The Future Electric Grid: How HVDC Could Transform the U.S. Power System

[thackney]

The Future Electric Grid: How HVDC Could Transform the U.S. Power System
https://www.powermag.com/the-future-electric-grid-how-hvdc-could-transform-the-u-s-power-system/
August 2, 2021

...One project that is basically doing what Bloom suggested is the SOO Green HVDC Link. SOO Green is a company owned by investment funds managed by Copenhagen Infrastructure Partners, Siemens Energy, and Jingoli Power. The SOO Green HVDC Link will connect the company’s converter station in northern Iowa to its Illinois converter station just west of Chicago, roughly 350 miles away (Figure 2). It will use paired 525-kV cross-linked polyethylene-class cables installed underground primarily along existing railroad rights-of-way to make the connection. Minneapolis, Minnesota-based Direct Connect Development Company is heading the project.



During the ARPA-E session, Trey Ward, CEO of Direct Connect, provided specifics about the project. “[SOO Green] is the first transmission project in the U.S., that’s going to be co-located underground along railroads and highways for its entire 350-mile route. So, we don’t need eminent domain to secure right-of-way for our transmission line,” he explained.

“It’s just two slender cables that are buried in railroad right-of-way, and each cable is no bigger around than a wine bottle. So, it’s really out of sight and out of mind. And what this does is it avoids landowner opposition, and it expedites the permitting because there’s no avian or viewshed impacts....

[IsailedawayfromFR]

From article

In the long term, however, Bloom suggested a well-conceived plan for the future would be crucial. “We’ve got to figure out how we [can] use our land more efficiently, and whether that’s transportation right of ways or existing transmission right of ways that could have more throughput, we really need to open up these opportunities and take some really progressive approaches to how we do transmission planning, and kind of [emulate] how they do transmission planning in the rest of the world,” he said.

This appears to me to be setting the stage for major force majeure issues in order for these proponents to get what they want.  Here's comes the government once again to decide what is best.

[thackney]

I would hate to be the backhoe operator that dug into that.  But probably has some decent protection and warning.

[rustynail]

And your phone can be charged by walking near the line?

[thackney]

And your phone can be charged by walking near the line?

Nope, no magnetic field.  Needs alternating current to generate.  Which is also what HVDC expensive to step down to lower voltages; transformers will not work.

[Kamaji]

What happens when a railroad right of way comes to a substantial water barrier?  The trains themselves can usually just waltz across a simple bridge across the river; will the cables simply be strung along the underside of the existing bridges?

[thackney]

What happens when a railroad right of way comes to a substantial water barrier?  The trains themselves can usually just waltz across a simple bridge across the river; will the cables simply be strung along the underside of the existing bridges?

Perhaps, or installed below or on the bottom of the water depending on span and depth.  Submarine cables on long and deep stretches have been in use for a long time.

[Fishrrman]

Wait until a train derails and plows up the right-of-way.
Particularly if it's a unit oil train, or one that's carrying hazardous (and inflammable) chemicals...

[IsailedawayfromFR]

Wait until a train derails and plows up the right-of-way.
Particularly if it's a unit oil train, or one that's carrying hazardous (and inflammable) chemicals...

It do happen


http://youtu.be/-tckExX0lKw

[Elderberry]

Nope, no magnetic field.  Needs alternating current to generate.  Which is also what HVDC expensive to step down to lower voltages; transformers will not work.

DC generates a Stationary Magnetic Field that will only induce a current in a "Moving Wire". So you'd have to move the phone around and around and around to charge it up.

To step down the voltage you'd have to use inverters or motor generators.

[Elderberry]

High-voltage direct current

https://en.wikipedia.org/wiki/High-voltage_direct_current

Comparison with AC

Advantages

A long-distance, point-to-point HVDC transmission scheme generally has lower overall investment cost and lower losses than an equivalent AC transmission scheme. HVDC conversion equipment at the terminal stations is costly, but the total DC transmission-line costs over long distances are lower than for an AC line of the same distance. HVDC requires less conductor per unit distance than an AC line, as there is no need to support three phases and there is no skin effect.

Depending on voltage level and construction details, HVDC transmission losses are quoted at 3.5% per 1,000 km, about 50% less than AC (6.5%) lines at the same voltage.[23] This is because direct current transfers only active power and thus causes lower losses than alternating current, which transfers both active and reactive power.

HVDC transmission may also be selected for other technical benefits. HVDC can transfer power between separate AC networks. HVDC powerflow between separate AC systems can be automatically controlled to support either network during transient conditions, but without the risk that a major power-system collapse in one network will lead to a collapse in the second. HVDC improves on system controllability, with at least one HVDC link embedded in an AC grid—in the deregulated environment, the controllability feature is particularly useful where control of energy trading is needed.

The combined economic and technical benefits of HVDC transmission can make it a suitable choice for connecting electricity sources that are located far away from the main users.

Specific applications where HVDC transmission technology provides benefits include:

•   Undersea-cable transmission schemes (e.g., the 580 km NorNed cable between Norway and the Netherlands,[24] Italy's 420 km SAPEI cable between Sardinia and the mainland,[25] the 290 km Basslink between the Australian mainland and Tasmania,[26] and the 250 km Baltic Cable between Sweden and Germany[27]).

•   Endpoint-to-endpoint long-haul bulk power transmission without intermediate 'taps,' usually to connect a remote generating plant to the main grid, for example the Nelson River DC Transmission System in Canada.

•   Increasing the capacity of an existing power grid in situations where additional wires are difficult or expensive to install.

•   Power transmission and stabilization between unsynchronized AC networks, with the extreme example being an ability to transfer power between countries that use AC at different frequencies. Since such transfer can occur in either direction, it increases the stability of both networks by allowing them to draw on each other in emergencies and failures.

•   Stabilizing a predominantly AC power grid, without increasing fault levels (prospective short-circuit current).

•   Integration of renewable resources such as wind into the main transmission grid. HVDC overhead lines for onshore wind integration projects and HVDC cables for offshore projects have been proposed in North America and Europe for both technical and economic reasons. DC grids with multiple voltage-source converters (VSCs) are one of the technical solutions for pooling offshore wind energy and transmitting it to load centers located far away onshore.[28]

[Kamaji]

Wait until a train derails and plows up the right-of-way.
Particularly if it's a unit oil train, or one that's carrying hazardous (and inflammable) chemicals...

Good point.  Mix in the flammables with huge voltages, and that's a recipe for disaster.

[thackney]

High-voltage direct current

https://en.wikipedia.org/wiki/High-voltage_direct_current

It comes down to cost and is an issue of distance between substations.  It is good for moving power a long distance and expensive for servicing multiple locations. 



Even more expensive when buried lines versus overhead.

That is why there are few HVDC lines in the US but common for connecting grids across large bodies of water.

[thackney]

DC generates a Stationary Magnetic Field that will only induce a current in a "Moving Wire". So you'd have to move the phone around and around and around to charge it up.

Insulated cables at 5kV and above are shielded by code.  Combine that with buried in the ground is going to make it very limited effect, but yes, I was wrong, only thinking about the ability to transfer power.

To step down the voltage you'd have to use inverters or motor generators.

I believe all of the HVDC lines use inverter type technology to utilize the power at lower voltages.