Sunday, 13 July 2014

Green myths: vertical farming

One thing that annoys me, usually by way of articles being shared on facebook, is tales of a Grand New Way of doing things*, called vertical farming. We can finally stop using land for growing stuff, and get it all from a building down the street, no food miles and all that. Before ranting on about this, The Guardian already kills it for me in this feature, probably without reflecting on it at all.

Wheat, maize and rice – these things that provide the bulk of our calories- will be very difficult to grow on a vertical farm because you need to accumulate a massive biomass for those crops - you might expect typically anything between 5 and 12 tonnes per hectare of grain from something like wheat, but to do that you have to accumulate upwards of 20 tonnes per hectare of dry weight of plant. So it's the weight of the plant. The crops that are likely to be grown are high-value nutritious crops – like tomatoes, lettuces, green crops.

The first point is; these are crops growing in greenhouses already, very tried and tested stuff. So why don´t we already stack these crops in storeys and move them into the city? Simple, it´s not worth it to use higher value land, and lots of lots of energy, to grow this stuff in a town centre, even a suburb, when you can grow it out in the sticks and drive it to market. The building of the structures, labour and energy usage, is expensive enough that it is often cheaper (and according to reports, expends less CO2 in the process, for those who are concerned about this), to ship/fly in tomatoes from North Africa instead of growing it in a greenhouse in a temperate country like the UK.

In fact, the primary input to producing these crops is sunlight, and common sense tells us that stacking crop production in storeys, requires the same energy to be retrieved from elsewhere. Hey, maybe we can replace the "saved" land with PV-panels as an educational demonstration of the law of diminishing returns.

The second point is; the savings in land area are minimal. According to these figures, the total amount of "croppable" land in the UK is 6,3 million hectares. Out of these, 163.000 hectares, or 2,6%, is used for horticultural crops. Big whoop. These crops are high value, nice to have, can yield a lot per area, but provides very little in the way of what we actually need in the Maslowian sense. When the G calls it "nutritious crops", this just plays into the idea that we´re somehow beyond needing proteins and calories to live another day, and that humans can subsist on vitamins, antioxidants and fibre.

*I´m not saying that Grand New Ways of doing things can´t happen, it certainly will, but people often mistake visions of "what would be cool" with what works. There is something that could considerably reduce the use of land, energy and other inputs (although not nutrients, as they would have to be fed into the process) from producing food, which is in vitro meats. But I don´t really see that stuff being produced in Islington either.


Mark Wadsworth said...

We don't need to invent new ideas.

The Dutch are really good at greenhouses (despite being a small densely populated country, they export tomatoes to the UK and not the other way round), as are the Spanish (they have so much sunshine, the greenhouses are used to trap water, not to trap sunshine), there's that tomato grower who gets 'free' CO2 pumped in from the power station next door etc.

The British just don't like greenhouses and polytunnels because... well because they don't.

Ben Jamin' said...

@ KJ

Just in case you haven't seen this.

As you say, growing things where there is most sunlight would appear to be the way forward.

Unless of course, you can bring the sunlight here.

Kj said...

MW: yeah, the Dutch grows mostly high value crops, and are probably good at it because of agglomeration of the industry, relatively good, flat soil, and probably awarding gas cheaply to greenhouse producers I think.

BJ: That´s good stuff. There is another project in the pipeline here: At least there is tremendous potential in doing desalination and energy production. I´m not sure about the potential for food production though. Maybe they can export cheap energy to Europe, so it becomes viable to grow stuff in greenhouses here :)

Ben Jamin' said...

@ KJ

I wrote many years ago (about 20) to the then Tory minister suggesting it would be in the UK's best interests to do a deal with Libya, and buy/lease as much of their desert as possible. While it was still cheap. Obviously I never got a reply.

It is my understanding, that since then, sovereign oil funds have been looking to do exactly this.

i.e swap one monopoly for another.

Oh, well.

Physiocrat said...

There was me thinking thanks to science and technology I was going to be able to grow all my food on my kitchen window sill. Silly me gets it wrong again.

Kj said...

BJ: I think there was a post here a few weeks ago that pointed out the position of the UK govt; doesn't do business, only contracts out stuff to foreign SWFs.
I'm rather excited about these projects, this is where sokar could already make sense, but slightly less sanguine about the political stability in the countries where this could be a big thing.

Phys: you could grow some lettuce. That's not all you food I hope.

Kj said...

All this being said, growing stuff on your own is very nice, but in no way is it more efficient or saves the world, it's just nicer in a recreational/aesthetic way. Which is why allotments attract a far higher rent than horticultural farmland, it's a higher value use than just growing stuff for market. But in no way is it valued as high as housing land, even in scruffy parts.

Dinero said...

in El Ejido Almería Spain there is an uninterupted area of polytunnels the size of the Isle of White.

Mark Wadsworth said...

Din, yes, we have commented favourably on that.

I guess the polytunnels are not to keep the warmth in but to keep the moisture in. But it seems to work, so good for them.