The Decades-Long Quest To End Drought (And Feed Millions) By Taking The Salt Out of Seawater

“The world isn’t short of water, it’s just in the wrong place, and too salty," says Charlie Paton – so he's spent the past 24 years building the technology to prove it.

By EMMA BRYCE

20 March 2018

In October 2017, Charlie Paton was driving across the parched plains of northwestern Somaliland when he passed a seemingly endless queue of rumbling trucks. Each was piled high with containers of grain – 47,000 tonnes in all – to be distributed as food aid across Somalia and Ethiopia. Paton was struck by the irony: it was the region’s harvest season, and yet here were trucks delivering industrial quantities of grain that would surely strip whatever meager business there was away from local producers. “Suddenly, the place is awash with food,” he recalls thinking. “Who’s going to buy food from a farmer when it’s free?”

Huge drops of food aid are common in the drought- and famine-plagued Horn of Africa. This year alone, the United Nations is appealing for $1.6 billion in aid just for Somalia – a fact that unsettles Paton. “That $1.6 billion could probably make the place self-sufficient, not just in 2018, but forever,” he says. And he thinks his invention could help make that a reality.

Paton is the founder of Seawater Greenhouse, a company that transforms two abundant resources – sunshine and seawater – into freshwater for growing crops in arid, coastal regions such as Africa’s horn. The drought-stricken landscape that cloaks this region doesn’t exactly inspire visions of lush agriculture – but then, Paton sees things differently: “The world isn’t short of water, it’s just in the wrong place, and too salty,” he says.

His latest project in Somaliland (an autonomous but internationally unrecognised republic in Somalia) takes that bullish optimism to the extreme. On a 25-hectare plot of desert land close to the coastline, he’s building the region’s first sustainable, drought-resistant greenhouse. Using solar power to pump in seawater from the coastline and desalinate it on site, Paton is generating freshwater to irrigate plants, and water vapor to cool and humidify the greenhouse interior. In January – less than a year after its launch – this improbable desert oasis produced its first harvest of lettuce, cucumbers, and tomatoes. “The idea is so simple that it’s rather insulting,” Paton says. “People say, ‘If that’s going to work then somebody would have done it before.’”

The prevalence of this attitude might explain why Paton’s invention is the first of its kind in the Horn of Africa. That – and the overwhelming challenges of investing there. “The main problem is drought. Somalia was hit by serious water shortage in 2016 and 2017,” says Amsale Shibeshi, who works with the NGO Pastoral and Environmental Network in the Horn of Africa, a partner on the greenhouse project. Though Somaliland has maintained relative peace since the 1990s, in neighboring Somalia the drought has fuelled persistent famine, which underlies disease outbreaks and ongoing political instability – with the militant fundamentalist group al-Shabab still influential there.

Today, only a fraction of Somalia’s overall land area is cultivated, and half the population is food insecure (data for Somaliland itself is scant, because it’s not internationally recognised.) Regular aid shipments bring products like rice, sorghum, sugar, and cooking oil to the region. Somaliland relies on these to a lesser degree than Somalia – in good years its pastoral farmers produce plenty of meat and milk from livestock – but it still has to import most fruits and vegetables from neighbouring countries, Shibeshi says. “It’s the centre of world water insecurity, which makes it the centre of food insecurity,” Paton says. “But if we could crack it here it would be a really big prize, because it’s not just Somaliland. Then it would work in Somalia, Eritrea, Sudan, Mali, and Mauritania.”

February 2018. At his suburban East London office, Paton – a lanky, blue-eyed figure with a head of closely-cropped silver hair – opens the front door, letting in a flurry of snow. To the left is a garage, an experimental workshop filled with pieces of metal and wood, where he and his son tinker around with designs for greenhouses in much warmer countries. Up a narrow flight of stairs Paton’s two young colleagues – Karl Fletcher and Chris Rothera – clack away on keyboards in a bright, clean-lined, airy interior that looks more like a trendy coffee shop than the birthplace of rugged desert greenhouses.

In this building, Paton has been developing his concept for more than 20 years – and his ideas have unusual origins. Back in school, he was neither sporty, nor academic, and he struggled with dyslexia. “If you don’t fit in, you rebel,” he says, settling into a chair at a long trestle table, adorned with a large sample of the latticed cardboard structure he uses to filter freshwater vapor into his greenhouses. By age 16, he’d been expelled. But then, Paton found an unexpected refuge in theatre, after taking his first job as a stage electrician for the London Festival Ballet. That became the springboard for a career in theatre lighting design, which many years later would fuel his curiosity in something completely different: the effect of light and heat on plants.

“It was this conflict between photosynthesis and transpiration – that was the kernel of the idea,” Paton says. He started by pondering an age-old conundrum: while sunlight is essential for photosynthesis and growth, the heat that accompanies it makes plants transpire and lose water. In arid places, the benefits of boundless sunshine are overwhelmed by the extreme heat and dryness, meaning farming becomes too water-intensive for it to make any sense.

Paton began drawing up an invention that could capitalize on the desert’s abundant sun, while simultaneously creating a freshwater-fuelled habitat for plants. He thought it could work. But without tests, it was hard to be sure. Paton asked his colleague, Philip Davies, a mechanical engineer with experience in climate modeling, to examine his greenhouse virtually. Davies looked at elements like temperature, humidity, and airspeed, using Tenerife in the Canary Islands – a region marred by decades of low rainfall and groundwater extraction – as an example. The tests were encouraging. Constructed in 1994, Paton’s Tenerife prototype became the basis for his company, Light Works Ltd., the ancestor to Seawater Greenhouse.

The structure’s double-layered fiberglass roof transmitted sunlight but captured heat, diverting it through ducts into a compartment at the building’s rear. There, the heat was used to distill fresh water out of seawater for irrigation. The rest was vaporized and sucked through the growing space by fans to cool and humidify the plants, reducing transpiration. Paton calculated that a square metre of crops adjacent to the greenhouse would have required eight litres of water per day to offset what they lost in transpiration. “But inside we were using closer to one litre per square metre per day, and we were growing a better crop.”

In 2000, Seawater Greenhouse launched another project in Abu Dhabi, and then in 2004 one in Oman. Today, these are used mainly as research sites for academics. But then Paton’s ideas caught the attention of businessman Philipp Saumweber, an ex-Goldman Sachs investment banker who had moved into the agricultural sector. By 2010, they had joined forces and were moving into the deserts of South Australia for the company’s first overtly commercial venture. At a site near the city of Port Augusta, they built a gigantic solar plant, designed to create enough heat to evaporate several thousand litres of freshwater a day from seawater that had been piped in from the Southern Ocean.

But, after disagreements about the precise aims of the project, Paton ultimately split with Saumweber, who now runs it under the auspices of Sundrop Farms. The greenhouse has since expanded to 20 hectares and supplies 15 percent of the Australian tomato market.

Somalian expats in the UK noticed the project’s huge success. But when they asked Paton if he could take it to the Horn of Africa, the designer hesitated. “It was just too expensive,” he says. The vast solar plant and huge workforce that made the Australian project work wouldn’t translate to the Horn’s harsh and often insecure territory. “But then I went back to the drawing board, and realized it could – if I made it really simple, and stripped it back to the basics.”

Paton, Rothera and Fletcher started work in Somaliland in early 2017, with a £518,000 grant from Innovate UK. It wasn’t easy. As a condition of their presence, the group had to be ushered everywhere by a team of armed guards. At one point the fierce desert winds became so hot that they had to halt construction entirely. But, at length, they began building on some land leased by the Somaliland government, which conveniently lay just 200 metres from the shimmering Gulf of Aden, an abundant source of free saltwater.

The location was perfect, but almost everything else brought a major challenge: the greenhouse had to be cheaper, and able to withstand the 42°C temperature extremes and searing desert winds. For Davies, the modeller – who now works at Aston University – these conditions made life extremely difficult. “It was reduced down to its bare bones. As the design became simpler the modelling actually became more challenging.”

Davies joined forces with Sotos Generalis and Takeshi Akinaga in the University’s mathematics department to build a climate modelthat would simulate the ideal growing conditions for crops. They factored in regional data on wind speed and direction, orientation, humidity, solar radiation, air temperature, and satellite readings of ground temperature.

The result is what Paton calls “a grown-up Bedouin tent”, a solar-powered one-hectare greenhouse made of lightweight, photoselective shade netting that reflects hot infrared light to shield the plants below. Cued by the model, Paton decided to take advantage of the desert’s prevailing summer and winter winds to push water vapour through the internal space – instead of using the standard fans, which would have doubled the cost.

At each end of the tent, the team built a 1.5 metre wall from layers of porous, resilient cardboard – a feature at other sites – which is designed to be soaked regularly with seawater pumped in from a beach well. As the hot, dry desert winds waft through the wall, they evaporate freshwater and vaporize it into the growing space, which cools and humidifies the interior. That reduces temperatures by 10 to 15 °C. As a result, crops are losing only one to two litres of water per square metre per day through transpiration, compared to the 15 they’d lose outside, Paton says.

A solar-powered desalination machine makes freshwater for irrigation. “[It’s] the size of a washing machine, costs about £6,000, and it’s the first one in the Horn of Africa. That’s completely nuts!” Paton says. Of every litre of seawater it processes, 30 percent is transformed into fresh liquid. The leftover super-salty brine is then evaporated in trays, leaving behind a crust of salt – the plant’s first product, being developed for sale in Somaliland and Ethiopia. (This is a bid to avoid the ecologically damaging process of pumping unused brine back into the sea, as most desalination plants do.)

Many hurdles lie ahead. Seawater Greenhouse is still working out how to supply vegetables to the local market, and Paton says the plant will likely produce only half the yield per square metre compared to the Australian project. He’s encountered academics who fear the high humidity conditions inside seawater greenhouses may even be damaging for crops. Others have enduring scepticism about the economic validity of the project.

“It belongs to an ‘alternative tech’ era and mindset – whereas closed environment agriculture has now moved in to the stage of big corporate investment and large-scale urban fresh veges supply,” says John Mathews, a professor of management at Maquarie University in Australia, and author of a book about the rise of new green industries. “This is the key to generating successful enterprises and avoiding bankruptcy – something that the seawater greenhouse concept has never grappled with.”

Mathews points out the commercial chasm between Paton’s idea and the spread of larger agritech ventures worldwide – especially those providing vast amounts of food for growing urban populations. But Paton doesn’t necessarily see himself in competition with the likes of Sundrop Farms. Rather, he seems to be driven by the challenge of enabling agricultural self-sufficiency in places where it was once deemed impossible. And, he wants to leave the task of scaling up in the hands of local pastoral farmers – who make up between 55 and 60 per cent of Somalia’s population. “I am confident that output, quality and profitability will all go up as experience is acquired. For that reason, my primary focus, now that we have a fully functional site, is to arrange scale-up and training in parallel,” Paton says.

This year he plans to build an on-site training centre to teach local farmers how to grow greenhouse vegetables. The structure’s modular design will enable farmers to adopt their own one- to five-hectare plots – the dream being a network of connected, drought-resistant farms running across the country.

“One of the exciting things is that it can work all the way along our long Red Sea coastline, bringing new sources of income in arid, pastoral areas,” Shibeshi says. “If you have a greenhouse, you aren’t worried about whether there’s rain or no rain.”

Paton is also interested in the long term restorative benefits of his invention. Davies’ model predicted that the greenhouse’s cooling and humidifying effect would seep into the surrounding environment: “You can see there would be a plume of cool air coming off the greenhouse,” he says. And since the region hasn’t always been barren, Paton thinks greenhouses could return parts of it to the naturally vegetated state it was in before overgrazing and drought took hold. “I believe that when you get to, say, 20 years, you’d have enough vegetation to do the job of the greenhouses because they’re creating shade and shared humidity – changing the climate.” Because vegetation sequesters carbon, that also has broader ramifications for mitigating the effects of climate change. 

The notion of a seawater-fuelled greenhouse – let alone the idea of reforesting a desert – remains too risky for some organisations, like the UK’s Department for International Development, which has rejected Paton’s funding applications multiple times. But for his doubters, Paton offers a rough calculation. He estimates that the $1.6 billion aid target for Somalia would be enough to finance 16,000 hectares of seawater greenhouses across the landscape, which could grow an astounding 4.8 million tonnes of fresh produce a year.

Many would say that’s a pipe dream, but Paton is used to incredulous reactions to his work. “Have you heard of the Shirky Principle? It’s that institutions exist to preserve the problem to which they have a solution,” he says. “Sending food to starving countries is this knee-jerk reaction. How much have we sent to Somalia and Ethiopia, and what dent has it really made? If some of that humanitarian aid could instead be directed towards encouraging self-sufficiency, everyone would win.”