In a world full of people who depend on water, the most urgent subject is scarcity. More than a billion people live in areas where water is scarce, and that number is likely to reach 3.5 billion by 2025. About 97 percent of the Earth’s water is saltwater, but only around 1 percent of it is potable. Water conservation is a big issue in first-world nations; we enjoy the luxury of plumbing, but a single leak can waste 3,000 gallons a year. Meanwhile, the sea level is rising at a rate of 3.4 millimeters per year.
Desalination is one option for converting saltwater to freshwater, but there’s an important reason why it’s not more prevalent: the process consumes a lot of energy, and it’s costly. Enough desalinated water to supply two U.S. households of five people a piece costs $1,000 to $2,500 per year, depending on the desalination plant. For one plant in California, the Carlsbad plant, an acre-foot of desalinated water costs $2,000. The county normally pays 80 percent less to import the same amount of treated water, but back in 2014 California’s drought was bad enough to undertake desperate desalination measures. The state is in a better place with freshwater supply now, due to record precipitation in the wet months of 2016/2017.
But that doesn’t lessen the extent of increasing water scarcity worldwide, nor does it mean California is in the clear. As temperatures rise due to climate change, freshwater evaporates. When water recycles to the Earth it is far more likely to fall into the ocean than anywhere else. Precipitation that does fall on land does not necessarily become potable water. Floodwaters are rising. This situation will only get worse as global temperatures continue to skyrocket.
In terms of public health and climate change, the University of Nevada Reno points to the following issues related to water:
- Undernutrition: Fish make up about 27 percent of dietary protein in the world’s most underdeveloped countries, and ocean acidification threatens that supply
- Drought and water contamination: Crops and livestock supplies will see shortages, leading to further undernutrition
- Floods: According to Dr. Kenneth Kunkel of the Cooperative Institute for Climate and Satellites: “We have been on an upward trend in terms of heavy rainfall events over the past two decades, which is likely related to the amount of water vapor going up in the atmosphere.”
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Improvements and innovation in the desalination process would help provide drinkable water for the billions of people in need. Desalinated water could also help grow crops and maintain livestock. Furthermore, we could start to chip away at the rising ocean, which is contributing to floods, and we could work on purifying the acidified water that’s ruining fish supplies. New research out of Penn State explores some of these ideas.
Researchers from Penn State College of Engineering are working on generating power by putting saltwater to work for us. If this solution pans out, it will make desalination a much more viable option, because the energy to do it will be readily available.
What’s exciting is the amount of energy this new process could potentially produce. According to Science Daily, the difference in salt concentration between river water and ocean water is enough to generate 40 percent of global electricity demands.
There are already multiple methods of obtaining energy from the junctures where rivers empty into the ocean. Pressure-retarded osmosis (PRO) generates the most electricity by allowing water to travel through a membrane that collects the salt. Turbines then convert the osmotic pressure into electricity. But the membrane eventually gets fouled up with bacteria, which ruins the process.
The other two technologies (“RED” and “CapMix”) that can derive electricity from river outlets don’t create enough power to be viable. So, Penn State’s researchers figured out a way to combine the two. The resulting method, which leverages a “custom-built flow cell,” produces as much electricity as PRO but without the fouled-up membrane. But the researchers have only tested it with synthetic seawater, and don’t know how well the cell will hold up over time. Further research will determine how the cell will be affected by elements in seawater and the passage of time.
Penn State is a major research university, one of the top 20, with over $800 million a year in expenditures. As the following graph shows, a sizable chunk of that comes from government grants:
Just like Bloomberg did with his response to Trump’s withdrawal from the Paris Accord, the industry sector, private individuals, as well as local and state governments will need to continue ramping up funding to fill the federal funding gap for scientific research. As Bill Gates has highlighted with his Breakthrough Energy Ventures, technological innovation is a big part of the solution to climate change. If we can use new tech to harness the power of coastal river outlets, we’ll solve about 40 percent of our current clean energy dilemma.