Supercritical carbon dioxide

Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure.

http://en.wikipedia.org/wiki/Supercritical_carbon_dioxide

E.g.

Supercritical CO2 is becoming an important commercial and industrial solvent due to its role in chemical extraction in addition to its low toxicity and environmental impact.

And,

Carbon dioxide is gaining popularity among coffee manufacturers looking to move away from some of the classic decaffeinating solvents of the past, many of which lead to public outcry because of real or perceived dangers related to their use in food preparation.

And,

Supercritical carbon dioxide can also be used as a more environmentally friendly solvent for dry cleaning as compared to more traditional solvents such as hydrocarbons and perchloroethylene.

And,

Recent studies have proved SC-CO2 is an effective alternative for terminal sterilization of biological materials and medical devices.

And,

Supercritical carbon dioxide is used as the extraction solvent for creation of essential oils and other herbal distillates. Its main advantages over solvents such as hexane and acetone in this process are that it is non-toxic and non-flammable.

And,

Supercritical carbon dioxide is also an important emerging natural refrigerant, being used in new, low carbon solutions for domestic heat pumps. [I knew about this at least]

And last but possibly the most surprising,

There is considerable work being done to develop a supercritical carbon dioxide closed-cycle gas turbine to operate at temperatures near 550 °C. This is a significant usage, which could have large implications for bulk thermal and nuclear generation of electricity, because the supercritical properties of carbon dioxide at above 500 °C and 20 MPa enable very high thermal efficiencies, approaching 45 percent. This could increase the electrical power produced per unit of fuel required by 40 percent or more. Given the volume of polluting fuels used in producing electricity, the environmental impact of cycle efficiency increases would be significant.

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I only stumbled on this by spotting the hotlink on the essential oil page I was reading:-

http://en.wikipedia.org/wiki/Essential_oil

http://www.cfact.org/2012/12/21/shroompocalypse-now/

The end of the world just got serious.

Global warming, we are told, has taken its toll on the world’s most fabulous fungus.

On the eve of the winter solstice, as the Mayan calendar ran out, the NY Times reported that yields of that most pungent fungus, the black diamond itself, the $1,200 per pound Périgord truffle is in decline and it’s your fault!

According to the Times:

A team of scientists writing in the British journal Nature says that part of that decline appears to be linked to climate change. They found that the French and Spanish black truffle harvest correlated closely with summer rains, and that the truffle habitat had suffered over the last few decades from hotter summers and less precipitation. That trend is expected to continue, according to most climate models.

http://www.boredpanda.com/category/art/optical-illusions-2/

Could be said of other recent efforts I can think of.

BTW, BEST preliminary at Wood for Trees is definitely a work in progress. Check out the 2010 El Niño:-

http://www.woodfortrees.org/plot/best/from:2000

I was asked by quite a few people about my opinion on the BEST analysis of Richard Muller and his group in Berkeley. Since I didn’t want to keep my friends without an answer, I took a more careful look into the analysis. Here is what I think of it.

There are two parts to the analysis. The first part is a reconstruction of the temperature over the 20th century. The second part includes analyzing this reconstruction and drawing various conclusions out of it.

I will divide my discussion into the two parts. Since I am no expert in temperature reconstruction, and in particular on the possible biases that may appear, the first part will be rather short.

[Read More..]

http://www.sciencebits.com/WorstBEST