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Comment by ZeroGravitas | Hacker News Reader

Yale360 seems to cover renewables issues as if the reader already has some very weird ideas about them. Probably a sensible and sadly necessary approach.

But in reality, land use has never been a problem for Solar. It's great that lots of people are working on the issue and improving it. Just as lots of people are working on making them cheaper, or more environmentally friendly or easier to finance or a thousand other metrics.

But none of those were ever fundamental problems with the tech. Their own source of data about the 'problem' puts Ground-based PV at about the same land use as Coal.

They also missed out 'floatovoltaics' (PV on water) and building integrated PV as well as solar PV as a paving solution. Probably all of which are likely to be bigger than ground mount PV, given the trend to bifacial panels.

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"Same land use as coal" isn't necessarily an equivalent metric. Solar might be taking up land that could otherwise be used for food, for instance.

Better energy density will also help locate solar power closer to where it will be used, like on top of buildings in the city rather than in a large plant out in the middle of nowhere, thus saving on transmission costs.

Finally, IMO photovoltaic pavement is probably going nowhere.

Solar shading would works, probably.

That seems like an excellent point. Why hasn't this already been done everywhere that gets sunny?

Solar may share land that is also used for food, so no: There is no competition between them.

In fact, sharing improves efficiency of the panels, cuts water loss, and often increases yield.

May share for some crops yes, but that hasn't traditionally been the case has it?

Did everyone always know that solar/crop dual use was often purely beneficial for both? No. Did somebody know? Yes. Does everyone know today? Evidently not.

> Did everyone always know that solar/crop dual use was often purely beneficial for both? (emphasis added)

"Often" != "Always". Therefore you also agree that solar still competes for land use with crops.

Furthermore, land that has already been allocated to grid scale solar has already been taken away from possible crop use. Sometimes it's not arable land, but that isn't always the case, therefore solar is still ostensibly taking up land that could be used for crops.

Finally, I even disagree that somebody knew that solar and farming could use the same land. Someone had an idea that maybe they could coexist, then ran an experiment that succeeded. They certainly didn't know the outcome beforehand.

> Therefore you also agree that solar still competes for land use with crops.

No. It just means that some places are better than others.

Since there is overwhelmingly more crop and pasture land than could ever be needed to satisfy power needs, solar may be placed exactly and only where it does the most good.

It has been known for centuries that most plants benefit from partial shade. It is an exceedingly tiny step of logic to go from "shade" to "shade provided by solar panels". In the past, providing shade just cost money. Now it yields direct revenue, year-round.

> It has been known for centuries that most plants benefit from partial shade.

Again, "most plants" does not necessarily include "crops", most of which have been selectively bred over millennia while grown under full sun. The step is not from "plants do well under shade" to "plants do well under solar panels", it's to "crops we've never grown in partial shade might actually do better in partial shade too".

You are really reaching now. It would be better to stop before you embarrass yourself too much.

What a compelling argument. Sounds like you fully justified your claim that we knew all of this centuries ago. Good job.

OK, be embarrassed.

That's because it's such a non issue that the cost of thinking about it for a little bit exceeds the downsides.

When it is an issue there are countless solutions from sharing with livestock (already done in some areas) to providing partial shade for non energy crops like lettuce or capcicum that increase yield to covering parking.

For reference, there are about 2.5 billion parking spaces in the usa which take 20-50m^2 each, very little of which is more than three stories deep. This is room for between 1 and 5 TW of net (ie. averaged over the year including nights) capacity or roughly the USA's entire energy consumption. You could also replace a small fraction (about 5%) of corn used for ethanol (not the total corn) and get a similar result.

Solar might also provide better shade for livestock and cropping growth, particularly in future days of greater heat.

> Sheep grazing under solar panels at farms in NSW's Central West have produced better wool and more of it in the four years since the projects began, according to growers.

> Local graziers have labelled the set-up a "complete win-win", with the sheep helping to keep grass and weeds down so as not to obscure the panels.

This is not something that works so well with open cut coal and down wind from city supplying coal burning power stations.

[1] https://www.abc.net.au/news/rural/2022-05-30/solar-farm-graz...

Not sure why you're getting downvoted. I think "floatovoltaics" are definitely a growth option with lots of upside - especially if located on man-made bodies of water e.g. dammed lakes (which often will have sufficient infrastructure already in place).

https://thesolarlabs.com/ros/floating-solar-farms/

Is PV at the same land use as coal currently on a per-watt basis or on a total land use basis?

Since solar may use up exactly zero acres, its watts per acre may be infinite. Wind, also, coexists easily with other uses.

Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea.

>Solar farms are often sited, stupidly, in deserts, not because it is a good idea, but because ignorant investors think it is a good idea.

Perhaps indulge our ignorance about deserts for a moment?

Deserts are hot and dusty. Efficiency falls quickly as temperature rises, and more as dust accumulates. Panels degrade exponentially faster as peak temperature increases. (Precisely: each fixed increase in temperature doubles rate of degradation.)

Siting panels on water and on farmland reduces operating temperature. Mounting vertically, in fence-rows, keeps off dust, collects more during morning and afternoon demand peaks, aids convective cooling, and protects crops from harshest afternoon sun.

They link to this, which has a table at the top:

https://ourworldindata.org/land-use-per-energy-source

I'd assume coal uses much more land in absolute terms, since it's what 50% of global electricity vs 3-5% for solar at the moment.

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