I carried out a research project looking into the opportunities for vertical farming in the community sector in Wales. We worked with four social enterprises and concluded fairly clearly that this was far from economically viable. Research and other vertical farming enterprises showed that there is marginal profitability for larger enterprises focusing on luxury micro greens for the restaurant and specialist retail markets only. The sustainability question remains complex but appears to be negative due to energy required. However, there is still significant opportunity for container growing under natural light in all kinds of urban and brownfield sites, such as rooftops, odd under-used greenspaces, and wasteland.
An insightful read Hannah. I've been following the development of the vertical farming sector closely over the last couple of years. In Scotland, we've got a few vertical farming businesses on a growth trajectory including Intelligent Growth Solutions that I'm sure you'll be familiair with. Their former CEO and investor David Farquhar spoke at an event I ran earlier this year in Glasgow.
In terms of the amount of energy required to grow salads, the book that really captured the reality for me is called "How the world really works" by Vaclav Smil. If contains many worked examples of how much fossil fuel energy is needed to grow, ship and sell different types of crops considering all of the different input costs, transportation, storage etc. The key takeaway is that in a full decarbonised world, lots and lots of green electricity will be needed to produce the volume of food that we've become used to in the West.
As you say Hannah, the economics of producing not only salads in vertical farms but many other crops using only green electricity don't stack up yet. If the population wants to enjoy the benefits of (relatively) cheap food (even accounting for inflation) then fossil fuels will still have a key role to play for the forseeable future.
One comment: "Most crops convert just 1% to 6% of solar energy into biomass. The theoretical maximum is around 11%." Don't these figures account for the whole solar spectrum? If so, these percentages could be dramatically larger for well-chosen-LED light. I was actually under the impression that LEDs with the spectrum tailored to the needs of the specific crops are actually routinely used, aren't they?
Same point + the economic aspect is a bit incomplete:
indoor means no costly climate hazards (a major theme for farmers even before AGW), less transport and, even more important, a better fit to consumer needs (price drop when every one outdoor is at production peak).
Did you ever plant an acre or ten or a thousand or millions of acres and provide LED light to promote better growth? “these percentages could be dramatically larger for well-chosen-LED light”. AT WHAT COST? I know of experiments of growing plants under LED light, the cost is huge relative to the harvest, the product is impressive, but the total harvest, is a tiny fraction of that same investment in using the sun to power the plant growth. We had a Grocery store that grew vegetables inside, that business did not last long. The LED light experiments are not done outside with natural rain, water must be supplied, another large expense.
LEDs with the spectrum tailored to the needs of the specific crops are actually routinely used, aren't they? YES, on many small projects, small relative to what is grown in huge fields.
I just pointed out that "Most crops convert just 1% to 6% of solar energy into biomass. The theoretical maximum is around 11%" refers to the whole solar spectrum. Obviously if lighting a crop with a light that is only 6% converted to biomass costs X, lighting it with a light that is 20% converted to biomass will cost much less. As far as I can remember, she does not explicit how she did the numbers, but with vertical farming you need lightning anyway, there's basically no way around this, so using tailored LEDs is the cheapest option.
Great article Hannah. The cost of LEDs is not likely to decrease much since we are already close to the maximum efficiency. The theoretical maximum luminous efficacy of a white LED, assuming perfect conversion of electrical energy into visible light, is approximately 400 lumens per watt (lm/W). LEDs on the market are already north of 200 lm/w, so there is only room for the cost per lumen to fall by half. This is limited by simple physics, and no amount of engineering will overcome it, unfortunately.
OTOH, plants only use a fraction of white sunlight, in the "photosynthetically active" wavelengths. LEDs can emit light enriched in PAR, up to the maximum practical conversion of electrical energy to those wavelengths. Doesn't overcome the theoretical limit of energy conversion efficiency, but extends it.
Very true. But unfortunately, there is still a limit to electrical energy-> light -> biomass, and we are not going to see too much of an improvement from here. Great point though.
I've been curious about vertical farming for a while, so thank you for this interesting and insightful read!
When considering the energy vs land-use tradeoffs of vertical vs traditional farming, was how the freed-up land would be used taken into account? If the land were "re-wilded" vs turned into a solar farm vs [insert other options], how much (if at all) would that tip the scale?
What are the benefits of vertical farming over conventional hydroponic greenhouse? While obviously the greenhouses take up more physical area, the sun is free, the climate and nutrients are controlled. Is vertical farming a solution in search of a solved problem?
Firstly, thanks for a really clear and insightful paper Hannah.
We published a paper looking into the land use issue, which showed that from a CO2 perspective, the balance shifted in favour of vertical farming if you used renewable energy and rewilded the land saved from farming:
Other factors that Hannah doesn't mention in her article is the cost of the externalities often not included in the cost calculations of conventional farming: the destruction of biodiversity from pesticides, the damage to waterways/oceans from nutrient runoff, the loss of topsoil, the loss of crops in storage/transport as crops are often shipped long distances (vertical farms can be located in cities) and the huge use of water (vertical farms use less than 90% the water of conventional farming). If you factored in the costs of the damage into the costs of conventional production, I think the numbers could look very different.
I run a vertical farm, so could be considered biased, but I actually believe we should be producing most of our food with regenerative agriculture and nature friendly farming. However, I do think that vertical farms have a role to play in a creating a sustainable and resilient system, but only in part and for particular crops.
Most of those probably wouldn't reduce the cost of production though right?
However, could government subsidies for producing healthy food and not fucking up the environment tip the balance? that way the advantages you claim would affect the cost more
That was essentially my analysis as well. I would add that vertical farming also has far higher labor costs compared to traditional farms. Even with cheap energy, they might not be financially viable.
Hi Hannah, thanks for the post. Feels like a parallel to data centres - supporting digitisation as a social opportunity with a huge energy cost. Do economic arguments like this favour investment in nuclear, to ensure a low carbon/steady supply of energy (this seems to be the path tech companies are taking)? Or is the cost of nuclear too high either way (given the price of veggies).
And if that were the case, it would be much better and produce healthier food to grow the veg in the soil and use an agrivoltaic set up to generate power using bifacial panels to maximise efficiency - dual purpose use of land
I like this idea, but worry that in the shitty UK climate it wouldn't work as well? I kinda imagined the vertical farming as having the advantage of being climate controlled.
I think a better solution for lettuce is just to stop growing lettuce. No calories, no taste. What's the point?
There was a very funny troll study (real but largely done to annoy people) a while ago that got a lot of attention in the right wing UK press showing that lettuce was worse on a per calorie basis than meat.
I carried out a research project looking into the opportunities for vertical farming in the community sector in Wales. We worked with four social enterprises and concluded fairly clearly that this was far from economically viable. Research and other vertical farming enterprises showed that there is marginal profitability for larger enterprises focusing on luxury micro greens for the restaurant and specialist retail markets only. The sustainability question remains complex but appears to be negative due to energy required. However, there is still significant opportunity for container growing under natural light in all kinds of urban and brownfield sites, such as rooftops, odd under-used greenspaces, and wasteland.
An insightful read Hannah. I've been following the development of the vertical farming sector closely over the last couple of years. In Scotland, we've got a few vertical farming businesses on a growth trajectory including Intelligent Growth Solutions that I'm sure you'll be familiair with. Their former CEO and investor David Farquhar spoke at an event I ran earlier this year in Glasgow.
In terms of the amount of energy required to grow salads, the book that really captured the reality for me is called "How the world really works" by Vaclav Smil. If contains many worked examples of how much fossil fuel energy is needed to grow, ship and sell different types of crops considering all of the different input costs, transportation, storage etc. The key takeaway is that in a full decarbonised world, lots and lots of green electricity will be needed to produce the volume of food that we've become used to in the West.
As you say Hannah, the economics of producing not only salads in vertical farms but many other crops using only green electricity don't stack up yet. If the population wants to enjoy the benefits of (relatively) cheap food (even accounting for inflation) then fossil fuels will still have a key role to play for the forseeable future.
Nice post!
One comment: "Most crops convert just 1% to 6% of solar energy into biomass. The theoretical maximum is around 11%." Don't these figures account for the whole solar spectrum? If so, these percentages could be dramatically larger for well-chosen-LED light. I was actually under the impression that LEDs with the spectrum tailored to the needs of the specific crops are actually routinely used, aren't they?
Same point + the economic aspect is a bit incomplete:
indoor means no costly climate hazards (a major theme for farmers even before AGW), less transport and, even more important, a better fit to consumer needs (price drop when every one outdoor is at production peak).
Did you ever plant an acre or ten or a thousand or millions of acres and provide LED light to promote better growth? “these percentages could be dramatically larger for well-chosen-LED light”. AT WHAT COST? I know of experiments of growing plants under LED light, the cost is huge relative to the harvest, the product is impressive, but the total harvest, is a tiny fraction of that same investment in using the sun to power the plant growth. We had a Grocery store that grew vegetables inside, that business did not last long. The LED light experiments are not done outside with natural rain, water must be supplied, another large expense.
LEDs with the spectrum tailored to the needs of the specific crops are actually routinely used, aren't they? YES, on many small projects, small relative to what is grown in huge fields.
?
I just pointed out that "Most crops convert just 1% to 6% of solar energy into biomass. The theoretical maximum is around 11%" refers to the whole solar spectrum. Obviously if lighting a crop with a light that is only 6% converted to biomass costs X, lighting it with a light that is 20% converted to biomass will cost much less. As far as I can remember, she does not explicit how she did the numbers, but with vertical farming you need lightning anyway, there's basically no way around this, so using tailored LEDs is the cheapest option.
Great article Hannah. The cost of LEDs is not likely to decrease much since we are already close to the maximum efficiency. The theoretical maximum luminous efficacy of a white LED, assuming perfect conversion of electrical energy into visible light, is approximately 400 lumens per watt (lm/W). LEDs on the market are already north of 200 lm/w, so there is only room for the cost per lumen to fall by half. This is limited by simple physics, and no amount of engineering will overcome it, unfortunately.
OTOH, plants only use a fraction of white sunlight, in the "photosynthetically active" wavelengths. LEDs can emit light enriched in PAR, up to the maximum practical conversion of electrical energy to those wavelengths. Doesn't overcome the theoretical limit of energy conversion efficiency, but extends it.
Very true. But unfortunately, there is still a limit to electrical energy-> light -> biomass, and we are not going to see too much of an improvement from here. Great point though.
I've been curious about vertical farming for a while, so thank you for this interesting and insightful read!
When considering the energy vs land-use tradeoffs of vertical vs traditional farming, was how the freed-up land would be used taken into account? If the land were "re-wilded" vs turned into a solar farm vs [insert other options], how much (if at all) would that tip the scale?
Likewise curious about this.
What are the benefits of vertical farming over conventional hydroponic greenhouse? While obviously the greenhouses take up more physical area, the sun is free, the climate and nutrients are controlled. Is vertical farming a solution in search of a solved problem?
Firstly, thanks for a really clear and insightful paper Hannah.
We published a paper looking into the land use issue, which showed that from a CO2 perspective, the balance shifted in favour of vertical farming if you used renewable energy and rewilded the land saved from farming:
https://www.actahort.org/books/1369/1369_15.htm
Other factors that Hannah doesn't mention in her article is the cost of the externalities often not included in the cost calculations of conventional farming: the destruction of biodiversity from pesticides, the damage to waterways/oceans from nutrient runoff, the loss of topsoil, the loss of crops in storage/transport as crops are often shipped long distances (vertical farms can be located in cities) and the huge use of water (vertical farms use less than 90% the water of conventional farming). If you factored in the costs of the damage into the costs of conventional production, I think the numbers could look very different.
I run a vertical farm, so could be considered biased, but I actually believe we should be producing most of our food with regenerative agriculture and nature friendly farming. However, I do think that vertical farms have a role to play in a creating a sustainable and resilient system, but only in part and for particular crops.
Most of those probably wouldn't reduce the cost of production though right?
However, could government subsidies for producing healthy food and not fucking up the environment tip the balance? that way the advantages you claim would affect the cost more
Trees are my favourite kind of vertical farming. A lime (Tilia) tree has leaves that are edible and similar to lettuce!
That was essentially my analysis as well. I would add that vertical farming also has far higher labor costs compared to traditional farms. Even with cheap energy, they might not be financially viable.
Have you crunched the numbers on coupling vertical farming with data centers to utilize the heat?
>The economics of producing leafy greens and lettuce in vertical farms can work, if electricity prices are low
Good thing all our means of producing electricity are benign, and we have no other use for electricity.
;-)
Hi Hannah, thanks for the post. Feels like a parallel to data centres - supporting digitisation as a social opportunity with a huge energy cost. Do economic arguments like this favour investment in nuclear, to ensure a low carbon/steady supply of energy (this seems to be the path tech companies are taking)? Or is the cost of nuclear too high either way (given the price of veggies).
Stop me if this is crazy: vertical farming of veg outside cities but surround it with solar panels/wind turbines to produce the energy?
Sure, that would massively increase the land footprint, but if we used grazing land (which the UK has TONS of) then could it work?
Let's put aside political feasbility, as I assume some wouldn't like it.
And if that were the case, it would be much better and produce healthier food to grow the veg in the soil and use an agrivoltaic set up to generate power using bifacial panels to maximise efficiency - dual purpose use of land
I like this idea, but worry that in the shitty UK climate it wouldn't work as well? I kinda imagined the vertical farming as having the advantage of being climate controlled.
Great post! Is the same case valid for horticultural farming using greenhouses?
I think a better solution for lettuce is just to stop growing lettuce. No calories, no taste. What's the point?
There was a very funny troll study (real but largely done to annoy people) a while ago that got a lot of attention in the right wing UK press showing that lettuce was worse on a per calorie basis than meat.
Wow, the embodied energy of hydroponic lettuce is equivalent to gasoline then!