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Another underestimated source of CO2, are turbulent waters. "The stronger the turbulences at the water's surface, the more CO2 is released into the atmosphere. The combination of maps and data revealed that, while the CO2 emissions from lakes and reservoirs are lower than assumed, those from rivers and streams are three times as high as previously believed." Alltogether the emitted CO2 equates to roughly one-fifth of the emissions caused by humans. Yet more stuff to model...

Nasia, I thought about your statement carefully - and I cannot agree with you. Water is not a greenhouse gas. It is instead a liquid. Also, I can't believe you keep feeding the troll! :-P But on a more topical note: I think it is an over-simplification to call water a greenhouse gas - water is one of the most important mechanisms in the way Earth handles heat input from the sun. The latent heat that you mention actually cools Earth: solar energy that would otherwise heat Earth's surface is ABSORBED as latent heat by water which consequently evaporates - the same water condenses into rain drops at high altitudes and releases this stored heat. In effect the water cycle is a mechanism of heat transport from low altitude to high altitude where the chance of infrared radiation escaping into space is much higher due to the much thinner layer of atmosphere above (including the smaller abundance of greenhouse gasses). Also, as I know you are well aware, the cloud cover that results from water condensation in the troposphere dramatically increases albedo which has a cooling effect on climate. Furthermore the heat capacity of wet air ("humid heat") is much larger than that of dry air - so any advective heat transfer due to air currents is more efficient in wet air - transporting heat from warm areas to a natural heat sink e.g. polar regions. Of course there are also climate heating effects of water like the absorption of IR radiation. But I stand by my statement (as defended in the above) that rain cools the atmosphere. Oh and also some nice reading material on the complexities related to climate feedback due to sea surface temperature: http://journals.ametsoc.org/doi/abs/10.1175/1520-0442(1993)006%3C2049%3ALSEOTR%3E2.0.CO%3B2

I enjoy trolling conversations when there is a gain for both sides at the end :-) . I had to check upon some of the facts in order to explain my self properly. The IPCC report states the greenhouse gases here, and water vapour is included: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-2-1.html Honestly, I read only the abstract of the article you posted, which is a very interesting hypothesis on the mechanism of regulating sea surface temperature, but it is very localized to the tropics (vivid convection, storms) a region of which I have very little expertise, and is difficult to study because it has non-hydrostatic dynamics. The only thing I can comment there is that the authors define constant relative humidity for the bottom layer, supplied by the oceanic surface, which limits the implementation of the concept on other earth regions. Also, we may confuse during the conversation the greenhouse gas with the Radiative Forcing of each greenhouse gas: I see your point of the latent heat trapped in the water vapour, and I agree, but the effect of the water is that it traps even as latent heat an amount of LR that would otherwise escape back to space. That is the greenhouse gas identity and an image to see the absorption bands in the atmosphere and how important the water is, without vain authority-based arguments that miss the explanation in the end: http://www.google.nl/imgres?imgurl=http://www.solarchords.com/uploaded/82/87-33833-450015_44absorbspec.gif&imgrefurl=http://www.solarchords.com/agw-science/4/greenhouse--1-radiation/33784/&h=468&w=458&sz=28&tbnid=x2NtfKh5OPM7lM:&tbnh=98&tbnw=96&zoom=1&usg=__KldteWbV19nVPbbsC4jsOgzCK6E=&docid=cMRZ9f22jbtYPM&sa=X&ei=SwynUq2TMqiS0QXVq4C4Aw&ved=0CDkQ9QEwAw

The article came out some time ago of course and was posted here, though the story here is still well written. If you are lazy to read the rel long article, here the summary explanation: The team found that a good half of the force came from heat from the RTGs, which bounced off the back of the spacecraft antenna. The other half came from electrical heat from circuitry in the heart of the spacecraft. Most of that heat was radiated through louvers at the back of the probes, which weren't as well insulated as the rest of their bodies, further contributing to the deceleration.

This is really cool. I know one of the authors and he is a good guy... the only thing that leaves me unsatisfied is that if the whole issue is related to thermal effects one should have seen the Pioneer effect all the time and not only at about 10 AU... ...or is there some thermal process that kicked in only at this distance?

Here's an update on this theory: NASA Releases New Pioneer Anomaly Analysis "The mysterious force acting on the Pioneer spacecraft seems to be falling exponentially. That's a strong clue that on-board heat is to blame, says NASA." Heat emission 'most likely cause' of pioneer anomaly "What's more interesting is that, contrary to the original analysis conducted all those years ago, the deceleration does seem to be decelerating at an exponential rate -- just as one might expect from the radioactive decay of plutonium-238, which powers the two spacecraft. Turyshev concludes, "The most likely cause of the Pioneer anomaly is the anisotropic emission of on-board heat.""

These features lead to a high heat-to-electricity energy conversion efficiency of 5.7% when cycled between 10 and 60 °C, opening a promising way to utilize low-grade heat.

An exhaustive overview of all possible advanced rocket concepts, eg.. "As an example, consider a photon rocket with its launching mass, say, 1000 ton moving with a constant acceleration a =0.1 g=0.98 m/s2. The flux of photons with E γ=0.5 MeV needed to produce this acceleration is ~1027/s, which corresponds to the efflux power of 1014 W and the rate of annihilation events N'a~5×1026 s−1 [47]. This annihilation rate in ambiplasma l -l ann corresponds to the value of current ~108 A and linear density N ~2×1018 m−1 thus any hope for non-relativistic relative velocity of electrons and positrons in ambiplasma is groundless." And also, even if it would work, then one of the major issues is going to be heat dispersal: "For example, if the temperature of radiator is chosen T=1500 K, the emitting area should be not less than 1000 m2 for Pb=1 GW, not less than 1 km2 for Pb=1 TW, and ~100 km2 for Pb=100 TW, assuming ε=0.5 and δ=0.2. Lower temperature would require even larger radiator area to maintain the outer temperature of the engine section stable for a given thermal power of the reactor."

The problem is not achieving a high energy density, that we can already do with nuclear fission, the question however is how to confine or harness this power with relatively high efficiency, low waste heat and at not too crazy specific mass. I see magnetic confinement as a possibility, yet still decades away and also an all-or-nothing method as we cannot easily scale this up from a test experiment to a full-scale system. It might be possible to extract power from such a plasma, but definitely well below breakeven so an additional power supply is needed. The fission fragments circumvent these issues by a more brute force approach, thereby wasting a lot of energy for sure but at the end probably providing more ISP and thrust.

Sure. However, the annihilation based photon rocket concept unifies almost all relevant drawbacks if we speak about solar system scales, making itself obsolete...it is just an academic testcase.

We discussed this today during coffee. The inventor claims that he claims that a pressure differential can push hydrogen through a proton conductive membrane (thereby stripping off the electrons) which flow through an electric circuit and provide electric power. The type of membrane is fairly similar to that found in a hydrogen fuel cell. If the pressure differential is cause by selective heating this is in essence a heat engine that directly produces electricity. The inventor claims that this could be a high efficiency alternative to thermoelectric devices and could even outperform PV and Sterling engines with an efficiency close to that of fuel cells (e.g., ~60% @ dT=600K). I could not find any scientific publications as the inventor is not affiliated to any University - he has however an impressive number of patents from a very wide field (e.g., the "Super Soaker" squirt gun) and has worked on several NASA and US military projects. His current research seams to be funded by the latter as well. Here are some more links that I found: http://www.theatlantic.com/magazine/archive/2010/11/shooting-for-the-sun/308268/ http://www.johnsonems.com/?q=node/13 http://scholar.google.nl/scholar?q=%22lonnie+g+johnson%22+&btnG=&hl=nl&as_sdt=0%2C5

Imagine a material that only admits thermal conduction for certain temperatures. Martin Maldovan from Georgia Tech holds a tiny thermoelectric device that turns cold on one side when current is applied. Recent research has focused on the possibility of using interference effects in phonon waves to control heat transport in materials. These are exciting news (see Nature Materials paper here http://www.nature.com/nmat/journal/v14/n7/full/nmat4308.html). Heterostructure research lead to outstanding new possibilities when applied to electronic transport (e.g. in quantum well and quantum dots) and to photonics (e.g. Quantum Cascade Laser tunnable lasers). Apparently the time has come to see selective thermal control in this way! Truly exciting!!

"we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell"

so what ...?

Depending on its properties it might be interesting as an ablative heat shield material.

Imagine if your clothing could, on demand, release just enough heat to keep you warm and cozy, allowing you to dial back on your thermostat settings and stay comfortable in a cooler room. Or, picture a car windshield that stores the sun's energy and then releases it as a burst of heat to melt away a layer of ice.

interesting indeed: Such chemically-based storage materials, known as solar thermal fuels (STF), have been developed before, including in previous work by Grossman and his team. But those earlier efforts "had limited utility in solid-state applications" because they were designed to be used in liquid solutions and not capable of making durable solid-state films, Zhitomirsky says. The new approach is the first based on a solid-state material, in this case a polymer, and the first based on inexpensive materials and widespread manufacturing technology. Read more at: http://phys.org/news/2016-01-material-harvest-sunlight-day-demand.html#jCp

Meet the incredible shrinking material. Most things swell when they warm up, creating engineering headaches, but now a 3D-printed material has been configured to contract instead. When two interlinked materials expand at different rates, they can warp or crack. It's a problem in buildings, bridges, electronics and anything else that is exposed to a wide temperature swing.

A good electrical conductor is normally a good heat conductor. Vanadium dioxide however seems to not be so, by being a good electrical conductor and a poor thermal conductor. Paper at http://science.sciencemag.org/content/355/6323/371

A new more efficient type of single photon light source consisting of a quantum dot reproduces 1954 Robert Dicke theoretical proposal. Applications in quantum communications directly on the target. "All light sources work by absorbing energy - for example, from an electric current - and emit energy as light. But the energy can also be lost as heat and it is therefore important that the light sources emit the light as quickly as possible, before the energy is lost as heat."

A North Carolina State University researcher has developed a more efficient, less expensive way of cooling electronic devices - particularly devices that generate a lot of heat, such as lasers and power devices.

"A light-emitting diode (LED) that emits more light energy than it consumes in electrical energy has been unveiled by researchers in the US. The device - which has a conventional efficiency of greater than 200% - behaves as a kind of optical heat pump that converts lattice vibrations into infrared photons, cooling its surroundings in the process."

Sorry, did not see that you have already posted this one ...

of relevance to this discussion: Koomey's Law, a Moore's Law equivalent for computing's energetic efficiency http://www.economist.com/node/21531350 http://hardware.slashdot.org/story/11/09/13/2148202/whither-moores-law-introducing-koomeys-law

Thermoelectric materials can see their performance radically improved via the utilization of an array of 'nanoscale pillars,' according to new research from the University of Colorado Boulder. These tiny pillars, built directly onto the thermoelectric material, will reduce the heat flow through the material by a factor of two while not affecting the electrical flow.

By wearing clothes that have been dip-coated in a silver nanowire (AgNW) solution that is highly radiation-insulating, a person may stay so warm in the winter that they can greatly reduce or even eliminate their need for heating their home. With as extra bonus: Besides providing high levels of passive insulation, AgNW-coated clothing can also provide Joule heating if connected to an electricity source, such as a battery. The researchers demonstrated that as little as 0.9 V can safely raise clothing temperature to 38 °C, which is 1 °C higher than the human body temperature of 37 °C. How about that for personal comfort during the cold winter months

sounds almost like the asbestos story re-started :-)

Found an European project that takes care of the environmental, health and safety aspects of nanomaterials http://phys.org/news/2015-04-unleash-full-potential-nanomaterials.html

apparently warm things attract each other instead. a symbolic prize of a virtual launch vehicle based on a smeg fridge/freezer for the most amusing/shortest refutation. "A ~1068 gm hollow copper sphere hovers above a 1000 W heat element." "After power was applied to the heat element for 400 s, the means of the first and last ~6 force measures indicate that the sphere's gravitational mass increased by 1.9 % or 20 gm."

interesting...

this looks like absolute humbug to me .... reminds me of some rotating superconductors :-)

more transformation optics ... 

I still believe that it is worth to check the thermal, mechanical and chemical properties of the developed metamaterials. For hyperbolic re-entries the radiation is still the dominating heat load source and a dominating bandwith may be indentified. A resistive metamaterial should be placed on the nose cap of the entry body in order to reduce local radiation heat load.