But perfectly controlled growth is another matter. “What we want is lean and hungry growth,” says Max. In other words, what he needs are not snowflakes of hydrate floating up the water column but chunks in an upward blizzard. Without robust crystal growth, the resulting hydrates will not have sufficient mass to deliver a significant amount of water.
Even if Max can get potable water from the top of his reactor, will such a system ever be commercially viable? To a certain extent, desalination is easy. “Take a bunch of seawater, squeeze it, pump gases through it, heat it, et cetera, and at some level, you can get most of the salt out,” says desalination consultant Birkett. But getting from that point to a competitive technology is an exponentially greater challenge.
The two proven approaches to desalination—heating water and then distilling it, or using an osmotic filter—have reached a level of maturity at which they can be economically workable, but only when getting freshwater from traditional sources is either impossible or too expensive. Pricey distillation plants, for example, are concentrated in the oil-rich states of the Middle East.
Most of the 15,000 desalination plants in the world employ a technology known as reverse osmosis. Powerful pumps force seawater against membranes that let pure water through and filter out the impurities. Since 1980, reverse osmosis has doubled its production capacity, in large part because of gains in membrane efficiency and life span. The costs have come down as well.
But constructing and maintaining a reverse-osmosis facility is still difficult and expensive. The largest desalination plant in the United States is in Tampa Bay, less than 20 miles from Max’s lab, and it has been off-line for months. The membranes used for pretreating the seawater—larger, particulate matter must be removed before the seawater is flushed against the high-tech desalting membranes—are clogged with colonies of tiny Asian green mussels. There also is the brine-disposal issue, or as it has been euphemistically dubbed within the industry, concentrate management. Desalination plants produce tons of unwanted salts.
But the greatest limitations to existing desalination plants are the cost of replacing membranes and the expense of the energy necessary to run the machinery. And that keeps a window of opportunity open for Max. He declines to reveal much, but when asked if his process could produce 1,000 gallons of water for 10 to 12 kilowatt-hours of energy—the rate to beat for any new technology—he nods and allows a rare silence to linger. “Let’s just say we’ll be competitive with freshwater at the going rate,” he says. A few months later he says computer models have put his costs at under 10 kWh per 1,000 gallons.
Max’s system offers some specific advantages that are difficult to measure in dollars, such as the prospect of a plant that doesn’t have to be stopped for months to clean filters or to service corroding equipment. Max’s invention also avoids a brine- disposal issue by removing only a small amount of freshwater at a time, about 5 percent per volume of seawater in the reactor. As a result, outflow should always remain within the natural variability of the oceans’ salinity.
Max’s research is timely. Reverse osmosis may be reaching the limits of its efficiency, and distillation plants remain expensive. Meanwhile, purification efforts to clean up polluted rivers, lakes, streams, and wells cannot meet the world’s growing water needs, and water shortages are already causing human and ecological suffering on a haunting scale. The United Nations estimates that more than a billion people lack adequate freshwater.
Is it possible the optimal chunk of hydrate simply does not exist? Might the reactor be destined to produce flurries of little crystals and never the larger masses of hydrate that float through Max’s dreams? “We know that the optimal chunk exists because we see it in nature,” says Holman.
Fishermen have pulled up basketball-size chunks of hydrate in their nets, and other researchers have scooped it from beneath the ocean floor. Nonetheless, Max may not be able to consistently and rapidly grow large enough chunks of hydrate to deliver freshwater at a good enough price.
“If I say we’re inches from success, it’s the same thing as saying I’ve reached an insurmountable barrier,” Max says. In other words, achieving optimal crystal growth may require only a bit more tweaking, or it may prove impossible. It’s an honest, true-to-science admission, but, as Kvenvolden puts it, “Max has bet the farm on this idea. You’ve got to admire that kind of visionary. And I think it will work.”