Ken Fabian

I admit I am still unclear on this. Won't the receiver in this case only gain heat from what is not converted to electricity and will radiate back less than reaches it? Seems to me the rate of absorption by the antennae is independent of temperature of the antennae. A cooling emitter - radiating away some of it's energy, yes - but a cooling receiver too (?), diverting what reaches it to electricity instead of raising it's temperature (and radiating it back). Again, adding to efficiency?? I recall one of the suggested possible uses for Optical Rectenna is surface coatings on walls for cooling rooms, an alternative to A/C - "waste" heat turned to electricity as a bonus.

Off the top of my head I don't think that is correct. I think IR intensity of the emitter is purely temperature dependent but is not dependent on a difference in temperature - ie is independent of the temperature of the receiver. Except maybe will be receiving IR or conducted heat back - which, if the receiver is heated by the process would counter intuitively increase the efficiency... ?? Doesn't sound correct, but... @sethoflagos Any thoughts on this?

I would expect waste heat in it's most accessible forms eg warm or hot water, would not radiate IR strongly. Maximising surface area, perhaps like filter cartridges do - folded or coiled sheets - would give better results but more area means more cost too. The antenna part looks suited to cheap roll to roll "printing" (already tried successfully) but they need very fast response diodes included, of yet unknown suitability for "printing" on thin films. Get fast enough diodes and the potential conversion efficiency is very high, better than photovoltaics and, significantly, able to utilize bands like IR that PV cannot. PV struggles with longer (IR) wavelengths whereas Optical Rectennas should be a bit easier, with slower diodes. I suppose Optical Rectenna's are more likely to be a rival to photovoltaics for daytime energy before being rival to energy storage - worthwhile but I think PV costs are not the constraining factor anymore. Until or unless it is very cheap to make and use scavenging waste heat may still be out of reach. Not sure I see much significance for EV's directly. Whilst a high fossil fuels (or nuclear) grid suits overnight charging a high renewables one will likely suit daytime charging better. We are seeing a couple of ways forward eg faster charging is a highly sought option, to be more like fast filling up our tanks from service stations. But other options include abundance of charger fitted parking spaces that suit daytime charging and I expect there will be benefits to electricity grids by having EV's plugged in when not in use. A parked and plugged in (or for convenience a hands free, perhaps wireless induction connected) EV can be more than just another unresponsive source of demand - just the option to vary charge rates according to overall balance of supply and demand would make them a load leveling option for electricity grid managers. Drive to work, have the charge rate to a set to reach minimum requirement as priority and vary charge rates after that to achieve full charge by a set time, at the grid operator's discretion. Even potentially they can draw on those batteries, (under agreed terms and conditions) as well as have them contribute to household electricity use. I believe there is a trial section of road somewhere in the US with induction charging built into it - ie charge as you drive. Which I think may be more the kind of solution we will need for decarbonising road freight vehicles, that we don't want to have to sit idle for long periods. Railway style overhead (being trialed in Europe) is probably more efficient and cost effective than in-road induction... not electrification everywhere but strategically, so battery electric vehicles charge up on approaches and exits to cities and town and on long, heavily used inclines. Faster charging would also reduce how much of this style of highway electrification is needed too. I also expect it will be possible to unify electricity accounts so that charging an EV anywhere is billed to a household account - and for solar fitted households to have their contributions to the grid count towards it, wherever the car is used.

Optical Rectenna can convert Infrared radiation - radiant heat - directly into electricity but in practice so far the yields are extremely low. Like an antenna does with longer (radio) wavelengths - like the old "crystal radio" that powered itself from the radio waves. Not sure how that works in entropy terms - heat loss in the conversion? Of all the out there possibilities this would be one I'd like to see get some serious attention because if they can be made to work we could not only make electricity from waste heat but from radiant heat of all kinds, including down-radiation from clouds and atmosphere by night as well as from sunshine by day.

Not sure it is intelligence but natural selection does work a bit like trial and error, where the errors get left out in future iterations and the things that work persist. It can look like Life is making choices... but I think it is survivor bias.

I wonder to what extent the emergence of heavier hairs on older women's faces is them just not bothering to pluck or depilate in pursuit of beauty anymore, ie it actually began at puberty and has been happening all along.

If it is electricity from collecting plant material you want you might do better with gasification and running an internal combustion engine off that - you won't need a steam boiler which is a dangerous piece of equipment that usually requires regular testing and certification for safety - and possibly certification for the operator as well. But not sure that steam or gasification will be compact or easy to transport. A small, mobile gasifier generator -

An obvious issue to me is that the graph is based on relative "per molecule" impact, not atmospheric concentration, ie number of molecules. Less effect per molecule with a lot more molecules still adds up to warming. And the scaling makes a Watt/m2 change look small and insignificant when it is not. If you believed the interpretation of graphs like that by sources like CO2 Coalition global warming should already be slowing and the observed warming isn't actually continuing to accelerate - as if the observations must be wrong. But that graph isn't being used to inform people who have a good understanding, who might know that - it is intended to mislead people who do not. If enhanced greenhouse effect is self limiting and the effect is going to save us from having to do anything about it it should be saving us already and it isn't. We don't have long running observations from space but over the time the Ceres satellite has been operational we observe that the net imbalance between incoming and outgoing energy has been rising. This is a graph based on Ceres satellite data - Without delving deeper into how the graphs were calculated (which I have no wish to do) it isn't clear if this is theoretical (modeled) direct IR to space in the absence of all those complicating indirect flows to space.

I think our current path has already changed in significant ways almost entirely due to the successes of renewable energy (and batteries and EV's). RCP8.5 scenarios are considered very unlikely now, not because climate science was wrong about the impacts of emissions but because we now expect renewable energy to - at the very least - to displace growth of fossil fuel use significantly, with less emissions than otherwise. For all the disparaging it is an extraordinary achievement. To call it on purpose might be a stretch; for some it was on purpose, but those were initially considered fringe. More widely the supporting of renewables seemed more about empty gestures, with it actually working and being cost competitive coming as a surprise. Now that the renewable options are cost effective in most of the world it might still get some government support (as fossil fuels still do) but fundamentally, now and for the near future, it is market economics at work. As well to channel Canute and get the tide to stop - but it is clear that Doubt, Deny, Delay politickers around here have shifted their focus to obstructing the things that will make renewables reliable as their scale grows - opposing transmission lines, battery farms and wind, especially off-shore wind. Astro turf nimby opposition and trying to wedge them between climate concerns and local environmental impacts. But I think that - having made up the for, by, about environmentalist framing themselves - they underestimate the wider community support for emissions reductions with renewables, from people who do not identify with environmentalism, who's commitment is because of the science based advice, not green politics. Ultimately we will require strong, enduring commitment to climate stability at levels we are yet to see, but governments even being able to say they are committing to zero emissions is a remarkable shift. Economic alarmist fear of what has to be done to reach zero emissions (along with denying climate change's harms) has been one of the most successful denier memes, yet the most direct and effective and acceptable emissions reduction pathway is building an abundance of low emissions energy to displace fossil fuels and, hey, that is the one thing we are succeeding at. Much better than expected. The enormous stocks of fossil fuel capacity in place make early contributions by renewables seem small but within just one decade of crossing price equivalence thresholds renewables have become the most built new capacity additions, by a very large margin. That quickly. Less than 7 years ago Australia installed a Big Tesla Battery, to widespread derision. More than 20 times that capacity of batteries are up and running. That quickly. Not just Tesla but multiple mega batteries factories are already up and running. That quickly. Amongst all the cause for pessimism there is one thing going right - renewable energy. So we should not be surprised that the deniers are going all out to undermine public confidence in it.

@thidmir There are some scientists who think we underestimate the potential for non-linear ice sheet collapse but even a pessimistic James Hansen doesn't expect sea level rise of 50m to 100m 70m. The hypothetical maximum is around 70m - where Antarctica and Greenland lose all their ice sheets. The sea level impacts are likely to continue for a long time after reaching zero emissions, which, by necessity is a near term goal, within the next few decades, ie well before sea levels can stabilise. But there is an expectation amongst those that study the cryosphere aspects of climate change that the rate will slow with zero emissions. I suppose the worse case scenarios where emissions reductions are abandoned and there are ongoing high emissions that put us back on the RCP8.5 pathway, but even that looks like a trend that must top out, as fossil fuel stocks decline. Better prediction can help us work out what to expect for varying emissions scenarios but we don't need precise sea level rise predictions to know we urgently need to bring emissions down. Sea level rise, however it develops, will require adaptation but apart from locally at small scale (levies, imported fill to raise ground levels, building better for those that can afford it) that looks like a global retreat to higher ground and accepting an irrevocable loss of environmental capital (land).

Geothermal power stations outside places with hydrothermal resources (ie local volcanism) to tap into are not being built much and appear to rely on hot rock that is nearer the surface. I think they do have significant advantages - can follow load as well as make power continuously. If costs can be reduced - and if some of the price distortion for fossil fuels get eliminated. But I think we may get more benefit from reducing costs for drilling boreholes for ground source heat pumps. These usually don't need to go much more than 100m and offer the potential for interseasonal energy storage, ie pumping heat down them during Summer for use in Winter. Even more appropriate for large buildings and district heating systems than for individual homes. I expect borehole heat pumps to be more energy efficient than cold weather air source heat pumps - and air source to be more efficient than resistance heating or gas or oil. But in the presence of reliable electricity the air sourced heat pumps may be a cost effective option.

@mistermack - linked in my first post - The manufacturer has cold weather air source heat pumps in production - https://www.lennox.com/media-room/news/lennox-industries-introduces-new-cold-climate-heat-pump-focused-on-accelerating-environmental-sustainability Alternatives to gas are necessary, for well known reasons; gas is cheaper because the externalities are not counted but those costs don't go away, they are passed on. Disproportionately onto people in warmer climates who didn't burn that much gas.

It is not the kind of climate I am familiar with but it does sound like insulation is where to start, irrespective of the heating method. Followed by draft proofing, more insulation, judicious use of thermal masses and more insulation. The cold weather air source heat pumps at least appear relatively easy to fit to existing homes, compared to ground source. We haven't heard the last word - I expect they will get even better. The cost advantage is in the running - but where the initial costs are high we will continue to see options that are less cost effective - sometimes a lot more expensive over the longer term - being preferred. Not only do wealthier people get the cheaper option because they can afford the up front costs they probably get access to lower interest rate loans to pay it off if they choose to go that way. As an aside we had someone from Austria, Europe visit who has been living in Australia and she spoke about telling her mother back home that she was staying in sub-tropical Queensland in Australia and wearing a jacket inside because it was cold. Because the homes, especially older ones have lots of windows that spend a lot of time open and can be drafty as well, for air flow in hot conditions and there is not much insulation and probably no dedicated heating system at all apart from the reverse cycle air conditioner, that is primarily for cooling and likely doesn't include bedrooms at all. Her family's home was well sealed, triple glazed and so on - and very rarely were the windows left open.

Apparently air source heat pumps are available that can work down to minus 15o C. If I read it right, 100% of the heating at double efficiency, that I take to mean heat delivered for electricity used. Down to about minus 20 (minus 5o F) has been a stated goal of a joint US Canada R&D program; maybe not always and forever pretty crap. If I understand correctly, some already commercially available - https://www.energy.gov/articles/doe-announces-breakthrough-residential-cold-climate-heat-pump-technology

I think the uncertainty of meaning has been part of the song's allure - lots of Australians have spent time pondering and arguing over it. Slang terms no longer used, that no-one is really sure the meaning of, suggestive of an age (already) passed. Not sure it ever fully made sense and what was comprehensible in it was kinda depressing. I do suspect if the lyrics were not by an already very popular poet who wrote mostly about and popularised Australian "outback" settler society and recent history it probably would not have been widely sung or known.

I think it is the job of courts and governments, not religions, with elimination of corruption and undue influence within them as central to finding a better balance for taxation levels and applying them without fear or favour. In a hypothetical kind of way religion can make ethical issues clearer to people and encourage ethical behavior and we can find numerous examples where they do. But lots of religion does not and prosperity gospel religions (eg Hillsong style Pentacostals around here) especially look to me to be inherently unethical, by outsourcing responsibility, accountability and outcomes to God whilst approving of wealth accumulation as evidence of God's favour, so long as people profess required belief and tithe. Where the balance points between taxation and the services taxes provide are, that maximise benefits communities at large whilst giving (and not constraining) incentives to do and invest and compete in enterprise will always be a bit mutable - I think must be under constant review - but it is the extremes that look fairly clearly to be inherently counterproductive.

Rather than exciting speculation about exotic super heavy elements in super dense asteroids what is needed is dull and ordinary astronomical observations to get more accurate estimates of their density. As well better observations of everything else that can be determined about them - which should be standard practice, to add to the inventory of known asteroids and their characteristics. Confirmation of unusual characteristics would give cause to investigate further, including with probes. If very unusual it would be very good cause. But without that confirmation it is like an anomalous experimental result - worth finding out why but it seems much more likely to be mistake than breakthrough.

I find the visualizations of cells and biochemistry fascinating. Something like this gives a good overview -

All that nickel-iron (never pure iron going by meteorites) is material that was the core of planetoids that got smashed and reformed and smashed and scattered. I don't see how any superheavy elements could remain strongly differentiated (as specific asteroids) yet leave no traces anywhere else. Not if these asteroids (if they actually have such densities) were formed within the solar system. I am thinking it would have to have origins very different to what occurred in this solar system - supernova remnants or something exotic? - and somehow it never got smashed together with the rest. Yet if such elements were tossed out by supernova - and our solar system includes supernova produced elements - we should find traces everywhere.

I am very doubtful. It would be WOW if true but our solar system's Asteroid materials underwent a lot of violent mixing during their formation so traces of those superheavy elements should appear in at least some (maybe most?) of the 10's of thousands of meteorite specimens that exist on Earth. Or within Earth based rocks. Or are people suggesting these particular (poorly observed) asteroids are truly outsiders, that didn't originate within the solar system and have always remained separate? My money is on these results being wrong.

An alternate future for fossil gas drilling? The future demand for hydrogen is probably overestimated - the current biggest use is oil refining/desulphurisation and that ought to go down and some projections are for reduced overall demand, which may make fossil hydrogen look more reasonable. But I have serious reservations about Hydrogen outside some hard to decarbonise uses - fertiliser and other chemical feedstock. I would have expected iron and steel but there are other options that avoid the need. If it isn't produced, stored and used on-site the economics are poor and transporting it at large scales is not as easy or cost effective as it sounds . I'm inclined to agree with this -

Jonas - it is the relative scales that make water use a non-issue. The USA (as an example) uses about 100 billion litres of water a day just for household use. The scale of hydrogen production from electrolysis is still very small but even at large scale it will not be a large user of water compared to many other uses. And energy sources like coal use a lot of water too, to wash the coal as well as reduce fire risks at mines and transfer facilities. More water is used again for cooling at power plants. I expect overall use of water would go down with large scale use of hydrogen replacing fossil fuels.

Yes, I make a decision whether to attempt catching something I drop - and step back when I drop a sharp knife. On the other hand I use my feet, to break the fall of breakable objects; it doesn't always work but often enough it does.

Aircraft manufacturers haven't become the major airline operators; they sell/lease aircraft to other businesses, that operate airlines. lf a viable sub-orbital aircraft that can operate much like an aircraft (take off and land on runways and not require major refurbishing each flight) were developed by the major manufacturers I would expect airlines to be the ones to operate them. And use them on existing heavily trafficked routes, which can expect to make profits. Space? It needs destinations with sufficient traffic as well as the vehicles - or need the availability of vehicles to make the destinations. So far the companies making rockets aren't selling them to others to operate, but are operating them themselves, I expect because they are not yet reliable enough. They appear to require their own dedicated launch facilities and operators and such operations remain complex endeavors that are yet to achieve the stage of being frequent, regular and routine. Apart from space tourism with very high ticket prices the only available destination is the ISS - and but for rare, expensive exceptions, those trips and the destination are all paid for by taxpayers.

In keeping with my pessimism about grand space dreams... I think the only way humans could reach another star may be the slow way - migrating from deep space object to deep space object and building a new industrial base at each stop. 10,000 generations later, maybe... if they remember why or don't find their artificial habitats perfectly satisfactory. Or maybe if such a form of human civilisation can thrive it could become an expanding sphere that ultimately reaches other stars as an inevitability, without any set destination. Unfortunately I think establishing an industrial economy anywhere in space - let alone within a single ship - is extraordinarily difficult, next to impossible. We can have knowledge in a can - libraries, archives, training courses, AI virtual experts - but how big a population to support having living expertise capable of not just maintaining what already exists but expanding on it? Any specialty on Earth is going to have at least some extraordinarily capable individuals with living knowledge that goes deep enough for serious problem solving. I worked at a plastic factory for a time, that had problems with an extruder, that ultimately required an engineer from the manufacturer to fly to Australia to diagnose and plastic extruders aren't that complicated; I think having the designs and the availability of that kind of living knowledge underpins the viability of our industries. At least asteroid/comet/planetoid civilisations wouldn't have such extreme resource or population limitations and might achieve sufficient size to do more than struggle to maintain even a pared down, optimised technological minimum within a planned economy. Of course not all would go on the next migration.