Intersting column in today's Washington Post about utilizing a newly perfected technology (underground high voltage direct current) to optimize solar and wind energy by having this capacity to move, in real-time, large amounts of energy around the U.S. According to the proposal, side benefits of building this network underground would be in its ability to help the U.S. recover from an EMP or solar storm.

Thought some peops on ETS would find this intriguing.

https://www.washingtonpost.com/news/capi...interstate-now/


"An EMP bomb placed high above Kansas City, Kan., could wipe out the U.S. electric system and much of our digital electronics.

"A year without electricity (no food, no running water, no gasoline) could kill 100 million Americans or more. Even our friendly, life-giving sun could generate a solar storm that would have a similar devastating effect.

"The core solution to both of these problems is a technology that was not fully ready five years ago but is ready now: an underground high voltage direct current (HVDC) electric transmission network."

Misleading IMHO.
Firstly it is not that new ! we have had a HVDC link to France for decades, underwater rather then underground I know but still very similar.

Secondly to suggest or imply that widespread use of such technology gives protection against an EMP event is very misleading.
The buried HVDC cable itself might well survive an EMP event, but to what purpose ? the power plant feeding energy into this link is unlikely to survive an EMP. The physically large and above ground converting plant would almost certainly be damaged also.

At the receiving end, the HVDC current would be converted to AC at lower voltages and distributed largely via overhead lines and transformers to customers. all this equipment is vulnerable, as is the consumers equipment.

IMO, HVDC is worth pursuing for general energy security reasons in large countries like the USA. It permits of surplus energy in one region being transferred to areas of shortage for example.
Build wind farms where it is windy, solar arrays in the sunniest parts, and hydro electric plants in the optimum places, and transport this energy as needed.

It is misleading though to consider it as a defence against an EMP event.

As I understand the EMP threat, the HV transmission lines act as an antenna for the EMP generates by a high altitude nuke. The EMP pulse from the transmission lines is what threatens the transformers and other system components. AFAIK, maybe I'm mistaken in my understanding.

IMHO, you are correct in that overhead transmission lines do act as antennae and pick up high voltage pulses that are apt to destroy both the equipment connected to the line, and possibly the overhead line itself.
A buried HVDC line should be far less vulnerable. Unfortunately though, the power to be fed into this new HVDC line still has to be produced, and virtually all power plants of significant capacity are above ground and therefore very vulnerable. The converting plant to turn relatively low AC voltages into the high voltage DC is also large and vulnerable, and for reasons of both space and cooling is invariably above ground.
It might be possible to bury both whole power plant and the converting equipment, but the costs would be vast, and the complications regarding cooling would be undesirable.

That still leaves the other end of the HVDC link. The converting plant is bulky and vulnerable, and the electricity once converted back into AC will be fed into the existing above ground network, none of which is protected against EMP.

Electricity post an EMP event is likely to be on a very small scale from portable generators, PV modules, and vehicles that were stored by luck or by design either below ground or in a well shielded building.

The EMP threat isn't restricted to miles-long conductors. Seems like this solution would only address that narrow definition.


The complexity of DC-AC and AC-DC conversion is significant.

I'm suspicious that the article's author has shares in a company that is planning to push this solution. It might help but there will still be miles of above ground wiring at less than transmission-line levels that can pickup the EMP and wreck much of our semi-conductor containing stuff.

(speaking as an EE with some hands-on experience with EMP resistant equipment)

Wasn't the inefficiency of DC over long distance part of the reason that AC is used most places except vehicles?

Yes, but technology has moved on since then.

DC is not inefficient in itself, the problem is that high voltages are needed for transmission over significant distances to reduce resistance losses but low voltages are needed for domestic and similar use.
Until recently, there was no cheap and simple way to convert one DC voltage to another. Therefore DC had to be produced at low voltages suitable for domestic use, this limited the distance between power plant and consumer to a few miles.

AC by contrast can be generated at medium voltage such as 11,000 volts, and stepped up to very high voltages for transmission and then stepped down near the point of use. Transformers are relatively cheap and simple, have no moving parts, and are suitable for unattended operation.

To change one DC voltage to another, involved until fairly recently, costly and complicated rotating machinery.
Towards the end of the DC era, generation and transmission was usually AC with conversion to DC near the point of use.

DC service was still available in New York until only a few years ago.

These days, modern power electronics facilitate efficient conversion to/from DC and also from one DC voltage to another.
The equipment is however bulky, expensive and vulnerable to EMP.

Thanks for the technical update. My knowledge of DC other than basic circuits was of the Edison/Tesla era.