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Comment by karterk | Hacker News Reader

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.

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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

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.

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.

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.

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.

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.

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.

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?

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.

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.

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.

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.

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.

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.

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)

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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.

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.

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.

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