Part 3 of 4
The headline in the Washington Post seemed otherworldly: As a major Indian city runs out of water, 9 million people pray for rain. India’s biggest cities including Chennai, Bangalore, Hyderabad and Delhi all face water scarcity due to lack of rain and population growth. The UN estimates their combined population at 60 million a small fraction of India’s 1.35352 billion estimated in 2018. Compare this to the populations of New York City, 8.6+ million, Los Angeles, 4+ million, and Chicago 2.7+ million and the US 325+ million. The Indian cities’ problems are acute, and the rest of the country is not faring much better.
In India and many parts of the world, monsoon season fills reservoirs that will provide by the populace until the next rainy season and that has always worked. But with climate change induced drought and population growth the water supply has not been enough. Rainy seasons have been less rainy, reservoirs have not filled and after consecutive dry years, the water has run out.
In response, the city of Chennaihas deployed the expected array of temporary solutions. There’s severe rationing and now that the water taps are dry, people have to haul water for daily needs from public wells and tanker trucks. Longer term solutions like building more and deeper reservoirs and constructing desalination plants are in the works but they take a back seat during the crisis.
Longer term, it will be necessary to augment many cities’ water supplies with supplies derived from technology. And while water scarcity looks like a third-world problem, it’s only because richer nations have spent enough on water infrastructure to avoid catastrophe. For instance, the California droughts of a few years ago were kept from becoming more serious because the state had invested in multiple water projects in the years leading up to the drought. But even in California and the American west in general, population is increasing, demand is rising and conditions are drier. New water projects are being drawn up.
There’s a limit to what we can do to optimize existing water resources. We can only ration so much or raise the price of water so high before some people are deprived. At some point we simply need more water because the optimization steps have run their course and demand increases continue.
Water from water
Around the world, countries have been investing in facilities that either recycle water or that extract it from the oceans. The two ideas have much in common because the ultimate result of taking impurities out and producing potable water is the same in both cases.
Desalinating sea water is one of the more popular approaches to make up for a shortfall but it’s not free and something that a country like India might be able to afford but at the cost of neglecting other issues.
A desalination plant in Carlsbad, CA (part of San Diego County) that opened in 2016 cost one billion dollars to build. It produces 50 million gallons of desalinated drinking water per day. But the county’s population is only a third of Chennai’s and it still has available sources of water. A city like Chennai would need significantly more water and investment to satisfy its need.
Invented in the US in the 1950s, membrane based high pressure osmosis removes salt and other contaminants and leaves freshwater. It requires a significant but manageable amount of electricity to achieve but it’s affordable. In current dollars in the US, it costs $2,000 to produce one acre-foot of fresh water from seawater. There are 325,851 gallons in 1acre-foot, enough to supply the water needs of a family of four for a year (and one acre equals 43,560 square feet).
So the problem in India and in much of the third-world is twofold. There’s the obvious water need as well as an energy component.
Producing new energy from solar, wind, geothermal or other sources is also a very doable thing but it, too, costs money. In one likely scenario a dry country could harvest renewable energy and use it to desalinate sea water. But in addition to the billions spent on desalination is a need to spend billions more on deploying renewable energy. So even though the solution to dry cities is apparent, it might be very difficult for many non-rich countries to do.
There’s also a question of balance to consider. If a country can only afford so much to spend on energy and water how does it allocate scarce resources? Much of the developing world has not adopted renewable power because until recently it has been more expensive than traditional coal fired power.
It’s hard to find exact cost numbers for constructing a coal-fired power plant because conditions are different from site to site. But in 2006 Duke Energy built a 600 MW coal plant costing $2 billion. Back then coal was less costly than natural gas and renewables but a lot has changed. Coal is quickly becoming the expensive option.
A rule of thumb right now is that 1 MW of industrial solar capacity costs $1 millionto build. This would appear to be less than the Duke story suggests for coal and Duke will have to buy coal for the life of the plant, another cost. But coal is what many people making purchasing decisions understand and world-wide there are some 1200 coal plants in design or under construction.
Coal generates a great amount of carbon pollution of course, so depending on it will only add to the problems of drought and eventually spur demand for desalinated water. It’s a merry-go-round you can’t get off unless you figure out ways to eliminate emissions and begin pulling some from the air.
That’s where we are at the moment. Demand for clean water is only increasing and so is the demand for clean energy. But the costs for both is also an active consideration. Ultimately, workable solutions for the developing world might come from creative financing. For instance, leasing power and desalination plants might be a way of reducing out of pocket costs but at the expense of raising the rates for power and water well into the future. Neither option may be ideal but facing immediate demands for the staples of life may leave few options.
The apparent lowest cost option might very well be to take food and water from a neighboring country but that’s freighted with other difficulties like war. This reflects the position some countries are now in and that others will be in by mid-century. It’s not a stable state and we need our best minds working on solutions.