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European Commission Joint Research Center Technical Reports: HVDC Submarine Power Cables in the World https://publications.jrc.ec.europa.eu/repository/bitstre
by philipkglass 5y ago
European Commission Joint Research Center Technical Reports: HVDC Submarine Power Cables
in the World
https://publications.jrc.ec.europa.eu/repository/bitstream/JRC97720/ld-na-27527-en-n.pdf 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/ https://suncable.sg/
- baybal2 5y agoThere can boosters on the cable
- lxe 5y agoIt's a power cable, not a communications cable.
- baybal2 5y agoThere is nothing preventing them to put more DC-DC up conversion mid-way.
- CyberDildonics 5y agoWhy would you use DC at all, and why would you put something in the middle? I don't think that makes any sense.
- baybal2 5y agoTo up the voltage
- CyberDildonics 5y agoYou 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.
- baybal2 5y agoBecause 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
- bduerst 5y agoWouldn'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_21st_century https://en.wikipedia.org/wiki/Space-based_solar_power#In_the...
- ZetaZero 5y agoI'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?
- wffurr 5y agoA giant cable seems less likely to be able to (accidentally?) be repurposed as a space-based death ray.
- mNovak 5y agoThe 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.
- beambot 5y agoThe 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.
- noja 5y agoHow does it compare to shipping batteries? Is there a way to move batteries efficiently?
- ed25519FUUU 5y agoBatteries 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.
- trhway 5y ago> 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)
- bryanlarsen 5y agoThe 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.
- boibombeiro 5y agoSomething related. Brazil exports more water in form of grains and meat ("virtual water") to China than the huge South–North Water Transfer Project.
- ncmncm 5y agoMaking 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.
- topynate 5y agoI make it as (100%-3.5%)^15 ~= 58.6% retained.
- philipkglass 5y agoThanks, I think your calculation makes more sense. The lower losses should improve the economics.
- mataug 5y agoIs ~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 ?
- Negitivefrags 5y agoThe 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.
- spywaregorilla 5y agoThat's pretty crazy, but a really cool idea.
- mataug 5y agoThat'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.
- disco_nap 5y agoAre 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?
- elil17 5y agoThe 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 https://doi.org/10.1093/gji/ggw195
- phreeza 5y agoI get (1-0.035)^15 ~= 57.5% retained, so even better than what you got, unless I am missing something?
- nuccy 5y agoTotal 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.
- 5F7bGnd6fWJ66xN 5y agoIs it possible to lay fiber optic cables alongside and use the wasted energy to power up the cables for transmission?