

Let's Build a Global Power Grid - bpolania
http://spectrum.ieee.org/energy/the-smarter-grid/lets-build-a-global-power-grid/?utm_source=techalert&utm_medium=email&utm_campaign=073015

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brownbat
Easily missed gems:

 _And superconducting DC cable requires even smaller rights-of-way than does
HVDC with traditional cables._

Some of the biggest obstacles to ensuring grid stability are rights-of-way
fights. There's abundant power just north of NYC in Canada, and NYC has one of
the most fragile grids in the US. A major project to implement the obvious
solution was tanked because of NIMBY fights all along the corridor. The
compromise was to try to build a buried line (under a lake!) at about a tenth
the capacity (essentially not helping) at about ten times the cost. Now Albany
is fighting against the buried line plan too. HVDC doesn't make these problems
disappear, but when you finally get anyone to agree to one thin line, at least
you can transmit a lot of power over it.

* * *

 _Although [supercooled transmission lines] do need to be cooled to liquid-
nitrogen temperatures—below 77 kelvins—the losses from refrigeration and other
sources are less than half those of conventional AC and DC overhead
transmission lines._

Moving power around the country through frozen ice lines, it's like magic in
some unbelievable fantasy novel (ie, the best kind of science).

* * *

 _China, which is now the world leader in the development and deployment of
grid technology, in particular HVDC._

* * *

 _The cost of the generated power with the HVDC supergrid would almost
certainly be much lower than what’s available today because operators would be
able to buy electricity from the least expensive source._

* * *

 _...governments and grid operators will need to agree on the rules for free
trade in electricity. Electricity trading through a wholesale market, perhaps
broken up into regions, would enable the kind of efficient power flows a
global supergrid would offer._

While baking in strong protections against ENRON-style disasters.

* * *

Not mentioned: DC converting stations serve as a firewall for blackouts. Post-
Fukushima, the southern part of Japan's grid was unaffected. It operates on 50
Hz, because it was mostly built on German tech, while the northern grid
operates at 60 Hz, because it was mostly built up on American tech. There's a
massive AC-DC-AC conversion system in the middle. Problems with balance or
shortages don't infect the other part of the system.

[http://www.japantimes.co.jp/news/2011/07/19/reference/japans...](http://www.japantimes.co.jp/news/2011/07/19/reference/japans-
incompatible-power-grids/)

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transfire
Er... no. Just as homes and business that can should be moving to solar and
wind, so too cities should be moving to next generation nuclear.
Interconnected grids to provide redundancy is good, but a global super grid is
unnecessary.

~~~
brownbat
HVDC and long transmission is actually one of the best ways to encourage the
expanded investment in solar farms, wind farms, or nuclear facilities.

Usually greatest output potential is far from people, be it offshore wind,
desert solar, or even nuclear near large lakes for cooling. Hydro or pumped
hydro and geothermal too. If it was easier to move this power from remote
regions to population centers with lower losses, clean power would boom.

The megaprojects cited in the article are extreme versions of this, but we
could build up to those gradually.

Development of better interconnections and long transmission lines even within
countries would be a start, and would encourage better siting for new plants.

[0]
[https://en.wikipedia.org/wiki/Desertec](https://en.wikipedia.org/wiki/Desertec)

~~~
elithrar
> If it was easier to move this power from remote regions to population
> centers with lower losses

Loss isn't really the motivating factor though: at about 330kV transmission
losses are < 3%[1].

Building transmission towers, the land/access corridors, and dealing with the
supporting infrastructure is the biggest barrier by a long shot: it just costs
a lot of money to build terrestrial (power|communications) networks.

[1]: [http://www.e-ijaet.org/media/9I9-DETERMINATION-OF-BUS-
VOLTAG...](http://www.e-ijaet.org/media/9I9-DETERMINATION-OF-BUS-VOLTAGES.pdf)

~~~
brownbat
Current systems emphasize short trips between generation and consumption to
minimize line losses.

Per your cite, Nigeria has a little over 5,000 miles of transmission lines.
The US has over 450,000 miles.
[http://www.naruc.org/grants/Documents/Silverstein%20NCEP%20T...](http://www.naruc.org/grants/Documents/Silverstein%20NCEP%20T-101%200420111.pdf)

Neither of these systems transmit power from one end straight to the other
end, but you can do neat things if you can increase your range.

The losses from AC compound rapidly with distance. There's a good bit here:
[http://www.tinyrevolution.com/mt/archives/003223.html](http://www.tinyrevolution.com/mt/archives/003223.html)

"In aggregate, the example system comprised of Argonne National Laboratory
plus a factory in Nebraska refining corn syrup suffers transmission losses of
785kW, or 0.52%. America is like this. The transmission efficiency looks high
(losses of only 10%) because most of the power we use (normalized to capacity)
travels only short distances (normalized to length). This does not mean that
line losses per distance are low. Mostly it means that the lines are short -
not at all adequate to carry power from North Dakota to someplace useful.

So, this is a nice, simple explanation, but is it true? To test it, this site
has a useful model of an electrical distribution network. There is a little
bit of math ahead, which I only include because I think some readers will like
it.

Following the diagram and the text below it, Ohio Edison operates 5757MW of
electrical power generation (let’s call it 6000MW). The source voltage is
18kV; this gives 300,000A of current in the generating facilities (rounding
for convenience).

The ratio of the step-up transformer to the transmission line is 350/18, which
we’ll call 20. This means that the current in the transmission line is
300,000/20, or 15,000A. Current is stepped down in this manner in order to
minimize transmission losses, but they cannot be eliminated.

In order to calculate the transmission losses, we’ll assume that the
transmission cable used for this application has a resistance of around 0.1
Ohms per km of length. This is at the low end of the range (so the loss
estimate will be low) according to a couple of spec sheets I looked at.

This yields (P=I^2R) 22.5MW lost power per km of length, or 0.4% per km.
That’s 0.6% per mile, or 10% of the total energy lost over a transmission
distance of just 18 miles. After 115 miles, only 50% of the power remains.

