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”.


New Zealand economic development, 1970s

The previous post outlines the background to my first job. The New Zealand government decided it had to do something about developing the economy, and I was hired by the national chemistry laboratory to find a use for lignin, since New Zealand had a lot of timber approaching harvest. Needless to say, I failed. There is now a saying, you can make anything you like from lignin, except money! I am not alone in that failure. In fact I did not stay with it very long because all the country’s troubles were exacerbated in the early 1970s with the first oil crisis. This hit new Zealand very hard because there was even some doubt as to whether we could get any oil, even if we paid enough for it. The government requested their science department to give options of what to do, and I was given the task of finding as much as I could about bioethanol ASAP. (Others were given similar tasks on different energy sources.) I presented my summary in about a week, plus typing and editing time. (No computers then!)  How had I done that so fast? My reasoning was, someone must have had this problem during the war, so I went back into the departmental files, and found all the details of farming practices, costs, processing costs, etc. All I had to do was to update the costs.

The net result of that was that the government knew enough to make ethanol if it wanted to, and it knew what the costs would be, subject to a small uncertainty due to different inflationary effects in different sectors. To the best of my knowledge, very little, if any, bioethanol was made.

This government knee-jerk reaction got nowhere in one sense. The problem was, the government had set up similar quests elsewhere, and the experienced bureaucrats beat the scientists all the time. They set up panels, committees, got large amounts of funding, and then commissioned all sorts of reports. What is interesting about this is that when the energy crisis died down, there must have been hundreds of cubic meters of reports somewhere, and when the next energy crisis came along about 30 years later, these reports were forgotten. Sound familiar?

However, in the 1970s, quite a bit was done on alternative fuels. There were cars running on compressed natural gas (the cylinders taking up most of the boot space on small cars), liquefied natural gas, and methanol/petrol blends. Service stations became interesting puzzles: where did you go in an unfamiliar service station to get what you wanted? The lasting lesson, however, was that once the oil crisis died down, the supply of these alternatives began to die. When that happened, you had to reverse the significant changes to your car. The better strategy, and one I followed, was to stick to petrol and pay the increased price. Also, in some cases, such as with methanol blends, the necessary information remained dispersed across so many reports. Nobody correlated everything, so the chances are, much of what was learned has been forgotten.