[jongpieter]

The volume weight ratio of leafy greens, is much higher compared to tomatoes. Second the shelf life of leafy greens is lower compared to fruit crops.

In respect to transportation costs, shelf life and transportation distance, it makes sense growing these crops near their distribution points.

Second not to forget the benefit of CO2 reduction in urban area's, as there is less and less space for nature in urban areas.

The only downside is the energy usage, this has been reduced using LED lighting, but is still compared to traditional greenhouse or open-field growing.

[yongjik]

According to some researches[1], city residents already generate less CO2 per capita, because they live in a densely packed area and can use resources efficiently (e.g., subways). It makes much more sense to keep people closer to each other and keep farms farther away. (After all, cabbages only have to be transported once in its lifetime. Human beings move in and out every single day.)

[1] http://news.berkeley.edu/2014/01/06/suburban-sprawl-cancels-...

[justinator]

This is true, but it's offset by the suburban sprawl around them. Not everyone who works in the city, lives in the city, so there's longer commutes, etc.

http://news.berkeley.edu/2014/01/06/suburban-sprawl-cancels-...

[brudgers]

I don't disagree. Weed is the leafy green with the best potential returns.

[mason240]

Transportation accounts for a minuscule amount of the total resources used to grow food on an industrial scale.

[hackuser]

> Transportation accounts for a minuscule amount of the total resources used to grow food on an industrial scale

Interesting.

Is that still the case if the true costs of greenhouse gasses emitted by transportation and refrigeration are accounted for?

Does that mean the 'buy locally' idea has little climate impact?

Also, to save my lazy, busy fingers from doing it myself, do you happen to know a good link to research on this subject?

[bjelkeman-again]

I have read some Dutch research which showed tha tomatoes grown in Spain had significantly lower CO2 emissions than the same tomatoe grown in the Netherlands, including the transport to the market, which I think was in the Netherlands. I have the paper (in Dutch) lying around somewhere.

The main reason was that the Dutch heat and light their horticultural crop and the Spanish did neither (or much less). The Durch have significantly higher yield per sqm, which is necessary, as their infrastructure (greenhouses, land) is much more expensive. It is slowly changing, as the Dutch are building low energy greenhouses now, but I am not certain if it is fast enough. The greenhouses in place are relatively expensive infrastructure to replace and the profit margins are negligible at the moment.

From an environmental point of view it is tricky, as the Dutch use a lot less pesticides on their horticultural crop than the Spanish do. So it us not all obvious what is better or worse. Although I read recently that in total the Dutch use more pesticides than any other European growers, but I think that is on outside crops, not those in the greenhouse.

[hackuser]

Thanks, that's very informative.

[ars]

> Does that mean the 'buy locally' idea has little climate impact?

No, buy locally has a large climate impact - only not in the direction you think. Local uses much more energy than non-local.

Local has no environmental benefits whatsoever - only negatives.

The only thing it has going for it is some nebulous social benefits of knowing your farmer.

I avoid local because it means the produce was grown not in the climate where it grows best, but rather forced (i.e. lots of extra resources) to grow near me.

[jestar_jokin]

But isn't part of the "buying local" movement also buying produce that's in season for your climate?

If you're buying local pineapples in Duluth, I can see it would defeat the purpose.

[ars]

Even if it's in season doesn't mean your climate is the best place to grow it.

If it was the best place, then it would be competitive on the open market, and produce from your area would be the primary produce on the market - without any hokey social movements.

[jacalata]

That's only true if you want to claim that the "best" place to grow $randomFruit cannot be more profitably used doing $randomThing. Downtown San Francisco could be the world best microclimate for tomatoes but it still probably wouldn't be worth using the land for that instead of an apartment.

[zbyte64]

If it is an off season then transportation is from the other side of the globe.

[brudgers]

The farmer pulling a turnip trailer thirty miles to the local Friday Farmer's market with an F350 dually can easily consume more energy and produce more CO2 per turnip than one shipped at industrial scale half round the world. The "last mile" can often be the least efficient.

[mason240]

Still a very small part of the total cost.

[jwr]

Well, but you could use solar power to supply power to those LEDs… oh, wait…

[reportingsjr]

This can theoretically be more efficient than growing plants under sunlight. Chlorophyll mostly absorbs light in the 400nm to 700nm band which is about half of all the photons that hit lights. Even in that band ~24%[1] of the energy in them in lost due to the higher energy photons (closer to the 400nm side) being converted to lower energy photons.

So right there plants are only 25% efficient at collecting energy from photons. This is why you see indoor plants grown under red LEDs. Modern commercially available solar panels are about 21% efficient so that is actually getting close to plant can do (I'm not going to include inefficiencies in power conversion right now). Solar panels in the high 40% efficiency range exist, but they are crazy expensive and only used on things like satellites.

So using current (very advanced) technology we could actually get about double the plant output per area land by using the most advanced solar panels we have to collect light energy to power LEDs.

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

[placeybordeaux]

You are ignoring conversion, storage, transport, LED, and LED -> plant losses.

[chongli]

You're ignoring land use. You can't build a huge conventional farm in the middle of the city. You can, however, cover all the buildings with solar panels. This gives you land that supports a high population and grows food in the same place. Heck, since you're using LEDs you could put the vertical farms underground, giving every resident access to fresh vegetables right in their own building.

[placeybordeaux]

I was responding to

>This can theoretically be more efficient than growing plants under sunlight

Which doesn't seem to be talking about all of the other externalities, just about sunlight vs man made light.

[pavel_lishin]

CO2 reduction is great, but isn't profitable in itself.

[kefka]

Well, my buddy and I were considering using for our automated hydroponics system, a wood pellet stove. It would provide heating, as well as saturate the air inside with more CO2.

Higher CO2 would, we believe, increase photosynthesis, decrease growing season, and make better tasting plants. We would use a tiny bubbler and a feedline from outside for O2 rich air for the fishes.

[AnimalMuppet]

It might not just increase CO2 inside. It might also increase CO. Be careful with that...

[pavel_lishin]

> Higher CO2 would, we believe, increase photosynthesis

Have you guys done a small-scale test?

[kefka]

We were going to, but medical emergency hit. We delayed it, and am in somewhat a holding phase.