Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Vertical farming does not save space

lowtechmagazine.com

Post reply on HN
Print view View original

231–240 of 464 posts

Re: Vertical farming does not save space

#231

Post by e_y_ »

dicroce wrote: post #219
e_y_ wrote: post #184

Earlier quoted context omitted.

Or maybe something like what's being investigated for greenhouses on Mars (which gets less than half the sunlight that Earth receives) using mirrors and optical fiber cables to redirect light.

Yes! I wonder if there is a way to make a light battery? :)

Light has a tendency to zoom off at, well, the speed of light, and colliding with objects causes it to lose energy. There have been some experiments in slowing down or "stopping" light although they involve some elaborate setups that almost certainly use more energy to trap the light than you'd get from storing it.

You could also store it in or orbiting in a black hole, but good luck getting it back in its original form! https://en.wikipedia.org/wiki/Photon_sphere

Re: Vertical farming does not save space

#232

Post by dataflow »

gh02t wrote: post #165
benjaminjackman wrote: post #157

Earlier quoted context omitted.

I don't know about commercial by 2030 but leap frogging ITER doesn't seem far fetched at all because of the all signficant advances in superconductors achieved after ITER was planned out. Also, if the new superconductors do work out, it's very likely that all other forms of energy generation and grid level storage will become almost immediately obsolete and any additional focus moving forward would be only on improvi…

I'm a nuclear engineer working at a laboratory known for fusion research. Commercial fusion power at any scale is not happening by 2030. 2040 or 2050 are more realistic and may still be a stretch.

What signs do you see that it might work at all (and that it's not a hopeless endeavor)? As a layman it's so hard to understand how something so hot and so confined could ever be made to react reliably with continuous fuel and energy production to produce power on a large scale.

Re: Vertical farming does not save space

#233

Post by hultner »

dragontamer wrote: post #166
SamBam wrote: post #151

Earlier quoted context omitted.

> Solar panels are maybe 30% efficient. So 10-acres of glass-roofs need to be replaced by 30-acres of solar panels Not remotely. Plants are also extremely inefficient, converting only about 1% of the solar energy that falls for their use. [1] Most of this inefficiency is from solar energy being in the form of frequencies that the plants can't use, but solar panels can. So the panels can capture this energy, then funn…

> I've read a bunch on this, and haven't been able to find an authoritative source for what the efficiency conversion is -- how many acres of solar panels power how many acres of vegetables, and is it greater or less than 1:1? -- but it's certainly not as simplistic as "solar would need 3x more land because they are 30% efficient." I own a townhome, so my only real ability to grow plants is through a grow-light conne…

We can also increase yield and desirable traits by providing the right wave lengths at the right point of the plants lifecycle, we can make the basil more intense, the lettuce bushier and more red. And we can control the environment to easier prevent vermin without pesticides, bad weather, etc. We also do large scale installations in the desert under ground where we previously couldn’t farm at all.

I was an engineer at a company called Heliospectra, we specialized in this and I personally built systems that on an industrial scale enabled above light/environment control down to umol of individual wavelengths every minute based on variables such as sensor feedback, algorithms for specific types of plants and traits as well as learning to adapt based on the environmental daily patterns from sensor feedback over time. It was actually quite fun to work on, I do still keep in contact with the company.

Re: Vertical farming does not save space

#234

Post by Retric »

tohmasu wrote: post #228
tohmasu wrote: post #223

Earlier quoted context omitted.

>"So 1.5 GW of solar = 1.0 GW of nuclear." That's not how it works. PV capacity factor is 11-12% to the 90-95% of nuclear meaning you need to install about an order of magnitude more PV effect not 1.5x.

Also one batch of PV panels equivalent to a reactor cost 6x as much and with a lifetime of 20 years to the 60 for a nuclear reactor so you will need to replace these at least twice. All 32.5 Million of them.

Replacing panels is just a cost question which dramatically favors solar. 2c/kWh is massively better than any nuclear reactor ever built or operated.

As we are talking land use, construction and decommissioning is a major hit to nuclear. But with solar you can operate continuously by just swapping panels and replacing wires etc as needed.

Basically, in steady state a 50 year nuclear power plant spends the first 30 years with the previous reactor being decommissioned, and it’s last 10 years with it’s replacement being built. Effectively you need 1.8 locations for a single power plant.

Also, I used a specific 75% capacity factor over it’s operating lifespan in that calculation. Some are higher, but the trend is down over time so you want to use an old reactor as your baseline. Here is 72.5% Decommission date 29 June 2020 https://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant

Re: Vertical farming does not save space

#235

Post by tinco »

pfdietz wrote: post #212
benjaminjackman wrote: post #188

Earlier quoted context omitted.

That's interesting, do you think that SPARC and HTS advancements like for example VIPER cables point towards a faster path to market for fusion than ITER?

No, because the fusion reactors using HTS still have horribly lower power density. The ARC design has a power density 40x worse than a PWR primary reactor vessel, and involves far more difficult engineering. How is this going to be cheaper than fission, which itself is not competitive?

Fission is only not competitive because of regulation and safety measures, is it not?

Re: Vertical farming does not save space

#236

Post by sir_bearington »

Retric wrote: post #225
manfredo wrote: post #211

Earlier quoted context omitted.

To put this in comparison, a solar farm would need 50,000 to 100,000 acres to match the net output of those nuclear plants. Plus the land used for energy storage, which would typically involve damming rivers which has its own set of ecological effects. And it's possible to build much denser plants. The Shin-Kori facility in Korea is massive energy relative to the land it uses. Nuclear power is far more energy dense t…

Try running the numbers for actual lifespan. Callaway is 1,190 MW on 2,767 acres at 87.70% over it’s useful lifespan, but that’s ignoring permits + construction = 10 years and decommissioning which takes ~30 year. Even a generous 55 year operating lifespan is still reduced to 87.7 * (60 / (60 * 10 + 30)) = 48% capacity factor. Using a 20% capacity factor for solar (aka non tracking in a good but not great area). That…

30 year decommissioning is a very pessimistic assumption. Also most new nuclear plants have operating lifetimes closer to 80 years than 55.

You also have to adjust for the overproduction necessary to make intermittent sources a reliable primary provider of electricity. In far north or southern latitudes, angle of inclination is such that solar panels collect ~70-50% less energy than near the equator. This gets worse with seasonal fluctuations, which are more extreme the closer to the poles you get. Add weather on top of this and it can drop even further.

This might not seem like too big an issue, but keep in mind that most of the world's electricity consumption is in North America and Europe. These places don't have as good weather for solar.

100,000 acres is roughly the ratio that the article came up with, a factor of 75.

> PS: That said, this is largely a moot point as even with reprocessing we would quickly run out of fuel with large scale indoor farming.

No, we wouldn't: https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s...

Re: Vertical farming does not save space

#237

Post by pfdietz »

manfredo wrote: post #227
pfdietz wrote: post #214

Earlier quoted context omitted.

Storage solutions are advancing fast enough that your argument cannot succeed. What you are saying used to be sort of plausible, but the sell by date on it passed long ago.

Right, as evidenced by the extensive storage infrastructure being deployed /s. The US has 25 GWh of storage, as compared to an hourly electricity consumption of 500 GWh. Literally less than ten minutes of storage. Almost all of it hydroelectric, which is a big infrastructure project on par with building nuclear power plants I'm sure you're eager to talk about how thermal storage, or concret weights with pulleys, or c…

> Right, as evidenced by the extensive storage infrastructure being deployed /s.

Invalid argument.

> The US has 25 GWh of storage, as compared to an hourly electricity consumption of 500 GWh. Literally less than ten minutes of storage. Almost all of it hydroelectric, which is a big infrastructure project on par with building nuclear power plants

Irrelevant point.

Storage was marginal in the past because there wasn't much of a business case for it. With renewables crashing in price and fossil fuels being phased out, that is changing. There are now strong market forces pushing development of storage technologies. Your insistence of carrying over the market conditions of the past into the future leads you astray.

Re: Vertical farming does not save space

#238

Post by Nition »

LeifCarrotson wrote: post #134
Nition wrote: post #17

Earlier quoted context omitted.

Say a plant needs 1/10th of actual full sun during the day, could you theoretically remove the electricity step entirely but "just" (putting "just" in quotes because I'm sure it wouldn't be easy) having some sort of fancy mirror setup on a 10 storey building to send 1/10th of the sunlight hitting the roof to each floor?

Close, it's 1/10th of the spectrum not 1/10th of the intensity. The 'fancy mirrors' required would simply be a prism. You'd separate out the red and blue light and aim it at the plants, and send the green and infrared light to solar cells, to be used for running red and blue LEDs. (Or you could use flourescence if you had something that glowed red or blue when exposed to green or IR light). Check out this spectral pl…

Do the plants actually need the full strength of that red and blue light for optimal growth though? I thought the comment above mine was implying that they don't.

So my proposition was that if we started with, say, midday sun, maybe we could divide that up (in brightness, not just by spectrum) to cover a larger area (multiple floors in this case).

Re: Vertical farming does not save space

#239

Post by pfdietz »

tinco wrote: post #235
pfdietz wrote: post #212

Earlier quoted context omitted.

No, because the fusion reactors using HTS still have horribly lower power density. The ARC design has a power density 40x worse than a PWR primary reactor vessel, and involves far more difficult engineering. How is this going to be cheaper than fission, which itself is not competitive?

Fission is only not competitive because of regulation and safety measures, is it not?

Not. Nowhere has it done well. It's just too complex with too many interdependent parts. Construction has proved to be beyond the competency of those trying to build plants. And now, it's just too late. The iteration time for nuclear designs is measured in decades, going up against renewable and storage technologies iterating in periods of a few years.

Fusion would make fission look dead simple. If fission reactors cannot be constructed on schedule or budget, how bad would fusion reactors be?

If you think regulation is the problem, explain just which regulations you mean.

Re: Vertical farming does not save space

#240

Post by hultner »

_carbyau_ wrote: post #210
ben_w wrote: post #155

Earlier quoted context omitted.

Are greenhouses in deserts harder to build or maintain than PV farms and power lines in the same desert? Not a rhetorical question, I genuinely don’t know. I assume it varies by desert, but farming and power are both way out of my domain.

My understanding was that you put the solar in the desert, so that you can put the vertical farm somewhere else where soil, water, transport logistics is easier. So the question is whether a greenhouse/farm in the desert is easier than solar in the desert connected through grid to vertical farm somewhere else. I have no data. My guess is the ongoing logistics of piping electricity out of the desert is easier than fer…

It is, I’ve worked on large scale projects to enable farming in deserts using underground vertical farms.
Post reply on HN