I am trying to understand how much electricity can be sent over the long-distance high voltage interconnects in the US (not sure if this is what is more relevant to me -- the context of the question is about trying to understand what are the most energy-intensive applications the US electricity grid could support, eg steel production at scale and unprecently large data centers).

My understanding is that typical high-voltage lines for long transmission operate at 155,000 to 765,000 volts and 700A, though could in theory support 4000A.

This means that each line can carry between 100MW and 3GW. Is my reasoning correct? Where can I find better references for the voltage and maximum amperage of transmission lines? Is it typical to have more than one line running in parallel, and how many if so?

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    \$\begingroup\$ @manassehkatz-Moving2Codidact thanks, I tried making this more specific. Is my edit helpful? \$\endgroup\$ Apr 2 at 18:19
  • \$\begingroup\$ Yes, that helps. As a general comment but not exactly an answer, I would note that in the past many industries have developed near inexpensive electric power. In particular, aluminum production has historically been centered around hydroelectric power generation. \$\endgroup\$ Apr 2 at 18:23

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Simple: as much as it's designed for.

Extant examples can be pointed to, but they're just that, examples; they aren't at all fundamental design limits, nor of technology, material or physics.

These examples don't seem very interesting, or useful.

The thing is, we don't simply transmit power for the sake of transmitting power.

We do it because it's the most economical solution, given possible alternatives: including transporting the fuel to a generator somewhere else, or building different types of generation capacity, which encompasses many kinds of tradeoffs.

The resulting solution ultimately affects cost to the end user, which in turn affects what amount and kind of users will settle in or leave the areas fed by that link. Sometimes this isn't a big deal (electrical costs might pale in comparison with other costs of living in an area, which both trade off against general profitability of business in that area), other times it's more of a core requirement (e.g., the predominant operating expense for aluminum smelters is electricity, so they are often placed near cheap and stable sources like hydroelectric).

So the overall problem can become quite involved. And the solution evolves over time: it is a dynamical system extending far beyond mere voltage and current.

The important take-away is that these are complex systems, with myriad stakeholders, and design cycles are quite long indeed -- intentionally so, because they are large and expensive projects, they can't be started half-heartedly, they certainly can't be moved or scrapped on a whim,

I don't know for what purpose you're asking this question, but it seems the sheer capacity of a line isn't a very interesting question. What's really interesting is what drives that choice of line: why it was built, what's at the ends, and what alternatives exist.

There are more than just AC interconnects, as well: HVDC interconnects are a common and powerful solution to long-distance transmission. The largest in the world deliver 10GW or so (Xilin Hot to Taizhou in China, if I've not skipped one; see https://en.wikipedia.org/wiki/List_of_HVDC_projects). As mentioned, fuel can move as well: whether via gas pipeline, traincars of coal, or other means; there are even water transmission pipelines, in certain mountain hydro dam projects, which could be considered interconnects of a sort (albeit usually one way, and very special purpose; there are however bidirectional cases, where a reservoir is used to buffer energy capacity throughout the day). These are national and international scales of power transmission -- likely a nation or federation chooses multiple of methods to meet their energy and fuel exchange needs, and the ratio of them, and the resulting size of pipelines, transmission lines, and other infrastructure, varies accordingly.


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