Martian Fluvial Flows, Placid and Catastrophic

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Despite the fact that, apart localized dust surfaces in summer, the surface of Mars has had average temperatures that never exceeded about minus 50 degrees C over its lifetime, it also has had some quite unexpected fluid systems. One of the longest river systems starts in several places at approximately 60 degrees south in the highlands, nominally one of the coldest spots on Mars, and drains into Argyre, thence to the Holden and Ladon Valles, then stops and apparently dropped massive amounts of ice in the Margaritifer Valles, which are at considerably lower altitude and just north of the equator. Why does a river start at one of the coldest places on Mars, and freeze out at one of the warmest? There is evidence of ice having been in the fluid, which means the fluid must have been water. (Water is extremely unusual in that the solid, ice, floats in the liquid.) These fluid systems flowed, although not necessarily continuously, for a period of about 300 million years, then stopped entirely, although there are other regions where fluid flows probably occurred later. To the northeast of Hellas (the deepest impact crater on Mars) the Dao and Harmakhis Valles change from prominent and sharp channels to diminished and muted flows at –5.8 k altitude that resemble terrestrial marine channels beyond river mouths.

So, how did the water melt? For the Dao and Harmakhis, the Hadriaca Patera (volcano) was active at the time, so some volcanic heat was probably available, but that would not apply to the systems starting in the southern highlands.

After a prolonged period in which nothing much happened, there were catastrophic flows that continued for up to 2000 km forming channels up to 200 km wide, which would require flows of approximately 100,000,000 cubic meters/sec. For most of those flows, there is no obvious source of heat. Only ice could provide the volume, but how could so much ice melt with no significant heat source, be held without re-freezing, then be released suddenly and explosively? There is no sign of significant volcanic activity, although minor activity would not be seen. Where would the water come from? Many of the catastrophic flows start from the Margaritifer Chaos, so the source of the water could reasonably be the earlier river flows.

There was plenty of volcanic activity about four billion years ago. Water and gases would be thrown into the atmosphere, and the water would ice/snow out predominantly in the coldest regions. That gets water to the southern highlands, and to the highlands east of Hellas. There may also be geologic deposits of water. The key now is the atmosphere. What was it? Most people say it was carbon dioxide and water, because that is what modern volcanoes on Earth give off, but the mechanism I suggested in my “Planetary Formation and Biogenesis” was the gases originally would be reduced, that is mainly methane and ammonia. The methane would provide some sort of greenhouse effect, but ammonia on contact with ice at minus 80 degrees C or above, dissolves in the ice and makes an ammonia/water solution. This, I propose, was the fluid. As the fluid goes north, winds and warmer temperatures would drive off some of the ammonia so oddly enough, as the fluid gets warmer, ice starts to freeze. Ammonia in the air will go and melt more snow. (This is not all that happens, but it should happen.)  Eventually, the ammonia has gone, and the water sinks into the ground where it freezes out into a massive buried ice sheet.

If so, we can now see where the catastrophic flows come from. We have the ice deposits where required. We now require at least fumaroles to be generated underneath the ice. The Margaritifer Chaos is within plausible distance of major volcanism, and of tectonic activity (near the mouth of the Valles Marineris system). Now, let us suppose the gases emerge. Methane immediately forms clathrates with the ice (enters the ice structure and sits there), because of the pressure. The ammonia dissolves ice and forms a small puddle below. This keeps going over time, but as it does, the amount of water increases and the amount of ice decreases. Eventually, there comes a point where there is insufficient ice to hold the methane, and pressure builds up until the whole system ruptures and the mass of fluid pours out. With the pressure gone, the remaining ice clathrates start breaking up explosively. Erosion is caused not only by the fluid, but by exploding ice.

The point then is, is there any evidence for this? The answer is, so far, no. However, if this mechanism is correct, there is more to the story. The methane will be oxidised in the atmosphere to carbon dioxide by solar radiation and water. Ammonia and carbon dioxide will combine and form ammonium carbonate, then urea. So if this is true, we expect to find buried where there had been water, deposits of urea, or whatever it converted to over three billion years. (Very slow chemical reactions are essentially unknown – chemists do not have the patience to do experiments over millions of years, let alone billions!) There is one further possibility. Certain metal ions complex with ammonia to form ammines, which dissolve in water or ammonia fluid. These would sink underground, and if the metal ions were there, so might be the remains of the ammines now. So we have to go to Mars and dig.

 

 

 

 

 

Ebook Discount

From May 27 – June 3  Jonathon Munros will be discounted to 99c on Amazon in the US and 99p in the UK. The third book in a series, in which the evil Jonathon Munro violates the only reason his evil behaviour has as yet not been punished. He is to be replaced by an android, who learns to behave like the real man. However. Jonathon’s inherent evil has been underestimated, and the android, knowing of Jonathon’s obsession with sex, and knowing that sex is needed for reproduction, decides to start reproducing itself. What could possibly go right? A dystopian hard science fiction novel that, while the third of a series, stands alone as long as you accept the characters have a past, and a problem that makes the Terminator seem modest.

http://www.amazon.com/dp/B00EK5T6WE

A Pox on Them

For those of us somewhat tired of Covid-19, there is more depressing news. An article in Nature (605, 419 – 422) noted that virtually every viral pandemic that has occurred since the beginning of the 20th century was triggered by the virus jumping from animals to people. Now for more bad news: an analysis of outbreaks over the past four centuries indicates that the annual probability of pandemics could increase several-fold in the coming decades because of human-induced environmental changes. We are doing it to ourselves! But wait: there is a fix, and it only costs the world around $20 billion a year, provided everyone cooperates. (Do I hear the “Good luck with that” comment?) That is asking for about $3 from every person, but given the way incomes are distributed, probably somewhat ore for those in the West.

According to Nature, that is small compared with the millions of lives lost and the trillions of dollars spent as a consequence of SARS-C0V-2. It is also 1/20 of the statistical value of lives lost each year to viral diseases that have spilled over from animals since 1918. Yet interestingly the WHO set up a panel to consider what should be done in the future to prevent such pandemics, and in an 86-page report apparently wild-life got two mentions and deforestation one mention. Either the “experts” did not understand where these pandemics originate, or they did not care. The article suggests four actions are required.

Spillover is more likely to occur when the number of animal-human interactions increase, such as in farming, the trade in wild-life, or when forests are cleared and the animals no longer have their normal environment for living. The article suggests four actions:

  1. Tropical and subtropical forests must be protected. Wildlife that survives such cutting of forests includes the wildlife that can live alongside people, and they also often host pathogens capable of killing people. As an example, bats in Bangla Desh carry Nipah virus, which can kill 40 – 77% of the people it infects. These now roost in areas of high human population because their forest habitat has been largely cleared. Loss of forest also increases climate change. Besides stopping such climate forcing, it also stops driving animals out of regions that have become too inhospitable for them to stay. Once upon a time, if the climate changed, animals could migrate. Now their environment tends to be in islands, and if they have to leave, that is into human living areas.
  2. Commercial markets and trade of live wild animals must be banned or strictly regulated. Some progress is being made here. In China, the trade and consumption of exotic wildlife has been banned since Covid 19.
  3. Biosecurity must be improved when dealing with farmed animals. We need improved veterinary care, better surveillance for animal disease, improved housing and feeding for animals, and quarantines to limit pathogen spread. Up to a point, we have made progress here, in controlling mad cow disease, but more is required. It is important to stop livestock pathogens since nearly 80% of such pathogens can infect multiple host species, including humans.
  4. More attention needs to be made to contain early outbreaks, and that includes increasing people’s health and economic security. A big problem is that people in poor health, and particularly people with immunosuppression, can host pathogens long enough for the virus to mutate before being passed on.

If we could stop spillover, we eliminate the need to contain it. As most will recall, disease surveillance, contact tracing, lockdowns, vaccine development and therapeutic development are expensive, and unless done properly, ineffective. As most will realize now, the response to Covid 19 immediately ran into people who refused to have their rights infringed, in the belief they were young enough to get through it, or did not even care. “It won’t happen to me.” That caused 6.25 known million unnecessary deaths, but Nature estimates the deaths to be between 15 – 21 million who would not have died but for the pandemic. By 2025 we will have spent $157 billion on Covid-19 vaccines.

So, the question is, will we do something about it? My guess is, probably not much.

And no sooner did Nature publish that article and we suddenly found we have a new disease: monkeypox. Now guess where that is likely to have come from?

Indigenous Rights in Science

Most readers will have heard of the fights for the rights of indigenous people, but what about people born in the country, whose ancestors have been there for a long period? What rights to they have? Should they have rights to the resources of their own country? You will have heard about animal poaching, where endangered species are smuggled out of the country, and will have a view on that. However, there is a new argument coming in the scientific community, reported in Nature (605, 18 – 19) and it came from an article in the journal Cretaceous Research. The article described Ubirajara jubatus, a 110-million-year-old fossil of a dinosaur that appeared to display the precursors to feathers. The fossil had been collected in Brazil decades earlier but no Brazilian had heard of it. The authors claimed the fossil had been exported with a permit signed by some official, and the skeptic might suspect corruption here.

The publication sparked a revolution. A massive Twitter campaign was launched, and eventually the paper was withdrawn, although how you withdraw a printed paper is another matter. The specimen is in the State Museum of Natural History in Karlesruhe, and apparently the museum is engaged in negotiations to return it.

This practice, called by some colonial palaeontology, has caused a storm across south America. A report that analysed 200 studies published between 1990 and 2021 found that more than half did not involve local researchers, and of the Brazilian fossils used, 88% of them were kept outside Brazil. One of the authors of the Ubirajara paper protested that the study cherry-picked data, and omitted a whole lot of earlier American practices. The author of the report states it picked on starting at 1990 because that was when Brazil introduced laws preventing the export of such fossils, and it would be wrong to criticise a practice that was perfectly legal before then. He also noted it was a curious defence to state that others were doing it, so why not him, despite the law?

Now the South Americans are attempting to persuade scientific journals to act to stop such colonial practices. They noted that none of the 200 studies published an acknowledgement of the permit they should have had to take the specimen out of the country. If you read scientific papers, you often see a remarkable list of acknowledgements, such a X made helpful comments. Acknowledging that you followed the law might seem to be a useful step.

Apparently, this “revolution” had some less that satisfactory behaviour. Members of the public began visibly harassing scientists involved in the Ubirajara research, while the Karlsruhe Museum had to close its Instagram account due to the flood of negative comments.

There followed a spat about how researchers local to where the fossil was found should be involved when the fossil has been in a foreign museum for ages. Our author who protested (above) then continued to protest that this would involve tokenism if they had to include a scientist from the region on the paper. Of course, a way out of that would be to return the fossil. Two other countries particularly affected are the Dominican Republic and Myanmar, both of which have significant fossilized amber, of Jurassic Park fame. What happens next is unclear, although it appears the move to return fossils is growing.

That thought leads to another. Scientific publication involves peer review. It would be interesting to compare the fraction of rejections from third world countries with those from major US/European Universities. Does the address “Harvard” give a serious advantage over some town in Myanmar? Or is it done truly on content?

On a completely different matter, a huge fang of an ichthyosaur has been found from the Swiss alps. From the size of the tooth, the reptile would have measured about 21 meters in length. You might have heard that ichthyosaurs were somewhat vulnerable and only lived in shallow waters. Not this beast. A carnivore the size of a sperm whale would not be a pleasant thing to encounter. However, it died out at the end of the Triassic so no current danger.

Banana-skin Science

Every now and again we find something that looks weird, but just maybe there is something in it. And while reading it, one wonders, how on Earth did they come up with this? The paper in question was Silva et. al. 2022. Chemical Science 13: 1774. What they did was to take dried biomass powder and exposed it to a flash of 14.5 ms duration from a high-power xenon flash lamp. That type of chemistry was first developed to study the very short-lived intermediates generated in photochemistry, when light excites the molecule to a high energy state, where it can decay through unusual rearrangements. This type of study has been going on since the 1960s and equipment has steadily been improving and being made more powerful. However, it is most unusual to find it used for something that ordinary heat would do far more cheaply. Anyway, 1 kg of such dried powder generated about 100 litres of hydrogen and 330 g of biochar. So, what else was weird? The biomass was dried banana skin! Ecuador, sit up and take notice. But before you do, note that flash xenon lamps are not going to be an exceptionally economical way of providing heat. That is the point; this very expensive source of light was actually merely providing heat.

There are three ways of doing pyrolysis. In the previous post I pointed out that if you took cellulose and eliminated all the oxygen in the form of water, you were left with carbon. If you eliminate the oxygen as carbon monoxide you are left with hydrogen. If you eliminate it as carbon dioxide you get hydrogen and hydrocarbon. In practice what you get depends on how you do it. Slow pyrolysis at moderate heat mainly makes charcoal and water, with some gas. It may come as a surprise to some but ordinary charcoal is not carbon; it is about 1/3 oxygen, some minor bits and pieces such as nitrogen, phosphorus, potassium, and sulphur, and the rest carbon.

If you do very fast pyrolysis, called ablative pyrolysis, you can get almost all liquids and gas. I once saw this done in a lab in Colorado where a tautly held (like a hacksaw blade) electrically heated hot wire cut through wood like butter, the wire continually moving so the uncondensed liquids (which most would call smoke) and gas were swept out. There was essentially no sign of “burnt wood”, and no black. The basic idea of ablative pyrolysis is you fire wood dust or small chips at a plate at an appropriate angle to the path so the wood sweeps across it and the gas is swept away by the gas stream (which can be recycled gas) propelling the wood. Now the paper I referenced above claimed much faster pyrolysis, but got much more charcoal. The question is, why? The simple answer, in my opinion, is nothing was sweeping the product away so it hung around and got charred.

The products varied depending on the power from the lamp, which depended on the applied voltage. At what I assume was maximum voltage the major products were (apart from carbon) hydrogen and carbon monoxide. 100 litres of hydrogen, and a bit more carbon monoxide were formed, which is a good synthesis gas mix. There were also 10 litres of methane, and about 40 litres of carbon dioxide that would have to be scrubbed out. The biomass had to be reduced to 20 μm size and placed on a surface as a layer 50 μm thick. My personal view is that is near impossible to scale this up to useful sizes. It uses light as an energy source, which is difficult to generate so almost certainly the process is a net energy consumer. In short, this so-called “breakthrough” could have been carried out to give better yields of whatever was required far more cheaply by people a hundred years ago.

Perhaps the idea of using light, however, is not so retrograde. The trick would be to devise apparatus that with pyrolyse wood ablatively (or not if you want charcoal) using light focused by large mirrors. The source, the sun, is free until it hits the mirrors. Most of us will have ignited paper with a magnifying glass. Keep the oxygen out and just maybe you have something that will make chemical intermediates that you can call “green”.

Biofuels to Power Transport

No sooner do I post something than someone says something to contradict the post. In this case, immediately after the last post, an airline came out and said it would be zero carbon by some time in the not-too-distant future. They talked about, amongst other things, hydrogen. There is no doubt hydrogen could power an aircraft, as it also powers rockets that go into space. That is liquid hydrogen, and once the craft takes off, it burns for a matter of minutes. I still think it would be very risky for aircraft to try to hold the pressures that could be generated for hours. If you do contain it, the extra weight and volume occupied would make such travel extremely expensive, while sitting above a tank of hydrogen is risky.

Hydrocarbons make by far the best aircraft fuel, and one alternative source of them is from biomass. I should caution that I have been working in this area of scientific research on and off for decades (more off than on because of the need to earn money.) With that caveat, I ask you to consider the following:

C6H12O6  ->  2 CO2 +2H2O + “C4H8”

That is idealized, but the message is a molecule of glucose (from water plus cellulose) can give two molecules each of CO2 and water, plus two thirds of the starting carbon as a hydrocarbon, which would be useful as a fuel. If you were to add enough hydrogen to convert the CO2 to a fuel you get more fuel. Actually, you do not need much hydrogen because we usually get quite a few aromatics, thus if we took two “C4H8” and make xylene or ethyl benzene (both products that are made in simple liquefactions) these total C8H10, which gives us a surplus of three H2 molecules. The point here is that in each of these cases we could imagine the energy coming from solar, but if you use biomass, much of the energy is collected for you by nature. Of course, if you take the oxygen out as water you are left with carbon. In practice there are a lot of options, and what you get tends to depend on how you do it. Biomass also contains lignin, which is a phenolic material. This is much richer in hydrocarbon material, but also it is much harder to remove the oxygen.

In my opinion, there are four basic approaches to making hydrocarbon fuels from biomass. The first, which everyone refers to, is pyrolysis. You heat the biomass, you get a lot of charcoal, but you also get liquids. These still tend to have a lot of oxygen in them, and I do not approve of this because the yields of anything useful are too low unless you want to make charcoal, or carbon, say for metal refining, steel making, electrodes for batteries, etc. There is an exception to that statement, but that needs a further post.

The second is to gasify the biomass, preferably by forcing oxygen into it and partially burning it. This gives you what chemists call synthesis gas, and you can make fuels through a further process called the Fischer-Tropsch process. Germany used that during the war, and Sasol in South Africa Sasol, but in both cases coal was the source of carbon. Biomass would work, and in the 1970s Union Carbide built such a gasifier, but that came to nothing when the oil price collapsed.

The third is high-pressure hydrogenation. The biomass is slurried in oil and heated to something over 400 degrees Centigrade in then presence of a nickel catalyst and hydrogen. A good quality oil is obtained, and in the 1980s there was a proposal to use the refuse of the town of Worcester, Mass. to operate a 50 t/d plant. Again, this came to nothing when the price of oil slumped.

The fourth is hydrothermal liquefaction. Again, what you get depends on what you put in but basically there are two main fractions from woody biomass: hydrocarbons and phenolics. The phenolics (which includes aromatic ethers) need to be hydrogenated, but the hydrocarbons are directly usable, with distillation. The petrol fraction is a high octane, and the heavier hydrocarbons qualify as very high-quality jet fuel. If you use microalgae or animal residues, you also end up with a high cetane diesel cut, and nitrogenous chemicals. Of particular interest from the point of view of jet fuel, in New Zealand they once planted Pinus Radiata which grew very quickly, and had up to 15% terpene content, most of which would make excellent jet fuel, but to improve the quality of the wood, they bred the terpenes more or less out of the trees.

The point of this is that growing biomass could help remove carbon dioxide from the atmosphere and make the fuels needed to keep a realistic number of heritage cars on the road and power long-distance air transport, while being carbon neutral. This needs plenty of engineering development, but in the long run it may be a lot cheaper than just throwing everything we have away and then finding we can’t replace it because there are shortages of elements.

The Case for Hydrogen in Transport

In the last post I looked at the problem of generating electricity, and found that one of the problems is demand smoothing One approach to this is to look at the transport problem, the other major energy demand system. Currently we fill our tanks with petroleum derived products, and everything is set for that. However, battery-powered cars would remove the need for petrol, and if they were charged overnight, they would help this smoothing problem. The biggest single problem is that this cannot be done because there is not enough of some of the necessary elements to make it work. Poorer quality batteries could be made, but there is another possibility: the fuel cell.

The idea is simple. When electricity is not in high demand, the surplus is used to electrolyse water to hydrogen and oxygen. The hydrogen is stored, and when introduced to a fuel cell it burns to make water while generating electricity. Superficially, this is ideal, but there are problems. One is similar to the battery – the electrodes tend to be made of platinum, and platinum is neither cheap nor common. However, new electrodes may solve this problem. Platinum has the advantage that it is very unreactive, but the periodic servicing of the cell and the replacing of electrodes is realistic, and of course recycling can be carried out because unlike the battery, it would be possible to merely recycle the electrodes. (We could also use pressurised hydrogen in an internal combustion engine, with serious redesign, but the efficiency is simply too low.)

One major problem is storing the hydrogen. If we store it as a gas, very high pressures are needed to get a realistic mass to volume ratio, and hydrogen embrittles metals, so the tanks, etc., may need servicing as well. We could store it as a liquid, but the boiling point is -259 oC. Carting this stuff around would be a challenge, and to make matters worse, hydrogen occurs in two forms, ortho and para, which arise because the nuclear spins can be either aligned or not. Because the molecule is so small there is an energy difference between these, and the equilibrium ratio is different at liquid temperatures to room temperatures. The mix will slowly re-equilibrate at the low temperature, give off heat, boil off some hydrogen, and increase the pressure. This is less of a problem if you have a major user, because surplus pressure is relieved when hydrogen is drawn off for use, and if there is a good flow-through, no problem. It may be a problem if hydrogen is being shipped around.

The obvious alternative is not to ship it around, but ship the electricity instead. In such a scenario for smaller users, such as cars, the hydrogen is generated at the service station, stored under pressure, and more is generated to maintain the pressure. That would require a rather large tank, but it is doable. Toyota apparently think the problem can be overcome because they are now marketing the Mirai, a car powered by hydrogen fuel cells. Again, the take-up may be limited to fleet operators, who send the vehicles out of central sites. Apparently, the range is 500 km and it uses 4.6 kg of hydrogen. Hydrogen is the smallest atom so low weight is easy, except the vehicle will have a lot of weight and volume tied up with the gas pressurized storage. The question then is, how many fuel stations will have this very large hydrogen storage? If you are running a vehicle fleet or buses around the city, then your staff can refill as well, which gets them to and from work, but the vehicle will not be much use for holidays unless there are a lot of such stations.

Another possible use is in aircraft, but I don’t see that, except maybe small short-haul flights driven by electric motors with propellors. Hydrogen would burn well enough, but the secret of hydrocarbons for aircraft is they have a good energy density and they store the liquids in the wings. The tanks required to hold hydrogen would add so much weight to the wings they might fall off. If the main hull is used, where do the passengers and freight go? Another possibility is to power ships. Now you would have to use liquid hydrogen, which would require extremely powerful refrigeration. That is unlikely to be economic compared with nuclear propulsion that we have now.

The real problem is not so much how do you power a ship, or anything else for that matter, but rather what do you do with the current fleet? There are approximately 1.4 billion motor vehicles in the world and they run on oil. Let us say that in a hundred years everyone will use fuel cell-driven cars, say. What do we do in the meantime? Here, the cheapest new electric car costs about three times the cost of the cheapest petrol driven car. Trade vans and larger vehicles can come down to about 1.5 times the price, in part due to tax differences. But you may have noticed that government debt has become somewhat large of late, due to the printing of large amounts of money that governments have promptly spent. That sort of encouragement will probably be limited in the future, particularly as a consequence of shortages arising from sanctions. In terms of cost, I rather think that many people will be hanging on to their petrol-powered vehicles, even if the price of fuel increases, because the difference in the price of fuel is still a few tens of dollars a week tops, whereas discarding the vehicle and buying a new electric one involves tens of thousands of dollars, and with the current general price increases, most people will not have those spare dollars to throw away. Accordingly, in my opinion we should focus some attention on finding an alternative to fossil fuels to power our heritage fleet.

“Green” Electricity

Before thinking about how to replace fossil fuels for electricity, we need to look at how the power demand varies through the day. Not unexpectedly, this varies depending on where you live, but if you take various parts of the US as an example of industrialized usage, there is a baseline that involves minimal usage at about 0500 hrs, and that baseline varies by up to 30% seasonally. The difference between day and night can vary by up to 60%, the biggest variation is in hot summer and is due to the use of air conditioning. This means there is a huge difference between peak demand and minimum demand, which in turn means that difference has to be supplied by generation that can be turned on and off. The big thermal plants do not turn on and off easily. You can run the plant without producing electricity, but now you are simply burning fuel for no purpose.

The most responsive generators are the gas turbine and hydroelectricity. Hydro is an obvious “green” source for load smoothing; you simply shut the gate, save water, and stop generating, but most suitable hydro sites are already used. Wind power is also useful; you simply let wind pass if you do not want power, but it runs into trouble when you need power and there is no wind. Solar means you charge batteries during the day and used the power later, but in a previous post I showed it is impossible to make enough batteries to power our vehicle fleet, so how do we make an even greater supply of batteries? A further alternative is to run your base load near maximum usage, and use the surplus to make something like hydrogen when it is not needed. More on hydrogen in a later post.

The “inconvenient truth” for some is the only general major base load provider to replace coal and gas for electricity generation is nuclear. Unfortunately, nuclear has a bad press. Other downsides include, currently, it is too expensive. Most people think it is too dangerous and it is too likely to leak radiation. Actually, the smoke from coal combustion also is cancer inducing to lungs, while in the US there are around 13,000 premature deaths per year due to coal, and 23,000 annually in Europe. Coal is nowhere nearly as safe as people think. So far, nuclear power has a death rate of 0.07 deaths per terawatt-hour of electricity, or about 1 death per 14 years. That figure is enhanced substantially due to stupidity at Chernobyl. Fukushima has 1 death attributed to it, although there are claims that the stresses of it on those who had to move caused a further 2,200. Up to 2004 (18 years later) 78 died from Chernobyl. This is not good, but it is avoidable.

Current reserves of uranium total 5.3 million tonne, about a third of which are in Australia. However, only about 36,000 t of that is U235, which is what is fissile, and has to be enriched. The depleted uranium waste from the enrichment process goes into armour-piercing military rounds. What happens in most nuclear power stations is the enriched uranium rods generate heat, then have to be taken away to be reprocessed, which involves removing the plutonium for weapons. A long time ago, when I was at school, we had a visiting energy expert who told us that in the future the world would develop breeder reactors, and the enriched uranium would produce more fuel in the form of plutonium than it consumed in making electricity, The need to feed the military complex means that did not happen.

What is possible is a new generation of reactor, based on the fuel being dissolved in molten salt. The reactor is now at thermal equilibrium so it is impossible to have a melt-down – there is nothing to melt. The one catch is the issue of corrosion. That can undoubtedly be dealt with, but we have yet to learn the real long-term issues. China is currently testing one demonstration plant, and it is designed to simply provide the boiling pressurized water to run an existing power plant. The idea is simply the coal-firing is removed, this heat source is plugged in and everything else continues working. As the U238 gets converted to plutonium, it also fissions and generates heat to make electricity. What the surplus neutrons in the reactor do is also to burn “hot” isotopes, so the waste disposal problems are far less. Finally, once going, it can also take thorium as a fuel, and there is far more thorium in the world. Simple fission could keep us going for centuries.

Arguably, nuclear is not “green”. My argument is we either use it or not, but it alone has any chance of providing the levels of electricity we need and replace fossil fuel burning.

Ultimately, fusion power would solve all our energy problems. There is only one problem with it: we do not know how to make it work. There is also one general problem. To change our ways, we shall have to spend a very large amount of money, and basically replace about two thirds of our existing electricity generating infrastructure. The alternative is to do nothing and then rebuild all our major coastal cities when the ice sheets collapse. That is also expensive. We have a choice, but unfortunately our politicians seem to want to do nothing and leave the problem for our grandchildren.

The IPCC Orders Action

The Intergovernmental Panel on Climate Change has produced Part 3 of a report, and with only about 2900 pages, that has one stark message: we need aggressive action to curb greenhouse gas emission AND we need aggressive action to absorb CO2 from the atmosphere, and the action must start now, not some indefinite time in the future. As I recall, this problem was highlighted thirty years ago, and in that thirty years, emissions have increased. There was not even a hint of a reduction. To give some idea of how seriously some take this matter, Germany closed down its nuclear power plants, and now it threatens not to use Russian gas, but instead burn lignite. We cannot do much worse than that can we?

Maybe we can, and maybe we are. According to an article by Lawrence et al. (Front. For. Glob. Change https://doi.org/10.3389/ffgc.2022.756115 (2022) tropical rain forests not only secrete carbon and take it out of circulation, saving around 0.5 of a degree C, but they also physically cool the planet by a further 0.5 degrees C. What the trees do is to emit much humidity from their leaves, with the result that they cool themselves (similar to sweating) and this humidity creates clouds, which reflect sunlight back to space. This is the sort of a geo-engineering proposal often made, but the trees do it for free. So, what are we doing? Why, cutting down the rain forests. Apparently a third has been removed, and another third has been heavily logged so it is not as functional as it should be. We are supposed to be trying to hold the temperatures to an increase of no more than 1.5 degrees C, we are nearly there already, so do we really need another degree of heating added in for no good reason?

According to the IPCC, carbon emissions will have to decline rapidly after 2025, halve by 2030, and hit “net zero” by the early 2050s. Given current efforts, a warming of 3 degrees is forecast. Emissions from existing and planned projects already exceed the allowable carbon budget. But even going to zero emissions will not suffice in the short term. Nations also need to extract carbon dioxide from the atmosphere.

So, what can we do? First, consider the problem. For our electricity, which has a little under 750 GW global capacity, wind power provides a little over 6%; solar provides a little over 2%, hydropower about 16%, nuclear about 10%. For fuels, earth consumes about 3.8 trillion cubic meters of natural gas, 35.4 billion barrels of oil, and 8.5 billion t of coal a year. Why we have a problem should be clear. Currently, about 2/3 of our electricity comes from burning fossil fuel. Worse, you don’t build a coal-fired power station today and turn it off tomorrow. Wind turbines need solid support. Making a tonne of cement produces roughly 800 kg of CO2, making a tonne of steel releases 1.85 t of CO2; combined they sum to about 16% of the world’s CO2 production. Wind power might be “green” but look at the CO2 emitted making and installing the equipment. Solar is free, but the demand for electricity is when solar is weak or non-existent, so massive storage is required, and that gets expensive, both in terms of money and in CO2 emissions for making the batteries. The point is, all new infrastructure is going to involve a lot of CO2 emissions before any energy is generated.

Transport is a particularly difficult problem. I think it is a common problem, but where I live the cities expanded significantly after WW 2, and they expanded with the automobile in mind. The net result is it is most people get around by car. Most people have access to a car, and that is petrol driven. The electric vehicle that might replace the petrol-driven car costs (here, at least) over twice that of the petrol driven car and you cannot really convert them. The reason is the electric vehicle needs a huge mass of batteries to have a useful driving range. Further, as I pointed out in a previous post, we cannot have everyone driving electric cars because we do not have the cobalt to make the batteries, and we still need ships and aircraft, which use a rather small fraction of the oil cut. We have to do something with the rest of the fuel cut. You may have noticed that large electricity production above and how so much comes from fossil fuels. Transport uses about 25% of the total energy production. That means to convert transport to electricity, we need to expand electricity generation by about another 250 GW. That is easy to write down, but just think of all the CO2 emitted by making the concrete and steel to build the power stations. Our current wind power would have to expand by a factor of 5.5 and we have to hope there are no still days. Of course, you may legitimately argue that if we charged batteries at night that would even the base load and you do not need all the additional installation. That is true, except green electricity generation  usually is not optimal for base loads.

My view is it cannot be done the way the enthusiasts want it done. We shall never get everybody to cooperate sufficiently to achieve the necessary reductions because society simply cannot afford it. We need a different approach, and in some  later posts, I shall try to offer some suggestions.

Molecular Oxygen in a Comet

There is a pressure, these days, on scientists to be productive. That is fair enough – you don’t want them slacking off in a corner, but a problem arises when this leads to the publication of papers: there are so many of them that nobody can keep up with even a small fraction of them. Worse, many of them do not seem to say much. Up to a point, this has an odd benefit: if you leave a lot unclear, all your associates can publish away and cite you, which has this effect of making you seem more important because funders like to count citations. In short, with obvious exceptions, the less you advance the science, the more important you seem at second level funding. I am going to pick, maybe unfairly, on one paper from Nature Astronomy (https://www.nature.com/articles/s41550-022-01614-1) as an illustration.

One of the most unexpected findings in the coma of comet 67P/Churyumov-Gerasimenko was “a large amount” of molecular oxygen. Something to breathe! Potential space pilots should not get excited; “a large amount” is only large with respect to what they expected, which was none. At the time, this was a surprise to astronomers because molecular oxygen is rather reactive and it is difficult to see why it would be present. Now there is a “breakthrough”: it has been concluded there is not that much oxygen in the comet at all, but this oxygen came from a separate small reservoir. The “clue” came from the molecular oxygen being associated with molecular water when emitted from a warm site. As it got cooler, any oxygen was associated with carbon dioxide or carbon monoxide. Now, you may well wonder what sort of clue that is? My question is, given there is oxygen there, what would you expect? The comet is half water, so when the surface gets warm, it sublimes. When cooler, only gases at that lower temperature get emitted. What is the puzzle?

However, the authors of the paper came to a different conclusion. They decided that there had to be a deep reservoir of oxygen within the comet, and a second reservoir close to the surface that is made of porous frozen water. According to them, oxygen in the core works its way to the surface and gets trapped in the second reservoir. Note that this is an additional proposition to the obvious one that oxygen was trapped in ice near the surface. We knew there was gas trapped in ice that was released with heat, so why postulate multiple reservoirs, other than to get a paper published?

So, where did this oxygen come from? There are two possibilities. The first is it was accreted with the gas from the disk when the comet formed. This is somewhat difficult to accept. Ordinary chemistry suggests that if oxygen molecules were present in the interstellar dust cloud it should react with hydrogen and form water. Maybe that conclusion is somehow wrong, but we can find out. We can estimate the probability by observing the numerous dust clouds from which stars accrete. As far as I am aware, nobody has ever found rich amounts of molecular oxygen in them. The usual practice when you are proposing something unusual is you find some sort of supporting evidence. Seemingly, not this time.

The second possibility is that we know how molecular oxygen could be formed at the surface. High energy photons and solar wind smash water molecules in ice to form hydrogen and hydroxyl radicals. The hydrogen escapes to space but the hydroxyl radicals unite to form hydrogen peroxide or other peroxides or superoxides, which can work their way into the ice. There are a number of other solids that catalyse the degradation of peroxides and superoxides back to oxygen, which would be trapped in the ice, but released when the ice sublimed. So, from the chemist’s point of view there is a fairly ordinary explanation why oxygen might be formed and gather near the surface. From my point of view, Occam’s Razor should apply: you use the simplest explanation unless there is good evidence. I do not see any evidence about the interior of the comet.

Does it matter? From my point of view when someone with some sort of authority/standing says something like this, there is the danger that the next paper will say “X established that . . “  and it becomes almost a gospel. This is especially so when the assertion cannot be easily challenged with evidence as you cannot get inside that comet. Which gives the perverse realization that you need strong evidence to challenge an assertion, but maybe no evidence at all to assert it in the first place. Weird?

A Food Crisis?

Arguably the biggest current problem for the world is the food supply, and particularly grain. About a third of all wheat and barley exports and about one fifth of the corn comes from Ukraine-Russia, and as you may have noticed, there is currently a war that is becoming bogged down in Ukraine while Russia is being sanctioned. Ukraine plants about 6 million hectares in wheat, and that has to be planted by May. I assume there also has to be some earlier soil preparation so time is running out. On top of that, it appears the weather has been very unkind for grain growing in China as heavy rain delayed planting. China’s wheat crop is the largest in the world, three times greater than the US, and 80% greater than Russia’s, however China remains a net importer and Chinese production this year have been estimated to be reduced by about 20%. Some of the problems for Ukrainian production are obvious, but others less so. Besides the actual problem of planting and managing the crops in a war zone that unfortunately is focusing its attention on some of the major grain growing areas, there is the problem of obtaining sufficient fuel and fertilizer.

The sanctioning of Russian oil means that fuel costs are almost certain to rise, and the turning off of Russian gas turns off the feedstock for the making of the hydrogen and providing the energy for ammonia production, which means that fertilizer in Europe will become very much more expensive. Such problems can be solved. There are other ways to produce the fuel and the fertilizer, but such alternatives cannot be just turned on overnight. Building a new route in the chemical industry takes many years even to build your first conversion plant, and nobody will build one until they see how the first one operates. So for the time being we are stuck with what we have.

The rich countries will grizzle but meet the increased price, but what will the poorer nations do? My guess is they will continue buying from Russia, sanctions or no sanctions. Political niceties go out the window when then choice is to starve.

What can be done? Obviously, ending the war would be a starter, and hopefully that will come to pass, but the various sanctions will stay, so the Russian wheat crop will be unavailable to the West. More interesting is the problem of if the West imposes sanctions on any country buying Russian wheat. If China purchases it, that will relieve the pressure on the rest of the world to some extent because China will get its wheat from somewhere. Fortunately, China has had a policy of storing surplus so its reserves may make a major contribution to easing the problem.

The obvious solution is to increase production elsewhere. At first sight, that is obvious, and in some places probably achievable, such as Sudan and Nigeria, except again part of the reason these places do not grow as much is because they have internal fighting. Climate change is also a big factor. Many countries have marginal production, but it is unclear whether growing conditions will get better or worse. New Zealand provides an example of a further problem. New Zealand is a net wheat importer, even though it can grow its own. The reason it imports is that its farmers can make more money growing something else, and that means if it did switch to wheat production in some regions, it would have to switch off something else and raise the price.

We have to be careful we are not just moving the problem. To switch in some regions that do not grow much at all would require a big investment in harvesting machinery, purchase of seed and fertilizer, and find skilled farmers. Seed is more troublesome than it might seem because seed often carries pathogens that suddenly thrive in a new environment. Thus the purchase of special seed in Bangla Desh in 2016 introduced a fungus that halved overall production. In some cases it may be better off to make the switch in what you grow because there are other flours that can be used, such as from legumes (less nitrogen fertilizer required) or millet. Some farmers could try that, but what happens if they guess wrongly? The invisible hand of the market is not kind to those who guess wrongly, so farmers tend to stick with what they know works well for them. Who carries the risk if we need big change?

We obviously have to do something, but what?