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Agriculture Sundrop Farms, KKR, Australia, solar thermal, agriculture, farming, desalination, solar desalination, Port Augusta

Published on December 5th, 2014 | by Leon Kaye


Can Solar Thermal Desalination Make Sustainable Agriculture Possible?

December 5th, 2014 by  

The jury is still out on solar thermal, which is certainly efficient but has its critics because of its costs, both financial and ecological. The International Energy Association (IEA) is still bullish about its future, and projects such as the Solana Generating Station in Arizona show potential. Large projects such as Masdar’s Shams 1 and California’s Ivanpah have scored plenty of attention, but the rapidly decreasing price of solar panels has made PV more attractive for large projects. But solar thermal technology could have promise for agriculture. At a time when many are pondering how we are going to feed nine billion people by 2050, new projects underway are leveraging solar thermal desalination technology to cleanse water and grow crops in water-stressed regions.

Sundrop Farms, based in Port Augusta, Australia, believes it has a solution. The company claims it is the only such company in the world that can build and operate greenhouses in areas that severely lack fresh water, arable land, or access to the electrical grid. In order to bring food closer to cities, “Sundrop Systems” turn energy from the sun and seawater into freshwater for irrigation, power for greenhouses and climate control to heat and cool crops as needed. Nutrients that end up as by-products from the desalination process can also be converted into fertilizer that in turn can be used within the greenhouse. In a way, one could describe this as a closed-loop system for growing food. The ability to grow food in places like brownfield sites or in areas where the climate is too harsh for agriculture, or even horticulture, could make this a more sustainable way to produce food—if it can become cost competitive. Sundrop Farms and its main investor, the American private equity firm KKR, have not publicly revealed any figures about the cost of these projects or whether they seek financial incentives from local governments.

Sundrop Farms, KKR, Australia, solar thermal, agriculture, farming, desalination, solar desalination, Port Augusta

Nevertheless, as more countries and municipalities consider desalination to meet their ever-growing water needs, alternatives to current desalination technologies are needed. Desalination using conventional fossil fuels leaves its own sizable carbon footprint, and the process is also expensive and leaves municipalities and businesses vulnerable to volatile prices. Solar desalination shows some promise, but is still several years off from becoming truly scalable. But Sundrop Farms’ application for farms could have potential.

Port Augusta, located in an arid region in South Australia, could become the perfect laboratory exploring solar thermal’s viability for agriculture. The town receives only about 10 inches of water (25 cm) of water annually—much of Australia has suffered even more as the country has coped with severe droughts for several years. Sundrop Farms and KKR are investing in a 20 hectare (49 acres) facility that will produce 15 million kilograms (33 million pounds) of vegetables and other tomatoes—which both companies say will produce 100 more times food than the current greenhouse onsite. According to a Factiva search, 11,000 parabolic mirrors will redirect sunlight on a 115 meter (327 feet) tall tower, which in turn will create steam that will power turbines and then provide energy for the mega-greenhouse. The project also promises 200 jobs, a solid economic boost in this town of 13,000 people.

If the project succeeds, Sundrop Farms has its crosshairs on new markets in the United States and Middle East. With the growing mantra to “buy local” catching on in the U.S.—often in communities where large-scale agriculture is not possible—do not be surprised if this is a technology we see in more cities in a decade. And as California and other states cope with an extended drought, seawater will take a more active role in irrigation with freshwater and groundwater supplies close to being tapped out.

A similar solar thermal project launched earlier this year in another water-stressed region. WaterFX, a California start-up, has built a solar thermal-powered desalination plant in the San Joaquin Valley that cleans saline drainage water and turns into freshwater for irrigation. The 6,500 square foot facility can produce eight gallons of safe and clean water a minute, and plans are underway to expand the plant so it can produce 2,200 acre-feet of water annually. Pilot programs are also on the drawing board in Chile, which is also has a large agricultural sector and has its own water challenges.

With 70 to 80 percent of the world’s freshwater devoted to farming, society will have to make some tough choices in the coming decades as we use water faster than it can be replenished. Technologies coming from companies such as Sundrop Farms at the very least will motivate other clean technology entrepreneurs to find new ways to harvest water and grow crops for an ever more crowded world—sustainably.

Image Credit: Sundrop Farms

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About the Author

is based in Fresno, California. He has written for Guardian Sustainable Business, Triple Pundit, Sustainable Brands, Earth 911, and Inhabitat. He also writes about his thoughts on sustainability on his own site, greengopost.com.

  • Henry WA

    Perth in Western Australia (population 1.9 m) relies on 2 desalination plants using reverse osmosis with a total capacity of 150 billion litres to supply 50% of its water. The balance comes mainly from Deep Aquifers as Perth Dams have only a third of the run-off that they had 50 years ago due to changes in the rainfall pattern. Cost of Desalination is approximately A$1 per kilolitre. The Water Corporation’s website states that the energy requirement in supplying desalinated water for an average family of 4 is equivalent to running a beer fridge. The desalination plants would appear to be ideal candidates for Demand Response when combined with wind and solar as they can be turned off when power supply is low or power demand high.

    • Larmion

      Drinking water is far more valuable (and needed in far lower quantities) than water for irrigation. It’s an apples-to-oranges comparison really.

      Producing the direct water use of a city through reverse osmosis can be done with the output of a wind farm or two. Producing the water needed for the agriculture that supports that city would consume more energy than the entire city uses for everything.

      Until the era of energy too cheap to meter arrives (never, in other words), any scheme that hopes to water crops through desalination is doomed.

  • Matthew Rose

    If one were to look upon KKR’s investment track record, one might not bet against this.

  • Michael G

    Everyone should read the NYT article at

    I got it from WaterFX’s web site http://waterfx.co/news/

    The water is nearly twice the cost of the water from the water agency but since that latter cost is unrealistically low (Bush 41 got the farmer vote with that), it is really not too expensive as these things go and is best considered as a supplement. It also purifies out the salts and poisonous minerals washed down from the mountains. One acre of this supplies water for 200 acres of farmland. We will pay a little more for food (America’s food bill is very low compared to most of the world’s) but our water woes could be a thing of the past.

    • Larmion

      Interesting (though highly site-specific) concept. Solar thermal purification is too expensive for creating irrigation water (every purification method is), but the facility also doubles as a environmental remediation method in this instance. That dual purpose makes it a far more attractive option than seawater desalination.

      • Michael G

        I’m not sure about the cost effectiveness. Without knowing the cost of water as a current fraction of food costs I can’t tell. (I searched on the web for about an hour and gave up.)

        Ultimately, it comes down to what is a fair price for water?

        If water is currently 10% of the cost of growing food, then doubling that to 20% would mean $10 worth of food now ($1 for water) would cost $11 ($2 for water) with this method of purifying water.

        Americans pay about 1/2 what other industrialized countries do for food, as a fraction of income. A 10% increase wouldn’t matter much in the long run, especially when the choice is expensive water vs. no water.

        • Larmion

          Rainwater is free and groundwater costs only what a pumping station costs. As such, any technique that requires significant building work to produce water by its very nature cannot be cost-effective. If farmers were forced to pay a higher price for water abstraction, that might change – but then economics would still favor using less water over desalination or other water treatment processes due to the low cost of things like drip irrigation.

          Of course, it’s a bit absurd to talk about water use in ‘America’ when it encompasses so many climate zones. You cannot compare Imperial Valley to a rainfed New England farm, for example.

          The American food expenditure point is a bit tricky. Americans have a higher disposable income than most citizens of the rich world. At a certain income level, all food related desires are met and food expenditure stops rising. Any increase over that level will thus cause a reduction in the percentage of income spent on food. As such, a percentage based indicator is rather misleading.

          Simple consumer preference also plays a role: many Americans seem to be content with a bland diet and omit many rather expensive foodstuffs seen as basic in Europe (fine cheeses, slow-fermented foods, seafood,…) or Asia (seafood, young leafy greens, spices,…).

          On a like-for-like basis, I’m not sure America is that much cheaper than Europe. Staples like a carton of milk or a loaf of (decent) bread didn’t appear exceptionally cheap to me last time I was in the US.

          • Michael G

            You are right on food – item-for-item food is about as expensive in the EU as in the US. But if wet Europe can see cheese and wine as essentials, the US needs to see the water component of food priced fairly. Almost 100% of many vegetables in the US come from CA. The entire country needs to know the real price of water in CA. That may make other parts of the US more viable than CA for things like avocados and almonds which are almost all grown in CA.

            The price of water has to be more than the extraction price in order to ration it or it will be cheap until it is all gone as it is now in various parts of CA. It should also include the replacement cost when it is over-used to the point that there is none left, and all the aquifers are dry. It should also include the cost of the huge infrastructure in CA to move it from where it is to where it isn’t.

            Of course more sensible use of what we have would be best, but if water is not priced in such a way as to encourage such use than it is too cheap. If the option is no water or desalinated water, desalinated water wins. It may be it is not truly economical to grow almonds and avocados in CA.

            There are parts of CA where water has to be trucked in. That has to go into the calculations for the price of water.

          • Agreed.

  • By reducing the Yankee average calorie intake to the Canadian calorie intake who btw need more calories than Yanks cause it’s cold up here, imagine, john lemmons, how much water you would not have to desalinate.

  • Marion Meads

    For lower purity water that has some salt remaining but is good enough for irrigation purposes of salt tolerant crops, nothing so far will beat the Electrodialysis method of crop water production.


  • Marion Meads

    The water doesn’t have to be completely salt-free in order to grow crops for food. In fact, a 50% freshwater plus 50% seawater can be used for properly selected crops. This means that the desalination plant doesn’t have to work that hard nor use a lot of energy, and can increase crop water production capacity. I don’t know how CleanTechnica could miss this news from last month. It could give California Agriculture a run for its money because many coastal areas of the world and other desert areas with high saline content would now be able to grow their crops for food!


  • Michael G

    I’ve pointed out in another context that at the historical rate of decline of PV generated energy, electricity will be essentially free in about 20 years. (15% rate of decline => 0.85^20 = 0.04 X $0.06/KWh (current cost/KWh) = $0.0024/kWh in 2035) That would make electrical desalination essentially free. Making Saudi Arabia a major producer of veggies?

    Still a lot of cost in building so many water plants and then moving the water around. Agriculture uses an enormous amount of water and it would be far better to start using the water we have with greater restraint. Drip irrigation was invented in California almost 100 years ago but too many farmers still don’t use it. And CA households have these lawns that more properly belong in England. As Larmion points out above, CA uses huge amounts of water on things like avocados and almonds just because we have so much sun.

    Or, maybe we could stop making the planet hotter?

    • Larmion

      Even if we stopped emitting greenhouse gasses tomorrow and then took some carbon dioxide out of the atmosphere, we’d still have a water problem. Large parts of the world use more water than is replenished through rainfall, snowmelt or other sources of aquifer replenishment. Climate change makes things slightly worse than they already are, but the problem long predates global warming – in pre-Roman times entire highly advanced civilizations in the northern Sahara collapsed because of aquifer depletion.

      Water is the saddest tale in the history of agriculture. There’s no shortage of it and we have a whole arsenal of simple, efficient ways of using less of it. It’s another sad example of the tragedy of the commons: why save what’s free and abundant? It’s time to start metering every single drop of water. Every. Single. Drop.

      • Michael G

        I don’t disagree at all. After global warming, water is the most pressing environmental and human issue to be resolved. I sometimes wonder if the silver lining to all we’re doing in destroying our environment is that maybe we will finally appreciate and properly value our “free resources. Hopefully, before it’s too late.

    • Bob_Wallace

      “$0.0024/kWh in 2035”

      You’re making the false assumption that there are no limits that will slow, and eventually halt, the down price movement. Unless we find a magic genie to give us the aluminum, glass and refined silicon the price from for PV panels will flatten out over time. The machines we need to make the panels will have some cost as will the buildings in which we manufacture and the transportation we use to move the panels to where they are to be installed.

      • Michael G

        I expected this type of comment. It reminds me of a paper published about the limits to further increasing the speed of microprocessors. Two professors at a distinguished university showed that it was beyond the limits of silicon and various other components plus manufacturing difficulties to make processors faster than… (wait for it!)

        100 MHz!!

        (Speeds are currently in multi-GHz range, in case you don’t follow it.)

        • Bob_Wallace

          I tried to determine the cost of panels needed to produce $0.0024/kWh electricity. The panel cost would have to below $3/kWh.

          Panels would have to sell and be installed for less than $0.003/watt. Well under one-third of one penny per watt. I can’t get the number more precise as the NREL LCOE calculator doesn’t return numbers $1/watt installed price but what you are predicting is essentially no cost manufacturing, transportation and installation. As well zero maintenance.

          Try not to make the mistake of applying history in inappropriate ways.

          • Michael G

            It is a mystery to me how someone who frequents this site can not see the changes coming. There won’t be any installation charge because PV will be made of different materials and become so light anyone can just lay it across their roof, AND it will be built into building materials such as windows, roofing, roadbeds so the installation will be ‘free’ as it will be part of the construction of buildings, cars, roads.

            Efficiencies will climb dramatically as semi-transparent materials with different work functions (so sensitive to different frequencies of light) are layered across each other.

            This is all apparent from the research press releases published here daily. How can you think it will always be these clunky, heavy, silicon and glass PV panels we have to use now? They will be laughable museum pieces in 20 years,

            This is all from work being done now. I am not postulating any Nobel-prize winning breaktrhoughs in science or engineering though I have no doubt they will come too.

          • Bob_Wallace

            Michael, this is a reality-based site. Not a science fantasy site.

            The glue it takes to attach your “anyone can just lay it across their roof” panels will cost more than your budget.

          • We’re jaded though, the public is trained constantly to believe lies…..
            Wow, at this local city council, quarterly police reports ‘say’ that the crime rate is falling even though one third of the police force is MIA for various internal reasons.
            At this rate we will hit zero crime or even a negative value crime rate with no police force in the near fictitious distant linear thinking future!

  • Chimel

    Even the biggest desalination plant in California can provide water for only a few thousands homes, irrigation would require orders of magnitude more desalination acreage and clean power. Still, every little bit helps, so I think clean desalination plants should be built wherever possible, no need to waste such a resource, as long as it is not an excuse to stop working on better managing irrigation water. Not sure cost is a big issue, the cost of not having water is surely much higher than the cost of desalination.

    The salts are way too concentrated to be used as micro-nutrients for crops, they are a waste mostly. We can use some as table salt (probably need to close all salt mines,) some to coagulate soybeans into tofu, some for other industrial uses, but that slurry is not easy or cheap to process for now.

    I had dreams too of pumping that ever rising ocean water into the dry Midwest, because I think it is wasteful today to grow crops without both irrigation and drainage, but maybe it would be better to grow human food where it can be irrigated and reserve the drylands for growing animal feed. As good as they are for corn, the U.S. ranks only 50 or so worldwide for wheat yield, mostly because of the low performance of the drylands. I don’t eat much corn products or corn-fed meat, but I eat wheat almost every day.

    It’s everybody’s problem too, not just a farming issue: For instance, going for a lentil dish on Meatless Monday instead of a burger saves over 500 gallon water, much more effective than trying to save on showers…

    • Larmion

      A very thoughtful post, especially the part about animal products. In the whole vegetarian/vegan versus carnivore debate, it’s far too often forgotten that ruminants have a place in sustainable agriculture, as a way to exploit excessively dry, poor or wet lands that cannot sustain arable farming but do allow grassy vegetations. On the other hand, the impact of intensive meat production on nutrient, water and land use is too often ignored by the meat-eaters amongst us.

      The most sustainable diet is one that includes small quantities of animal protein, produced mainly through extensive grazing of ruminants and farm/food processing waste fed pigs and poultry. Our current methods of meat production are entirely unsustainable, but the meat free world so many on this site dream about at night is far from perfect too.

      The need to process by-products from desalination is also a pertinent issue. Direct release into the sea destroys local ecosystems, storage on land threatens valuable agricultural land and industrial uses are limited.

    • Marion Meads

      The news below will give California Agriculture a run for its money. There are many coastal areas with brackishwater that can now be planted. With crops like these, the desalination plant doesn’t need to extract high purity water. Something like 50% seawater could very well be tolerated! So no need for supermassive amount of energy required for partial desalination.


      • Larmion

        a) ‘Partial desalination’ isn’t going to happen through solar thermal. Solar thermal uses flash or multi stage distillation, which basically means boil water and capture the (pure) vapor.

        A better option would be reverse osmosis, but that’s a very expensive method. The cost of simply reducing water use to a sustainable level is far, far lower in all but the most arid parts of this planet.

        b) You keep citing that link, but there’s really nothing special about it. At all. Salt tolerance in plants is a trait that has been bred into hundreds of different crop cultivars – it’s easy as 1,2,3. The problem is that the mechanism plants use to tolerate osmotic drought is quite energy intensive and puts a brake on the yield and stress tolerance of plants.

        Perhaps as importantly, if you continue to irrigate with water that is saltier than desirable, you keep building up salt in the soil. After a few decades, you’ll have cropland with a salinity level too high for even the best osmotic adjusters ever bred.

        Salt tolerant plants are lovely. I’ve seen a lot of great projects (mainly on rice) that allowed the use of naturally slightly brackish areas. The problem is that that sort of land is in limited supply and often of huge ecological value. The last thing we want to do is to start destroying the croplands we have just because irrigating with brackish water is cheaper for the first few years.

        Oh, and farming is about much more than crops alone. A healthy soil ecosystem also requires the vast number of bacteria, fungi and animals living in the soil, most which have little or no salt tolerance. Soil whose salinity rose due to human activity supports an ecosystem that makes the one found in the most destructive of monocultures look healthy.

        • Marion Meads

          Here’s what’s in the link. “..there are 1.5 billion hectares of salt-damaged land all over the world where different types of crops could be grown…”

          You did not read the link but just shrugged it off. You also don’t know how to farm. It is totally ignorant to say that you keep building up salt in the soil when you use water that contains salt. The key is drainage. If you have drainage, the amount of salt in the soil will be in equilibrium with the salinity of the water that you use.

          You also didn’t know a thing about electrodialysis. Electrodialysis in terms of capacity is the most efficient partial desalination technology there is, most efficient if you aim for a lower purity water. Combine this with the crops that were proven to be productive in brackishwaters, you have a knock out combination in terms of food production that should be able to feed twice the current world population. There would always be world hunger no matter what, as it is a social problem related to profit making.

          • Larmion

            I read the link acutally – even though I normally don’t read ‘science’ news on a site like yahoo.

            The number you cite sounds impressive, but the research is relevant only to a fraction of that.The article itself only speaks of 300 million hectares and even that seems optimistic judging by what little I could find by trawling web of science on the topic.

            Drainage only takes you so far, since you’re bound to hit an impermeable layer sooner or later. Every single acre of land in the world every irrigated with brackish water saw a gradual buildup of salt – that’s the reason we ended up with the vast acreage of salt-damaged land you mention yourself.

            I would love to see a peer-reviewed publication that shows there is no build-up of salt in a typical soil. Also, would a highly regarded researcher such as yourself really cite a yahoo link?

            Electrodialysis is a lovely technique on paper, but rarely used on a commercial scale. There is the issue of fouling for starters, but the technology also doesn’t scale that well. But that’s entirely beside the point. Every single technique known to mankind for reducing the salinity of water is currently too expensive to satisfy the water requirements of even efficient agriculture. That’s not going to change any time soon.

            As for your last claim: I would love to see sources backing you up on that one. While the amount of salt-degraded land is large, it’s not even close to enough for doubling world food production. Or perhaps you assume that brackish water could be used to turn currently unused land into arable land? If so, which land might that be? Arid soils currently suffer from more than a dearth of water: they’re also high in minerals (including ones toxic to plants such as various aluminium compounds), underwent little or no podogenesis and are typically remote.

            The last point is true: hunger is not just an issue of producing more. It’s mainly about wasting less of what is produced, both in the literal sense (food waste) and in a more abstract sense (feeding high grade fodder to cattle, for example).

  • Larmion

    a) Since when is it difficult to feed 9 billion people? Present day yields can already easily feed far more than that and further advances in crop science are allowing those yields to increase even further (even despite the effects of climate change and loss of agricultural land).

    b) The water volumes that can feasibly produced by desalination are absolutely marginal. It could allow some expansion of greenhouse farming and thus yield a tomato or two extra, but the volumes of food produced by horticulture are quite frankly marginal compared to arable farming. Greenhouse farming is great, but only for a limited assortment of high value fruits and vegetables.

    Water must be treated as a demand side issue, not a supply side one. The cost of desalination is prohibitive, while demand management is easy:

    – Improved irrigation practices (drip irrigation for example) can sharply cut water use.
    – Crop breeding for increased water use efficiency (WUE) is a hot topic in modern plant science and huge progress is being made.
    – The twentieth century has seen the rise of the growing of climate inappropriate crops, with the rise of irrigated farming of water hungry crops in Imperial Valley being perhaps the most famous example.
    – Apart from crops themselves, improved soil management can also reduce water use sharply.

    Not every problem can or should be solved by increasing the amount of inputs available. Increasing the efficiency by which existing inputs are used is often more cost-effective and sustainable.

    • Matt

      The amount of water pump out of the ground (or from rivers) to let dry land grow corn to feed cow in the US is crazy. But since the water is free they go for it.

      • Kyle Field

        Water may not be the current crisis, but it is right on the heels of climate change. While we don’t have a great track record for getting ahead of things like this, we do have the chance to start before it’s mandatory.

        • Larmion

          ‘Not the current crisis’? Excessive water use has been going on for over a century in much of the Americas and Southern Europe and as early as 3000 years ago entire civilizations collapsed due to aquifer depletion.

          Climate change is just beginning to show its effect and they’ve been mild so far. Sustained overconsumption of water has been destroying entire civilizations since the dawn of agriculture.

          So no, we can’t start early on this one. The best we can hope for is not letting it get any worse. And you know what the real tragedy is? Tackling climate change costs billions and requires the use of cutting edge technology. Water efficient farming costs very little and can be done using only old-hat tricks like drip irrigation and conventional plant breeding (though modern technology certainly can play a part too).

          • Kyle Field

            Water has been a crisis historically, yes. We have obviously moved beyond that in western societies as we now have potable water plumbed into houses, available for basically free…so I would say we are not in a crisis at the moment (other than occasional infrequent regional droughts, etc).

            If we were truly in crisis, it would be against the law to water your lawn…or anything in the yard that wasn’t edible for that matter. Also, if we were in crisis mode, drip irrigation would be the only legal method for agriculture…especially being so inexpensive to implement.

          • Martin

            Where does the water come from that goes into the potable water plumbing in our houses Kyle?

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