San Diego is about to construct a major desalination plant that will cost $900M to build, and will produce 50-million gallons of potable water a day from sea water. That’s enough to supply 7% of the population of San Diego, costing each resident $678.
That’s great, except for two things.
One, there are environmental concerns. These are serious enough, but probably can be addressed.
Two, in a better world, a readily achievable world, 50-million gallons of water could supply at least 35% of the San Diego population, not a paltry 7%. In an arid city heavily dependent on water from elsewhere, a city whose water supply will probably soon be compromised by global warming, this is a vital consideration.
In a better world, 50-million gallons of water
could supply at least 35% of the San Diego population,
not a paltry 7%.
How might it be possible to get so much more from this plant? Let me digress briefly to discuss the poor way we manage human waste, an important and germane topic generally avoided in polite society.
The first Victorian flush toilet was a huge improvement over outdoors privies, 130 years ago, and an even greater improvement over dumping the chamber pot out the second story window onto the sidewalk. It was a significant step forward not only for our dainty sensibilities, but, more importantly, for public health. But the water-flush toilet is becoming increasingly untenable in a world where the population is moving rapidly toward ten billion people, because it relies on vast quantities of water, which may end up being our most valuable and expensive resource. Our antique system wastes drinkable water on an epic scale.
Our antique system wastes drinkable water
on an epic scale.
Consider this: Urine is virtually sterile, and poses no danger of bacterial infection under any circumstance. Most fertilizer value of human and other animal waste comes from this sterile substance, not from feces. Thousands of years ago the Chinese collected urine from public facilities and distilled it into dozens of useful products, which included a number of significant medical products as well as fertilizer. For our purposes, however, fertilizer will probably be the only use.
Feces, by contrast, contain a multitude of bacterial dangers that make their direct management more problematic. Not untenable, just more difficult. It’s worth noting that the Chinese commonly used human feces as fertilizer for food production for thousands of years, and still do in some places. This was safely done because Chinese food does not include uncooked vegetables, which might otherwise increase the danger of bacterial contamination from incomplete composting. Cooking removes this possibility.
Enter Lowell Wood and the Bill and Melinda Gates Foundation. Wood’s design for an inexpensive system to manage human waste is focussed on the third world, but his system could also have major effects on San Diego. And Wood is not the only one working on such a device.
Imagine clean and odorless waste systems in the home,
with no plumbing or sewage systems.
The costly public treatment facilities
could eventually be removed entirely.
Imagine Wood’s clean and odorless waste systems in the home, using fecal fuel to evaporate urine and generate electricity. The excess electricity would be fed into the grid, the dried urea used as fertilizer. No plumbing, sewage, or septic systems would be necessary—at all—reducing both domestic and public infrastructure construction costs considerably. Most importantly, the millions of gallons of potable water presently used only for flushing away waste would be saved. The vast, complex, and costly public sewerage and treatment facilities would become unnecessary except for storm water, and even that should be drained into swales, where it would be absorbed to replenish groundwater.
Other water in the home is used for laundry, cooking, and bathing. The used water is called “gray” water, with contaminants from detergents and food waste. This water is easily purified in the home using current technology, including such things as ponds with living plants, and can be directly recycled within the home as water so pure it could conceivably even be used for medical injections. Home water consumption would be radically reduced. Systems like these have been used with excellent results in a number of commercial and domestic buildings. Wood’s device and others will also do these things, and utilize food waste as well.
Water for laundry, cooking, and bathing
is easily purified using current technology.
Now consider again the costs and benefits of San Diego’s very expensive new desalination plant. Wood’s toilet/water treatment device uses presently available technology, and could be put in place in many new and old homes in San Diego by the time their desalination plant is operational. Just looking at the changes outlined above, it doesn’t seem unreasonable to imagine that a typical home could require some 80% less water than we currently use, probably even less. If that were the case, the plant could serve not a mere 7% of the population in San Diego, but at least 35%, maybe even half. In addition, a significant chunk of municipal infrastructure could be simplified.
I am not a believer that technology will be our savior in all things. We are far too stupid politically and socially for that to happen. But we will soon be compelled by population growth and global climate change to make major changes in the way we do things. We are wasting far too much of what we have by failing to make integrated use of the technologies that are already here, let alone technologies that will be ready to use virtually within months. Projects like the San Diego desalination plant are a golden opportunity to do better thinking than we have exercised in the past.
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