Energy Sustainability

Sustainability is the buzzword. Our society must use solar energy, lithium-ion batteries, etc to save the planet, at least that is what they say. But have they done their sums?. Lost in this debate is the fact that many of the technologies use relatively difficult to obtain elements. In a previous post I argued that battery technology was in trouble because there is a shortage of cobalt, required to make the cathode work for a reasonable number of cycles. Others argue that we could obtain sufficient elements. But if we are going to be sustainable, we have to be sustainable for an indefinite length of time, and mining is not sustainable; you can only dig up the ore once. Of course, there are plenty of elements left. There is more gold in the sea than has ever been mined; the problem is that it is too dilute. Similarly, most elements are present in a lump of basalt; just not much of anything useful and it is extremely difficult to get it out. The original copper mines of Cyprus, where even lumps of copper could occasionally be found, are all worked out, at least to the extent that mining is no longer profitable there.

The answer is to recycle, right? Well, according to an article [Charpentier Poncelet, A. et al. Nature Sustain. https://doi.org/10.1038/s41893-022- 00895-8 (2022)] there are troubles. The problem is that even if we recycle, every time we do something we lose some of the metal. Losses here refer to material emitted into the environment, stored in waste-disposal facilities, or diluted in material where the specific characteristics of the elements are no longer required. The authors define a lifetime as the average duration of their use, from mining through to being entirely lost. As with any such definition-dependent study, there will be some points where you disagree.

The first loss for many elements lies in the production state. Quite often it is only economical to obtain one or two elements, and the remaining minor components of the ore disappear in slag. These losses are mainly important for specialty elements. Production losses account for 30% of rare earth metals, 50% for cobalt, 70% for indium, and greater than 95% for arsenic, gallium, germanium, hafnium, selenium and tellurium. So most of those elements critical for certain electronic and photo-electric effects are simply thrown out. We are a wasteful lot.

Manufacturing and use incur very few losses. There are some, but because materials are purified ready for use, pieces that are not immediately used can be remelted and used. There are exceptions. 80% of barium is lost through use; it is used in drilling muds.

The largest losses come from the waste management and recycling stage. Metals undergoing multiple life cycles are still lost this way; it just takes longer to lose them. Recycling losses occur when the metal accumulates in a dust (zinc) or slag(e.g. chromium or vanadium), or get lost in another stream, thus copper is prone to dissolve in an iron stream. Longest lifetimes occur for non-ferrous metals (8 to 76 years) precious metals (4 to 192 years), and ferrous metals (8 to 154 years). The longest lifetimes are for gold and iron.

Now for the problem areas. Lithium has a life-cycle use of 7 years, then it is all gone. But lithium-ion batteries last about this long, which suggests that as yet (if these data are correct) there is very little real recycling of lithium. Elements like gallium and tellurium last less than a year, while indium manages a year. Before you protest that most of the indium goes into swipeable mobile phone screens and mobile phones last longer than a year, at least for some of us, remember that losses occur through being discarded at the mining stage, where the miner/processor can’t be bothered. Of the fifteen metals most lost during mining/processing, thirteen are critical for sustainable energy, such as cobalt (lithium-ion batteries), neodymium (permanent magnets), indium, gallium, germanium, selenium and tellurium (solar cells) and scandium (solid oxide fuel cells). If we look at the recycled content of “new material” lithium is less than 1% as is indium. Gallium and tellurium are seemingly not recycled. Why are they not recycled? Metals that are recycled tend to be like iron, aluminium, the precious metals and copper. It is reasonably easy to find uses for them where purity is not critical. Recycling and purifying most of the others requires technical skill and significant investment. If we think of lithium-ion batteries, the lithium reacts with water, and if it starts burning it is unlikely to be put out. Some items may have over a dozen elements, and some are highly toxic, and not to be in the hands of the amateur. What we see happening is that the “easy” metals are recycled by organizations that are really low-technology organizations. It is not an area attractive to the highly skilled because the economic risk/return is just not worth it, while the less-skilled simply cannot do it safely.

Banana-skin Science

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

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

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

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

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

Biofuels to Power Transport

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

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

C6H12O6  ->  2 CO2 +2H2O + “C4H8”

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

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

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

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

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

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

The Case for Hydrogen in Transport

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

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

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

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

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

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

“Green” Electricity

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

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

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

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

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

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

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

Solar Energy in India

There is currently a big urge to move to solar energy, and apparently India has decided that solar energy would greatly assist its plans to deal with climate change. However, according to a paper by Ghosh et al.in Environmental Research Letters, there is a minor problem: air pollution. It appears that while India is ranked fifth in the world for solar energy capacity, parts of it, and these tend to be the parts where you need the power, suffer from growing levels of particulate air pollution. There are two problems. First, the particles in the air block sunlight, thus reducing the power that strikes the panels. Second, the particles land on the panels and block the light until someone cleans the detritus off the panels.

I am not sure I understand why, but the impact on horizontal panels ranged from 10% to 16%, but the impact was much greater on panels that track the position of the sun (which is desirable to get the most power) as they suffered a 52% loss of power from pollution. Apparently if it were not for such pollution it was calculated (not sure on what basis – existing panels or proposed panels) to be able to generate somewhere between an additional six to sixteen TWh of solar electricity per year. That is a lot of power.

But if you are reducing the output of your panels by fifty percent, that means also you are doubling the real cost of the electricity from those panels prior to entering the grid because you are getting half the power from the same fixed cost installation. The loss of capacity translates into hundreds of millions of dollars annually. China has the same problem, with some regions twice as badly off as the Indian regions, although care must be taken with that comment because they are not necessarily measured the same way. In all cases, averaging down over area is carried out, but then different people may select different types of area.

So, what can be done about this? The most obvious approach is to alter the sources of the pollution, but this could be a problem. In India, the sources tend to be the use of kerosine to provide lighting and the use of dirty fuel for cooking and heating in rural villages.

The answer is to electrify them, but now the problem is there are 600,000 such villages. Problems in a country like India or China tend to be very large, although the good news is the number of people available to work on them is also very large. Unfortunately, these villages are not very wealthy. If you want to replace home cooking with electricity, and domestic heating with electricity, someone has to pay for electric ranges. One estimate is 80 million of them. Big business for the maker of electric cookers, but who pays for them when the rural people are fairly close to the poverty line. They cook with fuel like biomass that gets smoky because that is cheap or free. Their cookers may even be home-made, but even if not so, they would have to be discarded as they could not be used for electric cooking.

There are claimed to be other benefits for reducing such pollution. Thus reducing air pollution would reduce cloudiness, which means even better solar energy production. It is also claimed that precipitation is inhibited from polluted clouds, so it is concluded that with more precipitation that would wash more pollution from the air. I am not sure I follow that reasoning, because they have already concluded that they will have fewer clouds.

If they removed these sources of air pollution, they calculated that an extra three TWh per year could be generated from flat surface panels, or eight TWh per year could be generated from tracking panels. The immediate goal is apparently to have 100 GW solar installed. It will be interesting to see if this can be achieved. One problem is that while the economics look good in terms of money saved from increased solar energy, the infrastructure costs associated with it were neglected. My guess is the current air pollution will be around for a while. It also shows the weaknesses of many solar energy projects, such as setting up huge farms in the Sahara. How do you stop fine sand coating panels? An army of panel polishers?

Can Photovoltaics Provide our Electricity?

The difference between a scientific assessment and a politician’s statements is usually that the first has numbers attached to it, and that forces the analysis to come to some form of realism. You may have heard politicians say the answer to climate change is simple: solar energy. The sun, they say, has huge amounts of energy. That is true, but so what? We cannot simply pipe it to our homes and cars.

According to a recent article by Lennon et al in Nature Sustainability the International Technology Roadmap has estimated that to get photovoltaics to replace other forms of power it needs a peak output of 60 TW by 2050. Of course, one still needs a huge battery storage system because the sun does not shine at night, and domestic electricity peaks tend to be near dawn and dusk, not in the middle of the day, but let us put that aside for the moment. Let us concentrate on the material demands of generating it. If that does not add up, what follows is immaterial because we can’t use it, at least on the required scale.

First, consider copper. From Zhang et al. 2021(Energy and Environmental Science, 14: 5587) the auxiliary systems (cables, transformers, connections in modules) require 2,800 kg/MW,  which, to get to 60 TW, requires 168 million t. That is about 20% of the estimated global reserves. Similarly, the amount of silver would be about 90,000 t, which is about 16% of the estimated known world reserves, but three times the supply available now. The estimate for silver is that 1 TW would consume between 53 – 117% of current silver production. As can be seen, 60 TW will be a problem. Indium usage tends to be 50% higher than that of silver, and there are some indications it could be even higher. Global reserves of indium could be as low as 2.7% those of silver. The most optimistic estimate for bismuth usage is that 1 TW would consume 50% of the global bismuth supply. On top of that, you may ask why is the global supply so large? That is because these metals are currently used for other things as well as PV modules, and the other uses are increasing in sales volume. Thus the touch screens on your mobile phones rely on indium. Further, although more indium and bismuth are used in these PV modules, bismuth has only about 2/3 the global reserves of silver. We need more of these elements and there is much less available. The total resource level is not that great, and when we have mined those resources, what then? Anyone who says, “Recycle them,” should be asked how they propose to do that. Thus a given mobile phone has tiny amounts of indium, and of a large number of other elements. Separating them all will be extremely difficult, but when the known resources are gone, now what?

However, the problem does not stop there. It is one thing to have, say, silver sulphide dispersed through various rocks, and another to having silver in a form ready for use in a photovoltaic.

Not only that, but there is material not directly involved in electricity generation. Thus aluminium is used in mountings, frames, inverters and in many other energy technologies. Now refining aluminium is rather energy intensive. There are two main steps: refining bauxite into alumina, then electrolysing the alumina. A tonne of aluminium ingot requires about 63 GJ of energy to make. Just for photovoltaics we need an extra 486 Mt of aluminium, which requires 30.6 quadrillion Joules. This is a huge amount of energy, so a lot of fossil fuel will have to be burned with the corresponding effect on climate change. We can cut this back by using recycled aluminium, but the recycled aluminium is currently being used. Unless there is a surplus of recycled material or potentially recyclable material, recycling adds nothing because the uses it is taken from will have to use virgin material.

We can have substitution. Replacing aluminium with steel reduces the energy demand to make the metal, but increases the loss due to corrosion, and because it is heavier, increases transport greenhouse gas emissions. It is possible to reduce demands by making things lighter, but there is limited scope here because simple costs have led to most of these cherries already having been picked.

On top of that, we have ignored another elephant in the room. Silicon comes from silica, which is very inert. There is no shortage of silica and rocks are made of that bound to metal oxides. However, the making of silicon is very energy intensive. To make high grade silicon we need 1 – 1.5 GJ of energy per tonne of silicon. We need 13 t of silicon per MW, so 60 TW of energy requires 780 billion t of silicon, or a minimum of another 780 quadrillion J of energy. We shall make a lot of greenhouse gases making these collectors.

Plastics and Rubbish

In the current “atmosphere” of climate change, politicians are taking more notice of the environment, to which as a sceptic I notice they are not prepared to do a lot about it. Part of the problem is following the “swing to the right” in the 1980s, politicians have taken notice of Reagan’s assertion that the government is the problem, so they have all settled down to not doing very much, and they have shown some skill at doing very little. “Leave it to the market” has a complication: the market is there to facilitate trade in which all the participants wish to offer something that customers want and they make a profit while doing it. The environment is not a customer in the usual sense and it does not pay, so “the market” has no direct interest in it.

There is no one answer to any of these problems. There is no silver bullet. What we have to do is chip away at these problems, and one that indicates the nature of the problem is plastics. In New Zealand the government has decided that plastic bags are bad for the environment, so the single use bags are no longer used in supermarkets. One can argue whether that is good for the environment, but it is clear that the wilful throwing away of plastics and their subsequent degradation is bad for it. And while the disposable bag has been banned here, rubbish still has a lot of plastics in it, and that will continue to degrade. If it were buried deep in some mine it probably would not matter, but it is not. So why don’t we recycle them?

Then first reason is there are so many variations of them and they do not dissolve in each other. You can emulsify a mix, but the material has poor strength because there is very little binding at the interface of the tiny droplets. That is because they have smooth surfaces, like the interface between oil and water. If the object is big enough this does not matter so much, thus you can make reasonable fence posts out of recycled plastics, but there really is a limit to the market for fence posts.

The reason they do not dissolve in each other comes from thermodynamics. For something to happen, such as polymer A dissolving in polymer B, the change (indicated by the symbol Δ) in what is called the free energy ΔG has to be negative. (The reason it is negative is convention; the reason it is called “free” has nothing to do with price – it is not free in that sense.) To account for the process, we use an equation

            ΔG = ΔH -T ΔS

ΔH reflects the change of energy between each molecule in its own material and in solution of the other material. As a general rule, molecules favour having their own kind nearby, especially if they are longer because the longer they are the interactions per atom are constant for other molecules of the same material, but other molecules do not pack as well. Thinking of oil and water, the big problem for solution is that water, the solvent, has hydrogen bonds that make water molecules stick together. The longer the polymer, per molecule that enhances the effect. Think of one polymer molecule has to dislodge a very large number of solvent molecules. ΔS is the entropy and it increases as the degree of randomness increases. Solution is more random per molecule, so whether something dissolves is a battle between whether the randomness per molecule can overcome the attractions between the same kind. The longer the polymer, the less randomness is introduced and the greater any difference in energy between same and dissolved. So the longer the polymers, the less likely they are to dissolve in each other which, as an aside, is why you get so much variety in minerals. Long chain silicates that can alter their associate ions like to phase separate.

So we cannot recycle, and they are useless? Well, no. At the very least we can use them for energy. My preference is to turn them, and all the organic material in municipal refuse, into hydrocarbons. During the 1970s oil crises the engineering was completed to build a demonstration plant for the city of Worcester in Massachusetts. It never went ahead because as the cartel broke ranks and oil prices dropped, converting wastes to hydrocarbon fuels made no economic sense. However, if we want to reduce the use of fossil fuels, it makes a lot of sense to the environment, IF we are prepared to pay the extra price. Every litre of fuel from waste we make is a litre of refined crude we do not have to use, and we will have to keep our vehicle fleet going for quite some time. The basic problem is we have to develop the technology because the engineering data for that previous attempt is presumably lost, and in any case, that was for a demonstration plant, which is always built on the basis that more engineering questions remain. As an aside, water at about 360 degrees Centigrade has lost its hydrogen bonding preference and the temperature increase means oil dissolves in water.

The alternative is to burn it and make electricity. I am less keen on this, even though we can purchase plants to do that right now. The reason is simple. The combustion will release more gases into the atmosphere. The CO2 is irrelevant as both do that, but the liquefaction approach sends nitrogen containing material out as water soluble material which could, if the liquids were treated appropriately, be used as a fertilizer, whereas in combustion they go out the chimney as nitric oxide or even worse, as cyanides. But it is still better to do something with it than simply fill up local valleys.

One final point. I saw an item where some environmentalist was condemning a UK thermal plant that used biomass arguing it put out MORE CO2 per MW of power than coal. That may be the case because you can make coal burn hotter and the second law of thermodynamics means you can extract more energy in the form of work. (Mind you, I have my doubts since the electricity is generated from steam.) However, the criticism shows the inability to understand calculus. What is important is not the emissions right now, but those integrated over time. The biomass got its carbon from the atmosphere say forty years ago, and if you wish to sustain this exercise you plant trees that recover that CO2 over the next forty years. Burn coal and you are burning carbon that has been locked away from the last few million years.

The Fusion Energy Dream

One of the most attractive options for our energy future is nuclear fusion, where we can turn hydrogen into helium. Nuclear fusion works, even on Earth, as we can see when a hydrogen bomb goes off. The available energy is huge. Nuclear fusion will solve our energy crisis, we have been told, and it will be available in forty years. That is what we were told about 60 years ago, and you will usually hear the same forty year prediction now!

Nuclear fusion, you will be told, is what powers the sun, however we won’t be doing what the sun does any time soon. You may guess there is a problem in that the sun is not a spectacular hydrogen bomb. What the sun does is to squeeze hydrogen atoms together to make the lightest isotope of helium, i.e. 2He. This is extremely unstable, and the electric forces will push the protons apart in an extremely short time, like a billionth of a billionth of a second might be the longest it can last, and probably not that long. However, if it can acquire an electron, or eject a positron, before it decays it turns into deuterium, which is a proton and a neutron. (The sun also uses a carbon-oxygen cycle to convert hydrogen to helium.) The difficult thing that a star does, and what we will not do anytime soon, is to make neutrons (as opposed to freeing them).

The deuterium can then fuse to make helium, usually first with another proton to make 3He, and then maybe with another to make 4He. Each fusion makes a huge amount of energy, and the star works because the immense pressure at the centre allows the occasional making of deuterium in any small volume. You may be surprised by the use of the word “occasional”; the reason the sun gives off so much energy is simply that it is so big. Occasional is good. The huge amount of energy released relieves some of the pressure caused by the gravity, and this allows the star to live a very long time. At the end of a sufficiently large star’s life, the gravity allows the material to compress sufficiently that carbon and oxygen atoms fuse, and this gives of so much energy that the increase in pressure causes  the reaction  to go out of control and you have a supernova. A bang is not good.

The Lawrence Livermore National Laboratory has been working on fusion, and has claimed a breakthrough. Their process involves firing 192 laser beams onto a hollow target about 1 cm high and a diameter of a few millimeters, which is apparently called a hohlraum. This has an inner lining of gold, and contains helium gas, while at the centre is a tiny capsule filled with deuterium/tritium, the hydrogen atoms with one or two neutrons in addition to the required proton. The lasers heat the hohlraum so that the gold coating gives off a flux of Xrays. The Xrays heat the capsule causing material on the outside to fly off at speeds of hundreds of kilometers per second. Conservation of momentum leads to the implosion of the capsule, which gives, hopefully, high enough temperatures and pressures to fuse the hydrogen isotopes.

So what could go wrong? The problem is the symmetry of the pressure. Suppose you had a spherical-shaped bag of gel that was mainly water, and, say, the size of a football and you wanted to squeeze all the water out to get a sphere that only contained the gelling solid. The difficulty is that the pressure of a fluid inside a container is equal in all directions (leaving aside the effects of gravity). If you squeeze harder in one place than another, the pressure relays the extra force per unit area to one where the external pressure is weaker, and your ball expands in that direction. You are fighting jelly! Obviously, the physics of such fluids gets very complicated. Everyone knows what is required, but nobody knows how to fill the requirement. When something is unequal in different places, the effects are predictably undesirable, but stopping them from being unequal is not so easy.

The first progress was apparently to make the laser pulses more energetic at the beginning. The net result was to get up to 17 kJ of fusion energy per pulse, an improvement on their original 10 kJ. The latest success produced 1.3 MJ, which was equivalent to 10 quadrillion watts of fusion power for a 100 trillionth of a second. An energy generation of 1.3 MJ from such a small vessel may seem a genuine achievement, and it is, but there is further to go. The problem is that the energy input to the lasers was 1.9 MJ per pulse. It should be realised that that energy is not lost. It is still there so the actual output of a pulse would be 3.2 MJ of energy. The problem is that the output includes the kinetic energy of the neutrons etc produced, and it is always as heat whereas the input energy was from electricity, and we have not included the losses of power when converting electricity to laser output. Converting that heat to electricity will lose quite a bit, depending on how it is done. If you use the heat to boil water the losses are usually around 65%. In my novels I suggest using the magnetohydrodynamic effect that gets electricity out of the high velocity of the particles in the plasma. This has been made to work on plasmas made by burning fossil fuels, which doubles the efficiency of the usual approach, but controlling plasmas from nuclear fusion would be far more difficult. Again, very easy to do in theory; very much less so in practice. However, the challenge is there. If we can get sustained ignition, as opposed to such a short pulse, the amount of energy available is huge.

Sustained fusion means the energy emitted from the reaction is sufficient to keep it going with fresh material injected as opposed to having to set up containers in containers at the dead centre of a multiple laser pulse. Now, the plasma at over 100,000,000 degrees Centigrade should be sufficient to keep the fusion going. Of course that will involve even more problems: how to contain a plasma at that temperature; how to get the fuel into the reaction without melting then feed tubes or dissipating the hydrogen; how to get the energy out in a usable form; how to cool the plasma sufficiently? Many questions; few answers.

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.