What to do about Climate Change

As noted in my previous post, the IPCC report on climate change is out. If you look at the technical report, it starts with pages of corrections. I would have thought that in these days the use of a word processor could permit the changes to be made immediately, but what do I know? Anyway, what are the conclusions? As far as I can make out, they have spent an enormous effort measuring greenhouse gas emissions and modelling, and have concluded that greenhouse gases are the cause of our problem and if we stopped emitting right now, totally, things would not get appreciably worse than they are now over the next century. As far as I can make out, that is it. They argue that CO2 emissions give a linear effect and for every trillion tonnes emitted, temperatures will rise by 0.45 Centigrade degrees, with a fairly high error margin. So we have to stop emitting.

The problem is, can we? In NZ we have a very high fraction of our electricity from renewable sources and we recently had a night of brown-outs in one region. It was the coldest night of the year, there was a storm over most of the country, but oddly enough there was hardly any wind at a wind farm. A large hydro station went out as well because the storm blew weeds into an intake and the station had to shut down and clean it out. The point is that when electricity generation is a commercial venture, it is not in the generating companies’ interests to have a whole lot of spare capacity and it make no sense to tear down what is working well and making money to spend a lot replacing it. So, the policy of using what we have means we are stuck where we are. China has announced, according to our news, that its coal-fired power stations will maximise and plateau their output of CO2 in about ten years. We have no chance of zero emissions in the foreseeable future. Politicians and environmentalists can dream on but there is too much inertia in an economy. Like a battleship steering straight for the wharf, the inevitable will happen.

Is there a solution? My opinion is, if you have to persist in reducing the heat being radiated to space, the best option is to stop letting so much energy from the sun into the system. The simplest experiment I can think of is to put huge amounts of finely dispersed white material, like the silica a volcano puts up, over the North Polar regions each summer to reflect sunlight back to space. If we can stop as much winter ice melting, we would be on the way to stop the potential overturn of the Gulf Stream and stop the Northern Siberian methane emissions. Just maybe this would also encourage more snow in the winter as the dust falls out.

Then obvious question is, how permanent would such a dispersion be? The short answer is, I don’t know, and it may be difficult to predict because of what is called the Arctic oscillation. When that is in a positive phase it appears that winds tend to circulate over the poles, so it may be possible to maintain dust over summer. It is less clear what happens in the negative phase. However, either way someone needs to calculate how much light has to be blocked to stop the Arctic (and Antarctic) warming. Maybe such a scheme would not be practical, but unless we at least make an effort to find out, we are in trouble.

This raises the question of who pays? In my opinion, every country with a port benefits if we can stop major sea level rising, so all should. Of course, we shall find that not all are cooperative. A further problem is that the outcome is somewhat unpredictable. The dust only has to last during the late spring and summer, because the objective is to reflect sunlight. For the period when the sun is absent it is irrelevant. We would also have to be sure the dust was not hazardous to health but we have lived through volcanic eruptions that have caused major lowering of the temperature world-wide so there will be suitable material.

There will always be some who lose on the deal. The suggestion of putting the dust over the Arctic would make the weather less pleasant in Murmansk, Fairbanks, Yukon, etc, but it would only return it to what it used to be. It is less clear what it would do elsewhere. If the arctic became colder, presumably there would be colder winter storms in more temperate regions. However, it might be better that we manage the climate than then planet does, thus if the Gulf Stream went, Europe would suffer both rising sea levels and temperatures and weather more like that of Kerguelen. In my opinion, it is worth trying.

But what is the betting any proposal for geoengineering has no show of getting off the ground? The politically correct want to solve the problem by everyone giving up something, they have not done the sums to estimate the consequences, and worse, some will give things up but enough won’t so that such sacrifices will be totally ineffective. We have the tragedy of the commons: if some are not going to cooperate and the scheme hence must fail, why should you even try? We need to find ways of reducing emissions other than by stopping an activity, as opposed to the emission.

Climate Change: Are We Baked?

The official position from the IPCC’s latest report is that the problem of climate change is getting worse. The fires and record high temperatures in Western United States and British Columbia, Greece and Turkey may be portents of what is coming. There have been terrible floods in Germany and New Zealand has had its bad time with floods as well. While Germany was getting flooded, the town of Westport was inundated, and the Buller river had flows about 30% higher than its previous record flood. There is the usual hand-wringing from politicians. Unfortunately, at least two serious threats that have been ignored.

The first is the release of additional methane. Methane is a greenhouse gas that is about 35 times more efficient at retaining heat than carbon dioxide. The reason is absorption of infrared depends on the change of dipole moment during absorption. CO2 is a linear molecule and has three vibrational modes. One involves the two oxygen atoms both moving the same way so there is no change of dipole moment, the two changes cancelling each other. Another is as if the oxygen atoms are stationary and the carbon atom wobbles between them. The two dipoles now do not cancel, so that absorbs, but the partial cancellation reduces the strength. The third involves molecular bending, but the very strong bond means the bend does not move that much, so again the absorption is weak. That is badly oversimplified, but I hope you get the picture.

Methane has four vibrations, and rather than describe them, try this link: http://www2.ess.ucla.edu/~schauble/MoleculeHTML/CH4_html/CH4_page.html

Worse, its vibrations are in regions totally different from carbon dioxide, which means it is different radiation that cannot escape directly to space.

This summer, average temperatures in parts of Siberia were 6 degrees Centigrade above the 1980 – 2000 average and methane is starting to be released from the permafrost. Methane forms a clathrate with ice, that is it rearranges the ice structure and inserts itself when under pressure, but the clathrate decomposes on warming to near the ice melting point. This methane has formed from the anaerobic digestion of plant material and been trapped by the cold, so if released we get delivered suddenly all methane that otherwise would have been released and destroyed over several million years. There are about eleven billion tonnes of methane estimated to be in clathrates that could be subject to decomposition, about the effect of over 35 years of all our carbon dioxide emissions, except that as I noted, this works in a totally fresh part of the spectrum. So methane is a problem; we all knew that.

What we did not know a new source has been identified as published in the Proceedings of the National Academy of Sciences recently. Apparently significantly increased methane concentrations were found in two areas of northern Siberia: the Tamyr fold belt and the rim of the Siberian Platform. These are limestone formations from the Paleozoic era. In both cases the methane increased significantly during heat waves. The soil there is very thin so there is very little vegetation to decay and it was claimed the methane was stored in and now emitted from fractures in the limestone.

The  second major problem concerns the Atlantic Meridional Overturning Circulation (AMOC), also known as the Atlantic conveyor. What it does is to take warm water that gets increasingly salty up the east Coast of the US, then switch to the Gulf Stream and warm Europe (and provide moisture for the floods). As it loses water it gets increasingly salty and with its increased density it dives to the Ocean floor and flows back towards the equator. Why this is a problem is that the melting Northern Polar and Greenland ice is providing a flood of fresh water that dilutes the salty water. When the density of the water is insufficient to cause it to sink this conveyer will simply stop. At that point the whole Atlantic circulation as it is now stops. Europe chills, but the ice continues to melt. Because this is a “stopped” circulation, it cannot be simply restarted because the ocean will go and do something else. So, what to do? The first thing is that simply stopping burning a little coal won’t be enough. If we stopped emitting CO2 now, the northern ice would keep melting at its current rate. All we would do is stop it melting faster.

Venus with a Watery Past?

In a recent edition of Science magazine (372, p1136-7) there is an outline of two NASA probes to determine whether Venus had water. One argument is that Venus and Earth formed from the same material, so they should have started off very much the same, in which case Venus should have had about the same amount of water as Earth. That logic is false because it omits the issue of how planets get water. However, it argued that Venus would have had a serious climatic difference. A computer model showed that when planets rotate very slowly the near absence of a Coriolis force would mean that winds would flow uniformly from equator to pole. On Earth, the Coriolis effect leads to the lower atmosphere air splitting into three  cells on each side of the equator: tropical, subtropical and polar circulations. Venus would have had a more uniform wind pattern.

A further model then argued that massive water clouds would form, blocking half the sunlight, then “in the perpetual twilight, liquid water could have survived for billions of years.”  Since Venus gets about twice the light intensity as Earth does, Venusian “perpetual twilight” would be a good sunny day here. The next part of the argument was that since water is considered to lubricate plates, the then Venus could have had plate tectonics. Thus NASA has a mission to map the surface in much greater detail. That, of course, is a legitimate mission irrespective of the issue of water.

A second aim of these missions is to search for reflectance spectra consistent with granite. Granite is thought to be accompanied by water, although that correlation could be suspect because it is based on Earth, the only planet where granite is known.

So what happened to the “vast oceans”? Their argument is that massive volcanism liberate huge amounts of CO2 into the atmosphere “causing a runaway greenhouse effect that boiled the planet dry.” Ultraviolet light now broke down the water, which would lead to the production of hydrogen, which gets lost to space. This is the conventional explanation for the very high ratio of deuterium to hydrogen in the atmosphere. The concept is the water with deuterium is heavier, and has a slightly higher boiling point, so it would be the least “boiled off”. The effect is real but it is a very small one, which is why a lot of water has to be postulated. The problem with this explanation is that while hydrogen easily gets lost to space there should be massive amounts of oxygen retained. Where is it? Their answer: the oxygen would be “purged” by more ash. No mention of how.

In my ebook “Planetary Formation and Biogenesis” I proposed that Venus probably never had any liquid water on its surface. The rocky planets accreted their water by binding to silicates, and in doing so helped cement aggregate together and get the planet growing. Earth accreted at a place that was hot enough during stellar accretion to form calcium aluminosilicates that make very good cements and would have absorbed their water from the gas disk. Mars got less water because the material that formed Mars had been too cool to separate out aluminosilicates so it had to settle for simple calcium silicate, which does not bind anywhere near as much water. Venus probably had the same aluminosilicates as Earth, but being closer to the star meant it was hotter and less water bonded, and consequently less aluminosilicates.

What about the deuterium enhancement? Surely that is evidence of a lot of water? Not necessarily. How did the gases accrete? My argument is they would accrete as solids such as carbides, nitrides, etc. and the gases would be liberated by reaction with water. Thus on the road to making ammonia from a metal nitride

M – N  + H2O   →  M – OH  +  N-H  ; then  M(OH)2    →  MO + H2O and this is repeated until ammonia is made. An important point is one hydrogen atom is transferred from each molecule of water while one is retained by the oxygen attached to the metal. Now the bond between deuterium and oxygen is stronger than that from hydrogen, the reason being that the hydrogen atom, being lighter, has its bond vibrate more strongly. Therefore the deuterium is more likely to remain on the oxygen atom and end up in further water. This is known as the chemical isotope effect, and it is much more effective at concentrating deuterium. Thus as I see it, too much of the water was used up making gas, and eventually also making carbon dioxide. Venus may never have had much surface water.

Geoengineering – to do or not to do?

Climate change remains an uncomfortable topic. Politicians continue to state it is such an important problem, and then fail to do anything sufficient to solve it. There seems to be an idea amongst politicians that if everyone drove electric vehicles, all would be well. Leaving aside the question as to whether over the life of a vehicle the electric vehicle actually emits less greenhouse gas (and at best, that is such a close call it is unlikely to have any hope of addressing the problem) as noted in my post https://wordpress.com/post/ianmillerblog.wordpress.com/885

the world cannot sustain then necessary extractions to make it even vaguely possible. If that is the solution, why waste the effort – we are doomed.

As an article in Nature (vol 593, p 167, 2021) noted, we need to evaluate all possible options. As I have remarked in previous posts, it is extremely unlikely there is a silver bullet. Fusion power would come rather close, but we still have to do a number of other things, such as to enable transport, and as yet we do not have fusion power. So what the Nature article said is we should at least consider and analyse properly the consequences of geoengineering. The usual answer here is, horrors, we can’t go around altering the planet’s climate, but the fact is we have already. What do you think those greenhouse gases are doing?

The problem is that while the world has pledged to reduce emissions by 3 billion t of CO2 per year, even if this is achieved, and that is a big if, it remains far too little. Carbon capture will theoretically solve some of the problems, but it costs so much money for no benefit to the saver that you should not bet the house on that one. The alternative, as the Nature article suggests, is geoengineering. The concept is to raise the albedo of the planet, which reflects light back to space. The cooling effect is known: it happens after severe volcanic eruptions.

The basic concept of sending reflective stuff into the upper atmosphere is that it is short-term in nature, so if you get it wrong and there is an effect you don’t like, it does not last all that long. On the other hand, it is also a rapid fix and you get relatively quick results. That means provided you do things with some degree of care you can generate a short-term effect that is mild enough to see what happens, and if it works, you can later amplify it.

The biggest problem is the so-called ethical one: who decides how much cooling, and where do you cool? The article notes that some are vociferously opposed to it as “it could go awry in unpredictable ways”. It could be unpredictable, but the biggest problem would be that the unpredictability would be too small. Another listed reason to oppose it was it would detract from efforts to reduce greenhouse emissions. The problem here is that China and many other places are busy building new coal-fired electricity generation. Exactly how do you reduce emissions when so many places are busy increasing emissions? Then there is the question, how do you know what the effects will be? The answer to that is you carry out short-term mild experiments so you can find out without any serious damage.

The other side of the coin is, if we even stopped emissions right now, the existing levels will continue to heat the planet and nobody knows by how much. The models are simply insufficiently definitive. All we know is that the ice sheets are melting, and when they go, much of our prime agricultural land goes with it. Then there is the question of governance. One proposal to run small tests in Scandinavia ran into opposition from a community that protested that the experiments would offer a distraction from other reduction efforts. It appears that some people seem to think that with just a little effort this problem will go away. It won’t. One of the reasons for obstructing research is that the project will affect the whole planet. Yes, well so does burning coal in thermal generators, but I have never heard of the rest of the planet being consulted on that.

Is it a solution? I don’t know. It most definitely is not THE solution but it may be the only solution that acts quickly enough to compensate for a general inability to get moving, and in my opinion we badly need experiments to show what can be achieved. I understand there was once one such experiment, although not an intentional one. Following the grounding of aircraft over the US due to the Twin Tower incident, I gather the temperatures the following two days went up by over a degree. That was because the ice particles due to jet exhausts were no longer being generated. The advantages of an experiment using ice particles in the upper atmosphere is you can measure what happens quickly, but it quickly goes away so there will be no long term damage. So, is it possible? My guess is that technically it can be managed, but the practical issues of getting general consent to implement it will take so long it becomes more or less irrelevant. You can always find someone who opposes anything.

Fighting Global Warming Naturally?

In a recent edition of Nature (593, pp191-4) it was argued that to combat global warming, removing carbon from the atmosphere, which is often the main focus, should instead be reviewed in light of how to lower global temperatures. They note that the goal of reducing warming from pre-industrial times to two Centigrade degrees cannot be met solely through cuts to emissions so carbon dioxide needs to be removed from the atmosphere. The rest of the article more or less focused on how nature could contribute to that, which was a little disappointing bearing in mind they had made the point that this was not the main objective. Anyway, they went on to claim nature-based solutions could lower the temperature by a total of 0.4 degrees by 2100. Then came the caveats. If plants are to absorb carbon dioxide, they become less effective if the temperatures rise too high for them.  

Some statistics: 70% of Earth’s land surface has been modified by humanity; since 1960 we have modified 20% of it. Since 1960 changes include (in million square kilometers): urban area  +0.26; cropland +1.0; pasture +0.9; forestry -0.8.

The proposal involves three routes. The first is to protect current ecosystems, which includes stopping deforestation. This is obvious, but the current politicians, such as in Brazil, suggest this receives the comment, “Good luck with that one.” This might be achieved in some Western countries, but then again they have largely cut their forests down already. If we are going to rely on this we have a problem.

The second is to restore ecosystems so they can absorb more carbon. Restoration of forest cover is an obvious place to start. However, they claim plantation forests do not usually give the same benefits as natural forest. The natural forest has very dense undergrowth. Unless there are animals to eat that you may end up generating fuel to start forest fires, which wipe out all progress. Wetlands are particularly desirable because they are great at storing carbon, and once underway, they act rather quickly. However, again this is a problem. Wetlands, once cleared and drained are somewhat difficult to restore because the land tends to have been altered in ways to avoid the land reverting, so besides stopping current use, the alterations have to be removed. 

Notwithstanding the difficulties, there is also a strong reason to create reed beds that also grow algae. The reason is they also take up nitrogen and phosphate in water. Taking up ammoniacal wastes is very important because if part of the nitrogen waste is oxidized, or nitrates have been used as fertilizer, ammonium nitrate will decompose to form nitrous oxide, which is a further greenhouse gas that is particularly difficult because it absorbs in quite a different part of the infrared spectrum, and it has no simple decay route or anything that will absorb it. Consequently, what we put in the air could be there for some time. 

 The third is to improve land management, for timber, crops and grazing, Thus growing a forest on the borders of a stream should add carbon storage, but also reduce flooding and enhance fish life. An important point is that slowing runoff also helps prevent soil loss. All of this is obvious, except, it seems, to officials. In Chile, the government apparently gave out subsidies for pine and eucalyptus planting that led to 1.3 million hectares being planted. What actually happened was that the land so planted had previously been occupied with original forest and it is estimated that the overall effect was to emit 0.05 million t of stored carbon rather than sequester the 5.6 million t claimed. A particular piece of “politically correct” stupidity occurred here. The Department of Conservation, being green inclined, sent an electric car for its people to drive around Stewart Island, the small southern island of New Zealand. It has too small a population to warrant an electric cable to connect it to the national grid, so all the electricity there is generated by burning diesel!

The paper claims it is possible to remove 10 billion tonne of CO2 fairly quickly, and 20 billion tonne by 2055. However, my feeling is that is a little like dreaming because I assume it requires stopping the Amazon and similar burnoffs. On the other hand, even if it does not work out exactly right, it still has benefits. Stopping flooding and erosion while having a more pleasant environment and better farming practices might not save the planet, but it might make your local bit of planet better to live in.

What are We Doing about Melting Ice? Nothing!

Over my more active years I often returned home from the UK with a flight to Los Angeles, and the flight inevitably flew over Greenland. For somewhat selfish reasons I tried to time my work visits in the northern summer, thus getting out of my winter, and the return flight left Heathrow in the middle of the day so with any luck there was good sunshine over Greenland. My navigation was such that I always managed to be at a window somewhere at the critical time, and I was convinced that by my last flight, Greenland was both dirtier and the ice was retreating. Dirt was from dust, not naughty Greenlanders, and it was turning the ice slightly browner, which made the ice less reflective, and thus would encourage melting. I was convinced I was seeing global warming in action during my last flight, which was about 2003.

As reported in “The Economist”, according to an analysis of 40 years of satellite data at Ohio State University, I was probably right. In the 1980s and 1990s, during Greenland summers it lost approximately 400 billion tonnes of ice each summer, by ice melting and by large glaciers shedding lumps of ice as icebergs into the sea. This was not critical at the time because it was more or less replenished by winter snowfalls, but by 2000 the ice was no longer being replenished and each year there was a loss approaching 100 billion t/a. By now the accumulated net ice loss is so great it has caused a noticeable change in the gravitational field over the island. Further, it is claimed that Greenland has hit the point of no return. Even if we stopped emitting all greenhouse gases now, it was claimed, more ice would be progressively lost than could be replaced.

So far the ice loss is raising the oceans by about a millimetre a year so, you may say, who cares? The problem is the end position is the sea will rise 7 metres. Oops. There is worse. Apparently greenhouse gases cause more effects at high latitudes, and there is a lot more ice on land at the Antarctic. If Antarctica went, Beijing would be under water. If only Greenland goes, most of New York would be under water, and just about all port cities would be in trouble. We lose cities, but more importantly we lose prime agricultural land at a time our population is expanding

So, what can be done? The obvious answer is, be prepared to move where we live. That would involve making huge amounts of concrete and steel, which would make huge amounts of carbon dioxide, which would make the overall problem worse. We could compensate for the loss of agricultural land, which is the most productive we have, by going to aquaculture but while some marine algae are the fastest growing plants on Earth, our bodies are not designed to digest them. We could farm animal life such as prawns and certain fish, and these would help, but whether productivity would be sufficient is another matter.

The next option is geoengineering, but we don’t know how to do it, and what the effects will be, and we are seemingly not trying to find out. We could slow the rate of ice melting, but how? If you answer, with some form of space shade, the problem is that orbital mechanics do not work in your favour. You could shade it some of the time, but so what? Slightly more promising might be to generate clouds in the summer, which would reflect more sunlight.

The next obvious answer (OK, obvious may not be the best word) is to cause more snow to fall in winter. Again, the question is, how? Generating clouds and seeding them in the winter might work, but again, how, and at what cost? The end result of all this is that we really don’t have many options. All the efforts at limiting emissions simply won’t work now, if the scientists at Ohio State are correct. Everyone has heard of tipping points. According to them, we passed one and did not notice until too late. Would anything work? Maybe, maybe not, but we won’t know unless we try, and wringing our hands and making trivial cuts to emissions is not the answer.

Geoengineering: Shade the World

As you may have noticed when not concerned about a certain virus, global warming has not gone away. The virus did some good. I live on a hill and can look down on some roads, and during our lock-down the roads were strangely empty. Some people seemed to think we had found the answer to global warming, as much less petrol was bing burnt, but the fact is, even if nobody drove we were still producing net amounts of CO2 and other greenhouse gases, and even if we were not doing that, the amounts currently in the air are still out of equilibrium and would continue to melt ice and lead to high temperatures. In the northern hemisphere now you have a summer so maybe you notice.

So, what can we do? One proposal is to shade the Earth’s surface. The idea is that if you can reflect more incoming solar radiation back to space there is less energy on the surface and . . .  Yes, it is the ‘and’ wherein lies the difficulties. We get less radiation striking the surface, so we cool the surface, but then what? According to one paper recently published in Geophysical Research Letters (https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087348 ) the answer is not good news. They have produced simulations of models, and focus on what are called storm tracks, which are relatively narrow zones in oceans where storms such as tropical cyclones and mid-latitude cyclones travel through prevailing winds. Such geoengineering, according to the models, would weaken these storms. Exactly why this is bad eludes me. I would have thought lower energy storms would be good; why do we want hundreds of thousands of citizens have their properties leveled by hurricanes, typhoons, or simply tropical cyclones as they are known in the Southern Hemisphere? This weakening happens through a smaller pole to equator temperature difference because most of the light reflected is over the tropics. Storms are heat engines at work, and the greater the temperature difference, the more force can be generated. The second law of thermodynamics at work. Fine. We are cooling the surface, and while it may seem that we are ignoring the ice melting of the polar regions, we are not because most of the heat comes from ocean currents, and they are heated by the tropics.

More examples: we would reduce wind extremes in midlatitudes, possibly lead to less efficient ventilation of air pollution, may possibly decrease low cloud cover the storm‐track regions and weaken poleward energy transport. In short, a reasonable amount of that is what we want to do anyway. It is also claimed we would get increased heat waves. I find that suspicious, given that less heat is available. It is claimed that such activities would alter the climate. Yes, but that is what we would be trying to do, namely alter it from what it might have been. It is also claimed that the models show there could possibly  be regional reductions in rainfall. Perhaps, but that sort of thing is happening anyway. Australia had dreadful bushfires this year. I gather forest fires were going well in North America also.

One aspect of this type of study that bothers me is it is all based on models. The words like ‘may’, ‘could’ and ‘possibly’ turn up frequently. That, to me, indicates the modelers don’t actually have a lot of confidence in their models. The second thing that bothers me is they have not looked at nature. Consider the data from Travis et al.(2002) Nature 418, 601.  For the three days 11-14 Sept. 2001 the average diurnal temperature ranges averaged from 4000 weather stations across the US increased on average 1.1 degrees C above the average from 1971 – 2000, with the highest temperatures on the 14th. They were on average 1.8 degrees C greater than the average for the two adjacent three-day periods. The three days with the increase were, of course, the days when all US aircraft were grounded and there were no jet contrails. Notice that this is the difference between day and night; at night the contrails retain heat better, while in daytime they reflect sunlight.  Unfortunately, what was not stated in the paper was what the temperatures were. One argument is that models show while the contrails reflect more light during the day, they keep in more heat during the night. Instead of calculations, why not show the actual data?

The second piece of information is that the eruption of Mount Pinatubo sent aerosols into the atmosphere and for about a year the average global temperature dropped 1 degree C. Most of that ash was at low latitudes in the northern hemisphere. There are weather reports from this period so that should give clues as to what would happen if we tried this geoengineering. This overall cooling was real and the world economies did not come to an end. The data from that could contribute to addressing the unkn owns.

So, what is the answer? In my opinion, the only real answer is to try it out for a short period and see what happens. Once the outcomes are evaluated we can then decide what to do. The advantage of sending dust into the stratosphere is it does not stay there. If it does not turn out well, it will not be worse than what volcanoes do anyway. The disadvantage is to be effective we have to keep doing it. Maybe from various points of view it is a bad idea, but let us make up our minds from evaluating proper information and not rely on models that are no better than the assumptions used. Which choice we make should be based on data, not on emotion.

What to do with Waste Plastics

One of the great environmental problems of our time is waste plastics, and there are apparently huge volumes floating around in the oceans of the world. These would generally get there by people throwing them away, so in principle this problem is solved if we can stop that irresponsible attitude. I can already hear the, “Good luck with that,” response. Serious fines for offenders would help, as would more frequent proper rubbish disposal bins. But this raises the question, what should we do with waste plastics?

The first answer is it is unlikely there is a single answer because there are such a variety of plastics. Some, like polyester or polyethylene, can be reasonably easily recycled for low specification uses, but the problem here is there is a limit to how many plastic buckets, etc, can be sold. Technically, quite a high level of recycling can be achieved. Quite a while ago, during the first oil crisis, a client asked me to devise a means of recycling mixed coloured polyethylene so I devised a process that recovered a powder that could be used to make almost anything that virgin polyethylene could make, except maybe clear: there was always a slight beige colour from residual dyes etc that could not be got out, at least in a one-cycle process. Polyethylene degrades – you will all have seen it go brittle from sunlight. This shortens the chains and oxidizes parts and I was proud of this process because it got rid of all the degradation and short-chain material.

A pilot plant was built, then the process was abandoned.  The reason was the oil prices tumbled, and there was no way the process could make money, particularly since big multinationals appeared to be dumping polyethylene into New Zealand. Some manufacturers loved this, and were able to export all sorts of plastic things, at least for a while. Part of the reason the process would have lost money, of course, was that despite getting the raw material rather cheaply, the yield at the end was lower because of the loss of the degradation products, but the killer was getting rid of the degradation products. They could be burnt for process heat, but that would need a specially designed burner, and there would still be the pigment remains to be disposed of. Good idea, but could not compete with the oil industry.

Another possible process is pyrolysis. This came to my attention when I recently saw a paper in the latest copy of “Energy and Fuels” put out by the American Chemical Society. Polyethylene gives a mix of oil, gas and carbonaceous solid, but you can get almost 80% in the form of oil that could be directly used as a diesel fuel after distillation. There appear to be a fraction that boils too high for the diesel range, and gets waxy, but those who have recalled a recent post by me will see that it would do well in the heavier marine heavy fuel oil. The resultant oil has a mix of linear alkanes and terminal alkenes, and the fragmentation is such that the double bond prefers the smaller fragment. There is also some miscellaneous stuff resulting from the oxidative degradation. Polypropylene, however, showed a lot more oxygen, with a range of alcohols, esters and also acids in addition to highly branched hydrocarbons, however, almost 20% was the single compound 2,4-dimethyl-1-heptene. It would manage with the light ends as petrol, and the heavier ends contributing to diesel. 

Polystyrene gave what corresponds more to a heavy oil, although 40% was actually styrene, which could be used to make more polystyrene. Importantly, the cetane rating for the oil from polyethylene was 73; for polypropylene, 61. Polystyrene oil was unsuitable for diesel, but if hydrogenated, the lower boiling cut would make a high octane petrol. The average pump diesel fuel has a cetane rating of about 50, and the higher the rating, the faster the engines can go, so pyrolysis of waste polyethylene and waste polypropylene will make an excellent diesel fuel, with the heavy ends going towards shipping.  However, the heavy ends of polystyrene would have to be dumped because they contain fluorinated material, presumably a consequence of additives, and you certainly do not want an exhaust stream rich in hydrogen fluoride. And here is the curse that plagues anything involving recycling: too many companies put in additives that will be impossible to remove, and which either prevent proper recycling or will have consequences that are at best highly unpleasant, while they offer no option for dealing with them.

How do we separate these plastics out? Fragment them, and stir in water. Polyethylene and polypropylene are the two plastics that float. Foam, of course, has to be omitted. So, will this end up being done? My guess is, not in the immediate future. In terms of economics, it cannot beat the entrenched oil industry, unless governments decide that cleaning up the environment is worth the effort.

Climate Change and International Transport

You probably feel that in terms of pollution and transport, shipping is one of the good guys. Think again. According to the Economist (March 11, 2017) the emissions of nitrogen and sulphur oxides from 15 of the world’s largest ships match those from all the cars on the planet. If the shipping industry were a country, it would rank as the sixth largest carbon dioxide emitter. Apparently 90%  of trade is seaborne, and in 2018, 90,000 ships burn two billion barrels of the dirtiest fuel oil, and contribute 2 – 3% of the world’s total greenhouse emissions. And shipping is excluded from the Paris agreement on climate change. (Exactly how they wangled that is unclear.) The International Maritime Organization wants to cut emissions by 50% by 2050, but prior to COVID-19, economic growth led to predictions of a six-fold increase by then!

Part of the problem is the fuel: heavy bunker oil, which is what is left over after refining takes everything else it can use. Apparently it contains 3,500 times as much sulphur as diesel fuel does. Currently, the sale of these high sulphur fuels has been banned, and sulphur content must be reduced to 0.5% (down from 3.5%) and some ships have been fitted with expensive scrubbers to remove pollutants. That may seem great until you realize 80% of these scrubbers simply dump the scrubbed material, a carcinogenic mix of various pollutants, into the sea. They also increase fuel consumption by about 2%, thus increasing carbon dioxide missions.

On the 19th February, 2020, the Royal Society put out a document advocating ammonia as a zero-carbon fuel, and suggested that the maritime industry could be an early adopter. What do you think of that?

First, ammonia is currently made by compressing nitrogen and hydrogen at higher temperatures over a catalyst (The Haber process). The compression requires electricity, and the hydrogen is made by steam reforming natural gas, which is not carbon free, however it could be made by electrolysing water, which would be a use for “green” electricity”. The making of hydrogen this way may well be sound, but running the Haber process probably is not. The problem with this process is it really has to be carried out continuously, and solar energy is not available at night, and the wind does not always blow. However, leaving that aside, that part of the scheme is plausible. Ammonia can be burnt in a motor, or more efficiently in a fuel cell to make electricity. If you could make this work there are some ships that use diesel to make electricity to power motors, so that might work. Ammonia has an energy content of 3 kWh/litre (liquid hydrogen is 2/3 this) while heavy fuel oil has an energy content of 10 kWh/l. The energy efficiency of converting combustion energy to work is much higher in a fuel cell.

Of course by now you will have all worked out why this concept is a non-starter. The problem is the ship, its fuel tanks and motors, are part of the construction and are deep within the ship. The cost of conversion would be horrendous so it is most unlikely to happen. Equally, if we were serious about climate change, we could convert ships to use nuclear power. Various navies around the world have shown how this can be done safely. Don’t hold your breath waiting for the environmentalists to endorse that idea.

However, converting to nuclear power has the same problem as converting to ammonia: a huge part of the ship has to be demolished and rebuilt, so that is a non-starter. So there is no way out? Not necessarily.  I have currently been spending my lockdown writing a chapter for a book in a series on hydrothermal treatment of algae. Now the interesting thing about the resultant biocrude is that while you can make very high octane petrol and high cetane diesel, there is a residue of heavy viscous fluid that can be mainly free of sulphur and nitrogen. What on earth could you do with that? It is a thick viscous oil, surprisingly like heavy bunker oil. Any guesses as to what I might be tempted to recommend?

Aircraft and Carbon Dioxide Emissions

Climate change requires significant changes to our lifestyle, and one of the more tricky problems to solve is air travel. Interestingly, you will find many environmentalists always telling everyone to cycle, but then spend tens of thousands of air miles going to environmental conferences. So, what can we do?

One solution is to reduce air travel. And there is no need in principle to adopt Greta Thunberg’s solution of sailing over the Atlantic. With a bit of investment, high speed rail can get you between the centres of reasonably close cities faster than aircraft, when you include the time taken to get to and from airports, and time wasted at airports. We can also reduce travel, but only so far. At first sight, things like conferences can be held online, but there are two difficulties: time-zone differences encourage doing something else, and second, the major benefit from conferences is not listening to set talks, but rather meeting people outside the formal program. For business, facing each other is a far improved way of negotiating because the real signals are unspoken. 

Some airlines are trying to improve their environmental credentials by planting trees to compensate for the carbon dioxide they emit. That is very noble of them, but apart from the fact it is their money doing it (and often it is not – it is the passengers who feel conscious stricken to donate more money for planting) it is something that should be done anyway. 

There has been talk of building electric aircraft. My personal opinion is this is not the solution. The problem is in terms of unit weight, jet fuel contains at least thirty times the energy density of the best batteries available. Even worse, for jet fuel, as you go further, you get lighter, but not with batteries. You could make a large aircraft fly, say, 1,000 to 2,000 km, as long as you did not want to carry much in the way of passengers or cargo. With thirty times the fuel weight for a long distance flight your aircraft would never get off the ground. However, the Israeli firm Eviation has developed a small electric aircraft for a load of 9 persons (plus two crew) powered by 920 kWh batteries with operating costs estimated at $200/hr. The range is about 540 nautical miles, or about 1,000 km. That could work for small regional flights, and it will be available soon.

Another option to be offered by Airbus is the E-Fan-X project. They will take a BAe 146 craft, which usually carries about 100 passengers, and which usually is powered by four Honeywell turbofan engines, and replace one of the inner ones with an electric-driven 2 MW propulsion fan motor. The idea is the takeoff, where the most power is required will use the normal jets, but the electric motor can manage the cruise. 

An alternative is to reduce fuel consumption. One possibility is the so-called blended wing, which is being looked at by NASA. This works; an example is the B2 bomber, however while it reduces fuel consumption by 20% it is most unlikely to come into commercial use any time soon. One reason is that there is probably no commercial airport that could accommodate the radically different design. It would also have to have extensive examination because so far the design has only had military applications, in which only very specific loads are involved. In principle, this, and other designs can reduce kerosene usage, but only by so much. Maybe overall, 25% is achievable, which does not solve anything.

Uranium 235 has an energy density that leaves kerosene for cold, but which airport wants it, and would you board it anyway? It could presumably be made to work, but I can’t see it happening anytime soon because nobody will take the associated political risk.

That leaves hydrogen. 1 kg of liquid hydrogen can provide the same energy as 3 kg of kerosene, so weight is not the problem, but keeping it cold enough and maintaining pressure will add weight. It cannot be stored in the aircraft wings because of the volatility. To keep it cold it is desirable to have minimum surface area of the tank. However, it is reasonably clean burning, giving only water and some nitrogen oxides. For a Boeing 747-400 aircraft, the full fuel load is 90 tonne less, but because the tanks have to be in the fuselage, they occupy about 30% of the passenger space.

That may work for the future, but the only real way to power current aircraft is to burn hydrocarbon fuel. More on that next week.