Can Desalination Counter the Drought?
newyorker.com
newyorker.com
These units are abominations. Couldn't just say 2.8 Watts per liter vs 4.0 Watts per liter? Or even 10.6 and 15.3 Watts per gallon? I'm not a metric purist, but the only advantage to using imperial units is that they are more familiar to the average American, but when does the average person deal with acre-feet?
It's like saying how many horsepower it takes to drive from SF to LA. Makes no sense.
1 kWh/(acre ft) = 2919 Pa
It makes a great deal of intuitive sense that the quantity that describes how hard it is to move water over a path is a pressure.
It just happens.
But expressing energy requirements as power per unit can be quite useful. As in, kW per person or square meter. Though in that case you'd be expressing water delivery as a rate: acrefoot/day, say.
An acre-foot of water is approximately the amount of water that a suburban household uses in one year, which is why that unit is used when talking about non-agricultural water usage.
When villifying almond farms for their water usage
Watt-hours really are as simple as they sound. A 14W bulb that's on for an hour used 14 Watt-hours.
Does the author mean 3,460 kilowatt-hours?
> Lambert showed me a series of pumps at the Carlsbad plant that collectively exert seven thousand horsepower of energy (eleven hundred pounds per square inch of pressure)
Holy hell, how am I supposed to reason about any of these numbers? The mix of units and ignorance of power/energy differences makes the numbers completely useless to the reader. Near the beginning of the article, the daily volumes are discussed in terms of millions of gallons, but later on, acre-feet is used.
Sorry if this comment is too ranty...
One of the by products of oil production is natural gas that accumulates as pockets in the wells. Compared to crude oil this is a lot harder to store and transport, so in most cases is just burned off (if you ever fly over The Gulf at night, you can see the flames from the wells doing this).
This by product is what is used to generate water and electricity. Sea water is heated with the natural gas, and turned into steam which runs turbines to generate electricity. The steam is then cooled, which provides desalinated water. The water is stored in tanks for a few days where limestone rocks are added (from other parts of the country) to provide minerals, then fed into the public water system.
The newest "M" plant produces 2,000 MW of electricity and 140 million gallons of water a day, with an overall efficiency of 85%. It cost around $3 billion to build.
http://www.power-technology.com/projects/jebel-ali-m-station...
The economic consequence is a drastic rise in the price of conventional agricultural products (especially land meats) and a corresponding relative fall in the price of unconventional products (nuts, seeds, beans, aquaculture) which drives investment in the latter to hopefully yield a less water-hungry agricultural system... but a very different palate. The general outcome of capitalist systems are heterodox (one of capitalism's advantages); we expect to see some compensation from desalination, tertiary sewage treatment, and more water-efficient farming practices. It would be less painful if we didn't fight reality with agricultural subsidies and water grants.
Although in CA looks like the majority of their electricity comes from natural gas and renewable resources[1] which is a start, I suppose.
[1]http://energyalmanac.ca.gov/electricity/total_system_power.h...
Come to think of it, I wonder if you could harvest the steam from a nuclear plant, run it through a condenser or distiller, and in that way produce electricity and purify water at the same time.
Most existing reactors in the US use the reactor core as the heat source, a convection cooling tower as the heat sink, and water/steam as the working fluid.
Using salt water as the working fluid in a BWR or SCWR would probably be dangerous, as it circulates around the reactor core. In a PWR, the working fluid and the fluid circulating past the reactor core are separated via heat exchangers in the steam generator, so that's probably the only widely used reactor type that could do distillation-based desalination without heavy modification.
But probably the most useful way to go about doing it is to keep the rest of the reactor as it is, and just attach the reverse osmosis desalinator pumps to the same driveshaft as the electricity generator. Even though boiling and condensing water is an integral part of steam engine operation, it really works best when that water has been completely demineralized already. Otherwise, your boiler fills with salt sludge, and your condenser gets clogged with mineral scale.
You're saving efficiency by taking out the two conversions between electrical and mechanical work and the transmission loss between generator and pump motor. The purified water and waste brine could also carry heat away from the steam engine's heat sink if it can go out hotter than the ocean water that comes in. I'm thinking that you'd heat the waste brine as hot as possible before dumping it in a solar evaporation pond. The infrastructure required to pump pre-heated water to the nearest community along with cold is probably not going to pay off unless you're supplying high-rises or a university campus.
The author's conclusion may very well be correct for all I know, but I think it is somewhat misleading to say that the water is "pumped long distances." There are points where it is pumped, but one of the things that makes the system so fascinating from an engineering standpoint is how much of it relies on gravity, including massive siphons that literally pull the water over mountain ranges.
I don't think that is physically possible. Water won't siphon more than 33ish vertical feet. It will just draw a vacuum in the pipe.
EDIT: Found a good link. The word "siphon" is quoted on every use in this link, suggesting that they're not actual gravity-powered siphons. See #10. http://www.kcet.org/news/redefine/revisit/commentary/concret...
EDIT2: Ok, they are gravity-powered, but not by the "pulling" action of the water on the downslope side of the siphon, as much as by the pushing action of the previous downward slope feeding into the siphon. Technically, it's still a siphon i guess, just operating at higher than atmospheric pressure.
A fifth of energy usage in California is water related, and a fifth of that is for pumping, over 10TWh anually.
http://www.kqed.org/news/science/climatewatch/waterandpower/...
This one goes into more detail and picks that 19% number apart. Also quotes the 10TWh number:
http://blogs.kqed.org/climatewatch/2012/06/10/19-percent-cal...
Where's the best place to start reading more about this?
https://en.wikipedia.org/wiki/California_State_Water_Project
I became interested while living in LA twenty or so years ago. The whole system represents a monumental engineering achievement, whatever its political, ecological, social, etc., implications.
Edit: that page doesn't discuss siphons much, as they are part of the aqueduct components of the system, but reading through it my twenty year-old impressions seem off. Siphons do play a big role in getting water over some heights, but there is a lot of pumping too. On the other hand they generate power from the flow at several places, so who knows how it all balances out?
Oh well, too late to go back now, but at least it warms the heart a bit to see this happening. I've always thought desalination was an amazingly powerful technology, and I'm glad to see it getting some use on a large scale.
Of course, that's not to ignore the side effects, like what to do with the leftover salt, but almost everything has some side effect.
Interesting statistics on CA's water use: https://www.thedodo.com/drought-1085519358.html
Basically personal use accounts for 4% of the total. Meat and dairy production takes 47% of California's water.
I understand the regret, but it's only too late when you're dead. If you want to do it you can find a way.
Anyway, it's not that I dislike the path I'm on, it's just the occasional twinge of that feeling that I wish the stuff I was doing had a more direct impact on the world. OTOH, given the path I'm on, I still hope to help make the world a better place, and if we'e successful I think we'll have a chance at doing that, albeit in a different way.
Then there's the salt. Salt's actually kind of on the downslope in terms of its use in de-icing. You're literally salting the earth around roadways. Places that see a lot of snow and have a lot of waterways (from personal experience, like Northern Wisconsin and the UP), actually use sand instead. You expect there to be snow on the roads for a number of months regardless, so you're just offering some traction. Certain places in the Northeast are the same as far as I'm aware. Here's a resource on road salt from New Hampshire[1]. Pickle brine[2] and beet juice[3] are also beginning to get some play. Not to say the rock salt market couldn't absorb some additional supply, but I don't know where the limit is if we're talking mass desalinization.
[1] http://des.nh.gov/organization/divisions/water/wmb/was/salt-...
[2] http://news.nationalgeographic.com/news/2014/02/140204-melt-...
[3] http://time.com/5761/salt-shortage-triggers-beet-juice-chees...
If nothing else, you could probably truck the salt to Coyote Dry Lake and just dump it on the existing salt flats there.
https://en.wikipedia.org/wiki/Qattara_Depression_Project
Build a canal/channel/etc to a below sea level place, harvest the hydro power, and get a nice new (saline) lake to boot.
Anyway, I don't think that the salt is totally worthless. Don't they have salt ponds in the bay around San Jose?
The energy input is the bigger problem; you can only get so much water from a glorified solar still.
As most people every remotely familiar with politics might guess, the technical challenges are not even remotely the most difficult obstacles to be overcome for such a project.
I'm from Canada & the reason they don't use salt in places like Edmonton & Winnipeg is that it just gets too cold and salt no longer works at that temperature. In Ontario where they get the lake effects they use salt everywhere.
CaCl2 works down to about -32C (-25F).
But at some point, you just can't dissolve enough stuff into the water to stop it from freezing. Fortunately, that is also about the point where ice stops being quite so slippery when you drive or walk on it. So you just throw down white sand for better traction instead, put on the winter tires, and you're good until it melts in the spring.
In Minnesota, Wisconsin, Ontario, Michigan, and New York, the temperatures are such that snow and ice could go through multiple freeze-thaw cycles. If they just left it, snow would melt and re-freeze into smooth, slippery ice. Ice would melt and seep into the roads, then refreeze and pop out big chunks of pavement each time. That's why they salt and plow. It's too cold for it to safely drain away, and too warm to just leave it alone.
If there were a substance that allowed snow and ice to stay frozen at higher pressures or higher temperatures, that might be useful there, too.
Well, the Atacama is 8000ft above the ocean, so the energy required to pump the water up there would be significant.
http://www.technologyreview.com/news/525121/molten-salts-mig...
http://www.usbr.gov/tsc/water/research/VTE.html http://www.sephtonwatertech.com/projects.html
Living by the great lakes, I'm sure the people of California would lay a pipe across 1700 miles of the country if they could, but irresponsible usage of water is always going to drain whatever freshwater source is available. I do hope projects like these can help in some small way, though.
This also isn't the first time there has been a drought in any part of this country, obviously, and looking at weather in Texas recently, for example, you can see how quickly rain will come and go. There are large numbers of people in California. I'm sure that some of them must be smart enough to figure this out. Otherwise, we're looking at the beginning of another dustbowl.
The future of climate change is only going to make these problems more severe, and this obviously isn't a conservative solution going forward.
It's also interesting that the Santa Barbara desalination plant is mentioned. I lived in Santa Barabara recently (12 months ago) and I was unaware that there was a desalination plant there at the time during the drought. Recently I had heard that it was going to start up again, after never having ran more than 1 month in its lifespan. I would be surprised that that project is still behind its timeline, but then again, I wouldn't really be surprised.
(Edit: After 1 year, the city council voted to restart the plant last Tuesday.)
And by the way, the "irresponsible usage of water" by the people of California is largely growing food for the rest of the continent. You may live near the great lakes, but you undoubtedly consume water from California. It's just packaged inside fruit and vegetables.
And certainly a number of foods could be produced elsewhere in the country or imported. If I ate a lot of almonds I might feel indebted but really I eat a whole lot more of foods that aren't plums, grapes, lettuce, artichokes, etc.
Talking about the agriculture aspect always takes me by surprise because the state represents a large percentage of the country's population but a smaller percent of its land area. Given that most areas of the country could be used for producing something, its not as if all food production could be removed from the state.
And I also think about Japan, because, even though it has a smaller land area, the climate allows the country to produce enormous amounts in agriculture, mainly rice, but other products, too. So obviously it depends on the land. It's also something where, the farmland in Japan is beautiful, while the farms on the West Coast don't really seem to be (subjective).
It's also really amazing to see this article slip off the frontpage, and I noticed this with attitudes while I was in the state, but it just seems like people don't care. So maybe it has something to do with people's attitudes, too. Dealing with big issues takes a bigger attention span.
Sort of—the real answer is to let markets set prices: http://marginalrevolution.com/marginalrevolution/2015/03/the... . People, including farmers, are quite good at figuring out how much of a given good or service they really need if the good or service is priced appropriately.
A twenty year drought is at the less severe end of what's possible.
California has had several 30 year droughts. It had one drought that lasted at least 180 years, and another drought that lasted over 220 years.
California's per capita water usage is roughly in the neighborhood of other western states (http://www.brookings.edu/blogs/planetpolicy/posts/2014/10/di..., scroll down), and although there's certainly room for improvement, it's really not bad considering the massive amount of agriculture in California.
Not mentioned in the article -- unless I missed it -- is that the Carlsbad plant is being built at a cost of around $950 million, and I wouldn't be surprised if it crossed the magic $1 billion line by the time it was operational. That's a huge amount of money for just one plant; it could take around 50 plants of that size to completely offset the effects of an extended drought, and there would still be significant costs in then moving all of that water into the central valley areas where it's needed for agriculture.
Everything that I've read recently is suggesting that what we're experiencing now is likely to be the new normal for California. This is because the Sierra snowpack has become nearly nonexistent in recent years, and it previously accounted for around 30 percent of California's total water storage, and it provided that water year-round. That's a 30 percent haircut right off the top.
Even when we get wet seasons, it's not expected that they will be cold wet seasons, which means we'll see less snow in the mountains. And, since most of the rain that falls west of Sacramento gets funneled directly to the Bay, wet seasons won't even be helpful in the long term.
So what's happening is California is experiencing some of the effects of climate change. (I know HN at large doesn't believe AGW is real, but that's not really what this comment is about.) That means there's going to have to be a lot of adaptation, and not just in one area.
California's environmentalists -- and I usually count myself among them -- are going to have to get used to the idea of more dams and more reservoirs. California needs to make up for that missing 30% somehow. It also needs to start adopting water conservation the way that energy conservation has been seeing adoption; we should be seeing affordable greywater systems that move water from your bathroom sink into your toilet tank, for example, and residential water storage systems for landscape use should become more common.
We're going to have to figure out how to handle the agricultural industry. They're adapting too. They should get more help and encouragement, with access to more resources for water conservation. California is one of the most technologically advanced states in the US; it should be possible to dedicate some of that technological expertise to new forms of irrigation.
Storm runoff has to be handled better. It should be captured and treated and stored, diverted into marshes and other wetland areas.
Of all of these various things that need to be done, desalination is one of the most expensive per-gallon solutions.
I have however gone back through a lot of my reading history and dug out quite a bit of other links and supporting data. Interestingly, that specific phrase, "new normal", came up quite a bit, which is probably why I used it without thinking about it.
Finding supporting articles wasn't super difficult, but synthesizing them into something coherent will take way more effort than I'm willing to put into a 10-hour-old HN thread which probably nobody will ever read.
So I'll synthesize it and post it to my personal site in due time, and then post that to HN (where I expect it won't get any traction at all, but at least I'll have something to point to the next time someone wants citations).
Ah, in that case, here's my understanding, in brief. There are several components:
1. California has had multi-hundred-year drought cycles in the past, according to tree ring data, and the last several hundred years have been unusually wet by comparison. It's possible that we're re-entering a long period of overall drought. (e.g. http://www.nytimes.com/2015/04/14/science/californias-histor...)
2. The current drought has been exacerbated primarily by a pattern of high and low pressure systems over the arctic, the polar vortex system. The newer "curvy" shape of the polar vortex is leading to systems which are keeping cold fronts from descending into the west coast.
3. The current working theory is that the shape of the polar vortex is influenced mostly by the temperature of the arctic, so it's not likely to return to what we thought of as normal until the arctic starts to cool down again, which might not be happening anytime soon. (e.g. https://en.wikipedia.org/wiki/Polar_vortex#Climate_change -- sorry for Wikipedia link.)
4. There has been a gradual decrease in snowfall over the Rockies and, I think, the Cascades region. (e.g. https://www.ncdc.noaa.gov/sotc/drought/201502, http://usatoday30.usatoday.com/weather/news/2011-06-10-clima...) A lab in Berkeley is responsible for measuring snow pack in the Sierra, and they have some data going back to the late 19th century. Unfortunately, all I can find are graphs of their data, not their actual data, so I have to contact them and see if they're willing to share that so I can see how the average is changing. My hunch -- although it's only a hunch at this point -- is that I'll find a slight overall decline in average snowfall, same as there is in the Rockies and Cascades. Seeing if this data is available is part of what's holding up a more comprehensive reply.
I have links to articles for most (all?) of this, but ... it's a little bit discombobulated still. I think it really needs to be presented more coherently to look very convincing. Part of the reason that I'm reluctant to start sharing links right away is that some of the sources I have at the moment are crappy little blogs -- thank you very much Google -- and I have to take the graphs they've ripped off and try to locate the primary sources they ripped them off from and then read them and make sure the context is correct and all that.
I'm not a meteorologist or climate scientist, it's likely there are areas that I'm oversimplifying or misunderstanding. But, I am an avid reader, and I haven't come across much material that's painting an optimistic view of California's climate in the near future.
For instance, ship the brine to someone who needs chill water, and then ship the warm brine off for salt extraction (apparently it's hard to profit off of sea salt if you can't get free BTU's from somebody, like a neighbor or the sun)
The answer is keeping that water where it is for longer. this means that it'll evaporate where it lays. Which means more rain.
It also mean that the water table is higher for plants and animals.
a brilliant example are johads: http://www.ecotippingpoints.org/our-stories/indepth/india-ra...
cheap, easy, quick and simple.
I'm no meteorologist or anything, so I honestly don't have any idea about this, but I can't help but wonder if that matters? I mean, if there's "more rain" overall, but it all happens somewhere else, that doesn't necessarily help California. Is there any connection between where water evaporates and where it ultimately falls as rain? That is, is it actually possible to cause more rain in a certain spot, but doing what you're talking about?