, but industrially speaking that's not terribly impressive. To put it into perspective, CO2 storage cylinders are often 1800 PSIG.
Compressed natural gas as a vehicle fuel is 4000PSIG Max. Compressed hydrogen storage is 5000-10000PSIG.
More importantly, it's not the max pressure that's the important metric but the differential pressure. You wouldn't be compressing it from atmospheric pressure - the MINIMUM pressure in the system is going to be somewhere around 400PSIG.
Of course, this prompts an important question: Where the hell did "2000 PSI" come from? Existing commercial trans-critical CO2 refrigeration operates at ~1300PSIG, so either the designers of this system have determined there's a good reason to go all the way up to 2000 or there's some journalist math/sensationalism going on here... 2000 PSIG is typically the relief valve setting, so maybe that's the confusion.
=Smidge=
Which graph [wikipedia.org], has no peaks?
This one: http://www.esrl.noaa.gov/gmd/w... I do want to clarify my earlier statement. Obviously, CO2 has varied in a lot in the past, but looking at your Vostok graph, it has been relatively slow moving for the last half million years, never crossing 300 ppm. Since the industrial age, we've crossed 300 ppm, quickly followed by breaking the 400 ppm level, even though volcanic activity isn't remarkable.