Reducing Greenhouse Gas Emissions

Leaving aside the obstinate few, the world is now coming to realize that our activities are irreversibly changing the climate through sending so-called greenhouse gases into the atmosphere. Finally a number of politicians (but not President Trump) have decided they have to do something about it. Economists argue the answer lies in taxes on emissions, but that will presumably only work if there are alternative sources of energy that do not cause an increase in emissions. The question is, what can be done?

The first thing to note is the climate is significantly out of equilibrium, that is to say, the effects have yet to catch up with the cause. The reason is, while there is a serious net power input to the oceans, much of that heat is being dissipated by melting polar ice. Once that melting process runs its course, there will be serious temperature rises, and before that, serious sea level rises. My point is, the net power input will continue long after we stop emitting greenhouse gases altogether, and as yet we are not seeing the real effects. So, what can we do about the gases already there? The simplest answer to that is to grow lots and lots of forests. There is a lot of land on the planet that has been deforested, and merely replacing that will pull CO2 out of the air. The problem then is, how do we encourage large-scale tree planting when economics seems to have led to forests being simply cut and burned? In principle, forest owners could get credits through an emissions trading scheme, but eventually we want to encourage this without letting emitters off the hook.

Now, suppose we want to reduce our current rate of emissions to effectively zero, what are the difficulties? There are five major sources that will be difficult to deal with. The first is heating. Up to a point, this can be supplied by electricity, including the use of heat pumps, but that would require a massive increase in electrical supply, and an early objective should be to close down coal-fired electricity generators. We can increase solar and wind generators, but note that there will be a large increase in emissions to make the construction materials, and there is a question as to how much they can really produce. Of course, every bit helps.

The second involves basic industrial materials, which includes metal smelting, cement manufacture, and some other processes where high temperatures and chemical reduction are required. In principle, charcoal could replace coal, if we grew enough forests, but this is difficult to really replace coal.

The third includes the gases in a number of appliances or from manufacturing processes. The freons in refrigerators, and some gases used in industrial processes are serious contributors. There may not be so much of them as there is of carbon dioxide, but some are over ten thousand times more powerful than carbon dioxide, and there is no easy way for the atmosphere to get rid of them. Worse, in some cases there are no simple alternatives.

The fourth is agriculture. Dairy farming is notorious for emitting methane, a gas about thirty-five times stronger than carbon dioxide, although fortunately its lifetime is not long, and nitrous oxide from the effluent. Being vegetarian does not help. Rice paddies are strong emitters, as is the use of nitrogen fertilizer, thus ammonium nitrate decomposes to nitrous oxide. Nitrous oxide is also more powerful and longer lived than carbon dioxide.

The fifth is, of course, transport. In some ways transport is the easiest to deal with, but there are severe difficulties. The obvious way is to use electric power, and this is obviously great for electrified railways but it is less satisfactory without direct contact with a mains power supply. Battery powered cars will work well for personal transport around cities, but the range is more questionable. Apparently rapid charge batteries are being developed, where a recharge will take a bit over a quarter hour, although there is a further issue relating to the number of charging points. If you look at many main highways and count the number of vehicles, how would you supply sufficient charging outlets? The recharge in fifteen minutes is no advantage if you have to wait a couple of hours to get at a power point. Other potential problems include battery lifetime. As a general rule, the faster you recharge, the fewer recharges the battery will take. (No such batteries last indefinitely; every recharge takes something from them, irreversibly.) But the biggest problem is power density. If you look at the heavy machinery used in major civil engineering projects, or even combine harvesters in agriculture, you will see that diesel has a great advantage. Similarly with aircraft. You may be able to fly around the world in a battery/solar-powered craft, but that is just a stunt, as the aircraft will never be much better than a glider.

One answer to the power density problem is biofuels. There are a number of issues relating to them, some of which I shall put in a future post. I have worked in this field for much of my career, and I have summarized my thoughts in an ebook “Biofuels”, which over the month of July will be available at $1 at Smashwords. The overall message relating to emissions, though, is there is no magic bullet. It really is a case of “every bit helps”.

Science, the nature of theory, and global warming.

My summery slumbers have passed, but while having them, I had web discussions, including one on the nature of time. (More on that in a later post.) I also got entangled in a discussion on global warming, and got one comment that really annoyed me: I was accused of being logical. It was suggested that how you feel is more important. Well, how you feel cannot influence nature. Unfortunately, it seems to influence politicians, who end up deciding. So what I thought I would do is post on the nature of theory. I have written an ebook on what theory is and how to form theories, and while the name I gave it was not one that would attract a lot of readers (Aristotelian methodology in the physical sciences) it was no worse than “How to form a theory”. Before some readers turn off, I started that ebook with this thought: everyone has theories. For most, they are not that important, e.g. a theory on who trashed the letterbox. Nevertheless, the principles of how to go about it should be the same.

In the above ebook, I gave global warming as an example of where science has failed, not because we do not understand it, but rather the public has not really been presented with the issue properly. One comment about global warming is that scientists have not resolved the issue. That depends on what you mean by “resolved”. Thus one person said scientists are still working on relativity. Yes, they are, but that does not mean that what we have is wrong. The scientific process is to continually check with nature. So, what I want to do in some of my posts this year is try to give an impression of what science is.

The first thing it is not is mathematics. Mathematics are required, and part of the problem is that only too often scientists do not state clearly what they are saying, preferring to leave a raft of maths for the few who are closely in the field. This is definitely not helpful. Nor are TV shows that imply that theories are only made by stunning mathematics. That is simply not true.

The essence of science is a sequence of simple statements, which are the premises. For me, the correct methodology was invented by Aristotle, and the tragedy is, Aristotle made some howling mistakes by overlooking his own methodology. Aristotle’s methodology is to examine nature and from it, draw the premises, then apply logic to the statements to draw some conclusions, check with observation, and if the hypothesis still stands up, try to determine whether there are any other hypotheses that could have given equivalent predictions. Proof of a concept is only possible if one can say, “if and only if X, then Y”, in which case observing Y is the proof. Part of the problem lies in the “only”; part lies in seeing the wood for the trees. One of the first steps in analyzing a problem is to try to reduce it to its essentials by avoiding complicating features. This does not mean that complicating features should be ignored; rather it means we try to find a means of avoiding them until we can sort out the basics. If we do not get the basics right, there is no point in worrying about complicating factors.

To consider global warming, the first thing to do is put aside the kilotonnes of published data. Instead, in order to focus on the critical points, try modeling something simpler. Consider a room in your house in winter, and consider you have an electric bar heater. Suppose you set it to 1 Kw and turn it on. That will deliver 1 kilojoule of heat per second. Now, suppose doors are open or not open. Obviously, if they are open, the heat can move elsewhere through the house, so the temperature will be slower to rise. Nevertheless you know it will, because you know there is 1 kilojoule per second of heat being liberated.

The condition for long term constant temperature (equilibrium) is
(P in) – (P o) = 0
where (P in) is the power in and (P o) is the power out, both at equilibrium. This works for a room, or a planet. Why power? Because we are looking to see whether the temperature will remain constant or change, and to do that we need to see whether the system is changing, i.e. gaining or losing heat. To detect change, we usually consider differentials, and power is the differential of energy with respect to time. Because we are looking at differentials, we can say, if and only if the power flow into a system equals the power flow out is it at an energy equilibrium. We can use this to prove equilibrium, or otherwise, but we may have to be careful because certain other energy flows, such as radioactive decay, may be generated internally. So, what can we say about Earth? What Lyman et al. found was there is a net power input of 0.64 watts per square meter of ocean surface. That means the system cannot be at equilibrium.

We now need a statement that could account for this. Because the net warming effect is recent, the cause must be recent. The “greenhouse” hypothesis is that humanity has put additional infrared absorbers into the air, and these absorb a small fraction of the infrared radiation that would otherwise go to space, then re-emit the radiation in random directions. Accordingly, a certain fraction is returned to earth. The physics are very clear that this happens; the question is, is it sufficient to account for the 0.64 W? If so, power into the ground increases by (P b) and the power out decreases by (P b). This has the effect of adding 2 (P b) to the left hand side of our previous equation, so we must add the same to the right hand side, and the equation is now
(P in + P b) – (P o – P b) = 2 (P b)
The system is now not in equilibrium, and there is a net power input.
The next question is, is there any other cause possible for (P b)? One obvious one is that the sun could have changed output. It has done this before, for example, the “Little Ice Age” was caused by the sun’s output dropping with a huge decrease in sunspot activity. However, NASA has also been monitoring stellar output, and this cannot account for (P b). There are few other changes possible other than atmospheric composition for radiation over the ocean, so the answer is reasonably clear: the planet is warming and these gases are the only plausible cause. Note what we have done. We are concerned about a change, so we have selected a variable that measures change. We want to keep the possible “red herrings” to a minimum, so the measurements have been carried out over the ocean, where buildings, land development, deforestation, etc are irrelevant. By isolating the key variable and minimizing possible confusing data, we have a clear answer.

So, what do we do about it? Well, that requires a further set of theories, each one giving an effect to a proposed cause, and we have to choose. And that is why I believe we need the general population to have some idea as to how to evaluate theories, because soon we will have no choice. Do nothing, and we lose our coastal cities, coastal roads and coastal agricultural land up to maybe forty meters, and face a totally different climate. Putting your head in the sand and feeling differently will not cool the planet.

* Lyman, J. M. and 7 others, 2010. Nature 465:334-337.

Geoengineering: to do or not do?

For those interested in science, and in global warming, a recent issue of Nature (vol 516, pp 20 – 21) showed some of the problems relating to geoengineering, which involves taking action to change the climate. Strictly speaking, we are already doing it. By burning fossil fuels we are warming the planet through the additional carbon dioxide in the atmosphere. The question is, can we reverse this warming in a controlled fashion? The argument behind geoengineering is simple: we can either try it or not try it. If we do, we have the potential to create massive new problems; if we do not, sea levels will eventually rise somewhere between 20 – 50 meters, drowning all our coastal cities, destroying a surprising amount of some of the most productive farmland, and altering rainfall distributions quite dramatically. Then, of course, there are more violent storms. So, what are the options?
One is to try to increase the amount of light reflected to space, which can be achieved by forming more clouds. One way to do this is to spray salt water into the air. This has the advantage of being easy to do, and easy to stop doing. It is harder to know the consequences, but we should be able to predict to some extent because volcanic eruptions will do something similar to what is being proposed. Climate scientists, however, complain that this may reduce rainfall in some regions and possibly worsen ozone depletion. Of course they also warn that rainfall will be reduced anyway. Meanwhile, a computer simulation produced results that indicated changes in rainfall consequent to geoengineering “could affect 25 – 65% of the world’s population”. Charming! No comment that the changes could be beneficial. No comment either about the fact that any given model has consistently failed to predict details of weather.
However, from my point of view, the most bizarre outcome came from the proposal to seed the oceans to grow microalgae, which grow very rapidly and take up carbon dioxide in doing so. When the algae die, they should sink to the ocean floor and trap carbon. Trouble was, in some of the few experiments, it seems they did not, possibly because the algae did not die, or possibly because the experimenters did not count it properly. One other outcome might be that they get eaten by fish, thus improving the world’s food supply, and another might be that they give off dimethyl sulphide (and use up quite a bit of solar energy in doing so) which goes to the atmosphere, gets oxidized by absorbing more light, and then forms clouds, which reflects light. Ideal?
As a potential means of fighting climate change, I admit to liking this idea, nevertheless there is a problem, but not what you might think. Or maybe you would. Yep, it is financial embarrassment. Entrepreneurs decided to seed the oceans this way to generate large volumes of carbon credits, which could be sold to those who wanted to burn more coal, a sure way of reducing greenhouse gases! Yeah, right! Anyway, that was headed off by an international treaty, in which this activity was stopped by labeling it “ocean pollution”, and no further experiments have taken place. Talk about useless politicians!
The problem is as I see it that the politicians cannot seem to recognize that a technical problem needs a technical solution. The economists cannot solve this, as shown by that response to an emissions trading scheme noted above. The problem is, changing the prices of forms of energy cannot in themselves generate energy. Conservation may be encouraged, and that is good, but ultimately our lifestyle requires a very high fraction of what we currently use. Worse, there is no point in denying the fact that the planet is warming, and the only solution is to cool it. Cutting emissions is definitely desirable, but it is not enough to retain our previous climate because the gases currently there produce net warming, and this extra warming would continue for at least a hundred years if no further gases were emitted during that time. If we do not want to do something, who pays the price for what happens?