Chile wants to export solar energy to Asia via 15,000km submarine cable | Hacker News Reader

Chile wants to export solar energy to Asia via 15,000km submarine cable

pv-magazine.com

122 pointsphilipkglass146 comments

European Commission Joint Research Center Technical Reports: HVDC Submarine Power Cables in the World

https://publications.jrc.ec.europa.eu/repository/bitstream/J...

According to table 1, losses for 800 kilovolt HVDC systems can be as low as 3.5% per 1000 km. That comes to 52.5% loss over 15,000 km. Losses should go lower at 1100 kilovolts (the highest voltage HVDC systems running today) but I can't find detailed loss numbers on those systems.

At 52.5% energy lost in transmission (47.5% retained), this is still considerably more efficient than making hydrogen via electrolysis, liquefying it for shipping, and then burning the hydrogen in the receiving country to generate electricity.

This particular plan is breathtakingly ambitious and would no doubt cost a fortune. It may appear more attainable when (if?) the similar but smaller Australia-Singapore Sun Cable project gets built:

https://suncable.sg/

There can boosters on the cable

It's a power cable, not a communications cable.

There is nothing preventing them to put more DC-DC up conversion mid-way.

Why would you use DC at all, and why would you put something in the middle? I don't think that makes any sense.

To up the voltage

You said that already, but why would that be a better approach to using a higher voltage from the start or using AC? This isn't exactly an unsolved problem.

Because of voltage drop.

You will have less loss if you correct for some voltage loss midway.

You lose more electricity if your line drops from 1000kv to 600kv than if it drops from 1000kv to 800kv twice, even if you count up conversion losd.

Megavolt range up conversion is rather inefficient (that's why HVDC links real efficiency is notably lower than its transmission efficiency,) but it will still be more economical

Wouldn't you be better of having microwave relay satellites than laying wire?

Test satellites for space-based solar power (SBSP) are already going into orbit as soon as next year:

https://en.wikipedia.org/wiki/Space-based_solar_power#In_the...

I'd be interested in seeing the math. Would multiple hops and satellites be required? What's the power loss for each hop? What's the cost and capacity for each satellite?

A giant cable seems less likely to be able to (accidentally?) be repurposed as a space-based death ray.

The loss on microwave relay is just incredibly high (think >90% power loss), because it goes as distance^2.

Also there's physical limits on how tight the resulting beam of energy can be -- it's not a laser beam, it'd be irradiating 100s m^2 if not km^2 with whatever it's peak W/m^2 is. Also it can't be anywhere near a useful radio band, because interference.

The distance^2 applies, but it's most pronounced for isotropic source (i.e. emitting across a sphere). If you create a tight beam (think columnated laser), you vastly reduces the overall system loss. The bigger problem for microwave links is converting electricity to RF & back -- you get big losses in the amplifiers, radiators & rectifiers.

How does it compare to shipping batteries? Is there a way to move batteries efficiently?

Batteries are not nearly energy dense enough to ship. A ship would need more energy than is even stored in the battery just to make it across the ocean.

> than making hydrogen via electrolysis

i'd say synth gas would be more versatile option. Also they can like Iceland export the energy as aluminum or similar products taking a lot of energy to produce. (and a bit dreaming - i think Andes is the place to build a large rail gun style space launcher, and not just for one launch per week like, i mean large spaceport launching stuff non-stop and this is where beside launch energy you'd need energy to produce fuel for the upper stages)

The viability of synthetic gas really depends on the price of your carbon source. Direct air capture of CO2 is pretty expensive but subsidies can make it work.

Ammonia is the conventional option for long distance shipping of hydrogen. The ammonia can be used directly as the fuel or cracked at the destination for its hydrogen.

Something related. Brazil exports more water in form of grains and meat ("virtual water") to China than the huge South–North Water Transfer Project.

Making synth gas or ammonia would give them a multitude of markets competing for the product, vs. just China at the end of a wire.

But Chile probably needs a lot of capital to build out the solar arrays. A guarantee like that might be necessary to get China to pony up.

I make it as (100%-3.5%)^15 ~= 58.6% retained.

Thanks, I think your calculation makes more sense. The lower losses should improve the economics.

Is ~50% retained more efficient than producing the solar power in Asia itself?

Wouldn't it be better to generate this power in the deserts of the middle east, and the wide open plains of Central Asia and transmit that over shorter distances despite producing less power per solar panel ?

The whole point is that you can generate the power at different times. The deserts of the middle east get sunlight at a different time then South America.

If we had a worldwide spanning power grid we wouldn't need to have a grid storage solution at all.

That's a good point, I can see how this could be better than battery based storage for night time. But I wonder if wind power coupled with some limited battery storage, geo thermal, and newer generation nuclear peaker power plants can solve this problem instead of laying a mega cable under the ocean.

It is not only about night time but also about inverted seasons. When it is summer in Chile it will be winter in China.

Thats fair, but I still think that a 15,000Km undersea cable adds a lot more complexity and cost when compared to diversifying renewable low carbon power generation within Asia

Also the cost of laying that cable is going to be baked into the cost power coming from Chile, and this might make it far less economically viable when compared to adding redundant power generation capacity in Asia.

_Microft linked to a great paper saying that 99.99% reliability can be achieved in 42 different countries using a mix of overprovisioned solar, wind and 3 hours worth of batteries.

https://www.nature.com/articles/s41467-021-26355-z

>nuclear peaker power plants

Is that even a thing? Why would one not run the nuclear plant 24/7 after it has been paid for and constructed?

A mix of power sources and some storage can of course solve this problem. The question is whether it is cheaper (or more desirable for other reasons). An infrastructure of a couple of HVDC lines that are vital for countries on different continents has very interesting geopolitical consequences for example. Imagine the bargaining power a country has if it can literally turn off the lights during the night in another country.

With fossil fuels it is at least easy to store months worth of energy, but still OPEC is quite powerful.

That's pretty crazy, but a really cool idea.

Are the losses thermal? How significantly could this change the ocean temperature near the cable? 50% of 600 GW is enough to cause a 10C increase in the temperature of 10 million liters of seawater every second?

The short answer is that if 10,000,000 L/s of well mixed water passed over the wire, it’s temperature would increase by 0.75 degrees Celsius.

The long answer is that this is not quite the right way to view the question. There will be a temperature gradient around the cable - a zone where water is heated. The question is, how hot is this zone and how large is it. The cable will be buried, which makes the zone larger and less hot. However, this all depends on the type of soil in the ocean floor.

One thermal study estimated that, with typical operating temperatures and burying depths, the sea floor temperature (of the soil, not the water) would heat by 10 to 18 degrees Celsius. This is enough to potentially interfere with ocean life, according to the authors of the study. Because of limits in the operating temperature of cables, a project like this would make a larger zone like this, but the maximum temperature would stay the same.

It’s important to note that we already mess up aquatic life by discharging thermal energy into bodies of water. High temperature water discharge from power plants can make rivers more friendly towards invasive species and shift the balance of aquatic ecosystems. This project might be a net neutral for aquatic life by reducing high temperature discharge into rivers while creating hot spots in the ocean.

Thermal study: https://doi.org/10.1093/gji/ggw195

What about the magnetic field? I think distance is required between the two sides of the cable to prevent arc, which also means there will be a magnetic field.

Negligible. The magnetic field is produced in the space between the conductors, and falls off very rapidly (inverse cube) as you move away from that.

Heat becomes an issue before magnets do. Magnets follow an inverse power law but thermal conduction regimes produce linear temperature gradients. The spacing required for cooling is greater than the spacing required for EM insulation except for very low power flows.

10,000,000 L/s over 15,000 km. That's 15,000,000 meters. That seems quite likely to happen, and then some.

What seems quite likely to happen?

10,000,000 liters per second flowing past the cable.

hmm, 500 gigawatts dissipated over 300k square gigameters of ocean surface gives a forcing effect of 1.6 milliwatts per square meter. Global warming right now is forcing 1w/sqm, so it's not a problem at this scale. But it's not a crazy question either.

It’s not evenly spread, though. It’s concentrated along the cable. It won’t heat up the ocean much as a whole, but it will create “hot spots”, which may change the balance of ecosystems in the regions of the ocean the cable passes through.

Worth it to stop carbon emissions? Absolutely, in my opinion.

Something that should be considered and minimized if possible? Also yes.

That's a good point. 500 gigawatts over 15 megameters gives 20kw/m of local heat to deal with, which sounds kind of yikes.. but then again a pool heater draws 5kw. Seems clear the biggest effect will be on the seabed-- but that's already true because you gotta drop the cable. I reckon the cable itself, and its underwater infrastructure, might have more impact than the heat it generates. Another consideration is that there have always been heat sources in the deep ocean.

I get (1-0.035)^15 ~= 57.5% retained, so even better than what you got, unless I am missing something?

Total losses in case of 1100 kV line can be found as follows. As correctly commented below 3.5% loss per 1000km yields to 58.6% retained power over 15000km. So I will use 41.4% loss on that distance for my napkin calculation.

P_total = V_in * I_in, and P_loss = (V_in - V_out) * I_out

Since the charge flowing into the cable should exit on the other side I_in = I_out, then:

1 - V_out/V_in = P_loss / P_total = 0.414, and V_out = 0.586 * V_in = 468kV.

Voltage drop in 800kV line: V_in - V_out = 314kV = I * R (since lossses in DC lines are mostly due to heating, unlike AC lines where there is also capacity induced resistance).

Assuming that the same wires are used to transfer 1100kV DC current (i.e. resistance is the same) we can outline two cases:

A) you want to transfer the same inflow power on the Chilean side, then the voltage drop would be a 800/1100 fraction in comparison with 800kV line, i.e. V_in - V_out (1100kV case) = 314 * 800 / 1100 = 228kV. So the total loss is 20.7% (1.54% per 1000 km)

B) you want to transfer the same outflow power on the Asian side (i.e. smaller current due to lower voltage), then the voltage drop would be 162kV (there is a simple quadratic equation, if instead of considering inflow powers, one considers outflows which depend on V_out), so the total loss is 14.8% (1.06% per 1000 km)

Summary: same (as in 800kV line case) inflow power on Chilean side - 20.7% loss, same outflow power on the Asia side - 14.8% loss.

Is it possible to lay fiber optic cables alongside and use the wasted energy to power up the cables for transmission?

What percentage of power is lost to line-loss at those distances? And if you are going to cover long distances you usually push up to 750kV or more: how long before there's an insulation breakdown somewhere along your 15,000km and you get some very energetic arcing and sparking underwater? Not to mention that it makes for an interesting asset to target (though only a few nations have the "tools" to attack power cable on the sea floor).

It's on the order of 1.5%/1,000KM, so something like 20%-25% loss.

Edit: a Chinese project with a 1.5%/1,000KM loss http://en.people.cn/n3/2018/0622/c90000-9474097.html

So the cost (price) of energy in the other end (china) should be 25%+ (plus the expected ROIC) to make this endeavor worthwhile

Also the cost of the infrastructure financing and depreciation - which I would imagine would be significant. But maybe not? Does anyone know what something like this would cost? I'm imagining A LOT.

Chile is among the best places in the world for solar power, projects are being completed with power guarantees at costs under $0.03/KWh -- a 25% increase or even 50% increase would be pretty cheap power, according to the EIA still at least 1/3 cheaper than electricity from an incremental advanced nuclear plant.

https://www.eia.gov/outlooks/aeo/pdf/electricity_generation....

Wikipedia gives 3.5% loss per 1,000 km as a ballpark figure.

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

Based on this [1] citation from the HVDC article on Wikipedia, losses are about 3.5% per 1000 km at 800 kV. That would correspond to losses in the range of 40-50% for the 15,000 km cable in question.

[1] https://en.wikipedia.org/wiki/High-voltage_direct_current#ci...

One challenge will be to get enough supply of submarine power cable to make this a reality. The Morocco-UK proposal (mentioned in the bottom of the article) involves the UK company literally setting up a new factory specifically to produce more cable, doubling the global output in the process. And that project is about 4000kms or so compared to 15,000 for this one. So supply will be slow to spin up to those levels.

Well, luckily Chile is the largest copper producer in the world

I'm curious about this from a security perspective.

With oil, coal, and natural gas, a cut in the supply network doesn't necessarily have an immediate impact. Buffers exist in some parts of the distribution network: ships holds, rail cars, and storage tanks.

With electricity, it doesn't seem like we have much infrastructure for buffering the supply. So cutting those cables might have an immediate and significant impact on the consumers.

Perhaps this creates a disincentive for any of these powers starting a war. But it also seems like an extra attack surface for terrorism, extortion, or natural disasters.

For one, the power cables seem to be thicker and better shielded than the fiber optic ones.

That aside, I don’t think any economy will rely purely on imported power - backups in the form of natural gas plants or grid scale storage will likely need to form part of the mix - there’s already the chance of some cloudy or rainy days over the solar farms, so it’s unlikely there isn’t a contingency.

There was a study recently that used historic weather, solar irradiance data and energy use data and worked out that a certain mix of (over-provisioned) solar, wind and 3 hours of storage would have sufficed to provide energy during almost all hours of the studied decades.

https://www.nature.com/articles/s41467-021-26355-z

I'm not sure where you're getting that "almost all hours" from? Here's the relevant figure, which seems to indicate hundreds to thousands of hours under your given scenario:

Please note the logarithmic scale on the hours!

https://www.nature.com/articles/s41467-021-26355-z/figures/4

(Note the green lines are 1.5x generation, with three lines at different saturations for 0 hours, 3 hours, or 12 hours of storage.)

Thanks, I'll have another look!

What you say makes sense to me. OTOH, I get the impression that some of our infrastructure has a financial incentive to eliminate any reserve capacity. E.g., that snowstorm in Texas last(?) winter.

So I'm curious if having any non-trivial amount of electricity supplied by a usually-reliable mechanism becomes a long-term risk.

There's actually some automatic de-risking with renewables because of their semi-unpredictable nature. If you have a coal, gas or nuclear plant that runs reliably, some executive will get a bonus if they cut costs by shutting off all the redundancies.

If you cost-cut redundancies with renewables, though, you'll hit a cloudy or non-windy day before bonus time comes around, and then you'll have a new executive who gets a bonus if they have reasonable redundancies.

So there's some resiliency that comes from intermittent renewables, like having a chaos monkey always running on the grid.

They would need to be thicker and better shielded. Sharks might very well be attracted to any EM generated and attempt to bite the cables.

https://www.oafrica.com/broadband/sharks/

Still sounds fairly fragile, but no more vulnerable I suppose than undersea fiber optic cables. But there is no alternative routing or satellite backup in this power transmission case.

Pretty much, destroying pipelines on sovereign soil vs destroying infra in international waters are different risk exposures. Especially one that crosses multiple jurisdictions.

I think that any country using links like this ought to have emergency backup power systems. I think this is actually a reasonable use of coal and/or natural gas: keep the infrastructure maintained and have it ready to take over if there's an emergency, but otherwise it sits idle. In most cases you wouldn't even have to build new plants, you'd just keep the old ones around that were displaced by renewables. (Though over time you may need to build additional plants as electric usage grows.)

Ideally you'd have some sort of international agreement that any fossil fuels used would be subject to a high carbon tax, so there'd be less temptation to just declare an emergency for no reason. But that would require more international cooperation on climate than what we've seen so far.

> The cable should be about 15,000km long and building a 1,300km cable would cost $2 billion.

For being able to time-shift solar, that seems like a bargain. A recent internet undersea cable[0] cost $300 million for the entire project.

[0] https://www.computerworld.com/article/2939316/googles-60tbps...

This idea has been floating around for a long time, I first encountered it as https://www.desertec.org/. It's great to see an ambitious project that would test the viability further.

There was a proposal to connect north Africa to Europe with HVDC lines, that seems a lot more feasible being only ~2000 km: https://en.wikipedia.org/wiki/Desertec#High-voltage_direct_c...

It's also a more compelling story when the connection is part of a "super-grid" that blends disparate energy sources from many countries, as this could even out a lot of the local fluctuations that make renewables challenging, and as other commenters here have noted, even better if you can pull solar from another timezone when your local solar cells are not producing anything.

Given the level of infrastructure investment that China is deploying currently, it wouldn't surprise me to see many more projects like this emerging. (Though China has enough territory that they could reap the gains of HVDC-connected renewable generation without necessarily involving other countries.)

Casey Handmer calculated that it was cheaper to produce solar power in Boston for local use than it was to ship solar power from Arizona to Boston.[1] Solar power is 3X as expensive to produce in Boston, but HVDC lines are even more expensive.

If it's uneconomical to ship from Arizona to Boston, then Chile to Asia seems even more problematic.

Although in this case the submarine HVDC line is competing against batteries since Chile and China are in different hemispheres. I hope with they have an accurate prediction for battery prices in their business plan, because the prices of batteries are dropping precipitously.

1: https://caseyhandmer.wordpress.com/2020/12/27/the-future-of-...

Source for cost is this document published in 2014 https://iea-etsap.org/E-TechDS/PDF/E12_el-t&d_KV_Apr2014_GSO...

I have no idea whether those are still reasonable estimates, just wanted to point to a possibility of price improvement.

Casey is doing a green methane startup which depends on cheap solar for its viability, so I'm sure he has more accurate numbers, at least privately.

The question is more of "when" than "if" his calculations are correct, since solar power prices are coming down a lot faster than HVDC line construction costs.

It appears that Casey's source is this $40/MWh project being built by 8 Minute Energy, so he has 2020 numbers.

https://www.energy-storage.news/news/developer-8minute-says-...

I think the chile to asia is going to be cheaper than AZ to Boston because there is just ocean between chile and asia. It will be much more expensive over land and dealing with all the things in the way (roads, houses, railroads, tunnels, mountains...).

One option would be to go along the shoreline of the Gulf of Mexico and across Florida, then up along the coast.

The articles have the cost at $1000/km for overland and $1500/km for undersea respectively.

Yeah but as others pointed out, you can't produce solar power at night, no matter how costly the transmission is compared to local panels. Chile can produce solar power while it's nighttime in China.

A big part of Casey's calculations are the cost of batteries. Batteries are expensive, but not as expensive as HVDC lines.

Doesnt China have it's own supply of deserts a bit closer to home?

Part of the idea is that the producer and consumer of the energy are on opposite hemispheres and at different longitudes. That means when its winter in China, it is going to be summer in Chile. There is also a considerable time difference between the places which helps to supply electric energy via solar power even while it is night in China.

Honestly it's kinda brilliant. With a big enough global network of overbuilt solar capacity you would avoid the problems of the duck curve and weather limitations.

It's hard to build an actual network out of DC power, which is partially why AC power took over.

It was hard to build a DC network in 1900. It's easy today with modern power electronics, which Nikola Tesla didn't have. In fact building a DC network is somewhat easier than AC now because phase-matching is unnecessary.

Looks like DC power is more efficient for long haul cables.

https://engineering.stackexchange.com/a/19759

That's a good link.

Summary: DC is always a bit more efficient than AC. The reason our grid is AC is because high voltage transmission is much more efficient than low voltage transmission.* But you don't want multi-thousand volt feeds coming into your house, so voltage conversion is necessary. If you don't have power electronics, you have to use magnetic transformers to convert between voltages, and magnetic transformers only work on AC. Thus our electric grid is mostly AC.

Now that we have power electronics we can convert voltages without magnetic transformers, and AC is no longer a requirement except for backward compatibility.

*unless you have superconducting cables

I was immediately thinking about early morning in Asia, still dark outside, everybody puts the kettle on.

If these long distance cables really can transport energy efficiently it might solve some of the challenges with renewables!

> I was immediately thinking about early morning in Asia, still dark outside, everybody puts the kettle on.

In the UK they actually have to plan for grid demand to skyrocket during ad breaks in certain TV shows because half the country puts the kettle on at the same time! In one episode of EastEnders, demand grew by 2290MW, nearly twice as large as any single UK nuclear reactor.

https://www.mylondon.news/news/zone-1-news/iconic-eastenders...

The UK have 3000W kettles whereas in North America is stuck with 1500W kettles.

Many kitchens in North America have 20A outlets, which should at least let us use 2000W kettles. Why won't anybody sell me a 115V/16A kettle with a NEMA 5-20 connector?

Presumably it would be very useful to China to be able to buy power during their night time. It might also be beneficial to Chile to be able to buy power from China when the situation is reversed. Better interconnections mean you can get more benefit from cheap solar and don't have to rely on batteries.

Dammit, the sun is my battery! and the earth's tilt, spin and orbit is my load balancer!

Wouldn't it be better to induce foreign investors to set up shop in Chile to take advantage of the really cheap and abundant electricity?

Manufacturing supply chains in East Asia far outpace those in South America, and extending those across the south Pacific just to get access to cheap electricity does not seem economical.

If electricity is all they need yes. But if we are talking about labor and source materials and export supply chain, then nothing (currently) beats China.

Not to mention water, which is generally needed for business but which the Atacama desert doesn't have much of.

https://www.mining.com/water-rights-under-scrutiny-in-chiles...

Doug Stewart, now at VEIR (veir.com), had a company (Wattershed) that was doing undersea HTS cables about a decade ago. I think their first deployment was going to be inter island in Hawaii?

Either way, this doesn't have to be hyper efficient. It just has to be better than "get lots of batteries". Like others, I'm more worried about redundancy / operational concerns than about power loss.

Hopelessly naive, I know, but shouldn't there be a global grid to optimally distribute electricity from solar irradiation rather than laying idiotic lengths of cable for political reasons?

You want to connect the Pacific rim for that grid to work but I can easily imagine some intermediate "links" that seem to make more sense

There isn't even a nation-wide electrical grid in the USA. Having a global grid is a futuristic pipe dream.

Not a pipe dream because it is futuristic, but because it is geopolitical.

> Having a global grid is a futuristic pipe dream.

It's more like a series of tubes.

If we condition on people taking the energy transition seriously the past might not be a good predictor of the future. But whether there will be a strong pull towards "optimality" might depend on what is the total cost of sub-optimal alternatives. I would think that a well distributed grid would also minimize (beside losses) also storage costs and would also have various other redundancy benefits...

The US doesn't have a nationwide grid because of the technical requirement to use AC back when electrification happened (which requires phase matching or DC intertie between subregions), and because of the politics of who regulates the grid (which is why Texas still has its own grid.)

The AC requirement is a legacy historical issue; a nationwide DC grid could be built in the US tomorrow if the political issues could be solved (and if it made economic sense to rip out the legacy AC infrastructure, which it doesn't.)

Current gang in Canberra/Washington would never do a joint infrastructure project with Beijing, so that Chile might as well go directly there.

If they can agree on carbon emissions, they could probably agree on some coordinated infrastructure. (It doesn't actually have to be common, rather coordinated.)

I am sure if politically unencumbered engineers were to sit down they would come up with more or less the same topology...

For sure. But PRC is the undisputed king of large scale infrastructure development in the 21st century, so that would be tantamount to Washington taking a back seat in a Beijing-driven project. Totally unacceptable optics.

It would seem to be more useful to connect more than just Chile and China (greater diversity of buyers and sellers of electricity), but maybe if China plans to consume the entirety of the cable's capacity, maybe a single point-to-point link actually does make the most sense in this case.

On the other hand, it's possible the cable will be under-utilized for half the day: when it's night time in Chile, they could buy power back from China, but will China have enough surplus? And is there enough demand in Chile (or its neighbors) to buy that much power?

Energy exporting will be an interesting business opportunity from now on.

With the deprecation of fossil fuel, majority of the nations on earth wont have the dirty, but easy option, any more. The clean energy tech is still way out of reach for most of these countries.

Building electricity transmission appears an easier option. It's easier in the sense that almost everyone knows how to build and mange them, to some degree. But it will still be very costly.

And if things go well, Africa might becomes the new source of electricity for its abundance of sunlight. Of course, like right now, they don't have any tech yet...

> between 200 and 600 GW of photovoltaic generation capacity

... they do that across the pacific with HVDC; would that be a viable "earth braking system?" Daylight savings with teeth.

I dont think this makes much sense - even if the fundamental premise (sending solar energy under thousands of kilometers at massive initial and maintenance costs) had immediate economic merit, there are closer places like Australia.

Even then, the fundamental benefit of solar energy is it's distributed nature. With something like nuclear power, however, there might be more use...

I believe the purpose of this is to generate solar power at night. Australia won’t help China there since it is in a nearby timezone.

Australia already has a plan for this in the works to supply Singapore with solar from the outback. It’s called Sun Cable - see: https://suncable.sg/

What's strange about all this to me is the whole "duck curve" that we've heard so much about doesn't seem to be factored in. Or if so, perhaps I've misunderstood it.

My understanding is that peak solar is maybe 10-4ish but peak demand is 3-9ish. Doesn't that mean you'd prefer to make investments ~5000mi (5 timezones) west of your main territory?

Here in the US you could do a lot having the west coast pick up a lot of the evening demand for the east coast, but then you'd need floating solar/wind or whatever to pick up the demand for the rest of the country as the sun continues to head west.

China had presented its concept of a Global Grid to the UN in 2015. (https://reconasia.csis.org/global-energy-interconnection/). They already have a ~3,200 km line at 1100KV UHVDC (https://www.reuters.com/article/china-power-transmission-idU...) Losses are estimated at 1.5% per 1,000km. 3.5% is for 800KV UHVDC. Implies a 23% loss for 15,000 km, which is very efficient. For perspective, ~20,000 km is the half circumference at the equator. Geopolitics should not be a concern for such a global grid. We are already living with a globally interdependent submarine internet cable, in the same geopolitical environment. This transmission line is a natural step for a much faster adoption into a renewable future, than batteries. In battery tech, research investments have to compete on multiple pathways for the development of battery chemistry which are very divergent from each other. UHVDC components and technology require very few fundamental breakthroughs in science and technology, and massive strides have already been made. A good read from ABB on the state and evolution of UHVDC technology here -> https://library.e.abb.com/public/db368ad7692f4c129637d9a7eff.... Do read the last two paras – “Conclusion” and “State of HVDC system and transformer technology”. TLDR: HVAC/UHVAC and HVDC/UHVDC are now almost fully interoperable to feed into each other at all voltage levels. Dielectrics supposedly the most complicated of the technology challenges also appears solved. With global political coordination, it should be easy to commit investments and policy frameworks to rapidly transform the world into a renewable reality.

Interesting.. i thought it wasn't a good idea, based on this video (The Problem with Solar Energy in Africa, https://www.youtube.com/watch?v=7OpM_zKGE4o) where is stated that Europe failed to do something similar connecting the North of Africa (Morocco and Algeria) to Europe (south of Spain).

I would have assumed corona discharge would be worse in sea-water & made this basically infeasible. The air or sea-water around such high voltage cables gets ionized, even if a strong insulator is used (via quantum tunneling?). I would have thought this effect would be worse in sea-water but perhaps not.

Sea water is highly conductive, with potential close to ground, so the high potential cable cannot be allowed to touch it. So the cable has to be well insulated from the water. Discharge can happen in this insulation, that's why it has to be thick enough.

Projects like this would be easy if we had cheap high-temperature superconductors. Until then it's gonna be very expensive because it will require very high voltage (which means very thick insulation) and high I^2R losses -- even with the high voltage -- just because of the distance.

"global supply capacity of these cables is estimated at 4000 KM/p.a" https://youtu.be/iJunxkln578?t=423 seems like a bottleneck.

I went a little ways down the rabbit hole.

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

https://en.wikipedia.org/wiki/List_of_HVDC_projects

Seems more efficient to desalinate water using solar and export it to China

A 15,000km water main would be quite an achievement too.

Transport of water seems to be more expensive than building the cable and desalinating the water in China...

Why not turn it into microwaves and bounce it via mirrors in orbit? Those cables are super expensive and there is a current shortage of cable manufacturing capacity globally.

Less efficient; and it'd be an incredible weapon if it accidentally wandered off path.

inverse square law

That applies to omnidirectional broadcast of power rather than beams.

You can't make a perfectly straight beam due to imperfect optics (and diffraction/Huygens principle), so a beam will only reduce the loss by a constant factor, but the area of the beam still increases by n^2 as it propogates.

No, EM radiation beam still obeys inverse square law.

The power loss when talking about cables is considered to be quite a bit at about 50% from napkin calculations.

The power loss of beamed microwaves is a bit more. https://doi.org/10.1016/j.egyr.2020.12.026

> Finally, the simulation of the long-distance high-power MWPT system can achieve 8.5 kW DC power with about 1% DC–DC transmission efficiency at the operating 2.45 GHz frequency and the 10 km distance away.

For sure, significant power loss. However, given the unavailability of submarine power cable manufacturing capacity [1], perhaps something is better than nothing?

[1] Xlinks has to manufacture its own cables, each 3,800km for this project due to insufficient global production capacity. https://xlinks.co/morocco-uk-power-project/

They have just overlooked that China has a solar area which is comparable (or just a tad inferior to Chile's).

Gobi Desert.

It's far easier to harness solar there and then push it onto the coast than building a 15,000km submarine cable

Gobi dessert doesn't produce solar power when it is night in China, but solar power from Chile can supply China at night.

Gobi is famously dusty, is that a factor? Also a lot of Chile is at high altitudes (thing Atacama), are PVs more efficient there?

I don't think altitude affects efficiency, but it does effect the light intensity, particularly in ultra-violet.

Most electricity is consumed in the early evening and during the winter. That's why such a cable would make sense because of the time difference and the inverted seasons.

Isn't cheaper turn the electricity into liquid hydrogen?!

Hydrogen can be stored for months, delivered by car, tubes, ships, etc

Do not have many losses across long distances

Not only are the hydrogen production facilities quite expensive, there is a huge loss in producing hydrogen from electricity and back. Also storage is expensive and has energy losses due to the compression work. And you need to transport the hydrogen over large distances. For the same amount of energy to be put into the Asian grid, you need at least 2-3x as many solar cells, if you go via hydrogen.

Electricity to hydrogen followed by conversion to liquid and cryogenic transport is about 65% lossy. That doesn't mean you would never do it given cheap enough input electricity but it's not the easy answer.

> Isn't cheaper turn the electricity into liquid hydrogen?!

Creating hydrogen is about 80% efficient, so you do lose a fair bit in the process.

> Hydrogen can be stored for months, delivered by car, tubes, ships,

That's the thing about hydrogen, it's tricky to store for long periods of time. It leaks real easy. And liquid hydrogen isn't very dense, about 7% of that of water, so it's hard to ship it in bulk. And at the point you're piping it, well you may as well just pipe the electricity direct.

And if you do store it, it has a nasty tendency to weaken it's container.

That tendency is usually exaggerated. At LH2 temperature and atmospheric pressure, it is not a problem. You get such troubles storing H2 at high pressure and temperature.

> isn't very dense, about 7% of that of water

That's not a good metric. Hydrogen has about 2-3x energy density per mass vs carbon fuels. H₂ is about 120MJ/kg, while carbon fuels are about 35-55 MJ/kg, gasoline/diesel is 45 MJ/kg.

Per volume, gasoline - 34 MJ/l, liquid methane 22 MJ/l, liquid hydrogen 8.5 MJ/l. Much smaller, but not laughable 7% (14x).

Chile has big plans to export green hydrogen and green ammonia as well as doing this.

Presumably once you ship some amount to the same location, the cable starts to make sense.

Governments should stick to governence and stop doing stupid shit.

Like what? Without government doing infrastructure probably most people would not have a electricity,water and a decent road in front of their home.

Or how would we imagine an alternate reality where the governments are weak, so the industrial billionaires would be the ones deciding what infrastructure to build, what science to research, what level of education is needed etc. I can only see just a few roads , with taxes on them, electricity only in the city, education and hygiene only for the rich(in fact there were governmental/king laws that forced people not to shit everywhere).

Imagine a power generation company run by Joe Biden with his white House staff vs Elon Musk with his Tesla staff. Which stock would you buy? I bet the Biden company will go bankrupt in a few years let alone go public.

Modern career politicians like Joe Biden are cut from a completely different cloth than the leaders that actually built America's infrastructure in the mid-20th century.

Do you really believe they will be going out there, researching, designing, and implementing anything?

They are policymakers and all their job entails is making choices. That's it. And when you are in a country and the options you present has a huge effect on that country, then the government's job is to represent the people in making the choice do either do it or not do it.

Then there are the lifelong politicians, those are mostly useless and more comparable to entertainers in an endless gameshow. It's the result of decades of min-maxing and targeting the lowest common denominator.

You mean Elon companies that have received a ton of money from various governments? Without the government Elon would make cars for rich kids only.

If only the government had helped Boeing and Ford, they could be as successful as SpaceX and Tesla.

First of all I said "goverments" so I don't meant he USA one n particular, Tesla made a lot of money from other goverments too.

Second, the US government from my understanding is doing an pretty open bidding, so SpaceX benefited from that, the reason no SpaceX appeared before is not something I can speculate , maybe there was a need for a new generation of people , or maybe we needed IT to evolve, I am not sure.

I also have no idea if SpaceX would ahve existed if they could not have benefited until now and from now on on government contracts.

Also let's not pretend to forget that SpaceX internet stuff is based on government research/invention. No government no roads for Tesla to run on, no Internet for Starlink to exist.

Reply on news.ycombinator.com