It all seemed so easy, in those innocent days before we knew the globe was warming and before anyone knew where Three Mile Island was, never mind Chernobyl or Fukushima. We would build a string of nuclear power plants along the coast (the energy they produced would be so cheap, we wouldn’t bother to meter it) and use it to strip the salt from seawater, and our water and energy issues would be solved. That was before we knew that a medium-sized nuclear generating plant would cost better than $3 billion to build and just as much to decommission, before the public developed its largely irrational fear of nuclear energy, and before anyone seriously started running out of usable fresh water anyway.
We know more now, about how energy and water issues intersect, about climate change and resultant droughts, about unforeseen consequences and collateral damage. We know more about how “easy” supply makes for heedless development. We probably don’t know enough, but enough to make us wary of the promises of engineers. Which is a pity. Because the way of the engineer is one way out, even now.
The way of the engineer — what Peter Gleick calls “the hard path” — relies on dams and reservoirs, pipelines and treatment plants, and often centralized water departments and agencies to bring fresh water in (or create it on the spot) and take waste water away. “Once easy sources of raw water are captured, however, this path leads to more and more ambitious, intrusive, and capital-intensive projects that capture and store water far from where the water is needed, culminating in the massive water facilities that dominate parts of our landscape.”1
Gleick acknowledges that the hard path brought great benefits to hundreds of millions of people:
Thanks to improved sewer systems, cholera, typhoid, and other water-related diseases, once endemic throughout the world, have largely been conquered in the more industrialized nations. Vast cities, incapable of surviving on their local resources, have bloomed in the desert with water brought from hundreds and even thousands of miles away. Food production has kept pace with soaring populations largely because of the expansion of artificial irrigation systems that now produce 40 percent of the world’s food. Nearly one-fifth of all of the electricity generated worldwide is produced by turbines spun by the power of falling water.2
We need more water than ever, for more and more purposes and for more and more people. Gleick is now a skeptic, but the hard path can perhaps still bring us some of that extra water.
There are three main ways of acquiring water where there isn’t enough — where the supply is over-allocated, or where the population has increased heedlessly, or where drought has diminished the supply in the first place.
The first and easiest is to conserve and store water for use in times of shortages; this implies thrift but it also implies dams and reservoirs, as we have already discussed in some detail. To oppose some dams, in some places, is rational; to oppose all dams, in all places, is destructive. Many countries don’t store nearly enough water for their security — Pakistan is a prime example — and while some water can be stored by aquifer recharge, reservoirs behind dams are the only realistic way of capturing the natural runoff. Climate change will make this more essential than ever. Those who oppose dams should therefore oppose bad dams and work to make the others as benign as they possibly can be.
The second way, which often intersects with the first, is to import water from afar from those ever-diminishing places where there is a surplus. Chapter 8 looked at some of the pros and cons of mass water movement. The same strictures apply here as to dams: some bulk transfers are good, some very bad. Upstream and midstream water should not be bulk-transferred from one water basin to another, and the fact that it has been done before (southern California) and is being done again (China’s North-South Carrier) doesn’t make it any better. But there are hundreds of places where bulk transfers are sensible and doable and should be encouraged. We should not laugh at dreamers like James Cran, with his Medusa bags: taking water from the Columbia estuary to San Diego and points south is neither destructive nor impractical. Yes, San Diego should conserve more and desalinate more, but these efforts can easily coexist with shipping water in bulk.
The third way of adding to the usable water stock is to manufacture it from water that is not otherwise usable — from brackish and contaminated supplies, even from fracking’s wastewater, or from the oceans. This means stripping from the water the stuff that makes it undrinkable, dumping that stuff somewhere, and injecting the clean water into the distribution grid where there is one. This is generally called “desalination,” though it is not always ocean water that is the source or salt that is being removed — the word has become a generic term for converting any non-drinkable water into water that’s safe. We’ll explore this solution in some detail below.
All three solutions are capital-intensive endeavours, which is why they have been dominated by the wealthy countries and transnational corporations, and why private capital has been enlisted in poor countries or in regions otherwise strapped for cash. As discussed in Chapter 5, rote opposition to private involvement in water delivery can hamper and prevent efforts to bring safe water to the world’s poor; the social justice movement should continue to oppose profiteering and exploitation but should adjust its efforts to make sure privatization of utilities is done in the best way possible, with the best possible contracts and comprehensive safeguards.
All three of these approaches have historically been resoundingly successful because of the economies of scale so familiar from mass manufacturing. A modern economy cannot function if half its citizens must fetch water from distant wells in buckets, taking most of an unproductive day to do so. It is much more efficient, and cheaper in the long run, to build and operate a communal water distribution system through pipes.
In many ways, all three of these system improvements still work and still deliver economies of scale. But as it becomes more difficult to expand existing networks to serve new populations or industries, whether because of the expensive extra energy required or the need to find fresh supplies somewhere else, or through increasing leakiness and waste, the cost per unit of water begins to rise. At some point, as Peter Gleick and many others have often pointed out, once economies of scale have been exhausted, the marginal cost (the cost of each additional litre) of water from piped systems will sooner or later become higher than the marginal cost of water conservation efforts. In many parts of the world, we have already passed that point. That will be the subject of the next chapter.
So let’s consider the third way: make more water as a way of reaching water security. The most obvious method is to clean up water that is dirty, or saline.
How Big Is the Desalination Industry?
Desalination has become a popular backup technology for many communities, not just in the American West but globally. Perth, Australia’s driest big city, would not have got through the Big Dry drought without it. In other places, desal is more than a backup: it is becoming a primary source of water.
There are plenty of reservations about desalination as a solution to water problems and we will come to these. But first, we need some sense of the scale of desal and what its proponents say about it.
As of 2013, the International Desalination Association (IDA) listed 17,277 “water factories” around the world, up from 4,000 a decade before, with a total capacity to produce 80.9 million cubic metres of potable water every day. To try to put this number into perspective, the IDA suggests that this would be about the same as thirty-two years of rain falling on Londoners’ heads, or twenty-one years of rain for New York, a more or less useless comparative. Is 80 million cubic metres a day a lot? Compared to what? If you multiply it out annually, it means desal is producing just shy of 30 billion cubic metres a year — but the global demand for fresh water is increasing by 64 billion a year. So by this measure, desal is not going to solve a global problem by itself.3
This doesn’t mean desalinating water is useless; far from it. These are just global averages and tell you little about the usefulness of desal or how it has brought water security to places where there was none before, or how it is being used as a bridge technology along the way to something better. Like other solutions to water problems, desalination is a local issue.
To put it in a single country perspective, Israel currently produces 1,532,723 cubic metres of desalinated water a day — about 40 percent of the country’s freshwater needs. That’s more than a drop in its particular bucket.
Israel has been building these plants at a breakneck pace, reflective of the urgency of its need. The country’s first plant opened at Ashkelon only in 2005, but more have been added since, at Ashdod, Hadera, and other places, with others on the drawing boards. The newest, the Sorek desal plant on the Mediterranean coast fifteen kilometres south of Tel Aviv is the largest and most advanced and it alone produces somewhere around 20 percent of the country’s municipal water, up to 624,000 cubic metres a day at full capacity. The costs are pretty low too — the plant can provide all the water for an average family for between $300 and $500 a year. Avshalom Felber, boss of the company that built and operates Sorek, IDE Technologies, points to the other advantage: “Basically this desalination, as a drought-proof solution, has proven itself for Israel. Israel has become . . . water independent, let’s say, since it launched this program of desalination plants. By meeting its water needs, Israel can [now] focus on longer-term agricultural, industrial and urban planning.”4 Israeli academics have also suggested that the country can start using its expertise to solve regional water problems. As Jack Gilron of Ben-Gurion University put it, “In the end, with everybody having enough water, we take away one unnecessary reason that there should be conflict.”
A 2014 survey of the issue by the Israeli newspaper Haaretz begins this way: “After experiencing the driest winter on record, Israel is responding as never before — by doing nothing. While previous droughts have been accompanied by impassioned public service advertisements to conserve, this time it has been greeted with a shrug — thanks in large part to an aggressive desalination program that has transformed this perennially parched land into perhaps the most well-hydrated country in the region.”5 It is also something of an exaggeration, as we saw in the water conflicts chapter, to say that the region can now coast along with a modest surplus. This understates the region’s problems by some orders of magnitude. And relying on one or two desal plants for so much critical water leaves the supply open to sabotage and military attack, something the Israelis know only too well.
Still, for the moment, the supply seems secure. In the winter of 2014 it was so secure that the national water company Mekorot actually reduced its demand from the desal plants to about 70 percent of production capacity. The other 30 percent is a sort of insurance policy against future drought and future demand. Israel is “no longer dependent on the mercy of God to give us rain,” as a scientist for the Ministry of Energy and Water Resources, Shlomo Wald, put it.
There are geopolitical advantages too. Israel is a small country, but its scientists have advised China, the United States, and other countries on building up their own capacity. IDE Technologies, the company that built Sorek, has been hired to construct a huge desal plant at Carlsbad, in California, and has already constructed China’s largest desal plant. As Wald said, “Israel is the heart of know-how in desalination worldwide. We don’t manufacture the membranes, we don’t manufacture the pumps. But the engineering and the way a desalination plant should be designed and built, I think, the international hub is here in Israel.”6
It is no surprise, then, that the Israeli embassy in India sponsored a trip for Indian water experts to visit desal and wastewater plants in Israel and to “sit down with their Israeli counterparts to hear about the newest technologies that help keep Israel green.” One of the visitors was Rajeev Jain, water expert in Rajasthan, who made it clear why he was there: “In India, we have a major crisis of water. Our problem is the same that Israel faced, but Israel is an expert at successfully implementing technologies that we aren’t able to implement. So we have come here to understand which technologies they use and how they manage these things.” Debra Kamin, a features writer for the Times of Israel, talked to some of the visitors and found they were uniformly shocked at how expensive water was in Israel, and even more shocked to discover that all citizens, regardless of income or place of residence, must pay the same amount. That wouldn’t be possible in India, Rajeev Jain told her, somewhat ruefully, “In India, much of the water generated by cities is illegally siphoned off by residents or lost to leaks, and in rural areas, most farmers get their water at no cost. [We] consider water a gift from God. And everything God has given, no one can charge for it,” he said. And he added, somewhat redundantly, “It is not easy to frame new policies.”7
Some of the Indian delegates to Israel had also been to Singapore, another world locus of desal expertise. Singapore is a country with virtually no water resources of its own (except rainwater collection) and is famously a master of water management. Late in 2013, Singapore officially opened its second desal plant, a 124-hectare facility called Tuaspring that can produce 265 million litres of potable water daily, tripling the amount it already gets from its earlier desal plant, SingSpring. This would account for about a quarter of the country’s daily needs, providing water at around 45 cents a cubic metre. Cutting the ceremonial ribbon, the prime minister, Lee Hsien Loong, took the opportunity to pat his countrymen on the back, reminding them of what it had been like when independence from Britain finally came in 1965: “We were almost totally dependent on water supply from Johor [Malaysia]. Singaporeans lined up at public taps for water, and employed night-soil collectors because homes lacked sanitation. But the republic has since turned a strategic weakness into a source of thought leadership and competitive advantage.” Political leadership made all the difference, he added virtuously, and largely accurately. Certainly, without the vision of his predecessor (and father), Lee Kuan Yew, nothing like it would have been achieved. The earlier Lee pushed through the notion of self-sufficiency, enlarging Singapore’s water catchments, upgrading infrastructure, building a deep sewerage system, and hiring private companies to build desal capacity. “The Government also engaged industry in public-private partnerships to explore and pilot new technologies and develop water infrastructure,” as the current Lee put it.8
China, for its part, might be planning massive water diversions, but it is not neglecting desal either. And, typically, the Chinese are thinking big. By 2019, a new desal plant in Tangshan, in Hebei Province near Beijing, should be producing a prodigious million cubic metres of fresh water daily, as much as a third of the needs of Beijing itself, a city of twenty-two million people. This is an add-on second phase of a project being built by Aqbewg, a joint venture between Aqualyng, a Norwegian company, and Beijing Enterprises Water Group, headquartered in Hong Kong. Phase One, using water drawn from the polluted Yellow Sea, produces about fifty thousand cubic metres of water each day for the district’s use. The project’s developers estimate the cost to consumers at $1.29 a tonne, double the current price but cheap at the price of the alternative, which is no water at all.9
So far there are few desal plants of any consequence in the United States, but this is changing. The largest plant in the country is at Tampa Bay, Florida. Another is at El Paso, Texas, and holds the record for being the furthest desal plant from the sea (El Paso cleans wastewater, not seawater). California, stricken by drought and planning for conservation, is not neglecting desal either. The Israeli-built billion-dollar Carlsbad plant, supposed to be ready by 2016, will be the largest facility of its kind in the western hemisphere, producing around 190 million litres of drinkable water every day. This is only one of the seventeen desal projects planned for the California coast as of 2014. The little resort town of Cambria, not far from William Randolph Hearst’s castle at San Simeon, is one of them; the town hurried a desal plant into production in less than a year. It will also recycle sewage wastewater, combining treated sewage with estuary water and groundwater to provide a third of the town’s needs.10
Carlsbad, big as it is, is not going to solve California’s problems or substitute for water sourced elsewhere. Just to compensate for the water imported from other river basins, southern California would have to build a Carlsbad-scaled plant every five kilometres along the coast (twenty-five plants between San Diego and Los Angeles alone), solving only one aspect of the problem by industrializing the entire Pacific coast, a prospect impossible to contemplate politically, and in any case anathema to the West Coast ethos, never mind to the surfer-dude and the rich-mansions-on-the-sea voting blocks. This is not to say some of them shouldn’t be built. This is not an either-or decision: in a quiverful of solutions, desal is but one arrow. The general manager of the metropolitan water district of southern California, Jeffrey Kightlinger, admits desal is needed and helpful. “There are two things that are changing the landscape for us,” he says. “One is we’ve grown a lot. We’re doing water for nearly 40 million people statewide. The second thing that really changed is the climate. Climate change is real. And it’s stressing our system in new ways. . . . We don’t have time to rehash the same debates over and over and over again. We’re going to have to start investing in things for the future.”11 Desal is among those things.
A number of techniques exist for cleaning sea or brackish water, but only one, reverse osmosis (RO), is cheap enough to be used on a large scale.
A technique called electrodialysis, in which salts are removed by an ion-exchange membrane, is in some ways more efficient than RO (it leaves a smaller residue and is thus good for wastewater treatment), but it is more intricate to operate and is difficult to scale up to industrial standards. GE produces a commercial model, used mostly in remote locations, but its market is fairly small.
Distillation, a method familiar to any student who in a high-school chemistry lab produced distilled water for experiments, is simple enough to do: the water is heated to steam to separate out dissolved solids, then cooled back to water in a separate vessel. This is the same method used to produce cognac — or moonshine. Distillation has some advantages over RO: it has no membranes that need cleaning, and the water doesn’t need to be pretreated because there are no filters prone to clogging. It also leaves less residue than RO. It is, however, more energy-intensive and therefore more expensive.
Reverse osmosis is simple, if rather difficult to keep operating because of the clogging problem. RO involves pushing dirty water (sometimes pre-filtered to get rid of larger objects such as gravel, weeds, or fish) through permeable membranes designed to let the water molecules through but to keep out dissolved salts, pesticides, and bacteria, whose molecules are larger. Brackish water is usually easier to clean than sea water because it is not as salty. The volume and the quality of the water produced depends on the pressure applied to force the water through the membranes, and on how efficient the membranes are — since they are the heart of the process, their actual design is generally regarded as an industrial secret.
Both RO and distillation produce somewhere between 30 and 40 percent clean water, with the rest being brine’s minerals. The resulting water is very clean: distillation leaves less than fifty parts per million of dissolved salts (drinking-water standards are usually around five hundred parts per million); RO is not quite that clean but still is well below levels that would cause concern. Nevertheless, for safety’s sake, wastewater desal plants usually add chlorine before sending the water off for consumption.
Residual brine is a major issue of desal. As reported above, for every hundred cubic metres of fresh water produced, somewhere around two hundred cubic metres of highly saline brine is left behind and has to be disposed of. Mostly, this is just dumped into the sea through outfall pipes; since it is saltier and denser than regular seawater, it generally sinks to the seabed, where it can cause problems for local plant life and sea creatures. Most plants therefore push the outfall pipes deep into the sea, preferably where a current is running, which will dilute it faster. IDE’s Felber dismisses the impact of returning salty water to the salt sea as minor, but no studies have been done on the impact of multiple plants in a contained sea, and Israel is not alone in building desal plants on the Mediterranean coast — Spain, France, Cyprus, Lebanon, and Egypt have already built some and are contemplating more. So far, France is the only jurisdiction that controls brine outflows; French regulations forbid brine discharge greater than 10 percent above ocean salinity. Most brine emissions are higher than that, usually 1.5 to 1.8 times as saline as seawater.
A novel solution is to mix the brine with cement to produce so-called saltcrete or stonecrete, which started as a way of immobilizing hazardous waste but is now also commonly used for paving walkways, driveways, and, when mixed with asphalt, even roads.
Curiously, desalinated water can actually be too clean. Water is one of nature’s natural solvents, and water without its mineral buffers can be, as a WHO report put it, “aggressive to cementitious and metallic materials used in storage, distribution or plumbing, and requires conditioning to address this problem.”12 In other words, water that is too pure can dissolve concrete and corrode metals, and you have to “de-clean” it before it can be safely injected into a distribution grid unless it is promptly mixed with non-desalinated fresh water. Generally, the WHO report suggests that somewhere between 1 percent and 10 percent of other water should be mixed into the desalinated reservoirs to make them non-corrosive. Sources are not always easy to find — if clean water is already available, why desalinate dirty water in the first place? Generally, partially treated but still saline sea water is added or, where available, untreated groundwater. For obvious reasons, the report adds hastily if redundantly, “This potential short-circuiting of the main treatment process should not allow pathogens and other undesirable microorganisms to be introduced into the finished desalinated water.” In some cases, the desalinated water is not diluted, but corrosion-inhibiting chemicals are added directly to the finished product. These include silicates (sands, mostly) but also orthophosphates and polyphosphates, chemicals already widely used in the world and thought to be benign to human health.
Another potential reservation about desalinated water was raised by a researcher affiliated with the WHO, Frantisek Kozisek, in a paper called “Health Risks from Drinking Demineralized Water,”13 in which he claims, based on earlier Soviet studies, that water with low concentrations of total dissolved solids causes minerals to leach from the body and can cause intestinal and urinary tract disorders. The most obvious effect of this is said to be diarrhea. Still, even while noting this study in a footnote, the WHO admits that it “remains controversial in many quarters,” and other studies, such as one from the Canadian Water Quality Association, have dismissed it as misleading.14 In a useful study, the US Navy, which has been offering desal water produced by onboard nuclear reactors to its sailors for more than forty years, has found no ill-effects whatever. Still, the WHO does suggest that in regions where populations had become accustomed to natural water with high mineral content, it might be prudent to add calibrated amounts of those minerals into desalinated drinking water.
Desal’s Energy Use
Apart from brine, energy use is desalination’s major drawback, and as a consequence, many scientists are investigating ways of making desal less energy-intensive. To take but one example of high energy use, Israel’s desal water is essential, but it may not be very sustainable — the desal plants currently operating use as much as a tenth of the country’s electricity production — and that comes at its own cost. Solving one problem (available water) by exaggerating another (greenhouse gases) is not anyone’s idea of ecological balance. Still, energy efficiency has been getting steadily better over the last decade. Peter Gleick’s Pacific Institute calculates that, in the United States, desalination plants use around fifteen thousand kilowatt hours of electricity to produce 3.8 million litres of fresh water. This doesn’t seem so high considering that it takes about the same fifteen thousand kilowatt hours to import the same amount of water from elsewhere (if an elsewhere can be found). Wastewater cleaning and reuse is more energy efficient than this, using only eighty-three hundred kilowatt hours for the same amount of product, but still, using even less energy would make the whole thing more palatable.
At the start of this chapter, I reminded readers of the fantasy common in the Nixon era that too-cheap-to-meter nukes could produce as much water as we needed. Nuclear energy’s proponents — and there are still some — keep timidly pointing out that nuclear energy is, by climate-change standards, a clean and green energy: nuclear power produces virtually no greenhouse gases. It might surprise you to learn that nuclear desalination has been running quietly, and generally successfully, in a handful of countries, sometimes for decades. True, one of them is Kazakhstan, not usually a go-to destination for technological sophistication or for ecological probity. Nevertheless, a fast-reactor at Aktau in Kazakhstan has reliably produced 135 megawatts of power while also desalinating 80,000 cubic metres a day of brackish water for thirty-three years and counting. The plant actually produces 120,000 cubic metres a day, the balance coming from an oil and gas co-generation facility. Japan, before it was spooked by Fukushima, was operating ten desal facilities with reactors. None of them were used for potable water — the output was generally used to cool the reactors — but they could have been. They ran for one hundred reactor-years without incident. The same thing has been done in several places in India, again mostly to provide clean water to cool reactors, but also to produce potable water; Pakistan has done the same thing at its Karachi Nuclear Power Complex, and so has China.
If you’re going to use conventional power sources, though, it behooves you to use the energy as efficiently as possible, so it is essential to improve the efficiency of the RO process. Here, lots of science is being done, if so far none of it advanced enough to take to market. An example is a process invented by a chemical engineer from the New Jersey Institute of Technology, Kamalesh Sirkar, who has devised what he calls a “direct contact membrane” that can extract fresh water from water that is 20 percent brine (typical seawater is 3.5 percent salt). This means he can process seawater several times, thereby increasing the yield. He figures he can produce about eighty litres of drinking water from one hundred litres of brine, a substantial increase.15
One of the most promising leads is a collaboration between Lockheed Martin, the aerospace company, and MIT; it involves using graphene, an allotrope of carbon that rather resembles, as the Economist once put it, “An atomic scaled chicken wire.” Most of the research into graphene has so far been focused on electricity generation (graphene is the best conductor of heat yet found), but membranes made of the substance contain nano-sized holes perfectly sized to let water molecules through yet still hold back hydrated chloride and sodium ions. As a consequence, far less pressure is needed to force the water through its filtering membrane, reducing energy costs by a startling two-thirds.16
Even without graphene, modern membranes are twenty times more efficient and one-fifth the cost of the earliest versions tested sixty years ago. And Israel’s IDE is generating power by using high-pressure brine from the desal plants to help rotate the pump motors that force the water through the membranes in the first place, a process it calls energy recovery. A standard turbine can recover about 80 percent of the energy input; IDE’s process takes this to 96 percent.17 Using this technique and other innovations, IDE believes that its Carlsbad plant in California will actually become carbon-neutral and, in addition, will use $12 million less fuel to operate each year.
What about using the sun or the wind to desalinate water? A test solar desalination project was running in 2014 in California’s parched Central Valley, in this case not to desalinate seawater but the billions of tonnes of contaminated water that lies beneath the surface, water so charged with toxic levels of selenium and other heavy metals that it must be periodically drained away to avoid poisoning crops. The company running the test, WaterFX, is effusive about the possibilities. As the company’s website puts it, “Renewable desalination is a global solution with the power to create freshwater from abundant resources such as solar energy and saltwater. . . . [It is] the kind of solution that is market driven, not government subsidized; it is politically, legally, financially, and sustainably achievable in the near term and is an approach that can put arid regions on a path towards true sustainable water independence. The data being generated by the . . . pilot proves it is a viable alternative to generate new sources of water alongside conservation and reuse.”
Instead of using reverse osmosis, WaterFX uses an off-the-shelf four-hundred-kilowatt parabolic solar trough designed for power generation to concentrate the sun to heat a reservoir of liquid that then transfers to a heat pump to boost output, all of which is then used to evaporate water and condense it out as pure H2O.
The test project, paid for by the Panoche water district, can produce 1,233 cubic metres for $450, twice what farmers used to pay the Central Valley Project when water was available but less than they were paying late in 2014, when prices ranged from $500 to $2,200. When the actual plant replaces the test project, it will cover thirteen hectares of land and produce about a quarter of a million cubic metres.
Another promising project was unveiled by IBM in 2014. The firm’s nine-metre-tall “sunflower” was designed for solar electricity generation, but it has an intriguing side product: very hot water that can be used to desalinate unclean water. The sunflowers — so named because they do rather resemble giant metallic flowers, and they do rotate to follow the sun — can convert, or so it is claimed, 80 percent of the sun’s energy into water and power more efficiently than conventional systems and a good deal more cheaply. The key development is to use microscopic tubes that carry water through the cluster of photovoltaic chips the device comprises — the same system IBM uses to cool its supercomputers, inspired, as IBM engineer Bruno Michel put it, “by the branched blood supply of the human body.” One such sunflower could provide power and water for several homes; a “plantation” of them could easily provide enough clean water for a small town, the company says.18
A larger-scale experiment is under way in Jordan, at Aqaba, where the Red-Dead project starts. The project uses a basket of conventional technologies, but in novel ways, to make fresh water. If they get it right, it will produce not just water but also food and electricity, which means that it has the potential to green large swathes of coastal desert. It is the brainchild of an environmental technology group based in Norway, a long way from the nearest desert. Still, governments are taking it seriously: in January 2011, Norway and Jordan signed a formal agreement to get the project underway, with funding finally approved in 2014. The twenty-hectare demonstration site is scheduled to open sometime in 2015. Four hectares will be greenhouses, the other sixteen solar reflectors, support buildings, and open-air crops. As its proponents put it, “The system is designed to utilize what we have enough of, to produce what we need more of — using desert, saltwater and carbon dioxide to produce food, fresh water and energy.”19
The Sahara Forest Project (SFP) works by bringing seawater into the desert and evaporating it. The SFP website explains it this way: “Sahara Forest Project combines solar thermal technologies with technologies for saltwater evaporation, condensation of freshwater and modern production of food and biomass without displacing existing agriculture or natural vegetation; a single SFP-facility with 50 MW of concentrated solar power and 50 hectares of seawater greenhouses would annually produce 34,000 tons of vegetables, employ over 800 people, export 155 GWh of electricity and sequester more than 8,250 tons of CO2.”
According to the company’s website, the three core components are:
• Saltwater-cooled greenhouses — greenhouses that use saltwater to provide suitable growing conditions that enable year-round cultivation of high-value vegetable crops even in desert conditions. By using seawater to provide evaporative cooling and humidification, the crops’ water requirements are minimized and yields maximized with a minimal carbon footprint.
• CSP (concentrated solar power) for electricity and heat generation — the use of mirrors to concentrate the sun’s energy to produce heat that is used to make steam to drive a steam turbine that powers a generator to produce electricity. The solar plant reflectors will concentrate sunlight onto a pipe carrying a heat-absorbing fluid that produces the steam.
• Technologies for desert revegetation — a collection of practices and technologies for establishing outside vegetation in arid environments, such as evaporative hedges.
Daniel Clery, in a piece for Science, says the key is an earlier version of the scheme, the “seawater greenhouse,” developed by British inventor Charlie Paton, who has already built demonstration projects in Tenerife, Abu Dhabi, and Oman.
In Paton’s scheme, seawater piped to the greenhouse trickles down over a grid structure that covers the windward side of the greenhouse. As natural breezes blow into the greenhouse through the grid, it evaporates the water, making an interior that is cool and moist — ideal conditions for growing crops. At the other end of the greenhouse, another grid evaporator, fed by seawater heated in black pipes on the greenhouse roof, loads more moisture into the air as it leaves the growing area. Now hot and very humid, the air passes through a maze of vertical polyethylene pipes cooled by cold seawater passing through them. Fresh water condenses on the pipes and trickles down into collectors, to be used for irrigation or drinking.20
Curiously, the SFP designers used as one of their models a peculiar Namibian beetle that has evolved a ribbed fantail, on which fog condenses, then drips down the ribs and into a small sac. Israeli scientists have already explored and mimicked this ingenious invention — an experimental station in the Negev uses fog-drip irrigation for small-scale agriculture, creating cones of moisture-trapping fibres around individual plants.
Jordan has long been exploring the notion of building such seawater greenhouse plants alongside its Red-Dead pipeline.
A pilot plant built by SFP in Qatar produced seventy-five kilograms of vegetables per square metre in three crops annually, a comparable value to commercial farms in more-verdant Europe, while “consuming” only sunlight and seawater. The Qatari plant uses the technology described above: mirrors in the shape of a parabolic trough heat a fluid flowing through a pipe that then boils water, the steam driving a turbine to generate power. Hence, the plant has electricity to run its control systems and pumps and can use any excess to desalinate water for irrigating plants. By one estimate (from the designers and yet to be demonstrated), a sixty-hectare greenhouse field “could provide all the cucumbers, tomatoes, peppers, and eggplant now imported into Qatar.”
On that note, we should leave the last word to Ezekiel, the prophet. Here he is on foreseeable consequences, with a touch of sunny optimism:
On one side and on the other, will grow all kinds of trees for food. Their leaves will not wither and their fruit will not fail. They will bear every month because their water flows from the sanctuary, and their fruit will be for food and their leaves for healing.