IPCC Conclusion: We Are Cooked!

Recall the saying, “There are lies, damned lies, and statistics”. I would add a further term at the end – ” There are lies, damned lies, statistics, and models.” What sparked this bout of negativity? Well, last week I went to a talk from one of the NZ representative of the International Panel on Climate Change. The talk was headed, “Where are we, and how do we get out of this?” The entire talk was devoted to where we are, and it was fairly grim, and the second part, how do we get out of this, was blank. Maybe there is no way out. Anyway, let me try to recall what was said. If there are errors here from the IPCC, assume they are due to my faulty memory.

The first thing to note is the goal back in the 1990s was to limit greenhouse emissions so as to keep the increase in temperature to 1.5 degrees C above pre-industrial levels. One could question that as a goal because pre-industrial was the so-called “Little Ice Age”, and arguably that is not a good reference point. Be that as it may, the governments of the world agreed to work on limiting emissions. First there was the Rio agreement in 1992, then the Paris agreement, which is supposedly legally binding on 196 parties, and the aim was to “pursue efforts” to limit the temperature raise to 1.5 degrees.

So how are we doing? It is one of the less successful agreements, in my view. The object was to limit and reduce emissions of CO2; what has actually happened is we have doubled the rate of emissions, and much of that since the “legally binding 2016 agreement”. The original target was not to hit the 1.5 degree rise before the end of the century. If we extrapolate current trends, we strike it in this decade. Oops!

So what are the effects? Currently, the odd good thing, but mainly the outcomes are bad to awful. What is somewhat unexpected is the effects differ by hemisphere, possibly because the Southern Hemisphere has most of the ocean, and ocean has an albedo about a third of that of land, so it absorbs so much more heat. The greatest increase in local temperature has come from that Arctic; it is heating rapidly. Funnily enough, the Antarctic is not following, and there are even spots where it is cooling. The heating of the Arctic does little for sea level rise because the ice was always floating, but the Greenland Ice Sheet is shedding water at a rate of 270 billion t/a, which contributes to the rising sea levels. Antarctica is losing ice at a rate of about 150 billion t/a, mainly due to warmer water undercutting the ice and melting from below. The end position is unclear; climate models suggest the two large Antarctic ice sheets should collapse, but there are some claims that the ice sheets are growing. Recall my comment on models?

The  other problem is weather. The winds are part of a gigantic heat engine, and the winds strengthen as the temperature difference increases. Accordingly, the rapid heating of the Arctic will moderate the temperature difference in the Northern hemisphere. Although that is not a free pass because hurricanes and typhoons are generated by seawater evaporating, so they will get stronger as the planet heats. The other problem for the Northern hemisphere is quieter wind systems lead to longer and more severe droughts. For the Southern Hemisphere, as we are  finding out, the wind systems become stronger and we have “atmospheric rivers” pouring large amounts of water from the tropics over us. But one interesting fact is that precipitation seems to be increasing over Antarctica. That may save us somewhat from being too inundated by sea-level rise.

So where does this leave us? Well, the IPCC has modelled a huge number of possible futures, but my feeling is, almost all of them will not happen. We know the situation is getting bad, but what is being done to fix things? Not a lot. And it is not that good plans are not being implemented. If this talk was indicative, we have NO GOOD PLANS. Does that mean we cannot do anything? No it does not. But as General Wesley Clark said there are two sorts of plans: those that won’t work and those that might work. You have to take one that might work and make it work, And herein lies some problems. We don’t know for sure what will work, although some seem highly probable, but we also have no mechanism to make them work. Recall what I said about the rate of emissions doubling when everyone was supposed to be reducing them? We have governments carrying out emissions trading schemes, as if that would solve the problem, but it is just raising costs; the rate of emissions is increasing. There might be a legally binding treaty, but if everyone is violating it, what good is that? There is no method to get governments to impose plans that might work, and politicians, usually, could not tell whether a plan could work, although they may well predict, correctly, if left to them it would not work. This is a highly technical problem that has to be understood to solve it. Politicians simply do not have the technical background.

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Cows and Climate Change

There is no doubt the climate is changing. When I as a child, tornados happened in Kansas. Now they happen here with some sort of regularity, and we have had a sequence of ex-tropical cyclones and cyclones over summer. Things have to be done, but they have to be constructive. One problem is the issue can only be understood in terms of science and the level of scientific understanding with decision makers is abysmal. It is like asking the blind to sort out dangerous chemicals by reading the labels. Consider the issues of cows. Cows burp methane. Methane is a greenhouse gas. Therefore we need to eliminate cows. Pass the oatmilk.

A recent paper in Nature Geoscience (R. J. Allen, https://doi.org/10.1038/s41561-023-01144-z, 2023) appears to throw proverbial spanners in works relating to methane. Data suggests that since pre-industrial times, methane levels have risen from approximately 0,75 ppm to 1.8 ppm. I am sceptical of the first figure; how did they measure it then, and more interestingly, why did they measure it then? I dislike calculated figures because the calculations tend to be loaded with the bias of whoever does the calculations. If an assumption is required, it becomes a loaded one. However, if we accept those figures, models tell us this leads to an effective radiation forcing of just under half a watt per square meter. Thus methane is a serious problem, at least according to a disparate bunch that includes vegans, those who accuse dairy milk of causing cancer, and a group who protest just about everything. The problem is that ruminants, including cows, emit methane, so the argument goes that banning cows would go a long way to solving the problem.

However, methane has a relatively short lifetime in our atmosphere (about a decade), when it undergoes a sequence of oxidative changes that eventually lead to carbon dioxide and since all the carbon came from plant material, and hence the atmosphere, it is not clear to me that banning dairying would make much difference. The vegans probably also ignore the fact that more methane appears to come from rice paddies. I am not suggesting that we do nothing about the methane. Anything that reduces a greenhouse gas is useful.

However, the point of this paper is that methane is not as bad as current models suggest. Models that only focus on the longer wavelength greenhouse effects overestimate the effect of methane by about 30%. This is because methane absorbs short wavelength UV in the upper atmosphere, and causes photochemistry to make compounds that absorb further longer wave-length electromagnetic radiation. This cools the surface because the high energy photons convert their energy to heat when they reach the surface of the  planet. There is less heat if they don’t get there.

An even larger effect (approximately 60% offset) arises if we include enhanced cooling due to cloud rapid adjustments. We get increased lower altitude clouds, which enhance the reflection of short wavelength light, and we get decreased high level clouds, which enhances outgoing longer wavelength radiation. This does not mean methane is good; it remains a greenhouse gas, but what it means is that everything is far more complicated than most models accept. Also, it cannot hurt to reduce emissions. However, equally, the extremes promoted by the extreme protestors are simply not valid.

A second proposal (Schmitz et al.  Nature Climate Change https://doi.org/10.1038/s41558-023-01631-6 2023) may seem a little odd. The objective is to enhance carbon capture  and storage in plants, soils and sediments. They do this by protecting and restoring wild animals, and restoring their ecosystem. The argument is such an ecosystem contains more carbon than farmland, or worse, wasteland, or in one case, waste space. The way this works is that a diversity of animal species with medium to large bodies assist seed dispersal and germination of large-seeded trees with carbon-dense wood, herbivory that reduces  plant competition and increases soil nutrient supply and enhances soil carbon storage. In terms of increases of CO2 reduction, in Mt/year, wildebeests on the savannah will provide 4.4, the musk ox 30, the grey wolf 260, and the champions, fish, 5,500. By simply protecting species currently there we can secrete 5.8 Gt of CO2 / annum. By restoring species we can go further, again in Mt/a, the African elephant, 13, bison 595, and the total comes to 6.4 Gt/a. (If you notice the numbers don’t quite add up, that is because I left out minor contributions.) Now surely pastoral cows also increase soil nutrient supply and enhance soil carbon storage. It also shows it is necessary to consider the whole system, and not cherry pick the facts that strengthen your case.

None of this suggests that we do not have a problem with greenhouse gas emissions. What it does suggest is there may be a multitude of ways to solve the problem, and contributions can come from a variety of sources.

Climate Change: A Space Solution”?

By now, many around the world will have realized we are experiencing climate change, thanks to our predilection for burning fossil fuels. The politicians have made their usual platitudinous statements that this problem will be solved, say twenty years out. It is now thirty years since these statements started being made, and we find ourselves worse off than when the politicians started. Their basic idea seems to be that the crisis gets unmanageable in, say, sixty years, so we can leave it for now. What actually happens is, er, nothing in the immediate future. It can be left for politicians thirty years out from now. Then, when the thirty years has passed it is suddenly discovered that it is all a little harder than expected, but they can introduce things like carbon trading, which employs people like themselves, and they can exhort people to buy electric cars. (If you live somewhere like Calgary and want to go skiing at Banff, it appears you need to prepare your car four hours before using it, or maintain battery warmers because the batteries do not like the cold one bit.)

Bromley et al. in PLOS Climate (https://doi.org/10.1371/journal.pclm.0000133) have a solution. To overcome the forcing of the greenhouse gases currently in the atmosphere, according to this article all you have to do is to reduce the solar input by 1.8%. What could be simpler? This might be easier than increasing the albedo.

The question then is, how to do this? The proposed answer is to take fine fluffy dust from the Moon and propel it to the Earth-Sun L1 position. This will provide several days of shading, while the solar winds and radiation slowly clear this dust away. How much such dust? About ten billion kg, which is about a thousand times more mass than humans have currently ever sent into space. Over a ten year period, this corresponds to a sphere of radius roughly 200 m, which corresponds to the annual excavation from many open pit mines on Earth. The advantage of using the Moon, of course is that the gravitational force is about 17% that of Earth so you need much less energy to eject the dust. The difficulty is that you have to put sufficient equipment on the Moon’s surface to gather and eject the dust. One difficulty I see here is that while there is plenty of dust on the Moon, it is not in a particularly deep layer, which mean the equipment has to keep moving. Larger fluffy particles are apparently preferred, but fluffy particles would probably be formed in a fluid eruption, and as far as we know, that is less likely on the Moon.

Then there are problems. The most obvious one, apart from the cost of the whole exercise, is the need for accuracy. If the dust is outside the lines from the edges of the Sun-Earth, then the scattering can increase the solar radiation to Earth. Oops. The there is another problem. Unlike L4 and L5, which are regions, L1 really is a point where an object will corotate. If a particle is even 1 km off the point, it could drift away by up to 1000 km in a year, and if it does that, perforce it will drift out of the Sun-Earth line, in which case the dust will be enhancing the illumination of Earth. Again, oops. Added to this are a small number of further effects, the most obvious being solar wind and radiation pressure which will push objects away from L1.

The proposed approach is to launch dust at 4.7 km/s towards L1, and do it from the Moon when the Moon is close to being in line, so that the dust, as it streams towards L1 continues to provide shielding while it is in-flight. The launching would require 10^17 J, which is roughly the energy generated by a few square km of solar panels. One of the claimed advantages of this is that the dust could be sent in pulses, timed to cool places with major heat problems. It is probably unsurprising that bigger particles are less efficient at shading sunlight, at least on a per mass scale, simply because there is mass behind the front surface doing nothing. Particles too small neither last very long in the required position, nor do they offer as much shielding. As it happens, somewhat fortuitously, the best size is 0.2 μm, and that happens to be the average size of lunar regolith dust.

One of the advantages claimed for this method is that once a week or so is over, there are no long-term consequences from that dust. One of the disadvantages is that which goes for any planetary engineering proposal: What is the minimum agreement required from the world population, how do you get it, and what happens if someone does it anyway? Would you vote for it?

A Solution to the Elements Shortage for Lithium Ion Batteries?

Global warming together with a possible energy crisis gives us problems for transport. One of the alleged solutions is battery powered cars. This gives three potential problems. One of these is how to generate sufficient electricity to power the batteries, but I shall leave that for the moment. The other two relate to chemistry. A battery (or fuel cell) has two basic electrodes: a cathode, which is positive, and an anode, which is negative. The difference in potential between these is the voltage, and is usually taken as the voltage at half discharge. The potential is caused by the ability to supply electrons to the anode while taking them at the cathode. At each there is a chemical oxidation/reduction reaction going on. The anode is most easily answered by oxidising a metal. Thus if we oxidise lithium we get Li  ➝ Li+  + e-. The electron disappears off to the circuit. We need something to accept an electron at the cathode, and that is Co+++, which gets reduced to the more stable Co++.  (Everything is a bit more complicated – I am just trying to highlight the problem.) Now superficially the cobalt could be replaced by a variety of elements, but the problem is the cobalt is embedded in a matrix. Most other ions have a substantial volume change of the ions, and if they are embedded in some cathode matrix, the stresses lead it to fall to bits. Cobalt seems to give the least stress, hence will give the batteries a longer life. So we have a problem of sorts: not enough easily accessible lithium, and not enough cobalt. There are also problems that can reduce the voltage or current, including side reactions and polarization.

In a fuel cell we can partly get over that. We need something at the cathode that will convert an input gas into an anion by accepting an electron, thus oxygen and water forms hydroxide. At the anode we need something that “burns”, i.e. goes to a higher valence state and gives up an electron. In my ebook “Red Gold”, a science friction story relating to the first attempt at permanent settlement of Mars, a portable power source was necessary. With no hidden oil fields on Mars, and no oxygen in the air to burn it if there were, I resorted to the fuel cell. The fuel cell chemistry I chose for Mars was to oxidize aluminium, which generates three electrons, and to reduce chlorine. The reason for these was that the settlement on Mars needed to make things from Martian resources, and the most available resource was the regolith, which is powdered rock. This was torn apart by nuclear fusion power, and the elements separated by magnetohydrodynamics, similar to what happens in a mass spectrometer. The net result is you get piles of elements. I chose aluminium because it has three electrons and hence more power capacity, and I chose chlorine because it is a liquid at Martian temperatures so no pressure vessel was required. Also, while oxygen might produce a slightly higher voltage, oxygen forms a protective coating on aluminium, and that stops that reaction.

An aluminium battery would have aluminium at the anode, and might have something in the electrolyte that could deposit more aluminium on it. Thus during a charge, you might get, if chlorine is the oxidiser,

4(Al₂Cl₇)-   + 3e-  → Al  +  7(AlCl₄)-   

which deposits aluminium on the anode. During discharge the opposite happens and you burn aluminium off. Notice here the chlorine is actually tied up in chemical complexes and the battery has no free chlorine. Here, the electrolyte is aluminium chloride (Al₂Cl₆). For the fuel cell, we would be converting the gas to a complex at the cathode. That is not very practical on Earth, but the enclosed battery would be fine.

The main advantage of aluminium is that it gets rid of the supply problem. Aluminium is extremely common on Earth, as the continents are essentially made of aluminosilicates. The cathode can be simple carbon. A battery with this technology was proposed in 2015 (Nature 520: 325 – 328) that used graphite cathodes. It was claimed to manage 7,500 cycles without capacity decay, which looks good, but so far nobody seems to be taking this up.

Now, for an oddity. For discharge, we need to supply (AlCl₄)- to the anode as it effectively supplies chlorine. Rather than have complicated chemistry at the cathode we can have an excess of AlCl₄– from the start, and during charging, store it in the cathode structure. During discharge it is released. So now we need something to store it in. The graphite used for lithium-ion batteries comes to mind, but here is an oddity: you get twice the specific capacity, twice the cell efficiency and a 25% increase in voltage by using human hair! Next time you go to the hair dresser, note that in the long term that might be valuable. Of course, before we get too excited, we still need such batteries to be constructed and tested because so far we have no idea how such hair stands up to repeated cycles.

What we do not know about such batteries is how much dead weight has to be carried around and how small they can be made for a given charge. The point about cars is that eventually the critical point is how far will it go on one charge, how long does it take to safely recharge, how much volume of the vehicle does it take, and is it flammable? The advantage of the aluminium chloride system described above is that there are probably no side reactions, and a fire is somewhat unlikely. The materials are cheap. So, the question is, why hasn’t more been done on this system? My guess is that the current manufacturers know that lithium is working, so why change? The fact that eventually they will have to does not bother them. The accountants in charge think beyond the next quarter is long-term. Next year can look after itself. Except we know that when the problem strikes, it takes years to solve it. We should get prepared, but our economic system does  not encourage that.

This and That from the Scientific World

One of the consequences of writing blogs like this is that one tends to be on the lookout for things to write about. This ends up with a collection of curiosities, some of which can be used, some of which eventually get thrown away, and a few I don’t know what to do about. They tend to be too short to write a blog post, but too interesting, at least to me, to ignore. So here is a “Miscellaneous” post.

COP 27.

They agreed that some will pay the poorer nations for damage so far, although we have yet to see the money. There was NO promise by anyone to reduce emissions, and from my point of view, even worse o promise to investigate which technologies are worth going after. Finally, while at the conference there were a number of electric buses offering free rides, at the end of the conference these buses simply disappeared. Usual service (or lack thereof) resumed.

Fighting!

You may think that humans alone fight by throwing things at each other but you would be wrong. A film has been recorded ( https://doi.org/10.1038/d41586-022-03592-w) of two gloomy octopuses throwing things at each other, including clam shells. Octopuses are generally solitary animals, but in Jervis Bay, Australia, the gloomy octopus lives at very high densities, and it appears they irritate each other. When an object was thrown at another one, the throw was far stronger than when just clearing stuff out of the way and it tended to come from specific tentacles, the throwing ones. Further, octopuses on the receiving end ducked! A particularly interesting tactic was to throw silt over the other octopus. I have no idea what the outcome of these encounters were.

Exoplanets

The star HD 23472 has a mass of about 0.67 times that of our sun, and has a surface temperature of about 4,800 degrees K. Accordingly, it is a mid-range K type star, and it has at least five planets. Some of the properties of these include the semi-major axis a (distance from the star if the orbit is circular), the eccentricity e, the mass relative to Earth (M), the density ρ  and the inclination i. The following table gives some of the figures, taken from the NASA exoplanet archive.

Planet     a              e            M        ρ           i

b           0.116      0.07       8.32      6.15      88.9

c           0.165      0.06       3.41      3.10      89.1

d           0.043      0.07       0.55      7.50      88.0

e           0.068      0.07       0.72      7.50      88.6

f           0.091      0.07       0.77       3.0        88.1

The question then is, what to make of all that? The first thing to notice is all the planets are much closer to the star than Earth is to the sun. Is that significant? Maybe not, because another awkward point is that the inclinations are all approaching 90 degrees. The inclination is the angle the orbital plane of the planet makes with the equatorial plane of the star. Now planets usually lie on the equatorial plane because that was also the plane of the accretion disk, so something has either moved the planets, or moved the star. Moving the planets is most probable, and the reason the inclinations are all very similar is because they are close together, and they will probably be in some gravitational resonance with each other. What we see are two super Earths (b and c), two small planets closest to the star, which are small, but very dense. Technically, they are denser than Mercury in our system. There are also two planets (c and f) with densities a little lower than that of Mars.

The innermost part of the habitable zone of that star is calculated to be at 0.364 AU, the Earth-equivalent (where it gets the same radiation as Earth) at 0.5 AU, and the outer boundary of the habitable zone is at 0.767 AU. All of these planets lie well inside the habitable zone. The authors who characterised these planets (Barros, S. C. C. et al. Astron. Astrophys. 665, A154 (2022).) considered the two inner planets to be Mercury equivalents, presumably based on their densities, which approximate to pure iron. My guess is the densities are over-estimated, as the scope for error is fairly large, but they certainly look like Mercury equivalents that are somewhat bigger than our Mercury

Laughing Gas on Exoplanets

One of the targets of the search for exoplanets is to try and find planets that might carry life. The question is, how can you tell? At present, all we can do is to examine the spectra of atmospheres around the planet, and this is not without its difficulties. The most obvious problem is signal intensity. What we look for is specific signals in the infrared spectrum and these will arise from the vibrations of molecules. This can be done from absorptions if the planet transits across the star’s face or better (because the stellar intensity is less a problem) from starlight that passes through the planet’s atmosphere.

The next problem is to decide on what could signify life. Something like carbon dioxide or methane will be at best ambiguous. Carbon dioxide makes up a huge atmosphere on Venus, but we do not expect life there. Methane comes from anaerobic digestion (life) or geological activity (no life). So, the proposal is to look for laughing gas, better known as nitrous oxide. Nitrous oxide is made by some life forms, and oddly enough, it is a greenhouse gas that is becoming more of a problem from the overuse of agricultural fertilizer, as it is a decomposition product of ammonium nitrate. If nothing else, we might find planets with civilizations fighting climate change!

COP 27 – the 27th Cop-out??

Currently, a number of parties have descended on Sharm el-Sheikh for COP 27. This is the 27^th “Conference of the Parties” to deal with climate change. Everybody, by now, should be aware that a major contributor to climate change is the increased levels of carbon dioxide in the atmosphere, and we have to reduce emissions. In the previous 26 conferences various pledges were made to reduce such emissions, but what has happened? According to Nature, CO2 emissions are set to reach a record high of 37.5 billion tonne in 2022. So much for a controlled reduction of emissions. In my opinion, the biggest effect from such conferences is the increased emissions due to getting all the participants to them. In this context there are apparently over 600 fossil fuel lobbyists at this conference. So the question then is, why has so little been achieved?

My answer is the politicians took the easy way out: to be seen to be doing something they implemented a carbon trading scheme. This allows money to flow, and the idea was that economics will make people transition to non-fossil-based energy by raising the price of the fossil fuels. To make this look less like a tax, they then allowed the trade of credits, and politicians issued credits to “deserving causes”. There were two reasons why this had to fail: the politicians had the ability to sabotage it by issuing credits to those it favoured, and secondly, there are no alternatives that everyone can switch to. Therein lies the first problem. Price does not alter activity much unless there is an alternative, and in most cases there is no easy alternative.

The second one is that even if you can develop alternatives, there is far too much installed capacity. The economies of just about every country are highly dependent on using fossil fuel. People are not going to discard their present vehicles and join a queue to purchase an electric one. They are still selling new petroleum-powered vehicles, and a lot of energy has been invested in making them. Like it or not, the electricity supply of many countries is dependent on coal-fired generation, and it costs a lot to construct a new plant to generate electricity. No country can afford to throw away their existing generation capacity.

In principle, the solution for electricity is simple: nuclear. So why not? Some say it is dangerous, and there remains the problems of storing wastes. It is true that people died at Chernobyl, but that was an example of crass incompetence. Further, in principle molten salt reactors cannot melt down while they also burn much of the waste. There is still waste that has to be stored somewhere, but the volume is very small in comparison. So why is this not used? Basically, the equipment has not been properly developed, the reason being that reactors were first designed so they could provide the raw material for making bombs. So, when the politicians recognized the problem at the end of the 1980s, what should have happened is that money was invested for developing such technology so that coal-fired power could be laid to rest. Instead, there was a lot of arm-waving and calls for solar and wind power. It is true these generate electricity, and in some cases they do it efficiently, however they cannot handle main load in most countries. Similarly with transport fuels. Alternative technologies for advanced biofuels were developed in the early 1980s, but were never taken to the next stage because the price of crude oil dropped to very low levels and nothing could compete. The net result was that technology was lost, and much had to be relearned. We cannot shut down the world industries and transport, and the politicians have refused to fund the development of alternative fuels.

So, what will happen? We shall continue on the way we are, while taking some trivial steps that make at least some of us, usually politicians, feel good because we are doing something. Unfortunately, greenhouse gas levels are still rising, and consider what is happening at the levels we are at. The Northeast Greenland Ice Stream is melting and the rate of melt is increasing because the protection from the Zachariae Isstrøm glacier that protected the coastal part of the ice stream broke off. Now, warmer seawater is penetrating up to 300 km under the ice stream. Global ocean levels are now predicted to rise up to a meter by the end of the century from the enhanced melting of Greenland ice. More important still is Antarctica. There is far more ice there, and it has been calculated that if the temperatures rose by four degrees Centigrade above pre-industrial levels up to two thirds of that ice could go.

Unfortunately, that is not the worst of the problems. If the climate heats, food becomes more difficult to provide. The most obvious problem is that most of the very best agricultural land is close to sea level, so we lose that. But additionally, there will be regions of greatly increased drought, and others with intense floods. Neither are good for agriculture. Yet there is an even worse problem: as soil gets hotter, it loses carbon and becomes less productive, while winds tend to blow soil away. So, what can we do about this? Unfortunately, it has to be everyone. We have to not only stop venting greenhouse gases into the atmosphere, but we have to work out ways to take it out. Stop and ask yourself, does your local politician understand this? My guess is no. Does your local politician understand what a partial differential equation means? My guess is no.

Trees for Carbon Capture, and Subsequent Problems

A little over fifty years ago, a 200 page book called The Limits to Growth was published, and the conclusion was that unless something was done, continued economic and population growth would deplete our resources and lead to global economic collapse around 2070. Around 1990, we predicted that greenhouse gases would turn our planet into something we would not like. So, what have we done? In an organized way, not much. One hazard with problem solving is that focusing on one aspect and fixing that often simply shifts it, and sometimes even makes it worse. Currently, we are obsessed with carbon dioxide, but all we appear to be doing is to complacently pat ourselves on the back because we shall be burning somewhat less Russian gas and oil in the future, oblivious to the fact that the substitute is likely to be coal.

One approach to mitigate global warming involves using biomass for carbon capture and storage (See Nature vol 609, p299 – 305). The authors here note that the adverse effects of climate change on crop yields may reduce the capacity of biomass to do this, as well as threaten food security. There are two approaches to overcoming the potential food shortage: increase agricultural land by using marginal land and cutting down forests, or increase nitrogen fertilizer. Now we see what “shifting the problem” means. If we use marginal land, we still have to increase the use of nitrogen fertilizer. This leads to the production of nitrous oxide gas, and these authors show the production of nitrous oxide would be roughly three times as effective as a greenhouse gas as the saving of carbon dioxide in their model. This is serious. All we have done is to generate a worse problem, to say nothing about the damage done to the environment. We have to leave some land for animals and wild plants.

There is a further issue: nitrogen fertiliser is currently made by reacting natural gas to make hydrogen, so for every tonne of fertilizer we will be making something like a tonne of CO2. Much the same happens if we make hydrogen from coal. Rather interestingly for such a paper, the authors concede they may have over-estimated the problems of food shortages on the grounds that new technology and practices may increase yields.

Suppose we make hydrogen by electrolysing water? Ammonia is currently made by heating nitrogen and hydrogen together at 200 times atmospheric pressure. This is by no means optimal, but higher pressures cost a lot more to construct, and there are increasing problems with corrosion, etc. Hydrogen made by electrolysis is also more expensive, in part because electricity is in demand for other purposes, and worse, electricity is also made at least in part by burning fossil fuels, and only a third of the energy is recovered as electricity. When considering a new use, it is important to not that the most adverse in terms of cost and effectiveness must be considered. Even if there are more friendly ways of getting electricity, you get favourable effects by doing nothing and turning off the adverse supply, so that must be assigned to your new use.

There is, however, an alternative in that electricity can directly reduce nitrogen to nitride in the presence of lithium, and if in the presence of a proton-donating substance (technically an acid, but not as you would probably recognize) you directly make ammonia, with no high pressure. So far, this is basically a laboratory curiosity because the yields and yield rates have been just too small, but there was a recent paper in Nature (vol 609, 722 – 727) which claims good increased efficiency. Since the authors write, “We anticipate that these findings will guide the development of a robust, high-performance process for sustainable ammonia production.” They do not feel they are there yet, but it is encouraging that improvements are being made.

Ammonia would be a useful means of carrying hydrogen for transport uses, but nitrogen fertilizer is important for maintaining food production. So can we reduce the nitrous oxide production? Nitrous oxide is a simple decomposition product of ammonium nitrate, which is the usual fertilizer used, but could we use something else, such as urea? Enzymes do convert urea to ammonium nitrate, but slowly, and maybe more nitrogen would end up in the plants. Would it? We don’t know but we could try finding out. The alternative might be to put lime, or even crushed basalt with the fertilizer. The slightly alkaline nature of these materials would react in part with ammonium nitrate and make metal nitrate salts, which would still be good fertilizer, and ammonia, which hopefully could also be used by plants, but now the degradation to nitrous oxide would stop. Would it? We don’t know for sure, but simple chemistry strongly suggests it would. So does it hurt to do then research and find out? Or do we sit on our backsides and eventually wail when we cannot stop the disaster.

Burying Carbon Dioxide, or Burying Cash?

In the last post, I expressed my doubt about the supply of metals for electric batteries. There is an alternative to giving up things that produce CO2 and that is to trap and sequester CO2. The idea is that for power stations the flu gases have the CO2 removed and pumped underground. That raises the question, how realistic is this? Chemistry World has an article that casts doubt, in my mind, that this can work. First, the size of the problem. One company aims to install 70 such plants, each capable of sequestering 1 million t of CO2. If these are actually realized, we almost reach 0.2% of what is required. Oops. Basically, we need to remove at least 1 billion t/a to stand still. This problem is large. There is also the problem of how we do it.

The simplest way is to pass the flu gases through amine solvents, with monoethanolamine the most common absorbent used. Leaving aside the problem of getting enough amine, which requires a major expansion of the chemical manufacturing industry, what happens is the amine absorbs CO2 and makes the amine carbonate, and the CO2 is recovered by heating the carbonate and regenerating the amine. However, the regeneration will never be perfect and there are losses. Leaving aside finding the raw materials actually synthesizing the amine takes about 0.8 MWh of energy, the inevitable losses mean we need up to 240 MWh every year to run a million tonne plant. We then need heat to decompose the amine carbonate, and that requires about 1 MWh per tonne of CO2 absorbed. Finally, we need a little less than 0.12 MWh per tonne of CO2 to compress it, transport it and inject it into the ground. If we wanted to inject 1 billion t of CO2, we need to generate something like 840 TWh of electricity. That is a lot of electricity.

We can do a little better with things called metal organic frameworks (MOFs).These can be made with a high surface energy to absorb CO2 and since they do not form strong chemical bonds the CO2 can be recovered at temperatures in the vicinity of  80 – 100 degrees C, which opens the possibility of using waste heat from power stations. That lowers the energy cost quite a bit. Without the waste heat the energy requirement is still significant, about half that of the amines. The comes the sting – the waste heat approach still leaves about 60% of what was absorbed, so it is not clear the waste heat has saved much. The addition of an extra step is also very expensive.

The CO2 content of effluent gases is between 4 – 15%; for ordinary air it is 0.04%, which makes it very much more difficult to capture. One proposal is to capture CO2 by bubbling air through a solution of potassium hydroxide, and then evaporating off the water and heating the potassium carbonate to decomposition temperature, which happens to be about 1200 degrees C. One might have thought that calcium oxide might be easier, which pyrolyses about 600 degrees C, but what do I know? This pyrolysis takes about 2.4 MWh per tonne of CO2, and if implemented, this pyrolysis route that absorbs CO2 from the air would require about 1.53 TWh of electricity per year for sequestering 1 million t of CO2.

When you need terawatt hours of electricity to run a plant capable of sequestering one million tonne of CO2, and you need to sequester a billion t, it becomes clear that this is going to take an awful lot of energy. That costs a lot money. In the UK, electricity costs between £35 – 65 per MWh, and we have been talking in terms of a million times that per plant. Who pays? Note this scheme has NO income stream; it sells nothing, so we have to assume it will be charged to the taxpayer. Lucky taxpayer!

One small-scale effort in Iceland offers a suggested route. It is not clear how they capture the CO2, but then they dissolve it in water and inject that into basalt, where the carbonic acid reacts with the olivine-type structures to make carbonates, where it is fixed indefinitely. That suggests that provided the concentration of CO2 is high enough, using pressure to dissolve it in water might be sufficient. That would dramatically lower the costs. Of course, the alternative is to crush the basalt and spread it in farmland, instead of lime. My preferred option to remove CO2 from the air is to grow plants. They work for free at the low concentrations. Further, if we select seaweed, we get the added benefit of improving the ecology for marine life. But that requires us to do something with the plants, or the seaweed. Which means more thinking and research. The benefit, though, is the scheme could at least earn revenue. The alternatives are to bankrupt the world or find some other way of solving this problem.

Will We Do Anything To Stop Global Warming?

There is an interesting review on climate change (Matthews & Wynes, 2022, Science 376: 1404 – 1409). One point that comes up early is how did this sneak up on us? If you look at the graph on global temperatures, you will see that the summers in the 1940s were unusually hot, and the winters in the 1960 – 1980 period were unusually cool, with the net result that people living between 1940 – 1985 could be excused for thinking in terms of extremes instead of averages that the climate was fairly stable. As you will recall, at 1990 there was a major conference on climate change, and by 1992 goals were set to reduce emissions. It is just after this that temperatures have really started rising. In other words, once we “promised” to do something about it, we didn’t. At 1960 the CO2 levels in the atmosphere were about 320 ppm; by 1990 the CO2 levels were about 365 ppm, and at 2022 they are about 420 ppm. The levels of CO2 emissions have accelerated following the treaty in which much of the world undertook to reduce them. Therein lies out first problem. We are not reducing emissions; we are increasing them, even though we promised to do the opposite. (There was a small reduction in 2019-2020 as a result of the Covid lockdowns, but that has passed.) In short, our political promises are also based on hot air.

The current warming rate is approximately a quarter of a degree Centigrade per decade, which means that since we are now about 1.25 degrees warmer than the set 1850 baseline, we shall hit the 1.5 degrees warming somewhere just after 2030. Since that was the 1990 target not to be exceeded, failure seems inevitable. According to the models, to hold the temperature to 1.5 degrees C above our baseline we must not emit more than 360 Gt (billion tonne) of CO2. The IPCC considers we shall emit somewhere between 400 -650 Gt of CO2 before we get carbon neutral (and that assumes all governments actually follow up on their stated plans.) What we see is that current national targets are simply inadequate, always assuming they are kept. Unfortunately, there is a second problem: there are other greenhouse gases and some are persistent. The agricultural sector emits nitrous oxide, while industry emits a range of materials like sulphur hexafluoride, which may not be there in great quantity but it is reputedly 22,800 times more effective at trapping infrared radiation than CO2, and it stays in the atmosphere for approximately 3,200 years. These minor components cannot be ignored, and annual production is estimated at about 10,000 t/a. It is mainly used in electrical equipment, from whence it leaks.

Current infrastructure, such as electricity generators, industrial plant, ships, aircraft and land transport vehicles all have predictable lifetimes and emissions. These exceed that required to pass the 1.5 degree C barrier already unless some other mitigation occurs. Thus, the power stations already built will emit 846 Gt CO2, which is over twice our allowance. People are not going to abandon their cars. Another very important form of inertia is socio-political. To achieve the target, most fossil fuel has to stay in the ground, but politicians keep encouraging the development of new extraction. The average voter is also unhappy to see major tax increases to fund things that will strongly and adversely affect his way of life.

One way out might be carbon capture. The idea of absorbing CO2 from the atmosphere and burying it may seem attractive, but how is it done, at what cost in terms of money and energy required to do it, and who pays for it? Planting trees is a more acceptable concept. In New Zealand there is quite a bit of land that was logged by the early settlers, but has turned out to be rather indifferent farm land. The problem with knowing whether this is a potential solution or not is that it is impossible to know how much of such land can be planted, given that a lot is privately owned. However, planting trees is realistically something that could help, even if it does not solve the problem.

The article seems to feel that the solution must include actions such as lifestyle changes (carless days, reduced speed limits, reduced travel, a reduction of meat eating). My feeling is this would be a very difficult sell in a democracy, and it is not exactly encouraging to persuade some to purchase electric vehicles then be told they cannot use them. The article cites the need for urgency, and ignores the fact that we have had thirty years where governments have essentially ignored the problem. Even worse, the general public will not be impressed to find they are required to do something that adversely affects their lifestyle, only to find that a number of other countries have no interest in subjecting their citizens to such restrictions. The problem is no country can stop this disaster from happening; we all have to participate. But that does not mean we all have to give up our lifestyles, just to ensure that politicians can get away with their inability to get things done. In my opinion, society has to make changes, but they do not have to give up a reasonable lifestyle. We merely need to use our heads for something better than holding up a hat. And to show that we probably won’t succeed, the US Supreme Court has made another 6:3 ruling that appears to inhibit the US Federal Government from forcing certain states to reduce emissions. We shall cook. Yes, this might be a constitutional technicality that Congress could clear up easily, but who expects the current Congress to do anything helpful for civilization?

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”.