> Sunshine and seawater. That’s all a new, futuristic-looking greenhouse needs to produce 17,000 tonnes of tomatoes per year in the South Australian desert
> The $200 million infrastructure makes the seawater greenhouse more expensive to set up than traditional greenhouses, but the cost will pay off long-term, says Saumweber. Conventional greenhouses are more expensive to run on an annual basis because of the cost of fossil fuels, he says
From the #1 google result for "cost of a ton of tomatoes" http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=15889:
> Processors agreed to pay growers $83 per ton in 2014, up from $70 per ton last year.
So assuming 100% profit margins (ie the tomatoes grow themselves, no human labor needs to be paid, nothing needs repairing or replacing, tomatoes deliver themselves to processing plants, etc, etc), the 17,000 tonnes produced would yield ~$1.4M annually. That's an awful (0.7%) annual return on $200M. Much less than you could get by investing the $200M in an index fund.
Which is to say there's a 0% chance it will "pay off in the long-term".
They are grown differently and treated differently because appearance basically doesn't matter. They're also not required to be available for retail year round. They'll be processed within days of harvest in the fall.
Greenhouse in the desert can't compete with processing tomatoes. What they can compete is with the green house tomatoes sold in grocery store in the middle of winter.
> Average costs of production were up sharply for tomatoes to $843 per tonne
But more importantly, the second of these plants will probably be cheaper than $200m, and the 50th will be a lot cheaper.
You almost have to fix the problem before anyone even realizes it is a problem to get it done at a reasonable cost.
Of course, if all tomato growers closed shop and put their money in index funds, we wouldn't have tomatoes any more. But that would make the price of tomatoes shoot up and the return on index funds crash down, making tomatoes a better investment than index funds.
Unless, of course, angry hordes murder you because they tend to dislike people who watch famines as a normal market mechanism and suggest diversifying into cakes.
How Sundrop Farms compare to the average production cost at 843 AUD/ton would be interesting though.
There seems to also be huge regional differences, in 2008 the price received for a ton of tomatoes was 224 AUD in Victoria and 1809 AUD in Queensland.
Or, you know, the ideal notion that having a planet to spend $10 in is better than having a ruined hellscape to spend $11 in.
I'm thinking at this as proof of concept. If it works, there are many rich areas of the globe where fertile soil is at a premium and cannot grow much. Basically, transform oil dollars into local grown food.
So my $200M inestment will struggle to compete with a $40M investment in 5 years? That is a reason not to invest.
Is this really surprising in the world of agriculture? You get big loans to get a big lot of earth and pay it over multiple generations.
Also the article is unclear if the $200M investment is in USD or AUD, which makes a fairly significant difference.
If I invest 200 million in a greenhouse then I'm less exposed to all risks and rewards in the Australian economy (assuming that there's a weak correlation between the state of the economy and amount of Tomato's consumed, which seems reasonable) + all the risks in the Tomato business.
Now, it might be easier to insure against Tomato specific risks but I still don't think that the Tomato business (as awesome as this greenhouse sounds) is a clear winner here.
A seawater greenhouse is a greenhouse structure that enables the growth of crops in arid regions, using seawater and solar energy.
The technology was introduced by British inventor Charlie Paton in the early 1990s and is being developed by his UK company Seawater Greenhouse Ltd.
The technique involves pumping seawater (or allowing it to gravitate if below sea level) to an arid location and then subjecting it to two processes: first, it is used to humidify and cool the air, and second, it is evaporated by solar heating and distilled to produce fresh water. Finally, the remaining humidified air is expelled from the greenhouse and used to improve growing conditions for outdoor plants. https://en.wikipedia.org/wiki/Seawater_greenhouse
Making Namibia’s desert green using seawater
They don't appear to be using evaporation and distillation, but instead generate electricity and run the desalination plant with that... I'm guessing, by pressured osmosis, as used elsewhere in Australia.
My question is: why don't they do it as you assumed? Whatever a solar still might lose in efficiency, it must surely make up in the reliability and simplicity of no moving parts.
Personally I think the original design could be made to work, but it needed more R&D than Sundrop was prepared to spend at the time.
Generally I'm against terraforming though, especially because we've not shown we can be good custodians of our home planet.
This is a stark example, but it applies across the board. As I hinted at before, dominating something is less interesting than working with it.
Is a termite mound any less "nature" than some random patch of earth and rock? What about bird nests, beehives and beaver dams?
We are nature. The Universe is one continuous stream of change.
Sure, but we're not the only expression of nature that exists. By optimising a planet for the desires of one type of organism you do not necessarily optimise it for all living organisms. If we want to be good custodians of a planet we share with other organisms we should seek to balance our needs/desires with those of other organisms we live alongside. Due to our position on the planet at the top of the food chain due to our abilities gained through tools/technology we have a greater ability to influence the quality of life of fellow Earth inhabitants. Whilst nature can be seen as indifferent, humans are not indifferent about the world they inhabit. If it makes it more straightforward to understand, see it as selfishness... I want to live in a world with a rich diversity of life that can thrive alongside humanity because it makes life more interesting for me.
We are not looking at underground water in those pictures we are looking at evidence of likely very short term water causing a tiny amount of erosion in just the right situation. However, it's long been known there is actually quite a lot of ice on Mars.
They say plants are grown in coconut husks instead of soil. Does the coconut husk act merely as a plant holder, or is it the one that provides the nutrients that the plant would otherwise obtain from soil (with/without fertilizer)? That part is not clear to me.
Edit: "There is no need for pesticides as seawater cleans and sterilises the air..."
What does this even mean? Do we normally use pesticides to clean and sterilize the air? Are the pests that we fight with pesticides eliminated when the enclosed air in a greenhouse is cleaned and sterilized in this manner?
The coconut husk is just an inert medium which has good water retention rate. The nutrients are supplied via water by irrigating the plants frequently or submerging the roots. The whole method of growing plants like this is known as hydroponics.
 If you are interested in hydroponics, this guy has a lot of amazing videos that explain various aspects of it - https://www.youtube.com/user/Just4Growers .
Nutrients are added to the irrigation water.
when I first started with hydroponics I was amazed at how little fertilizer/nutrients needed to be added to the system to produce the volume I was producing.
I think with traditional farming a lot of fertilizer is lost to the environment which isn't so in closed hydroponic systems.
Do you have a cite on this for further reading?
Among other factors, fertilizer runoff is a studied cause of substantial ecological effects. There's a huge rabbit hole to start you off.
which is ultimately very energy intensive
If you think about the context in which we are operating though (desert with a lot of sunlight) it might be possible to colocate a solar powered reactor producing all the ammonia required for the hydroponic farms in the desert. This is just handwaving though: it seems like apart from electricity, the next biggest input is natural gas. While this may not be a problem in, say, Saudi Arabia, probably would be in Namibia.
The stems and such are mostly water and a little bit of carbon, I guess other sources of nitrogen would have an excellent ROI (a modest amount of fertilizer vs high capital and labor costs).
The tomato plan contain mild toxic content, and is quite smelly so not even goats seem happy to eat it. Not sure what they actually do with composted tomato plants.
As made clearer in other articles , they are adding nutrients to the water.
In response to delbel: As mentioned in , the farm has a 10-year contract with Coles, one of Australia's big supermarkets, and that was what enabled the farm to be funded. Consequently, you can go to Coles and buy these tomatoes for about A$7 per kg. 
Yes, that is how plants work.
If the title was "using only sunlight and nutrients" or "using only seawater and nutrients" it would make sense to mention the third ingredient, so I'm confused at why you jumped straight to condescension.
It's really weird to be on a HN thread where most of the people don't know much about the topic, you get really weird pedantic posts seemingly out of nowhere. Biology and space seem like the most common ones, where people who are very smart point out missing details, the kind of missing details that are handwaved by the actual professionals and the kind of details that would turn an article like this into a textbook chapter.
If this greenhouse system did not require an external nutrient supply, that would also be a noteworthy innovation. Note that people are asking if the nutrients are coming from the coconut husks, or from composting leftover tomato plant matter, specifically because it only said sun & seawater are used. Anybody who grows anything is interested in reducing inputs to their plant systems, and greater feedback interactions among their biodiversity.
I was able to figure out it was a hydroponic setup from the headline and that the novel part was that they were powering desalination with solar power, not that they have figured out how to grow plants without any nutrients.
The Seawater Greenhouse design is not a conventional greenhouse. It cools rather than heats a crop, it is an open design, rather than a conventional "closed" design.
The system, as designed by Charlie Paton, uses evaporative cooling in the greenhouse. Essentially they have a cardboard wall, sort of like a thick honey comb with holes through it, over which they pour seawater. The air is pulled through the wall by large relatively slow fans. When the air moves through the "honey comb" wall, the air changes direction (30 degree angle channels). Particles and insects in the air essentially get stuck in the seawater. Seawater is particularly bad for insects and other small pests as the salt clogs up the exoskeleton and the breathing channels when the water evaporates.
Even though the greenhouse was standing in an area of vegetation with a significant insect population outside, we hardly saw any insects on the inside. But you could often find quite a few insects in the seawater tanks used to hold the water for the evaporators. The stable climate created in the greenhouse and the seawater "barrier" created by the evaporators means the pest insect pressure is lie and you can easily control it with natural enemies (bio control). (There where poisonous spiders in the canopy of the crop but they don't affect the crop, but act as biocontrol. Just don't let them bite you.)
Plants grow much better in a cooler and high humidity environment. The plants don't have to put so much effort into transpiration to keep an acceptable temperature for photosynthesis. The evaporators with seawater handles both of those things.
The temperature during my visit peaked on Christmas Day at 43 C, but inside the greenhouse it was a much more acceptable 35 C. (We had our Xmas dinner just behind the evaporators, the most pleasant place in Port Augusta at that point.) The energy used for this cooling primarily comes out of the water and the surrounding air. Some energy is used for pumping water. Without the evaporative cooling the temperature in the greenhouse would have been at a level which would have killed the plants. During my visit the plants and crop grew so fast that we had to help harvesting to keep up.
The evaporators are also covered by sea salt, which is hydroscopic (absorbs water) which means that when the temperature drops at the end of the day you don't get water (dew) collecting on the plants. This is important as dew on the plants and produce allows botrytis (mold) to grow and potentially destroy the produce. This also avoids having to burn sulphur in the greenhouse to kill the mold.
 pictures from my wife during the visit https://www.flickr.com/photos/ankertje/7044271777/in/album-7...
P.S. The Wikipedia page for seawater greenhouses really needs some better photos. I've contributed to Wikipedia in the past but now lack the time/motivation, but if you or anyone has the motivation and permission, you could make the world a better place by adding some of these photos to Wikipedia.
Can you please tell us about the nutrition for the plants - is there some soil involved, or fertilizers?
Do you know how often the cardboard needs to be replaced?
I would bet it was the desert climate that reduced the need for pesticides. I am willing to predict that they will eventually need to use pesticides.
Saudi Arabia installed center pivots in the desert to grow wheat back in the seventies. I believe at the time the US price of wheat was $3.00 per bushel and the Saudi's production cost was $12 a bushel but they still thought it was worthwhile to have some home grown wheat.
Could there be ways to mitigate or prevent the mechanism of infestation in the first place?
Pests can probably arrive through:
- People's boots/clothes.
- The water.
- The soil/fertiliser.
- The air.
Nom nom nom nom.
Same thing goes for insects.
Nature is constant warfare. Farming is like picking a side and arming it.
Here is one example but there are many examples and projects:
https://www.youtube.com/watch?v=D4Nb-rqGfWI&spfreload=10 | Reversing Desertification With Sticks, Rocks, and Ancient Wisdom
Permaculture is more practical in the long run, doesn't require much tech.
>I think if we could get Earth in a living and stable state, not a constantly degrading and dying state caused by our actions, then we have won some right to go to the stars. But at present I don't think we'd be welcome anywhere else in the universe. You wouldn't welcome anybody who'd laid waste to their house and wanted to live in yours, I'm sure. -- Bill Mollison, Co-founder of Permaculture (4 May 1928 – 24 September 2016)
If he wants to put people on Mars in 8 years, this should have been a top priority a decade ago.
What about fertilisers? I would assume they still use conventional ones made from fossile fuels. Anybody got more information, did I miss sth in the article?
I assume they're supplementing liquid nutrients, as they're growing hydroponically in coco husks? If so, that makes the headline seem ridiculous...
The coolest thing in the story for me is using salty air to repel pests. Though I wonder about the longevity of that solution. I've never seen a bullet-proof solution to pest control, and especially in self-contained environments, it's usually just a matter of time. Nevertheless, makes me wonder about a saltwater humidifier....
There's a lower tech approach that's been extensively proven and in production since 1998, it produces not just veg, but firewood/biomass, shrimps, fish, fresh water and more:
And if they could only fix their political problems (to put it mildly) Gaza as well. It could make a real difference in their future.
This method could help them do that.
Humanity is turning the world into farms, destroying natural forests but then engineering new types of habitats.
I wonder what the Earth would look like in 200 years.
What I am worried about is the rapid growth of the human population and its energy use. You can't have exponential growth forever. Most of the issues come from that. Farms and monocultures sound nice, but are they sustainable? Are the resources being recycled somewhere, or are we going to be plugging holes with bacteria digesting plastic and producing plant food?
We don't. Look at the more developed nations.
that's an epic way to miss the point completely.
(this is covered in the article, but the headline forgets that part)
It's really nice experiment, but I don't see how that's gonna pay off. You need to sell a hell lots of tomatoes to earn $200 million back.
And Coconut Husks.
Pretty close though.
Commodity prices are usually expressed in tonnes. It seems at the moment the price is between $70-$80 per tonne. At $70 per tonne, the price would be about $1.2 million. You also need to pay operating costs. If the infrastructure is $200 million, I don't see how they will possibly pay it back. Even at current low interest rates, I don't think you would be able to pay off your loan.
And yes, commodity prices for food are ridiculously low. All of the money goes to distributors. Fix that and we can have nice things like this.
Maybe as you imply they aren't sold as commodities because the shelf life is too low.
I mean, how much of that is government subsidies.
If you assume its towards the higher price, and the grower sells at 10% of retail, that's over $1 billion over 10 years (the length of their contract).
I think they are taking the worst case there, and the amount going to distributors is highly variable depending on the the food itself. If you google around, you should be able to find graphs of various products (probably including tomatoes).
Nature does a pretty good job of producing food mostly by itself. We may as well take advantage of that where we can before playing in hard mode.