Superconducting Power Cable Supplying German City

Finally somebody does this. Serious(?) talk of using superconductors for transmission lines can be easily found as far back as 47 years ago.

Why in the world does anyone think that this is the first superconducting cable? A fairly long run was installed soon after the middle of the 20th century in New York State and used to feed power towards New York City. This was installed by General Electric and a Utility that I cannot remember. The last I heard it was still on line and operating but that was a few years ago. It was cooled and insulated with liquid nitrogen. The actual capability far exceeded the load carried on it. It had the capability of very high gigawatts of power. If this was from that newsletter more research should have been done to verify facts!!

The middle of the twentieth century is the 1950's. Liquid Helium would be needed for the known superconductors of that era. In 2008 a transmission line was put in at work. Now the one in Essen, Germany is the longest and most recent of the four installed and two planned transmission lines. At least according to Wikipedia, if you can believe them.

It was late 60's or early 70's. I saw the northern end around the late 70's and it was not new. It was liquid nitrogen. Much later I was told it was still in operation. Why do you think wikopedia in infallible? Have you never seen an error or omission in wikopedia?

I don't believe that Wikipedia is infallible. I do believe that Wikipedia is very convenient to cite. Very often it takes multiple citations to well respected authors work to give a layman's perspective of a complex topic.

Shoji Tanaka, the director general of the Superconductivity Research Laboratory in Tokyo Japan, wrote an article that identifies the highest critical temperature discovered by 1975 was 22.5 K and that it was another ten years until somebody improved on this. A scientific review paper written by V.L. Ginzburg, P. N. Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, puts the warmest critical temperature in 1973 instead at 23.9 K. This paper conveniently also points out the nominal temperatures of cryogenic fluids. "Let us also recall that at atmospheric pressure the boiling points of He, H2, Ne and N2 are equal to: Tb ,He = 4.2 K, Ть ,H2 = 20.3 К, Tb ,Ne = 27.2 К and Tb ,N2 = 77.4 K." Additionally the critical temperature is the point where the smallest of current densities transitions out of superconduction. (This is what makes critical temperature numbers vary slightly from paper to paper is the frequently unstated testing methodology.) A superconducting power transmission line fabricated in the 1960's technology will certainly have to be much colder than the boiling temperature of even hydrogen.

I know that vague anecdotal memories are extremely fallible. They are difficult to refute because they contain so little information but a lot of ego.

It was in the 80's (1986) that "high" temperature superconductors were discovered that would work with liquid nitrogen vice helium. (I have a special interest in it. On my bucket list is to hold a true room temperature superconductor in my hand!)

In case of damage to the cable, repairs are more complex than for a traditional cable.

.....you think?

Still an interesting extant development.

There is a large crater to fill!

But it only takes 5 days for the system to get back to operating temperature? I see no problem with that ... ummm ... wait, was that 5 days? Never mind!

13.5 million euro for a 1 KM cable which must be run underground.

No wonder they say there is no current market for this!

The article says: "In practical terms, the cost of the superconducting cable is still a factor of two more than copper cable. Additional costs arise when the cooling system, installation and civil works are added - but Schmidt emphasized that the money recouped from the lack of power losses must also be considered, and that the maintenance costs for conventional 10 kV technology are higher."......and bec. it cant be run the cheapest way (overhead) and must be run underground, its actual cost is higher still.

But wait:

"While the system's energy balance is still being measured, the first estimate is that its total power consumption is around 6.7 kW or 160 kWh per day."

The cable itself has almost no loss, considering the cooling system and coolant pumps, to transmit 40 MW, its loss is 6.7 KW/40 MW = .0001675 of power transmitted. Lets compare this to a single core, type 2XCY, unarmoured cable carrying 11KV. Manufacturer's charts show its voltage drop for a 3-phase system (3 x 1 core x 240mm2) = 0.242 v/am[/km = 0.000022 which is on the order of 8 times lower than the superconductor when its pumps and cooling system is taken into account. so where'e savings ???

The economics that I have seen run out as cost vrs benefit when one looks at transmission in the area of 10 - 1000 GW rates into large highly populated areas. Right now I know of no applicable area but the cost savings are mainly due to reduced right of way costs which is the value of underground installations in general. Utilities that have expressed interest count the elimination of large HV overhead lines and the sale of desirable real estate as a way of paying for the installation. Once installed the maintenance would be similiar to typical underground which is much less than overhead. The conduction of power produces almost no heat so the losses are very low due to the energy transmitted. The main problem is heat gain from the outside environment and it is this that must be taken into account. One idea proposed was for vacuum insulation, essentially a long skinny thermos bottle if you get the idea. At one time one could look at the curve of increasing energy demand and from a 60's perspective imagine the need for this technology in the then future which is now. In the meantime the demand leveled out and the growth of demand is somewhat stable. The need for more compact power transmission is still with us. One reason this may never be feasible is that large cities are excellent areas for rooftop solar and if we ever find a good way to store power we will cut down on transmission to the point that the only reason to replace existing grid is for reliability reasons.

Interestingly, one of the ideas for storage that keeps rearing it's head every few years is the idea of a large superconducting coil that just keeps a current (DC) circulating that can be tapped for energy. superconducting energy storage

No worries!

In our community, they're building a new high school at the cost of $175M http://www.signalscv.com/section/36/article/133047/ . At an exchange rate or 1.045 euro/$, that gives us 12.4 km of superconducting transmission lines.

We also have a new water treatment plant, which will cost over $100M. This is a necessity, because the old water treatment plant (completed less than 10 years ago) did not take into account the reduced chloride levels from the state. So, add on another 7.1 km of superconducting transmission lines.

Add it together and you get 19.5 km of superconducting transmission lines in exchange for a unneeded high school (k-8 has 2,500 students and the new high school is for 1,800 students???) and a waste of $100M on a mismanaged sanitation department.

That's 12.11 miles of superconducting transmission lines, easily enough to convert all our standard transmission lines to superconducting, cryogenic lines - I'll take this over the school and sewer plant!

Does anyone know how this compares with DC transmission costs? I realize Germany uses 50Hz, so capacitance losses are less than the US

Does anyone know how this compares with DC transmission costs? I realize Germany uses 50Hz, so capacitance losses are less than the US

I'll bet that it depends greatly on how one compares the two technologies. If you only consider the resistive power loss then I'm certain a superconductor will produce less power lost than any other technology. The relevant question you want answered is will the refrigeration cost be more or less than the resistive power lost. A very nice paper on precisely this was written in 2000.

The funny thing I find, the more I look into superconducting transmission lines is that they are much more prevalent than just the one German city and the feed for BNL.

When I was finishing school, an experimental test run of DC vrs AC was done out west (US). When I came back at the end of my carreer working with the Grid, both were still operating and I asked the question about economics. Both ended up costing about the same, the reliability was similiar, and the operation cost was similar. The only problem was that personel that moved between the two systems had a hard time keeping their head on straight because the practices were so different. What worked on one, caused trouble on the other. They both terminated near my home town that I returned to towards the end of my career. I was surprised. I didn't know which was going to be better on cost, but I expected one would be.

Thank you:

4wsilver said: "The economics that I have seen run out as cost vrs benefit when one looks at transmission in the area of 10 - 1000 GW rates into large highly populated areas. Right now I know of no applicable area but the cost savings are mainly due to reduced right of way costs which is the value of underground installations in general. Utilities that have expressed interest count the elimination of large HV overhead lines and the sale of desirable real estate as a way of paying for the installation."

Since San Onofre nuclear power plant (two nuclear generators) produced (iirc) about 3.5 GW, there maybe not much use for a technology that shows a cost benefit only when transmitting over 10 GW.