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Massachusetts Considering Desalination Plants
Iphtashu Fitz writes "Despite a reservoir system containing some 412 billion gallons of water for Boston and surrounding communities, some eastern Massachusetts towns are facing water shortages and are now considering water desalination plants as a new source of fresh drinking water. The city of Brockton, 20 miles south of Boston, has plans in the works to build a $40 million plant and could begin construction as soon as this September. Currently there are fewer than 100 desalination plants in the US and most of them are in smaller communities, but that seems to be changing. The largest desalination plant in the country is located in Tampa, FL, which expects it to provide 10% of the citys drinking water by 2008. California also has at least 10 large scale plants on the drawing board. Some environmental organizations like the Conservation Law Foundation dispute the need for desalination plants however. They argue that many water shortages could simply be solved by better conservation of existing supplies."
They should try talking to the arab states which produce 60% of the worlds desalinated water . They are even considering injecting the desalinated water into the ground to raise the groundwater level.
Powerplants have done this for years with thier incoming and cycled water, but there is plenty of room in the stack and obviously plenty of heat left. Most of the "smoke" you see is water vapor. You don't get water vapor unless there is a big heat and/or humidity difference.
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
I've always wondered if it was feasible to create clean desalinated water as a by-product of a nuclear power plant. Since turbines need to be powered by steam anyway, why can't they find a way to recycle this water? I guess too many people would be waay to paranoid about such an idea though.
Most desalination is done with reverse osmosis anyway. It's much more energy efficient than distillation.
What's the main by-product? Salt. And lots of it. Hopefully they have a use for it but if they don't, it can be just another source of pollution.
I'll wager that millions of dollars are spent cleaning and transporting water in that area (and all over the US), where half of it will be used to water the lawns of suburbia. I would like to see more effort to reduce usage before plants are built for desalination.
I used to live in the area (south of Boston, but not in Brokton, thank goodness)..as long as I can remember, we've had water bans during the warmer spring/summer months. It was almost frightening watching the local resevoirs literally dry up.
Where do they plan on getting this sea water though? I sure hope it's far far far away from Boston Harbor...It's green from all the polution and I'm afraid desalination is only a small part of the process of preparing it for consumption.
The problem with the plant here in Tampa is that while it may be the largest, it isn't doing anything except sitting there. The filters have turned out to be too expensive and need replacement too often to make it worthwhile to turn on.
The only people who acutally use reverse osmosis for desalinization is steam power plants. Yes, this includes most any plant that uses boiling water to generate electricity: Nuclear, coal, Combined cycle gas turbine, oil, etc. They need super squeaky clean water so their turbines don't corrode.
Most desalinization plants, on the other hand, just boil water very efficiently and then cool it down again, using the cooling water to heat up the incoming water. If I remember right there are usually 3 heat exchangers in one unit. One to preheat using the water being cooled, one to boil using an external hot water source, and one to cool to room temp using an external water source. The whole process takes place in a vacuum so the water boils at much less than 212 F. In a ship desalinating plant you would use the diesel jacket water cooling water, normally at 150F or so. This is more than sufficient to boil the water at the lower pressure. Shoreside, you would use a low-temperature boiler I would imagine.
You would not use reverse osmosis because quite simply nobody needs to drink water that clean. The heating process doesn't kill bacteria (not hot enough) but UV filtering is done after desalinization to wipe out most anything left. Thats basically the whole process.
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
Which method is cheapest overall?
Reverse osmosis has been shown to be the most economical in many cases due to its lower energy consumption, leading to lower unit water costs. However, the process has higher up-front investment costs compared to thermal processes. Its unit water costs are primarily determined by membrane life and energy cost (Ericsson et al., 1987; Wade, 1987). Reverse osmosis plants have flexibility of operation in the face of fluctuating water demand and benefit a little from economies of size.
Several economic trends for multistage flash distillation plants are apparent: a relatively low investment cost, benefits from economies of size (relative to other processes), site specific costs (for example pretreatment requirements, energy costs) have a direct affect on the unit water costs, and low flexibility in response to variable water demand (meaning that freshwater production cannot be adapted to fluctuating demand ) (d'Orival, 1967; California Coastal Commission, 1993). The main economic drivers for multistage flash distillation are costs of materials and energy, and increasing plant capacity to take advantage of economies of size (Water Corporation, 2000).
Comparing multistage flash distillation and reverse osmosis, the distillation process has been the preferred method due to its reputation as a mature and reliable process. However, reverse osmosis plants are replacing the older multistage flash distillation plants of the Middle East and being the first choice for desalination implementation in Australia. This is due to their simpler operation, reductions in energy consumption and ultimately, cheaper unit costs of fresh water (Anon, 1999a; Glueckstern, 1999). The overall cost of fresh water from a reverse osmosis plant is often less than half of that produced by means of distillation (Water Corporation, 2000). As technical advancements of membrane processes improve their costs and efficiency, they will continue to be the preferred choice for countries moving into desalination.
Presently, the reported costs of desalinating water using current technologies fall within the range A$0.80/kL to A$2.10/kL, depending upon the process, location and the potential for blending with marginal quality groundwater (Water Corporation, 2000). These costs do not include disposal or distribution costs.
Read more here.
I grew in Santa Barbara. In the early 90's we had a killer drought- our water supply (Lake Cachuma) went down to about 3% capacity. Low-flow toilets and showerheads were distributed freely and it was a ticketable offense to water your lawn between 11am and 4pm. So the taxpayers sank like 32 million bucks into a desal plant. I believe it was ON THE VERY DAY the plant was to go into operation that IT POURED, and the thing has rarely, if ever, been actually used. Guess it'll do as a backup...
Do the rich snobs who were against the proposed wind farm have a problem with unsightly desalination plants being built in the same state? Has anyone checked?
Maybe the MA legislature could pass a law requiring those rich snobs to only drink expensive, bottled water-- that way they don't have to sully their lips with "commoner's" water, and there's more of it to go around for us mere mortals without having to build some structure that will mess up their view.
Any large northern city goes through thousands of tons of salt every time it snows, at a cost of several million dollars. 65T of salt per day is ~ 24K Tons / year. That's probably less salt than a millon-person community in New England would use in a typical winter.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
I would like to know how this is modded insightful. Nowhere in that sentence is any mention of controlling people. It seems like common sense to me. The fact is, people waste water. Not out of malice, but as a result of ignorance. Watering your lawn in the middle of a summer day does little for the grass; it mostly evaporates. There are many other cases of misuse of our most precious (and unfortuanately, neglected) resource.
From the article: "The seawater will add about $50 to $75 to residents' annual water bills."
If you ask me, adding $50 to an annual water bill is more controling than promoting conservation. For $40 million, the city could probably afford to outfit every citizen with a cistern of some sort to use for watering lawns and cars. Hell, depending on how many people live there, it might even be cost-effective to just buy the whole town efficient washing machines (the sideways kind.)
harmonious design
The problem isn't the lack of water, it's the overpopulation of the area. As the article stated there is already a large reservoir system, and there is a large number of natural fresh water sources. I live in the area in a town that has over 100 fresh water ponds. The population, although having not risen to the point of being overcrowded, has gone past the point that nature could easily support. Mankind doesn't develop in accordance with nature, adapting it's environment rather than adapting to it, and this is a result of and step in that process.
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Desalination doesn't necessarily need to consume any power at all. If you can use the sun to evaporate water from a container, and then let it condense and drip into another one, you can effectively produce both salt and water for "free".
These solar desalination devices are present in many survival kits, and in fact I've seen people improvising them with mere plastic bags.
I don't know if anyone's tried scaling it. I imagine that for densely populated places that demand very large amounts of drinkable water on a daily basis, it would require impossible amounts of evaporation surface.
I actually started thinking about the problem about 5 years ago when the tap water in the area went from perfect, to tasting like bleach. Bottled water is expensive, and what are we paying the government and the water company for anyhow?
Basically, the way we need to do it is to have a second set of water lines. The set we have right now can be used to carry low-grade water. It will be the kind of water you use for your toilet, washing your hands, watering your plants, etc. That should not be unhealthy to drink, but it can have all sorts of additives, and generally taste awful.
The second set of pipes will be high-grade water. Like it used to be, through them the water company will pump pure, clean, quality water. That will be what you drink/cook with. People would save a fortune on buying bottled water, or water filters.
What's more, there's really little change from what we have now. Except, the fresh water won't be mixed with the recycled water, and the water company can be even more aggressive in recycling water, since they know that it's not for human consumption. No more need to spend a lot on making recycled water taste slightly less repulsive, they can just keep a tiny quantity of water clean. Your water bill will certainly be a lot less too, since the water you are spraying on your lawn doesn't have to be good enough to drink.
The improvements in water fountains boggle the mind.
After all, providing clean drinkable water is perhaps the #1 task of any government, anywhere, and they've really dropped the ball lately. This is their primary job. Babies are getting serious medical problems because pregnant women drank tap water. This is really serious stuff.
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Err when would that be?
Power plants reduce their output to match forecast demand. There is never a point where there is surplus electricity.
Certain types of power such as hydro are used to meet peak demand because they can be turned on and off very quickly with little or no wasted energy. This is one of the reasons why gas turbines have become popular, they cost more to run than coal powered plants but they have low capital costs and they can concentrate on meeting the high profit peak energy market.
Just about the only type of power plant that is never turned down is nuclear. But very few countries have enough nuclear power to do more than meet the base load, they are capital intensive and it makes no sense to build them unless there is continuous demand.
There are a few anomalous situations where a country does have an excess of power. The Canadians have more hydro power than they need to meet peak load and so they are in the fortunate position of running hydro for base power needs. Thats why they have aluminium smelters in Canada. Aluminium double glasing would be completely uneconomic if it wasn't for the cheap power. It takes thirty years for alumninium double glasing to save the amount of energy it took to make even in a relatively cold climate like the UK.
The other country that has a bizare power situation is France where de Gaul decided that 80% of the power needs would be met by nuclear plants. The result is that the French export huge quantities of power to the rest of Europe at way below cost. But even then the power is being sold, it is not being 'thrown away'.
The amount of renewable energy (including nuclear) available at a given time is fixed. So every unit of power used by the desalination plants will result in additional carbon emissions. It makes a lot more sense to save energy by making better use of existing water resources.
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Interestingly enough, you probably don't want to drink that straight up. De-ionized water will kill you (it will cause an electrolytic imbalance in your system) It happened at Intel some time ago that some guys thought "hey, this de-ionized stuff must be really great water" and decided to use it to make coffee and whatnot. A short while later they were essentially dying of diarrhea. Not fun.
When things get complex, multiply by the complex conjugate.
Aqueous Solutions (pdf) is a chapter from Natural Capital. It explores various options for using water efficiently.
Did you know that agriculture uses four fifths of the water in the US? That a short visit by a conservation specialist can cost-effectively save 10 to 20% of the farmer's water use? (i.e. they start saving money right away!).
In urban settings, much of the peak demand for water is used in landscaping. Education and better pricing structures can also dramatically reduce the need for water.
Conservation is so incredibly cost effective that desalination plants should really only be a very last resort. Please read the above linked chapter, and tell your elected officials to do the same thing before they go on wasting millions of dollars.
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Read the piece,"Foyers which lies on the shores of Loch Ness is a combined pumped storage and conventional hydro-electric scheme".
In other words they are using off peak electricity to pump water UP into the reservoir so they can release it back again at times of peak demand.
This is yet another way to meet on peak demand without having to build additional generating capacity. The off peak power still has to be paid for.
As for the argument about starting and stopping coal stations. Sure the optimum efficiency of most power stations is at about 80% to 95% of full load. But that does not mean that it costs nothing to run the station at 80% of load when there is only demand for 50%.
I have worked on power plants, albeit ones that were using power generated as a by product of generating steam for other uses. Sure it takes days or even weeks to turn a plant up from startup to full load. But all modern plant designs allow the output to be controlled over much shorter periods. If you are running chain grate you simply slow down the rate the chain is moving, or you decrease the amount of coal per bucket. If you are running pulverized fuel you have very fine control over output.
The reason that most coal plants run at full output most of the time is that they are capital intensive but cheap to run and there is almost always sufficient demand to use their entire output. The economics of the power industry have meant that almost all of the new plants built over the past twenty years have been gas turbine or similar low capital, high cost generators. That means that there is more than enough industrial demand to keep the coal stations busy.
Sorry, but there is no free lunch here, every kw/hr of electricity used by the desalination plants will be generated using carbon based fuels that would not have been used otherwise.
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Ocean Thermal Energy Conversion, or OTEC would produce both electricity AND fresh water (from condensate). Building an OTEC plant big enough to be worthwhile would be an enourmous construction expense, though. Payback for return on investment would take forever, but there would be no pollution produced.
And what a lot of those bozo's don't realize is that unless you're getting the river water from near the source, you're drinking recycled sewage.
Damn shame about the Miramar plant - that water could be put to good use and would be better quality than what's already going into San Vicente.
A Shadeless room is a brighter room.
When will people learn that the environmentalists sloagan "we can conserve enough to survive on" for whatever resource is completely detached from reality?
Conservation advocated by the big eco groups would result in:
-no economic activity
-no jobs
-imploding social spending system
-dramatic lowering of the standard of living
There are actual reasons for conservatio and alternative fuels:
- remove dependence on middle eastern oil so that terrorist funding and radical Islam funding Saudi Arabia, Iran, Syria, etc do not have money to fund terrorists around the world.
- remove dependence on foreign governments, e.g., OPEC members, for energy and trade dollars - this protects the US economy and national security
- remove dependence on buying product from dictatorial, totalitarian, religious totalitarian, and communist countries - there is no need to fund the US enemy's economies
No. Price rationing would occur. If the water company overcharged, consumption would drop too much for it to still be profitable. They'd be forced to find a fair rate, or go out of business. Unless the water company isn't privately owned.
Assuming that there are caps. I'm speculating here. There are water and power caps in my area, actually kind of a price-averaging. I hate them, because it creates a minimum price that I have to pay, no matter how little I use. I'm just venting here; it's a stupid system the ensures there will always be a minimum consumption that is both more expensive and less efficient than necessary.
Fred
"A fool and his freedom are soon parted"
-RMS
My family of three uses less than 700 gallons of water per month. We have a composting toilet, an Oxygenics shower head and water-efficient appliances (made by Miele). The graywater (all our effluent) goes through a planting bed where we grow ornamental plants, herbs, miniature fruit trees, etc. From the planting bed, the effluent goes to tree irrigation. We're very comfortable.
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Of course there is, and it's generally the nighttime. In Mass there is even a generation facility, Northfield Mountain, which during the nighttime pumps water from the Connecticut River up into a high reservoir using that surplus electricity. Then, during the day, when demand is high and supply short, the reservoir dumps through turbines back into the river to feed the grid.
My understanding is that there is no financial gain to this; it is entirely about "banking" surplus power in the form of potential energy (the water in the reservoir at elevation) for times of need.
Michael J.
Root, God, what is difference?