Wednesday, January 7, 2009

Of Natural Gas Pipelines, and the flows through them

Those of you who are following the Russian:Ukrainian dispute may have noted that President Putin has ordered that supplies through Ukraine be shut down, and gas flow increased through the pipelines that don’t go through Ukraine, so as to keep Europe supplied.

Unfortunately this won’t work very well, and this is why. When you put a pipeline into the ground you make it of a certain size. The original pipeline from the Yamal Peninsula through Ukraine to Germany is 1.42 meters (56 inches) in diameter and has 41 compressor stations with 125 turbines to pump the gas along the way. The second pipeline from Yamal, but which flows through Belarus is of the same diameter. Now you might think that all they would have to do to increase the flow, would be to spin the turbines faster, pump up the pressure and speed up the gas flow down the pipe.

But here is the problem, as you increase the flow of gas, so you increase the friction between the gas and the wall of the pipe. And as that friction builds more and more of the power of the turbine has to be used to overcome it, so that there is less power available to actually keep the gas moving. It reaches a point where, beyond a certain point, flow of gas out of the far end of the pipe will start to drop off, if the starting pressure of the gas down the line is too high. Thus the normal flow of gas through a pipeline of that diameter is restricted to some 33 billion cu m/year.

If you want to put more gas through you have to resort to a little trick. You may not know, but when they pump the oil from the North Slope of Alaska down to Valdez they want to keep it hot. The reason is that the hotter the oil is then the thinner (or less viscous) it gets, and the less resistance there is to flow. (If you heat honey in a microwave you’ll see what I mean).

With gas they do it the other way around. If they lower the temperature then the volume of the gas will reduce (This is thermodynamics, in case you were wondering), in inverse proportion. Or Volume/Temperature = Constant. So that by cooling the gas, and reducing the volume, they can get another 7 billion cu m down that pipe each year.

If you want to increase flow much above that then you have to add another pipeline, and they did that back in 2005, with the Yamal pipeline that now goes through Belarus, but which has the same diameter, and thus the same liabilities, as the original in terms of flow. Now they are starting another one that will connect to the Bovanenkovskoe field. Incidentally, with the drop in the price of natural gas, there is now some question as to whether Gazprom can afford to develop both the Bovanenkovskoe and Shtokman fields at the same time, with the latter being the anticipated loser,, since the first rigs are already drilling at the former.

To supply the West without going through Ukraine they are currently building the Nord Stream pipeline that will carry gas from Portovaya Bay (near Vyborg in Russia) to Greifswald in Germany. The Russian sections of this are currently being built. Vyborg is where the power station is that supplies electricity from Russia to Finland, which, since they operate at different voltages, is also a bit of a trick. The only problem with the Nord Stream is that it is still a way from permitting let alone completion.

The other pipeline that they could use is the Blue Stream, and this is a twin pipe each 24 inches in diameter (1.25 inches thick) and capable, at full performance, of delivering 16 billion cu m/year, though it may not reach that level until 2010.

In the meanwhile there is still fierce competition with the plan to bring Azerbaijan gas from the Shah Deniz field, to Europe through a pipeline called Nabucco. The idea, which would bypass Russia, is being fiercely contested by the Russians, and it success remains in some doubt..

None of these future pipelines help in the current situation, and with Russia now cutting supplies even further, things could get ugly faster than had been expected, even as the winter gets harsher.

(Not that Prime Minister Putin would want to dominate the news over anything else in the next couple of weeks, of course not.)

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