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US Army deploys its first floating solar array (theverge.com)
178 points by imartin2k on June 17, 2022 | hide | past | favorite | 253 comments



Water surfaces are a great place for solar farms (the water provides cooling which improves efficiency), but the real deal are open sea platforms, not lake-based. The engineering challenges seem big, though, I'm aware of only one company deploying those successfully.

But it has promising potential: seas form the majority of the globe's surface, and solar sea platforms seem to be, perhaps surprisingly, biodiversity hotspots. Any solid structure in the ocean will attract dwellers, but those platforms also seem very popular with fish gathering underneath in large numbers.


Offshore solar also neutralizes one of solars biggest downsides which is that is uses far more space than traditional generators. Land will only continue to get more expensive so I suspect this will actually become a problem at some point, especially in high density countries.


There are many large arid, desert-like land available in almost every part of the world which can be put to use for Solar. I don't think cost of land is a huge issue.


Well, ideally you want to produce the electricity close to where it's needed, and a significant proportion of the world's population lives in coastal areas (much more than near deserts I suppose).


This. You can't produce all of the worlds electricity in deserts and ship it around the world


Why not? Australia is going to be exporting its solar power to Indonesia through a 2,800 mile direct current cable[1]. Thats approximately the width of the mainland united states. It won't be as efficient as generating it nearby but if its already commercially viable then it will only become more viable as solar becomes cheaper and more abundant.

[1] https://en.wikipedia.org/wiki/Australia-Asia_Power_Link.


COuntries will be looking to become energy independent, especially with the russia fiasco Europe is facing. At the very least they will try to make sure a majority of their energy isn't imported from one country.


Don't tell me what I can't do!

HVDC transmission losses are only around 3.5% per 1000km.

So you could get around 80% of the energy you produce in Mali to Norway. Doesn't seem so bad.


Furthermore, there is strictly negative benefit to siting solar farms in deserts. It makes them run hot, thus less efficiently, and shortens their lifetime.

Siting solar on farmland increases farm yield and cuts water loss.


There's a proposal to use solar power in the desert to create pure Hydrogen gas via electrolysis, then fill autonomous blimps with that hydrogen to ship it to where energy is needed. You wouldn't want to fly over populated areas, but otherwise seems like a feasible idea to transport that solar power.


For that you'd need to use kilotons of water a day, which is usually hard in a desert.

It could work on an arid sea shore though, say, in North or South Africa. But there seem to be closer-by large consumers, and maybe producing freshwater would bring more value than producing hydrogen.


> you'd need to use kilotons of water a day, which is usually hard in a desert

North Africa, India, Australia and other have deserts right next to the ocean.


There is absolutely no need for deserts to site solar farms, so the premise is nonsense.

Solar farms are wholly compatible with agriculture. Look up "agrivoltaics".


There are currently experiments in europe, to combine the too. Turns out alot of plants just need 2 hrs of sun and shut down after too save on evoparation. Meaning 35 % of the sunlight needed and the rest as solar seems feasable.


As a thought experiment I once imagined electric trains running between populated areas and desert solar farms. Maybe they carry "green hydrogen" or perhaps just big batteries. After a few minutes and a good chuckle I moved on.


We have these 'electricity trains' already in a sense, but they are tractor trailers containing fuel oil. It's not as crazy as it sounds, but there are better solutions available.


Usually, the issue with this kind of thing is that

* this is a form of energy transmission that requires labor for the actual transport (the train crew) and so is automatically much more expensive and difficult than a dumb pipeline or power line which requires much less staffing

* it's hard to create energy storage that isn't also a bomb in the wrong conditions, and train tracks pass through populated areas. Fuel already has restrictions on where it can be routed because there have been fuel train explosions.


You very much CAN send electricity long distance and there's been serious discussion of providing electricity for Europe from north Africa.

Producing hydrogen near the ocean and shipping it on a tanker is another realistic alternative.


There were huge projects started to site solar farms in Africa, serving Europe.

They collapsed. The reason they collapsed was that there turns out to be less than zero value in siting solar farms in the desert, and solar panels have got so cheap that you do better posting more of them nearby instead of paying for the long cable.

The reason solar farms in the desert have negative value, vs. siting nearby, is that panels in the desert get hotter, so run less efficiently than over water or plant life, and last many fewer years. Furthermore, panels in farmland improve yield and water demand.


The question was if it's technically possible - and it is.

Projects like https://en.wikipedia.org/wiki/Desertec were based on the cost estimates at the time. Now solar panels are much cheaper and it's a good thing.


The cheaper the panels are, the closer by you want them.


You also can’t produce all the clean energy via ocean based solar and ship it to where humans live.


Offshore cables exist, and if you want to go the route of producing it into some intermediate form, a good majority of heavily populated areas are also ports.


Yet, you really can.


If you put solar in the desert SW, and intend for it to power homes in New England, how much does the transmission lines to move that power cost? And how much do you lose in transit?


There is an efficiency loss, but the problem is actually the cost of building and maintaining the infrastructure.

Theres plenty of resources out there around this idea.


I don't recall where I had seen it, but there was a study at some point on the cost of covering the Sahara in solar panels. The CO2 emissions from the resources for the transmission lines- in steel and concrete especially- meant it would be a net positive CO2 contributor even after shuttering fossil fuel power plants.


This means that we need to learn how to build transmission lines with less steel and concrete. Use more aluminum maybe? More plastics and carbon fiber? More glass?


plastics and carbon fiber are made with hydrocarbons generally. Aluminum might actually be worse, since aluminum requires very high amounts of energy to produce.


Solar energy used to produce aluminum has zero marginal cost. So, unless you assume use of fossil fuels to produce the power used to refine the aluminum, this is nonsense.


Hydrocarbons are not a problem per se. It's burning the hydrocarbons, specifically the carbon part, which has the detrimental effect on climate.

Plastics and carbon fiber effectively keep the carbon from becoming CO₂.

Aluminum takes a lot of energy, but, unlike steel, the process does not release any CO₂, and is fully electric. It can be powered by hydro (and often is), nuclear, or solar energy directly.That's the point.


Another idea I saw on yt a few months back:

Charge some solid state battery (it's not battery it was something better) and then transport it.

Similar on how we ship oil across the planet.


Robert A. Heinlein wrote a book called Friday that had something like this. They would use huge solar arrays to charge proprietary solid state batteries called Shipstones which were used everywhere. There wasn't even a power grid anymore because people would just buy a Shipstone and put it into their house and replace it every so often like coal in a coal bin.


I love Friday and just reread it last weekend. Often I think that Elon Musk believes he is a character in a Heinlein novel. Tesla is Shipstone, the cars are just a mechanism to build better batteries. SpaceX, that's just DD Harriman from the man who sold the moon/sail beyond the sunset. The Boring company is how you build Luna City ala The moon is a harsh mistress. Or maybe a space catapult. Or maybe, I'm just hoping for Heinleinian hero.


Anti-hero, more like. Or, in the instant case, over-funded buffoon.


A big problem with that is energy density. Hydrocarbons are on the order of 50MJ/kg. Li-ion batteries are on the order of .5MJ/kg.


Lithium tech at this exact instant is not the end state of battery development.

So, not a big problem, a speed bump. Check back next year.


I think the problem here is the weight of the batteries and the need for power to move them. Maybe hydrogen by electrolysis would be more favorable, but then you need to pipe in water.


You don't necessarily need to pipe the water to the electricity, you can move the electricity to where the water is (and if the electrolysis works with seawater, you don't need freshwater either). And then you can turn it into something like Methane or Ammonia for longer term storage. And the long term storage is important to level the power production over the course of months.


I think the issue at hand is that long distance transmission of electricity has transmission loss, and is expensive from an infrastructure standpoint. The broader point is that remote solar generation presents some challenges.


Transmission loss matters very little anymore. You just add more panels at the source. Marginal cost of the loss is zero. It is very, very cheap to deliver power by transmission line.


Yes, I made exactly that point above. But the point I'm making is that long distance transmission of water is also expensive from an infrastructure standpoint, possibly even more expensive than power (and also sometimes has transmission losses, depending on how they're moving it)


> But the point I'm making is that long distance transmission of water is also expensive

Oh yeah, in case I wasn't clear that's exactly what I meant also.

The dream of covering a chunk of the Sahara in PV to power Europe and Africa seems like tilting at windmills.


But not for the reason you think.

The right place to put PV for Europe is in Europe. You will want solar farms in the tropics producing ammonia to ship around to wherever the wind flags for a few weeks, and to Finland in winter.


Transmitting power is not, in fact, expensive.

Building an HVDC transmission line has capital cost, but marginal operating cost is near zero.


Desert-like land is terrible for solar panels because the solar panels get too hot (and lose efficiency).

The big, successful desert solar power projects I've seen are giant arrays of mirrors using some kind of weird heat engine, rather than PV-cells.

Cheap, widespread desert solar power would be good to figure out, but with regards to PV-cells, desert environments look like a no-go.


How much efficiency do they lose? Desert land is orders of magnitude cheaper than German farmland, and the latter appears to be economic to cover in PV panels, so if we could get the cost of materials down we could deal with losing 20% or maybe even 90% efficiency.


I don't know the answer to your question, but lets assume 20%.

If PVs are 20% less efficient in the desert, you'll need 25% more PVs. (Ex: Instead of buying 1MW worth of panels, you need 1.25MW of panels to generate only 1MW of power)

If PVs are lol 90% less efficient in the desert, you'll need 900% more PVs (instead of buying 1MW worth of panels, you need 10MW worth of panels to make 1MW)

-----------

Because PVs are the "expensive part" of solar power (and land is really, really cheap, even German Farmland), we're more interested in reducing the number of PV-panels to buy, rather than reducing the cost of land acquisition.


Panels that normally get 20% conversion efficiency are typically 12% in the desert summer. So, a huge loss.

You want your solar panels mixed into farm and pasture land, instead. Which there is quite a lot of.


Land use is absolutely no problem at all for solar.

Solar coexists synergetically with agriculture, operating more efficiently, cutting water demand, and improving yield. Also with parking (keeping cars cooler) and roofs (extending life).


I'd be curious if there are sources showing that solar panels could improve agricultural productivity, but I have doubts, since plants and panels compete for the same resource, sunlight. In terms of cooling, it should be noted that contrary to popular belief, solar panels heat up whatever is underneath them, they don't cool.


You may doubt, but most plants can only use a small amount of light. Once that is exceeded, they endure any more, and benefit from relief.

Some crops lose a bit of yield, shaded, like wheat, but the value of power year-round exceeds the loss.


The cost of land might to be a huge issue with deserts, but the cost of transmission is.


Yet, the cost of transmission is not. A long transmission line might be expensive to build in the first place, but operating expense is near zero.

That is not the reason solar in the desert is a dumb idea. The dumb idea is putting it where it is maximally hot, instead of spread out in farmland where it is actively beneficial and also generates revenue year-round.


Transmission from Arizona or Nevada to California looks reasonable. The cost may be reasonable, too, at least the Nevada part.


The eastern half of Southern California is already desert so you might as well just use that, though one of them had trouble getting of the ground and costs weren't the greatest: https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Pr...

Others, including https://en.wikipedia.org/wiki/Ivanpah_Solar_Power_Facility are doing better


Except, desert is a dumb place to put solar.


Great idea but then again we come back to the problem of getting that power back to land. I imagine ocean currents complicate linking these things together or with big cables back to land - not to mention big storms. I do really like the idea of fish gathering below the platform - multiuse stuff is always great. We could probably also do some hydropower while were at it!

Best use case for something like this seems like for powering remote outposts and islands - land is at a premium at these places often plus you probably do not want to be clearing large areas of uniquely biodiverse land for power delivery. Some giant ones off the coast of Fiji could be a cool one for sure!


Actually, you can manufacture ammonia from just water, air, and electricity. And ammonia not only has great uses (right now we burn a huge ammount of NatGas to make it) in agriculture, but it's quite energy/space efficient for shipping. We already ship quite a bit of liquified ammonia (<200 psi at >100F). If you have a lot of "free" energy in the ocean it makes sense to make/store/ship ammonia on the spot.


This of course also enables storage for delivery of power at night.

I think there is some physical-chemical development work left to do for maximally efficient commodity-grade solid-state fuel cells that work with ammonia and air, but it is eminently doable today. In the meantime, you can burn ammonia in combined-cycle turbines where NG is burned now.


Thanks, with solar and wind there do seem many times when there is a surplus of energy. I'm thinking somethings like water cracking to H, Aluminium smelting or Steel Furnaces could be done with such supluses but Ammonia sounds like a good one for the list too.


All of it will happen at the same time, different places.


I would imagine the problem for offshore solar farms wouldn't be bigger as for offshore windmills? That is a relatively expensive, but also not that difficult problem today? What did I miss?


Waves.


Are you saying that waves don't exist around offshore wind farms?


Waves will tend to destroy floating offshore solar farms. Wind farms are less affected because their cross-sectional area near the water surface is small relative to their mass.

But if the panels were in a semi-flexible frame with underwater floats, the waves could be made to mostly run under them.


> ocean currents complicate linking these things together or with big cables back to land

They would be connected by cables to the ocean floor (depends on depth I presume). But the currents shouldn't be an issue. Storms unless there is debris should also be fine (but I don't know what ocean weather is like).

Cables back to land are indeed an issue, especially with high energy. Maybe we'll come up with efficient energy guns, or create fuel on said platforms (hydrogen?).


"Maybe we'll come up with efficient energy guns"

Very likely not. Creating fuel seems more practical, but anchoring floating objects is a known problem as well.


30 ft (10 m) waves on a regular basis would not be unusual


Presumably, that also affects cables for offshore wind farms, and yet we routinely build those in seas that can get rough.


A big enough farm can also be a focused microwave phased array antenna, beaming power to any point overhead. Or even multiple points, given more than one frequency.


> only one company deploying those successfully.

which one? i specifically recall a membrane based design, and the other a floating grid

also, are there estimates of costs ?

Edit: lake floats are ~30% more expensive at the system level. i am asking about ocean systems


https://swimsol.com/

Disclaimer: I know someone who works there. These are meant for ocean deployment, right now I believe they mostly use them in locations with somewhat tempered wave conditions like atolls and bays. It's a floating grid structure that holds the panels a few feet above the water. I don't work there myself, for cost estimates,... you'd have to contact them.


At last report there were 3 GW of floating solar. That number is surely higher already.


Seems aligned with General Pershing's vision of “Infantry wins battles, logistics wins wars.”

Having a source of electricity that doesn't require diesel fuel can be advantageous. It's silent, with a lower heat signature too.


I appreciate the sentiment but this is a permanent installation for a US base in North Carolina. Also there is nothing tactical about a solar farm.

JP-8 (similar to diesel) is easy to source the world over, has high energy density, is easy to transport and runs nearly everything in the military.

Solar is a nice idea but we’re nowhere near (economical) panel efficiencies necessary to transition field electricity use. Keep in mind, the further you get from the flag pole the less electricity you need. Things are designed that way for obvious reasons.


Only thing even close for energy density and thus potentially useful for logistics would be a small modular reactor, which could then be used to create diesel on site. Trucking the reactor in though has obvious security concerns.


Wouldn't the early iterations of something generally be pretty lame?

Seems possible in 50 years or so things could be more mobile or advanced in other manners.

Either way, certainly interested in seeing what the USAF will be doing to get to 0 emissions. I have a sense they may be able to harness resources towards goal a bit more effectively than some of our more fractured systems of governance.


Only if you can also make energy storage super small and portable for those times when the sun isn’t shining.

Seems easier to invest in micro reactors.


Micro reactors are an obvious dead end.

"Super small" energy storage is called synthetic fuel, something that has already been demonstrated practical for military deployment.


USAF can go carbon-neutral by sourcing synthetic fuel. Zero-emission, never.


Emitting only water vapor is well within foreseeable development. LH2 fuel would provide better range, besides.

In certain circumstances, ammonia as fuel would make more sense.


Replacing compact, lightweight, low-maintenance kerosene tanks with larger cryogenic containers and fighting hydrogen's propensity to penetrate metals and rubbers and make them brittle is not an easy sell. It may make sense in some cases (like large cargo planes), but in a lot of others, like small, high-g semi-autonomous combat aircraft of the future, it may not be practical.

Or maybe metallic hydrogen at standard conditions will be attained soon enough.


People will do whatever makes better sense according to experience and instant circumstances. There is no need to speculate.

But LH2 aircraft, wherever actually deployed, will be impossible to compete with.


Sun does not even produce enough watts per square meter to be practical for transportation of heavy artillery (nevermind that it produces zero at night). It's ridiculous to imply solar ever has potential beyond supplemental energy.


> with a lower heat signature too

The visibility will be extreme though, for the same energy density. If mobility is a concern, then the energy density/lb would be incredibly low, compared to fuel. I think this would only make sense if you were near a body of water (obviously) for an extended period of time, and you didn't care if everyone flying over knew you were there.


What happens when someone airbursts munitions over your solar farm?


Nothing much, as compared to someone potentially shelling a nuclear power plant or a diesel fuel depot.

Besides, solar panels are so cheap these days, that it might cost more to destroy them with munitions than to install/purchase them in bulk.


Indeed. Of all energy sources, solar and wind are some of the safest in case of war, terrorism and social unrest.

Nuclear, gas, oil... not so much! Same for dams.

And even if you avoid immediate loss of life and environmental damage you still have an emergency to handle.


An EMP is cheap to generate and could take out a whole array.


Good question, you can fill out the draw; just have it done before you leave today.


If anyone is interested, I just completed a Master's thesis on a feasibility study for floating solar on a specific reservoir in southern California: https://bren.ucsb.edu/projects/exploring-feasibility-floatin...

Happy to answer any questions you might have about the possibilities of the technology!


This all seems pretty incredible and kind of like a no-brainer. What are some of the challenges in a project like this? Are there any limitations to scale?

Lastly, do you know off-hand if these bold claims (see below) are exaggerated or oversimplified in any way?

> Covering just 10 percent of the world’s hydropower reservoirs with floatovoltaics could generate as much electricity as all the world’s operating fossil fuel power plants combined

> We found that countries in the Americas and Africa could benefit most: even low coverage of reservoirs by floatovoltaics should generate all the solar energy needed to decarbonize their electricity sector. Brazil and Canada could be hotspots, each requiring only about 5% coverage of their plentiful reservoirs to satisfy their massive solar-energy needs. Last year, Brazil implemented regulatory changes to help the industry to develop (see ‘Brazil’s photovoltaic boom’).

https://www.nature.com/articles/d41586-022-01525-1#ref-CR13 (linked in the article)


There are not significant limitations to scale other than the usual economic reasons. There are competing uses of many reservoirs, however - likely recreational boaters would strongly oppose taking over large sections of reservoirs, so floating solar is more likely going to be located in practice near to the dams / in existing keep-out zones.

Yes, those claims are technically correct, in the same way that the claims we could power all of humanity's needs with a fraction of the sahara desert are also technically correct. In practice, competing needs for the water bodies and especially the cost of transmission lines / the lower cost of nearby desert land for many of the sites means that it's certainly an oversimplification.


really, the competition against cheap desert land is what makes the difference - that is why it really makes sense in places with limited land (Japan, South Korea, eastern China, coastal California, etc)


And yes! I agree it's a no-brainer. Big barriers: 1) Getting all the stakeholders to agree (US Bureau of Reclamation, the local reservoir joint-powers authority, the Santa Barbara city council, the local utility, etc) 2) Avoiding NIMBYs and those that might be worried about ecosystem effects (e.g. Audubon society). While the evidence suggests it's not an issue for wildlife, those folks tend to be very conservative (even if they are missing the forest for the trees, IMO)


Only complaint about the abstract is "...without occupying scarce available land".

Land for solar in the county is not scarce. Look up "agrivoltaics". There are good reasons to float solar on reservoirs, that just isn't one.


Agrivoltaics are far more expensive, and farmers have to change their behavior significantly. Floating solar doesn't require any of that partnership and ongoing behavioral change, just slightly more expensive up-front costs.

Also - in SB county, there is an ordinance banning utility-scale solar within the county (thanks local zoning laws....). We get exempted because the reservoir is federal land.


Agrivoltaics are a little more expensive, but produce revenue in fallow fields.

Farmers have grown used to changing their behavior, in recent centuries. The successful ones today did. The successful ones tomorrow will have.

Laws can be changed. In Colorado, they were already. Others will follow.


How do you service a panel, or whatever quantization, near the center?


you can walk on the floats between the panels, see: https://www.dynamicslr.com/wp-content/uploads/2021/09/floati...


Leave gaps.


The Army's story has a much more interesting bit:

An electronic “recloser,” funded by the Environmental Security Technology Certification Program, is also being demonstrated as part of the system. Reclosers respond to transient events, like a tree limb brushing against a power line, to quickly reset the system and restore power. This technology provides better protection for system power lines and minimizes damage to sensitive electronic equipment in the event of power interruption.

https://www.army.mil/article/257375/army_floating_solar_arra...

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


Is this recloser different than the automated mechanical reclosers I see around town? Solid state?


I think they meant to write “electric recloser” and the author didn’t know what they were talking about. They’re very common and not noteworthy at all.


I've never heard of a floating recloser, I think it's a novel take on the device.


Isn’t that just a recloser on a barge


What about a floating computer?


I wonder if floating PV would be an interesting alternative to the shade balls used in some reservoirs[1]? You could get the benefit of lowered evaporation and some extra pv real-estate. Maybe the math is favorable, maybe not.

[1] https://en.wikipedia.org/wiki/Shade_balls


Yes! Check out the Healdsburg project: https://www.northbaybusinessjournal.com/article/news/healdsb...

"It was a desire to shade the recycled wastewater, not capture the sun’s energy, that first led city officials down the road to the solar installation, Crowley said. The city hoped to prevent algae from blooming in the two ponds — which hold treated water from the city’s municipal sewer system."

They were going to pay to cover the reservoir, and instead they get paid for the solar output.


Only bit of nonsense in the article was, "'You couldn’t go out and buy a bunch of vineyard land for a solar project and make it economical,' Healdsburg utilities director Terry Crowley said."

You could site solar in a vineyard, though, and get both better crop yield and better efficiency. But that is not a reason not to put solar on your reservoir, too.


https://www.smithsonianmag.com/innovation/california-is-abou...

Canals and reservoirs seem like perfect places to shade with solar.


Only bit of nonsense in the article was "Building these long, thin solar arrays could prevent more than 80,000 acres of farmland or natural habitat from being converted for solar farms." Solar can be erected in working farmland, too.


Water companies tend to use a lot of energy which is a major cost for them. That is the math that is going to be most significant.


I don't see the goals overlapping other than the fact that they both float. The solar panels will cost 1000x that of rubber balls, and the cost of repair/maintenance of floating panels will be much higher than land mounted panels. There may be some circumstances where you can kill two birds but I bet it's rare.


As the sibling points out, canals seem like a good place to shade water with solar, though probably not floating.


Canals are tough because the maintenance of the canal is much harder, and the flow of the canal also makes things tricky. Dr. Brandi McKuin has done some work here, looks like the best way to do this is to hang the panels suspended on cables over the canals, but that requires a lot of steel and is thus fairly expensive. I don't think we've cracked that nut yet...


Floating is overwhelmingly better, because cold panels are more efficient than dry ones.


^ small nit - cold panels are more efficient than hot ones, not dry ones!


Dry panels get hotter than wet ones can.


Balls generate zero revenue. Solar arrays generate net revenue.


this is correct ^, it is net positive for healdsburg, for instance


I wonder if this could have a military purpose as well, as in whether this could be used in a combat area. Any of the other types of electrical power generation systems are very "centralized", as in there is only a few points where just a few hundred kg of hexagon delivered by a precision missile that slips past air defense would easily terminate the power production.

On the other hand, a mesh of solar panels deployed over a larger body of water is a pretty difficult target to destroy. Imagine that it is floating over a 1km by 1km (or even 1 mile by 1 mile) area - what are you going to use against it? Unguided artillery? Would take a huge amount of shells, even though they're cheap it's probably infeasible. The same with unguided air-dropped bombs. Guided munition? Even worse than the unguided stuff, no high value targets to hit. The only way to defeat such a meshed power plant would be a small nuclear bomb.

(the above assumes that there's no single energy collection point, of course, otherwise that place would be targetted)

The other upside is that there is no need to supply oil, which is currently the preferred way of delivering energy to the combat area. The downside is the time it would take to deploy such a mesh, a diesel generator works pretty much instantly.


With respect, an M777 battery could saturate a grid square in minutes. The expected injury radius of a 155mm is ~150m, so conservatively 100 rounds would blanket a 1km*1km array. A six gun battery can fire ~36 rounds per minute comfortably. 100 rounds could be fire and the battery could be packing up before the first one hit.


Yeah, people drastically underestimate the raw firepower of artillery. The M270 is called "the grid square removal system" for a reason. (Grid square refers to 1km x 1km area.)


We no longer have the M26 rockets used in grid square removal. They've all been decommissioned in favor of M30/M31 GMLRS guided rockets, which don't have submunitions. Oddly, "grid square removal system" is actually a backronym, as the original designation of the M270 was General Support Rocket System (GSRS)


That's largely due to the general move away from cluster munitions. There's still plenty of the M30 series, whose 160,000 preformed tungsten fragments would be an ideal weapon for use against a fragile and static solar array.


As a note: the US Military isn't going away from cluster munitions because we don't want to leave UXO for civilians to accidentally blow themselves up with, but rather because we don't want to leave UXO for US military to accidentally blow themselves up with. If we drop 12x M26 missiles on a grid square, then that's something like 7.7k submunitions. With a 14% dud rate, that's 1k submunitions somewhere waiting for us to roll over them.


This. As a former infantryman the one thing that still strikes me with awe to this day is the destructive power of artillery. People cannot fathom what it’s capable of.

Go up in a tall building, maybe to the 20th floor or so. Eyeball a built up area 1km square. Now picture every structure reduced to rubble in an instant. Now imagine 10km square reduced to rubble in just a few minutes.

Quick work for an artillery battery.


Never experienced it myself but seeing those piles of shells from WWI just sends my brain to uninitialized memory.

https://rarehistoricalphotos.com/shells-creeping-bombardment...


https://www.youtube.com/watch?v=IUvcdKGD-FM <-- What it's like be hit by 130mm artillery.

One thing that the video can't simulate is how loud those explosions are. You don't just hear the sound wave, even from a safe distance you feel the pressure wave in your entire body.


Reminds me of a day I was fishing from a pier at the beach some time ago. Older dude came up to me and started talking and got into his "time in 'Nam." He pointed at some apartment buildings across the bay, "we'd call in an airstrike and they'd make one pass and everything would be gone. Those buildings? You'd just see some bricks and rubble left behind." To 25 year-old me that was a pretty sobering thought.


That injury radius must be on land right? Like if it hits water how destructive could the splash be?


Gunners would use proximity fuzes to airburst above the target in this application. TBH 100 rounds is wildly conservative - I can't imagine a better target for artillery than a fragile and static solar array.


What's the range? 15 miles?

I agree though. Solar on the battlefield doesn't make sense since it is not mobile and cannot be concealed or protected.

I do think the centralized nature of massive diesel generators and their fuel supply lines are a tactical weak point though. I like the idea of flexible distributed power grids for troops but I'm not sure solar fits the bill.

It would be cool to hear some input from generals and see some proof of concepts.


> What's the range? 15 miles?

For M30A2, 70km or ~43 miles.


> Imagine that it is floating over a 1km by 1km (or even 1 mile by 1 mile) area - what are you going to use against it?

Shrapnel generating warhead 100 meter over the solar field. Good luck finding and bypassing all the damage and short circuits.

Or send the precision missile to where the cable lands.

> the above assumes that there's no single energy collection point, of course

Probably not a literal single point, but I would assume any solar field would have a relatively low number of shore connections.


Almost certainly usable by the military, but not the way most people in the thread are responding. The military does a lot of humanitarian aid and rebuilding type work outside of war zones. If this solar array can be quickly and easily deployed off a boat and then you just drag a cable on shore to power a local town that could be very useful compared to having generators and having to ship diesel constantly.

Massive Earthquake knocks out the infrastructure in Haiti? Just send the solar boat and, even without batteries, you have a daytime power plant set up in a day. I wonder how much power storage you could get with a hand full of tractor trailer/shipping container sized batteries.


The weakness isn’t the array itself but the cable(s) transporting the energy to where it needs to be consumed.

Cut the cable and the array is just more debris floating in the ocean.


I have no idea how fragile solar panels are, but wouldn't cluster bombs or possibly thermobaric weaponry work reasonably well against large surface areas like this?


US Army strategy often assumes air superiority by US forces.

Mortars are simply a more likely risk than cluster bombs. Further it’s fuel rather than generators that’s a problem, it’s bulky, flammable, and finite.


Sparkling sand (or anything else) over them would be enough to absolutely destroy their output


That would have hardly any effect. Soot would, though.


I doubt it would have "hardly any effect" tbh, naturally occurring dust/sand is already a big issue: https://jrenewables.springeropen.com/articles/10.1186/s40807...

> In desert area, the accumulation of dust on PV panel surface is very high. The reduction in solar efficiency due to dust on PV panel is approximately 40%


Seabird feed laced with laxatives


People are mentioning thermobaric weapons, small nuclear bombs where in fact a couple of bog standard 155m shells with proximity fuses would render something like this inoperational. Alternatively send out a single CAS like A10.


> Imagine that it is floating over a 1km by 1km (or even 1 mile by 1 mile) area - what are you going to use against it?

Same way you render a nuclear power-plant useless, cut the cable(s)


I'm not convinced that a solar array / electricity production would be the prioritised target if they were in range.


> Imagine that it is floating over a 1km by 1km (or even 1 mile by 1 mile) area - what are you going to use against it?

an EMP?


> The only way to defeat such a meshed power plant would be a small nuclear bomb.

Unless actively defended: set collision course. If you suspect that it might be a tie, set collision course on an unmanned confiscated civilian vessel.


EMPs are cheap to produce.


Out of top of my head this (https://en.wikipedia.org/wiki/TOS-1) can destroy such target.


> The only way to defeat such a meshed power plant would be a small nuclear bomb.

Or to quietly cut off the underwater power cable.


The power cabling connecting the array to the shore seems like a nice spot to target.


Is it not more efficient for the larger ships to over provision on nuclear?


Deploying the panels at sea, dragging them behind a warship, seems to be quite a challenge compared to deploying in a “pond” of calm water


It struck me last time I was in US (I'm from UK) how few properties have solar panels on the roof. I wonder why that is? Cheaper energy? Roughly 1 in 30 homes have solar installed in the UK (https://www.theecoexperts.co.uk/solar-panels/popularity-of-s...) though I can't lay my hands on stats for US.


Probably cheaper energy, and also perhaps a different subsidy/regulatory environment. I know in California, the utilities are fighting to make solar users pay more than they currently do, saying the solar customers don't pay their fair share of distribution and transmission costs.

Also, as a former leased-solar customer, there are some downsides. Having solar in my area adds a few thousand dollars to a roof replacement. Furthermore, solar panels are sort of an acquired taste, aesthetically speaking.

When I had solar, it was nearly a wash in terms of how much I saved vs how much I paid monthly to SunRun, the company I leased them from. It did allow me to run my air conditioner nearly all the time because I was incentivized to use the power I generated, but it also meant I had a loud box outside my bedroom window and the clicking of the relays woke me up many mornings.


There are a handful of potential reasons depending on where in the US you're looking at, as usual there is wide variation by state and by urban/rural divide:

- some states have little in the way of tax or other financial incentive to help offset initial installation cost

- some neighborhoods have various visual restrictions, self-imposed or otherwise, that may not accommodate solar panels

- some power companies have campaigned to limit net metering, which limits the cost savings homeowners can see from solar to protect the utility

- some local or state government officials view renewables as a "political" issue in the sense of "yuppies getting bent out of shape about global warming" and make efforts to limit renewable usage for political points

- owners of most rental buildings don't pay for electric, the tenants do, but the tenants cant make capital improvements and the owner has little incentive to


It can really vary from community to community. My little town (60k people, large university and Fortune 100 company campas) seems to have a lot of house installations, but then income and education levels are higher here, as well as a strong "green" mentality.


In the US it's approximately the same -- 3.2%.


The zoning and other regulations around solar are onerous in the U.S.: https://www.nytimes.com/2022/06/08/opinion/environment/defen...


More and more outbuildings in rural areas have solar panels. Installing solar is cheaper than getting permits/electrician to run mains power to your buildings. I've seen new barns with the roofs completely covered in solar panels.


How would this impacts the marine life? Lakes, and most water bodies for that matter, are complex ecosystems.


The article describes artificial reservoirs as the water body of choice, which are less complex (partly because they already destroyed the ecosystem that was there) than naturally forming lakes, and has the added benefit of reducing solar driven evaporation in the same vein as this[0]

[0]https://www.youtube.com/watch?v=uxPdPpi5W4o


This seems to be most important part. It could be beneficial as prevents evaporation and warming. LA reservoir even has floating balls for this https://www.nationalgeographic.com/science/article/150812-sh...


All local impacts have to be weighed against the global impact of CO2 emissions.


I don't think CO2 emissions are much of a priority in warfare.


There are no ways to accurately predicts how eco systems react and how far the domino effect would go. You could wipe out entire food chains and not be aware of it before it's too late


there are no experts in that domain?


It's an area of open research, but especially if it doesn't cover 100% of the water body it's fairly benign: https://www.sciencedirect.com/science/article/pii/S136403212...

For instance, birds perch on the panels, turtles loaf on the floats, fish hide from predators under them. It changes the water body, but not in a way that would be different from, say, trees that have fallen halfway into the water and are shading part of the surface.


If you space them out enough you wouldn’t have huge areas of no sun. It would emulate an ecosystem of water under shade trees. Shade actually attracts a lot of biodiversity.


Including canals, which the author disclaimed for some reason. Here at least they have all kinds of aquatic and bird life.


... which would then also benefit from the presence of floating solar panels. Panels floating in a canal would need to be anchored against current, easily done.


Why are we not building giant solar arrays in the southwest and high voltage DC lines to send the power to population centers?


My guess: We run into problems here in the Netherlands now that everybody with solar panels is producing huge amounts of power around noon... And the grid can hardly take it anymore (sometimes people can't push the power to the grid anymore even). We can't store it, and most people don't have smart devices that can start (like laundry) based on power production.

That problem should first be solved.

Edit: In some provinces we can now neither build more power plants nor add any larger industries because the grid can simply not take it. I guess decentralization is key. For myself I'm looking into a small EV that is usually at home and can be charged during the day. But this only works when the car is at home during day time. Another pro-wfh argument ;). Electric scooters (max 45 kph), electric bikes (max 25 kph) and "speed pedeleces" (max 45 kph, they are in between scooters and bikes [0]) are also becoming really poplar here, they use comparatively little, but it's nice when they replace cars.

[0]: https://www.speedpedelecs.com/ (it's a brand and a category at the same time)


well, luckily for the US, we have massive hydro power dams in the west that are low because of 20 years of drought, so we can actually do pumped storage.

Ideally, we would pump salt water from oceans to the salt water reservoirs and use surplus energy to desalinate to refill the fresh water ones.


Better, just pump sea water to the desert, and let it spread out and evaporate. The mountains will catch the water vapor and fill your reservoirs.

Releasing in Death Valley, you don't even need to pump. A siphon once started will just run indefinitely. (The high point of the siphon would need to be less than 30 feet above sea level.)

You might need to bulldoze up the salt in the fall and take it somewhere.


My thoughts exactly. Solar -> Desalination, with all other energy consumption in the middle. Granted, I am not up to date on desalination. I know MIT released something recently but idk the details. Is energy the bottleneck now or is it still material?


Giant solar farms (like Solar Star in LA) will connect to the higher voltage grid rather than the low voltage grid used domestically. Exporting large amounts of power and moving that power geographically is exactly what this is designed for. There may be issues with lack of capacity in district and national grids. But it is a different problem to the domestic solar issue. It can be solved by reinforcement of existing lines, upgrading substations and building new ones.


The main issue with our grid is mostly that we lack the capacity to transport the power. In the past power generation and heavy power consumption were typically relatively co-located. Now, with wide spread energy production with solar panels the energy is coming from everywhere and this power needs to be transported to where it is consumed.

Moreover, in order not to overload the grid other power generators need to scale down, even if those would be closer.


This is not true. Enron was famous (notorious) for leveraging the, then, capacity of long distance interconnects to move power from far off generation capacity to advantageously priced markets. Just take a look at the sheer size of CalISO, MISO, and ERCOT. You could build solar anywhere and wheel it to where it’s needed. That’s not the long pole in the tent (right now).


My reply was to someone talking about the grid in the Netherlands. That was what “our grid” referenced.

Furthermore, we have three levels of grid. The very high voltage, highways, the regional high voltage, aNd the local grid. Each have their own challenges. For Solar it is mostly the local grid that gets overloaded. On my connection I’m hitting 250V on sunny days instead of the standard 230.


All fair points. I assumed utility scale solar in the US.


Exactly this, (lack of) storage is the problem. Daytime demand isn’t high enough to deal with PV output leading to cut offs on grid feed-in from consumer PV installations. Given that car batteries aren’t an option yet to power homes this is a problem that will stick around for a bit.


>Given that car batteries aren’t an option yet to power homes this is a problem that will stick around for a bit

One was posted here not too long ago.. so this may not be far off. But it's a bit of a chicken-egg situation because powering your home with a car battery is not very practical by itself. Investing in both solar and the car at the same time would also be a hefty chunk of change for any individual household


That’s exactly the point. The few car models that do support grid feed-in require an expensive converter to take DC from the car and deliver AC to the home. The hardware to do that is just expensive and currently that doesn’t pay off


Hardly anybody uses car batteries at this point, and not just because of availability. It's a bit of a pain in the ass compared to just buying LFPs. Even at fairly high retail pricing for complete batteries, 30kWh of LFP is $10K. That'll power a typical home for a day. If you just buy cells and BMSs, it's cheaper. That's what most of the off-grid folks do these days.


The thing is that you don’t want just the car battery but you want to use the capability of the car to deliver power back to the grid (or your house at any rate). The rest of the time you want to use the car as a car. The idea behind it is that you don’t need a separate battery pack at home for the times the grid is over-subscribed.


Car batteries (E.g., in Nissan Leaf) are, in fact, an option to power homes. A controller/converter box is under $900.


I would say that home batteries like the Power Wall seem like a nice solution.

However I am a bit worried about the lifespan of those batteries and what happen to them at their end-of-life (recycling? CO2e cost of making a new one?...)


For standalone houses, seems like a bank of traditional lead-acid batteries like datacenters use is a better option. Doesn't require exotic materials, EOL handling is well understood at this point, etc.

If I'm doing the math right, every ten car batteries in the bank should get you about 8 kWh. The average home in the US uses about 11,000 kWh/year[1], or about 30 kWh/day, so a bank of 20-60 batteries seems like a good starting point, depending on how much reserve capacity one is comfortable with, how variable solar generation is, etc. That's an up-front cost of about $4,000-$12,000 every 5-7 years, but at least at the low end that should actually be cheaper than paying for electricity from the grid over the same period. A 20-battery bank should fit in about the same footprint as a refrigerator.

That's also significantly cheaper than a PowerWall of the same capacity[2], which was $7,500/14 kWh ($535/kWh versus about $250-$275/kWh for lead-acid) before Tesla stopped selling them without a solar panel bundle.

For apartments and other colocated housing, it might still make sense as long as there was some sort of central vault for the battery bank.

[1] https://www.eia.gov/energyexplained/use-of-energy/electricit...

[2] https://solarmetric.com/learn/tesla-powerwall-review-costs-s...


Thanks for the thourough estimations!

However I strongly advise against buying lead batteries, which are very dangerous for the health and environment (arguably not while they have not yet reached their end-of-life, but once expended a lot of them end up being dumped into the wild, and I am not even confident in their recycling).


Use the spare power to pump water up mountains.


Maybe the Netherlands have excess solar power in some days/hours, but what about neighboring countries?


In the end, I'm confident little power is wasted; instead, power is sold on the spot market at low and sometimes negative rates. Datacenters will gobble it up to lower their prices too, making "bottom feeders" like crypto miners hit their "I am willing to pay this much" prices.

Then there's of course various energy storages; I believe one thing they want to implement is that any leftover electricity is put into generating hydrogen gas, which can be stored and later burned cleanly to generate power if needs be.

But yeah, that's a bunch of rambling from an amateur who amortizes grid capacity; in NL we have a problem that the grid is full. It's not really affecting day to day things yet, but it means that new companies - power generating or consuming - are not being connected to the grid because it would cause overloads. I'm not sure if they bleed power off anywhere yet.


There are numerous options for super-cheap energy storage. They just aren't built out yet, because the money is better spent, still, on adding generating capacity. What is being built is factories to produce them.

Excess renewable generation is not a problem; if there is too much sloshing on the grid, you turn them off.


I'm sure that the solution is rather storage than cryptomining (to me it looks like the same as just burning the energy into waste heat).

For example, molten salt storage.


Germany, Belgium and Denmark also have quite a bit of renewable energy and the sun is usually similar, so they usually don't really need it when the Netherlands has too much either.


Building power transportation networks makes building out large solar arrays look cheap. Getting the right of way and environmental impact statements for these things that cross rivers and cities is a massive undertaking.


We are, see the multiple square mile installations in the Mojave desert (in particular Rosamond). Output of that region is ~520 MWh/acre. https://www.google.com/maps/@34.8097025,-118.4587554,15367m/...

Side note, land in the area is available for purchase at $3k/acre. And if you look closely, you can see the plots where classic subdivisions were initially scratched into the surface before land owners realized no one wanted their land even at 3k/acre. https://www.google.com/maps/@35.1339826,-118.0179071,2422m/d...

Edit: when I click the link, Google Maps helpfully informs me that traffic in the region is "light". :)


Desert solar arrays will come to be seen as a dumb idea. But not before we build even more of them. They have to be dusted, and because of the heat, efficiency suffers and they don't last very long.

The place for solar, at maturity, will be sharing farm and pasture land.


“We” aren’t building anything. Utilities are an income producing asset for their investors. There are, in fact, a multitude of utility solar installations going on right now all over the US. These things take time to build and learn from. It’s not a slam dunk and the profits aren’t guaranteed. Not withstanding the unsolved engineering challenges, of which there are many startups exploring.

We’re not stupid it just takes time.


We already have built many solar arrays in the southwest. And the power generated does get sent to population centers, both from the renewable and the non-renewable plants. If you are asking why we don't expand those efforts, that is a good question... but it is absolutely already in place.


It's inefficient. HVDC is _more_ efficient over long distances, but not enough to make it worthwhile


Because it's not economically viable, yet. It'll happen when it happens.


I run a 46 panel array on my rooftop at my home in Florida. On a good day it generates around 80 kWh. On a cloudy day, 35-45 kWh. On stormy days it generates about 15 kWh. It cost me $40,000. At night, it generates no power, but needs a 20amp AC connection for the controller and 60 amps for the micro inverters.

I save about $50-80 a month on my electric bill. Solar in its current incarnation is not ready to power the world, it destroys the biome in which the panels are deployed, costs an awful lot to fabricate....

I am more interested in personal nuclear energy or recycled nuclear energy production. Solar is a distraction that when you start asking the right questions, feels more like gas-lighting than a solution to renewable sources of energy.


That sounds horribly expensive. I have a 12 panel array here in the Netherlands, and I paid € 3500 for it.

There was no biome on my roof that I was aware of.


You paid over 2x, too.


You can buy a pallet-load of 45 350W-peak panels for under $7000 nowadays. A used Nissan Leaf at 60% battery capacity is another $7000, and a converter/inverter to charge/discharge it is under $1000.

Furthermore: personal nukes will never happen. And, solar does not destroy biomes. And, its cost to fabricate is still falling at an exponential rate. So, you are zero for three, and paid too much.


Lets say 50kWh/day average, giving 1,500kWh/month. If it's only saving $65 on your electricity, doesn't that mean your electricity is around 4c/kWh? My math must be wrong. Are there other fees, or did you also include the payment for the panels?


A few points, my array was installed in 2018, so fairly recently. It still is one of the largest home arrays my installer, PES Solar maintains.

This amount of money I save on my monthly bill is the amount of money my local electric company pays me for the electricity the array generates. The way I was forced to install my array is such that it feeds the grid directly. They deduct this from my monthly bill where my home generally uses around 4500 kWh.

Now, I think they are not giving me fair market value for the electricity and I'm looking into purchasing either Tesla Powerwalls or another brand so I'm drawing from a battery bank and the array before drawing from the grid.

However, my conclusions at this time are that Solar is NOT ready for primary home usage unless you want to live a subsistence lifestyle.

I don't want panels in a field or on a lake for the same reasons I don't like our current versions of pavement or cement. Everything under it dies. Further, birds above the arrays are killed. This is not a reasonable alternative to energy dense fossil fuel yet.

We need to be more creative and realistic in our future energy sources.


Wonder how effectively this could be paired with pumped water storage. Excess solar energy could get used to pump water that could get used to provide power at night/store energy for cloudy days. You'd also get a double bang for the buck for the space being used if the water is covered with panels, and solar panel coverage of the reservoires would presumably help minimize evaporative losses


It's likely well-suited for that, but in general hydro + floating solar could be ideal as the power infrastructure is already in place. Pumped hydro is not 100% ideal as the drastic changes in water level can cause some problems with designing a solid system.


If they are anchored a ways from shore, then it would not matter if the water level goes up and down. You don't routinely let reservoirs get that low. When you have free power, you can pump water up to it. Desalinating, even, if necessary.


In the short term, THIS is the future I really believe in.

Then, a tiny bit further in time, using deserts.

And then even further, spatial solar.

Edit: this needs a bit of context, where I am living they are erasing whole forests from mountain tops in order to install new solar panel fields, so obviously I think that floatovoltaics are very nice instead.


Desert solar will be abandoned in the near future.

Orbiting solar, for terrestrial power, will not happen at all.

There is never any value in "erasing whole forests" for solar. Solar coexists synergetically with existing pasture and farmland, and warehouse roofs and parking lots, and reservoirs and canals.


> Desert solar will be abandoned in the near future.

Why is that? Isn't it the best place to build area-hungry, sun-hungry equipment??

> Orbiting solar, for terrestrial power, will not happen at all.

So you don't believe that a Dyson Sphere (or Swarm) is the best way to non-destructively accomodate an energy-hungry advanced civilization?


Farmland and pasture are also area-hungry, but nearer by populations. Solar (and wind) co-exist synergetically with those. Likewise, with reservoirs and canals.

Vertical fence-rows of bifacial panels, aligned N-S, are minimally disruptive of existing farm methods, and harvest morning and afternoon sun while relieving crops from heat stress and water loss. They do not accumulate dust.

Peppers and tomatoes may get 2x-3x yield, so protected.

Panels on greenhouse roofs are also helpful.

Some crops do best directly under horizontal panels, using morning and afternoon light, protected by them from storm rain and hail.

In pasture, herds keep weeds off panels.

* * *

Aneutronic fusion will be solved long before we need much power in space. The current fusion work has no future except insofar as it develops plasma management tech.


I'm not speaking of power in space, but power produced in space. It can be transmitted to Earth.

Also, you speak about vertical solar panels, do you know that then you get a worse efficiency than with slightly reclined panels, which would neither accumulate much dust, especially if they can also occasionally rotate on their supporting pole?

As for aneutronic fusion, it is still much more limited than space solar, because it relies on supplies of boron. Of course not on a short time scale, but my allusion to the Dyson Sphere was a long term speculation, not a short term one.


> power in space, but power produced in space ... transmitted to Earth

... will not happen.

Efficiency decreases in importance as panel cost continues on down the steep exponential learning curve. Other considerations become increasingly important, such as mounting cost. Fenceposts are cheap.

Boron is very plentiful, and not much would anyway be needed. By the time we need more we will be equipped to make it or use something else.

In the long term, being found to still depend on solar irradiation for power would be distinctly embarrassing. In any case, all the action will be out in the Kuiper Belt where the truly irreducibly valuable commodities cold and room are abundant, and solar irradiance is hardly noticeable.


> Fenceposts are cheap.

It's a problem of available space (or rather, area).

When you run out of space on Earth (you filled all the deserts, or all the space that would not deprive natural species of their habitat and photosynthesis), and I predict that it will happen (as there potentially no limit to our energy consumption), you need to go to outer space (first in Earth orbit, then later (to avoid to completely shade off the planet) in Solar orbit).

As for energy transmission, I can think of some ways to make it happen, for example use a high-altitude balloon as a receiver, tethered with a cable to transmit down the current. That could answer your worries of transmission efficiency through the atmosphere (in space's void though, no problem). Worth investigating.


We won't run out of room on the ground. Population will level off, and concentrate in cities.

There will be no value in transmitting microwaves from space, because we get plenty of light already. Eventually, aneutronic fusion will provide more convenient concentrated power.

In the meantime, solar coexists nicely with farm crops and reservoirs, and we have many, many, many times as much of that as we would need to put solar onto, so it will only be on the best places for it, sharing with crops that get better yield by it.

When the population in space is large, they will almost all be descended from other people already there. Very few will have moved out there.


> Why is that? Isn't it the best place to build area-hungry, sun-hungry equipment??

Dust is a problem. Efficiency reduces once there's a layer of dust on top of the panels.

Could happen anywhere, but I imagine the problem would be more pronounced deserts, with its sands and winds.


Ok but still, if you build a gigantic solar panel field, and with dust let's suppose it reduces the energy output to 20%, isn't 20% of a huge lot still a huge lot?

Moreover there are probably solutions to remove the dust when it becomes too thick, like to rotate the panels to let it drop off.


It'll keep accumulating and won't stay at 20%.

Just so it's clear, dust is a problem regardless of whether it's in a desert or an urban area.

> Moreover there are probably solutions to remove the dust when it becomes too thick, like to rotate the panels to let it drop off.

Too much complexity. Moving parts that can fail for whatever reason. Sand can get into the rotation mechanism and clog the whole thing. Too many things that can go wrong. Costs will be high.

I know that in some non-desert places they use water to clean the panels at regular intervals, but that's probably a bad idea in deserts because water and sand might mix to form mud. And where are you going to get water from? Like, you might have to spend a significant fraction of the generated power to pump water... You see where this is going, right? Too much hassles.


But you don't see dust accumulating indefinitely on roofs, do you? Why would it on solar panels? (granted you install them with a slope and at some height on a pole).

As for maintenance of a mechanism, we do not shy away very large off-shore wind turbine fields (or also in-shore, if you want to reply that there is little sand at sea), so I don't really see it as a compelling argument.


> But you don't see dust accumulating indefinitely on roofs, do you?

I do, actually.


Ok, my bad then. In which region?

I've never seen people shoveling off kilos of dust from their roof like they would do for e.g. snow.

For example the wind bringing Sahara dust to Southern Europe only leaves a thin layer of dust, it would never reach anywhere close to 0.2 mm. That still leaves a lot of light going through, so maybe it becomes my hypothetical 20% (maybe roughly the same as a very cloudy weather).

Precision: I'm speaking of a sloppy roof, of course, not a flat one.


> In which region?

South Asia.

> I've never seen people shoveling off kilos of dust from their roof like they would do for e.g. snow.

And I've never seen people shoveling off snow from their roof. Because it doesn't snow here. Doesn't mean it doesn't snow anywhere in the world. Same thing with the dust. You have snow. We have dust.

You're lucky to live in a place that's not dusty.

Tangential anecdote: the replacement intervals of air filters of cars (including those that are sold in both USA and here) are drastically different. Over here for most cars the filters should be changed at around 10000 km. In USA it's more like 24000 km (for especially dusty conditions) to 48000 km for those same cars.

(I picked USA because it's a random developed country. I do not assume you're from there.)

How about indoors? We sweep/vaccum away plenty of dust. Do you people not have to do that?

> That still leaves a lot of light going through, so maybe it becomes my hypothetical 20% (maybe roughly the same as a very cloudy weather).

We don't have to speculate; there's studies on this. I'm posting a couple of links I skimmed through:

1. https://news.mit.edu/2022/solar-panels-dust-magnets-0311

2. https://www.nrel.gov/news/features/2021/scientists-studying-...

From the 2nd link: "The energy lost annually from soiling amounts to as much as 7% in parts of the United States to as high as 50% in the Middle East."

Middle-east is all desert, and there's as much as 50% energy loss there.


Thanks a lot for the references!

But do you realize that I was speaking of 20% output and not of a 20% reduction (i.e. 80% output) which makes my speculation worse than what it is actually in the Middle-East?

In my opinion, on a huge solar grid, 50% is still pretty much helpful (solar is roughly forever free energy, modulo the maintenance cost).

> How about indoors? We sweep/vaccum away plenty of dust. Do you people not have to do that?

We're speaking of enough dust hanging on a smooth sloppy surface (not a floor, but a plane with an angle) and thick enough to block more than 80% of the light (for dust, that makes very thick).


What happens to the plant/animal life under these floating solar arrays?


It's an area of open research, but especially if it doesn't cover 100% of the water body it's fairly benign: https://www.sciencedirect.com/science/article/pii/S136403212...

For instance, birds perch on the panels, turtles loaf on the floats, fish hide from predators under them. It changes the water body, but not in a way that would be different from, say, trees that have fallen halfway into the water and are shading part of the surface.


Not just "fairly benign": actively favorable.


I wondering what the effects are to the flora and fauna in a setup like this.


It's an area of open research, but especially if it doesn't cover 100% of the water body it's fairly benign: https://www.sciencedirect.com/science/article/pii/S136403212...

For instance, birds perch on the panels, turtles loaf on the floats, fish hide from predators under them. It changes the water body, but not in a way that would be different from, say, trees that have fallen halfway into the water and are shading part of the surface.


Quite confused as to why the army is doing this?

Schlepping fragile glass panels into battle doesn't sound viable and if their aim is to green up their operations there are likely better ways.


The US military is sometimes quite involved in disaster relief efforts, so I feel as though this makes sense. Also, I think they're constantly tinkering around with new toys and techniques.


I think they're willing to lose the panels in the event there's a battle at Fort Bragg.


It's for a military base on American soil. It's not a bring with you to battle sort of thing.


It's probably cost-effective, either compared to buying utility energy or especially compared to backup diesel generators. It could simply be a financial decision with some nice co-benefits...


I was expecting a lighter than air inflatable.


$orry


Inventing Screamers is bad, actually.

https://en.wikipedia.org/wiki/Screamers_(1995_film)


All these ridiculous Rube Goldberg contraptions for solar and wind when we could just build more and different types of nuclear reactors.


Its not though. It is modest and conservative iteration of existing technology that is very well understood and easy to model.


Yet, solar does not produce electricity reliably, needs additional electric backup power and uses large amounts of material and area for producing relatively small amounts of energy.

Nuclear works everywhere, everytime. There is a reason they put nuclear reactors into submarines and aircraft carriers and space probes.


> There is a reason they put nuclear reactors into submarines and aircraft carriers and space probes.

The first two have ready access to infinite amounts of coolant, which is absolutely not the situation "everywhere", and the last one actually never delivered more power than solar panels due to very inferior power/weight ratio of all space-based nuclear reactors produced to this date -- the most widespread space-based reactor BES-5 generated something like 7-8 W/kg.


I am in favour of nuclear power but it is not so black and white.

You have just listed three types of project with access to vast resources. The number of nuclear powered vessels is vanishingly small. And spacecraft overwhelmingly use solar when they can. If your goal is to move a ship or launch a communication satellite then the last thing you want to do is add the considerable extra complexity of nuclear power. Nuclear engineering is hard.


Solar panels do not suddenly render large swaths of fertile land un-inhabitable.


Neither does nuclear. 80% of the population of the exclusion zone in Fukushima prefecture have already returned to their homes. People can even move back to Futaba, a town next to the Fukushima Daiichi Nuclear Power Plant.

Nuclear power produces cheap, emission-free and reliable electricity. It's as safe as wind power and it's life-cycle emissions are even less.

> https://ourworldindata.org/what-is-the-safest-form-of-energy

> https://www.iea.org/reports/projected-costs-of-generating-el...

> https://www.energy.gov/ne/articles/what-generation-capacity


> Nuclear power does not produce cheap, emission-free and reliable electricity

Fixed that for you. Nukes produce the most expensive electricity of all. Always have, counting subsidies. Their value proposition gets even worse each day, as renewables cost continues on down. They will be mothballed soon as too expensive to continue operating at all, as people choose to buy cheaper power elsewhere.

As the amount of time they can find a market for power declines, their cost per delivered KWh multiplies without bound.


Nukes are themselves ramshackle Rube Goldberg contraptions.

They will all be mothballed by 2050 as their power cost is increasingly and, finally, overwhelmingly undercut by solar.




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