9/19/17

Why Sodium Conductors are Important for Large Elpipes

The elpipe needs to be based on sodium conductors to be economical. I came to this realization just before I signed an employment contract with Alevo. Jostein Eikeland prevented me from talking about this vital fact all during the time I was at Alevo. I think that was a mistake.


Sodium is about a factor of 7 times less expensive than aluminum. In prior art transmission projects the actual metal purchase price for the conductor is 1 - 2% of the total cost (including the cost of transformers and or ac-dc converters needed).    Elpipes  are envisioned as extremely efficient transmission lines; The  default efficiency of elpipe  transmission, for all  my illustrative calculations  shown in my various publications and on this website has been 1% loss per 1000 km.  This is about 3 times better than the best previous major long distance powerlines, which are two overhead 800 KV HVDC lines in China. Such low loss is needed to construct a truly continental scale electricity grid.  


Such elpipes use way more metal than prior art transmission lines per kilowatt - kilometer; considering the cost of an entire  transmission project, 15 - 25% of project cost would be for metal if the conductor is strictly aluminum. If the conductor in such a transmission project could be exclusively sodium (it cannot) the corresponding percent of total transmission project cost for the conductor drops  to 1.87 - 2.31%.  Even after including other vital  conductive metal parts made of steel, copper, or Invar, cost for the conductive metal will still be low compared to an aluminum based elpipe, about 3 - 6% of total project cost.   

A continental grid  based on elpipes would be billions of dollars less expensive if made primarily using sodium conductor.


In order to have a renewable energy based economy, it is critical to have an electric grid that is larger than the largest expected weather system. The larger the area covered, the more likely it is that there are renewable energy generators in multiple different weather systems. Spreading the risk for wind turbines to be becalmed or solar generators to be shaded out across a very large grid enables renewable energy in aggregate to be far more reliable. Such a supergrid can get by with far less balancing resources than grids of today.


Cost per unit conduction capability for any metal depends on these factors: cost of the ore per kilogram of metal produced, cost of refining the metal from the ore, and density of the metal. The major cost advantage of sodium over aluminum as the primary elpipe conductor is that much less energy is required per kilogram of sodium produced and the density of sodium is much less than that of aluminum.

I  advocate using sodium electrolyzed from sodium  oxide derived from the carbonate (trona) as opposed to starting with sodium chloride. The chlorine byproduct that would be produced from making  sodium out of sodium chloride would have unacceptable environmental consequences.

No comments:

Post a Comment