Explosion in Fertilizer Plant in Texas


In April 2013 an explosion happened in a fertilizer production plant in Texas which had huge impact. It looks like it was ammonium nitrate which exploded. This is used for producing fertilizer. But it is also quite explosive and can be used in pure form or mixed with other substances as explosive. The worst known accident with ammonium nitrate happened in 1921 in the Oppau-plant of BASF in Germany.

For feeding the current earth population the nitrogen holding compounds that are generated by natural processes and become available to the plants are not sufficient. Therefore it is necessary to rely at least for part of the agriculture on chemical fertilizers, implying the need of production, transport and storage of these substances, of which ammonium nitrate is an important example. So it should be better to make the plant working with ammonium nitrate safer than to refrain from working with this substance.

Share Button

Fahrenheit or Celsius


Fahrenheit is such an odd American unit like square foot, pound or gallon. Or even worse: cubic foot, who has three feet? Nobody needs this crap any more and we should all switch to the metric system. Habits take a generation or two for this, but it will come… So now it is the metric system we should all strive for and of course Celsius degrees instead of Fahrenheit. Physics classes become a lot easier… Freezing of water at 0°C, boiling at 100°C. And the intermediate range is divided evenly and the scale is extrapolated to the top and the bottom. Quite simple, right?

Unfortunately not quite true. We have indeed introduced the metric system in most industrialized countries in many areas, but the temperatures have actually been excluded. The metric unit for temperature is Kelvin (K) and not °C. The next question is what an even subdivision of the temperature scale really means. Ok, the lines on the thermometer should have equal distances, but what liquid are we using for the thermometer?
What is the melting point and boiling point of water? Even slight quantities of dissolved substances and the air pressure have quite significant influence on them. But this can all be described and the temperature scale is precise enough for practical purposes. But the real thing is Kelvin (K).

If we are not using the metric system for temperatures anyway, we should ask, why. Everybody knows it: The Kelvin temperatures are clumsy and unintuitive. To some extent it is also just a matter of habit.

Most measurement units that we encounter in our daily life are used in a wide range of magnitudes. Lengths can be millimeters and thousands of kilometers, which is all really part of our daily life, not just some lab stuff. Times can be seconds and years. Masses can be milligrams and tons. When talking about temperatures we like to know the temperature of water and air and how it feels, most of the time. The melting point of aluminum is by itself interesting and maybe even useful to know when doing a chemistry or physics exam, but for most of us it is not really part of our daily life.

But for the feeling of temperatures and mapping of the relevant range the Fahrenheit scale is almost perfect:

  • A temperature difference of 1°C feels quite significant, but 0.1°C seem like exaggeration. 1°F might be a perfect step
  • The freezing point of water can be of some interest, for example in order to know if it is possible to go swimming in a lake or if icy highways can be expected. But some other temperatures need to be considered interesting: Down to about 0°F it is still quite ok with moderate clothing to move around outside. For much lower temperatures serious equipment is needed or it is good to keep the time outside really very short.
  • Our body temperature is near 100°F and temperatures up to this seem to be quite warm, but still bearable for a longer period of time for most of us. If it is warmer than that, it really gets way too hot for most of us. This is especially true for water temperatures.

It is unlikely that a switch from Celsius to Fahrenheit will ever happen in any country. But from all these non-metric unit Fahrenheit is the one that I consider most reasonable, much better than Celsius.

When working with temperatures in scientific context, especially in physical chemistry, the advantages of going all the way for metric units show up. Many formulas become much simpler when using Kelvin, not so much because of the scaling factor and more because of the fact that this ugly summand can be eliminated.

So the theoretical max of the efficiency of a temperature powered engine is \frac{T_1-T_2}{T_1} or the ideal gas formula is p \cdot v_m = R_m \cdot T (intensive form) or p \cdot V = n \cdot R_m \cdot T (extensive form). The intensive form abstracts from the quantity by using the volume per mol instead of the volume. Actually I prefer that, because the extensive forms imply an integration over the volume and a homogeneity, while intensive quantities describe matter at one point or a small vicinity of one point, as long as we can still abstract from the granularity due to the molecules and atoms. Measurements like temperature and pressure start to make sense with certain large number of molecules. Or what is the pressure or temperature of a single molecule?

For conversions between Fahrenheit, Celsius and Kelvin the following special values can help:

  • -40^{\rm o}{\rm C} = -40^{\rm o}{\rm F}
  • 0^{\rm o}{\rm F} = -17\frac{7}{9}^{\rm o}{\rm C}
  • 0^{\rm o}{\rm C} = 32^{\rm o}{\rm F}
  • 10^{\rm o}{\rm C} = 50^{\rm o}{\rm F}
  • 20^{\rm o}{\rm C} = 68^{\rm o}{\rm F}
  • 30^{\rm o}{\rm C} = 86^{\rm o}{\rm F}
  • 100^{\rm o}{\rm F} = 37\frac{7}{9}^{\rm o}{\rm C}
  • 100^{\rm o}{\rm C} = 212^{\rm o}{\rm F}

From these the conversion formulas can be deduced, but they are not so hard either:

  • k = \frac{5}{9}(f+ 459.67)
  • f = \frac{9}{5}k - 459.67
  • k = c + 273.15
  • c = k - 273.15
  • f = \frac{9}{5}c+32
  • c = \frac{5}{9}(f - 32)

k, f and c are the temperatures in K, °C and °F, respectively.

Share Button

Rail Projects in Northern Scandinavia


The European region north of the arctic circle in Finland, Norway and Sweden is often called „Cap of the North“ („Nordkalotten“ in Danish, Norwegian and Swedish, or „Pohjoiskalotti“ in Finnish). That area is thinly populated, but there are some towns with a few 10’000 inhabitants and a more densely populated area in their vicinity, like Tromsø, Narvik, Alta, Harstad and Kiruna. I don’t want to take the arctic circle as a hard boundary, but rather write about rail projects in the north of these three countries, at least those I have heard of. Railroad construction in this area is mainly motivated by freight traffic. The Iron Ore Line from Narvik to Kiruna has been built to access the huge iron ore deposits in northern Sweden, mostly Kiruna. Now northern Sweden contains further iron ore deposits and also in northern Finland a lot of mining, mostly for iron ore, could be possible. Finland has already been called the „new Australia“ because of that. Even northern Norway contains some smaller share of iron ore deposits, mostly in the area of Kirkenes near the Russian border. This mine is the reason for the northernmost railroad in Norway connecting the sea port of Kirkenes with the mine, being just a few kilometers long. Because of declining profitability mine and railroad had already been closed down, but because of increasing demand and increasing prices for iron ore, they have been reopened.

The railroad to Narvik does not have any connection to the remaining Norwegian railroad network via Norway. The Nordland Line is running from Trondheim to Bodø. Bodø is situated pretty much half way through the whole country, between the Swedish border in the south in Svinesund and Grense Jakobselv at the Russian border in the northeast. Since the 1920es plans have existed to build this railroad line, but not only to Bodø, but also the Polar Line to Kirkenes and Vadsø in the northeast. During the second world war the construction of these lines was accelerated, which resulted in parts of the line from Trondheim to Bodø being built, even though the whole line was opened in 1962. North of Fauske and Bodø to Narvik some tunnels, bridges and railroad dams have been built, some which have been incorporated into the highway E6. Today a railroad to Kirkenes and Vadsø can no longer be considered reasonable, because the train would no longer be the only means of transport, since the area has been well equipped with highways, ports and airports. The number of inhabitants is too low to justify daily passenger trains in a situation where other means of transport exist. Even freight traffic is covered well by ships and trucks in this relation. The part of northern Norway north of Tromsø has so little population, that its contribution to air pollution created by Norway is not very significant.

Another question is the extension of the Nordland Line from Fauske to Narvik, Harstad and Tromsø. In this case a railroad from Trondheim to Tromsø with branches to Bodø, Narvik and Harstad could be imagined. This is a project that is discussed in Norway every couple of years, but it does not seem to have priority. Connecting towns and cities with somewhat more significant population this could provide potential for running freight and passenger trains several times per day with an acceptable number of passenger and acceptable amount of freight. A problem is the Tysfjord, which cannot easily be crossed or bypassed. In spite of almost unlimited resources for highway construction it has not been possible to build a ferry free section of the highway E6 between Fauske and Narvik. For a railroad three scenarios could be considered:

  • Ferry Line: The railroad leads to the fjord, probably to Drag, and is trajected by a railroad ferry, going to Narvik and Lødingen. This would allow for integration of Harstad, but the ferry would probably make the rail connection too unattractive to compete with highway, ship and air transport. So this variant will probably no longer be considered, if the line is ever built.
  • Fjord Line: The railroad follows the eastern shore of Tysfjord, with many tunnels.
  • Mountain Line: The railroad runs near the Swedish border across the mountain range, intersecting with the Iron Ore Line from Kiruna to Narvik near Bjørnfjell, this allowing for a branch to Narvik by just providing a connection.

More concrete than this are connections from the coast inland. Finland has lost its ice free port in Petsamo in the Arctic Sea during the second world war. It is no longer such a big deal because ice breakers have become more of an option, allowing even otherwise frozen ports in the Baltic Sea to stay open during the winter. The relationship between Norway and Finland is now good and Norwegian ports can be used by Finish companies. But trucks are not very useful for transporting huge quantities of iron ore. Such plans do exist for accessing a new mine near Pajala in northern Sweden using 90 ton trucks between the mine and the next railroad connection in Svappavara. It has even been authorized. But there are downsides. The highway and the bridges will be used up in as little as five years and the houses near the highway will need triple glass in an area where there were just a few cars per hour. There will be a 90 ton truck every two minutes, day and night. In the long run a railroad might be a better solution. In principle several options exist for connecting the new iron ore mining areas in northern Finland and Sweden with the sea ports that have been discussed recently:

  • Connections to the south via the existing railroad network to the south to Swedish and Finish ports (Kemi, Oulu, Luleå,…)
  • Connections going south or east via the Finish railroad network to Russia.k
  • Construction of a new railroad line from Pajala and northern Finalnd to Skibotn in Norway.
  • Construction of a new railroad line from Pajala and northern Finalnd to Kirkenes in Norway.
  • Construction of a new railroad line from Pajala and northern Finalnd to Svappavara.

It needs to be considered that Finland and Russia are using broad gauge (1520 mm in Russia, 1524 mm in Finland), while Sweden and Norway are using standard auge (1435 mm). While the difference between Russia and Finland is within the tolerance, having to change the track gauge is a hardly acceptable obstacle for freight traffic. The Iron Ore Line from Kiruna to Narvik is already quite congested, so there is not really much spare capacity for providing connections to other mines. But its capacity is extended to some extent by providing more and longer two track sections for allowing trains to meet and by improving the track bed for allowing higher axle loads of 30 tons.

Skibotn is a village with 700 inhabitants having just a small boat harbor. A port for huge sea ships could be built there, but it would be completely new. Also the slope from there to Finland is quite steep making it quite expensive, but still possible to build a railroad. Being in Skibotn in 2012 I have been told that this connection is no longer seriously considered.

Kirkenes already has the rail line for the first few kilometers, but in 1435 mm, which would have to be converted to 1524 mm. If the line is built, it will have to pass Lake Inari in the east or in the west. Kirkenes already has a sea port with options for extending its capacity. Other than Skibotn, Kirkenes might have some potential for passenger traffic, maybe for one or two daily trains, one during the day and one during the night. Because it is the northeastern end of the Hurtigruten it is a relevant tourist destination. Considerations exist also to connect Kirkenes to the Russian railroad network, but they are much less concrete than connecting to Finland, even though the route is much shorter.

Already south of the arctic circle it is worth mentioning that a new railroad line from Boden to Happaranda has been opened in 2012 running parallel to the shore of the Baltic Sea and shortening the trackage significantly. A huge drawback of the Swedish railroad network north of Sundsvall is that the trunk railroad lines have been built far away from the coast for military strategic reasons, leaving the connection of the major towns and cities which are near the coast to branch lines. This is no longer very competitive in these days. This has been fixed to some extent by the Bothnia Line running from Sundsvall to Umeå somewhat near the coast. This is a mostly single track high speed railroad line opened in 2010. An extension from Umeå to Luleå (near Boden) is considered as North Bothnia Line.


Share Button

Why Aluminum Recycling matters

This is an English translation of the German article Aluminiumrecycling.

Why is aluminum recycling so important?

aluminum (or aluminium) is occurring on the earth surface in chemically bound forms and it is the third most frequent element in the crust of the earth, after oxygen and silicon. So other than the lanthanides it is not really rare. Aluminum ore can be found in large quantities and they are relatively cheap. Many minerals could be used, but bauxite is what is really used for obtaining metallic aluminum. The process of obtaining aluminum from bauxite is really expensive. Aluminum is very reactive and a lot of Energy is needed to gain it. Purely chemical and thermal processes do not work or are not competitive. Current aluminum production work with Electrolysis. Using electrolysis with an aluminum salt dissolved in water would yield hydrogen, so it is necessary to do it with molten salt. First Bauxite contains chemical compounds and salts of aluminum, silicon and iron, which are separated and split to obtain aluminum hydroxide, which is heated to gain aluminum oxide. This is molten and put into the oven. Which contains a cathode of graphite on the ground, near which liquid aluminum is collected. The Anode consists also of graphite and oxygen is gained there, which slowly burns the anode, so it has to be replaced frequently. The heat of this process is sufficient to keep the aluminum oxide liquid, once the process has been started. So the production of aluminum from bauxite uses much higher magnitudes of the energy then the process of aluminum recycling. Even the burning of aluminum that is thrown into the regular garbage does not even nearly compensate for the energy usage in the aluminum plant, considering the whole process and the fact that thermal power plants have a limited efficiency due to thermodynamic principles.

In the old days the problem could be solved by simply transporting bauxite to countries like Norway and Iceland, where water power is available in large quantities. These days powerful electrical power transmissions exist from Norway to Central Europe. So Norway can now sell electricity to other parts of Europe and contribute to reducing the usage of German coal power plants. Electricity in Norway has become more expensive and Norwegian aluminum plants have a harder time then some years ago.

In short, recycling of aluminum is a good thing for the environment. So I recommend that you think about it and try to take it serious, if there is a way to deliver aluminum separate from your garbage.

Share Button

Gutes neues Jahr für 2013!

Frohes neues Jahr — Bonne Année — Felice Anno Nuovo — Bun di bun an — Happy New Year — Prosperan novjaron — السنة الجديدة المبتهجة — 高兴的新年 — Godt nytår — שנה חדשה שמחה — 明けましておめでとう — Feliç Any Nou — 기쁜 새로운 년 — FELIX ANNUS NOVUS — Een gelukkig nieuwjaar — Godt nytt år — Szczęśliwego nowego roku — Feliz ano novo — Próspero ano novo — Весёлого нового года — Gott nytt år — Feliz año nuevo — Yeni yiliniz kutlu olsun — Hyvää Uutta Vuotta

Share Button

Draining with Osmosis

For a change I am writing this about a non-railroad issue. It is the English translation of the German article Entwässerung mit Osmose.

Osmosis is described quite well in Wikipedia. In short, mixing of salt solutions with different concentrations sets free some energy. For example when mixing fresh water with sea water, this energy is equivalent to a falling height of 270 m (not 2.8!!!). By using a semi-permeable membrane between the two salt solutions, water molecules will diffuse through the membrane until the sea water side is about 270 m higher than the fresh water side, if dilution of sea water during this process is neglected.

About 30 years ago I have heard about the idea of building osmotic power plants at the mouths of rivers to the sea. They seem to have built a prototype of this recently in Norway and intend to produce 10% of the electricity demand of Norway by osmotic power. This indicates that the concept might become mature soon, even though few countries have as much precipation per inhabitant as Norway, so the achievable percentage will be much lower in most countries.

Another interesting use case of this technology could be draining land areas that are below sea level, like part of the Netherlands or New Orleans. I am sure that there are more of these. Today draining is mostly done by using electric pumps, which consume quite a significant amount of energy. As long as the height difference against the lower tide is less than 270 meters, draining could actually be achieved by using some kind of osmotic pumps without using electricity. Since the height difference is less, it would even be possible to produce some surplus electricity.

I expect that we will see this implemented in areas where applicable within the next ten years, since the osmotic power plant shows that the technology needed for this is becoming mature.

Share Button

A Track is not enough

(translation of Ein Gleis alleine genügt nicht)

Building and maintenance of transportation routes is often considered to be a responsibility of the state.  It is assumed that everybody can then use this routes.

For transportation of persons this is only partly true.  A highway can be used by individually owned means of transportation, like bicycles or cars or motorcycles.

For using a railroad line as passenger, a scheduled operation is needed, because passengers do not have their own trains.
This operation works best, if the whole system is planned or at least coordinated centrally, with connection in major stations, maybe even with operation in consistent intervals and better usage of the track capacity.  Such systems have been established in some countries, for example it has been done very well in Switzerland.
Now such a system works best, if the portion of the travelers using it is as large as possible, if only it can be assumed that railroad network capacities are expanded when congestion is getting too high.  In many parts of the world the demand for expanding congested highways with tax money is considered self evident, even though planning, financing and building may take its time.  So if railroad lines are subject to such expansion where high numbers of travelers cause congestion, then the system can work better with more travelers for the following reasons:
  1. Longer trains and bilevel trains can transport more people with only one railroad engineer (motor man) and one trains path.  Less energy per passenger is used in this case.
  2. If trains operate more frequently, the system gets more attractive for travelers.
  3. If many trains are operated, more connections can be offered without transfer.
  4. If many trains are operated, some of them can skip part of the stops and still leave a high level of service for all stops. This can be used for shortening travel times and saving energy that would be needed for acceleration.  An example are the New York subway lines 1, 2, 3 and 9.  Lines 1 and 9 combined serve all stops, with about 1/3 of the stops only being served by line 1, 1/3 only by line 9 and the remaining 1/3 by both.  Lines 2 and 3 are express lines that skip about 3/4 of the stops.  All 4 lines are bundles throughout most of Manhattan.
  5. If many trains are operated, it is possible to provide stops closer to the real source and destination of the trip, this shortening the „last mile“ of the door-to-door connection.

To make full use of these advantages, the railroad operator must be well run, like for example in Japan or Switzerland.

I makes some sense to have a government controlled organization that does not only build and maintain railroad lines (or has them built and maintained by some companies), but that also provides a scheduled operation.  This could be a well run federal railroad operator, like in Switzerland, but it could also be an organization that plans the whole system with all schedules and lets companies operate the trains as subcontractors.

It can be seen that this system works quite well in Switzerland, while the attempt to leave passenger traffic to private companies has generally failed in the United States.


Share Button