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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."
Wouldn't it be just easier to buy bottled water than build a whole plant ??
what harm is there from desalinaiton plants? sea level dropping? why are environmental groups protesting it?
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The city of Brockton, 20 miles south of Boston,
I hear that Ogdenville and North Haverbrook have also installed desalinazation plants and look....it put them on the map!
Conservation only works when people contribute to the effort. These days people use water for household uses, lawns, washing cars, etc. Once we are used to having it on demand, it's kinda hard to think about conserving. Ususally it's too late when a shortage occurs. Might as well start building the plants now, by the time they are finished being built, they will be needed.
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They should do what I saw in family guy. They just had a machine combined an oxygen molecule with 2 hydrogen. The water it made was really good.
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.
When did Massachusetts get so evilly ambitious?
At the moment the biggest problem with desalination plants is not just their high build cost, but their high operational cost.
When using technologies such as reverse osmosis the energy costs for pushing high volumes of water at high pressures through the membranes is prohibitive, not to mention the wear on the equipment it's self. In a traditional water treatment plant most of the filtering is done with gravity.
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I seem to recall a story from the western U.S. where the city instituted rigid conservation controls. The result was that they were successful.
Well, sort of. The subsequent drop in water usage also resulted in a drop in water revenue and sewer revenue (water usage was metered). The city ended up losing so much money due to not keeping up with fixed costs, that they tossed the measures out the window. They needed the money more than the conservation.
Desalination on a large scale is absolutely necessary for humanity's survival over the next 100 years.
"If you want to improve, be content to be thought foolish and stupid." - Epictetus
Because ocean water is so plentiful, there is absolutely no danger in reducing sea level (the very idea is absurd), and the only enviromental issue is the huge amount of power needed to get the salt out of the water.
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.
Oh if only we hadn't dumped all that salt into the oceans!
Just another example of putting WAY too much emphasis on the "common" and none on the "sense."
common sense: noun
What those who are ignorant of the subject matter think; usually wrong.
"City officials dismiss worries about water privatization, saying that a 20-year contract ensures affordable water rates and that the desalinated water will only supplement more traditional supplies."
Is twenty years really all that long when talking about public utilities? Also, what's the projected growth rate for this place over the next twenty years? Is the supplementary nature of the desalinated water the plan for the long term or just initially?
Water is a hell of a commodity to control; even if you have to wait twenty years to actually control it.
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 Quabbin Reservoir is big(412 billion gallons) and supplies Boston and some neighboring towns. The MWRA (Mass Water Resources Authority) also was responsible for building the outfall systems required to handle the use of this water. The problem isn't the existence of the water but the pipes and connections. Some towns see the MWRA as costly and are exploring other means. I doubt that 16 mile pipes and the costs of desalination are cheaper for Brockton than an MWRA hookup, but that doesn't figure sewer costs in. GIGO.....
Add to that the fact that we are experiencing a building boom due to high house prices (think 900 square foot house for $250k) and we anticipate extensive demands on town water services.
That is why our water commissioner formally proposed a desalination plant for our town.
Despite the fact that the state has cut funding for just about everything, our kids are asked to bring paper, tissues and other basic supplies to school, and we had to shut off the town street lights and close a library to save money the town focus seems to be upon building our way out of this hole :(
At least elections are next tues.
Oh and on a related note, I took a vacation recently to the Carribean and the place we stayed had desalinated water....it tastes awful.
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 support the use of desalinization as a source for water, it is better ecologically and economically, than taking your water in from other places, just look at Mono Lake. I'm suprised that our technology in desalinization isn't better considering the largest Desalination plant in the country hopes to provide only 10% of it's city's water supply by 2008!
You seem to be completely unfamiliar with all the techniques of water desalination. Saltwater Desalination: Chapter 1 will educate you. Of particular interest is http://www.coastal.ca.gov/desalrpt/dc1tbl1.gif this chart which shows that distillation consumes much less power than reverse osmosis
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
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...
They argue that many water shortages could simply be solved by better conservation of existing supplies.
Well DUH. The people aren't trying to solve a 'water shortage' problem. They are trying to solve a "demand exceeds supply" problem. They don't have a reason to deny people the water they want to use if the people are willing to pay a higher cost. Eventually they hit a price point where people will naturally conserve water.
Water is a reusable natural resource. It's not easy to come up with a reason to conserve it, since they are already conserving it with water treatment plants.
Think of the water system as a closed system. The only unaccounted for openings are evaporation, and letting it go into the water table (ground, streams, ocean, etc). Otherwise the water is contained entirely in storage, pipes, and treatment plants. To offset evaporation and adding to the water table a system must have a certian amount of intake from wells or another water source. A water shortage doesn't necessarily mean that not enough water is being produced, it means that the system has reached its capacity --> the treatement plants are supplying less water per day than people are consuming, and they are draining (slowly) their reserves of treated water. Alternately more and more water is being stored in additional piping added by new neighborhoods/buildings or evaporated/drained into the environment by new lawns and pools and not enough used water is getting back to the treatment plants. The wells and other 'new water' sources are too stressed.
There are two ways of combating this - either take in more water from the environment, or increase the efficiency of the treatment system (more plants, better plants, etc) Obviously the second problem can only be solved by getting more 'new water' into the system. In many cities it makes more sense to place a new well than to upgrade the treatement plant, especially if the treatement plant isn't at capacity. In many cases a well cannot be placed because it puts too much strain on the water table, so a desalination plant makes very good sense.
The environmental people are not complaining so much because they feel we are destroying the planet as they are complaining because it's a symptom of our consumerism which they fundamentally oppose on principle. If they can get everyone else to 'think green' in general then they hope that other problems which do directly affect the environment will also abate.
Oh, and yes, desalination does stress the water source. If they do not process the salt into other forms then the source many become too salty near the plant. If they do not replace the salt then it may not be salty enough. Either way, a desalination plant affects the water source. Whether that's bad or good is subjective.
-Adam
Big deal. Just build a nuclear power plant next to them. Problem solved. Oh, and the excess energy can be used to power the baby seal slaughterhouse and for rendering whale blubber.
Is it just me, or does this sound like a headline from the newspaper in the original Sim City? :)
Right up there with "Metroville Builds Airport".
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We can thank Ted Kennedy for pushing for this initiative. He is tired of salt water ruining his clothes when he goes driving.
Don't blame Durga. I voted for Centauri.
Boiling a pound of water at atmospheric pressure takes roughly 1000 BTU's, and there are 140,000 BTU's in a gallon of fuel oil. So a gallon of oil can boil 140 pounds of water or about 18 gallons. That is a lot of oil.
But if you boil a pound of water to remove the salt, condense it, you are throwing away all of that heat released when it condenses, almost as much as required to boil it. How can you recover that heat since you are going to boil at a slightly higher temp and condense at a lower temp and heat cannot move uphill?
One technique is multi-effect distillation. You boil and then condense at atmospheric pressure. The condensing at atmospheric pressure is hot enough to boil at some pressure below atmospheric. You condense and then use that heat to boil at an even lower pressure. You keep going until you are what ever vacuum pressure boils water at room temperature. The same 1000 BTU's to boil a pound of water is used several times to boil several pounds of water in several "effects" (stages of the still).
The other method is mechanical vapor compression. If you take the vapor from boiling and compress it in an centrifugal compressor, it can condense at a somewhat higher temperature, and you use that heat to boil the water feeding the compressor. While it seems like pulling yourself up from your bootstraps and violating a thermodynamic law, it is not that much different than a heat pump.
There is some minimum energy required to desalinate water, it is much less than 1000 BTU per pound, and if you know the osmotic pressure for that salt concentration, you take that pressure and the volume of water you want and use work = pressure times volume. That energy is not without consequence, and that is why you probably want to desalinate brackish (slightly salty -- often available from wells when pure water is not available) than going for sea water.
Also, there is some effort in approaching the thermodynamic "reversible" minimum energy of desalination. The multi-effect stills and the vapor compression still have to move large amounts of heat through heat exchangers at small temperature differentials. With reverse osmosis, you probably are pumping harder than the bare minimum to oppose the osmotic pressure so you get enough fluid through the membrane to make it worthwhile.
Multi-effect distillation is probably the way to go for big plants, vapor compression for mid-sized, and reverse osmosis is really probably only effective for small-scale stuff because the membranes are expensive and need replacement. Even with what I said, the energy needs are not trivial -- perhaps you want some kind of cogeneration where you run a multi-effect still from the waste heat stream of a gas turbine.
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.
I don't try to be right, I just try to make people think
One of the nice features is that you can buy things like water and electricity from your neighboring cities for a price. This price tends to be higher per unit of supply than you could provide with a structure like a power plant or water pump, but requires far less up front cost. The not so nice thing is that your neighbors will occassionally renegotiate the price with you, meaning you'll pay more each month if you want to continue getting these supplies.
The joke in the previous post is based on the fact that you could import water (based on the bottled water comment) or that you could build a costly desalination plant (as the article suggests is happening). In sim-city you'll get shafted in time if you don't provide your own facilities, thus the neighbors raising the cost of bottled water is funny.
Now I feel like one of those people that analyzes a joke until it isn't funny. However, I went to the trouble of explaining for the poor non-sim-city player so I'm just going to post it... blah. The interesting thing is that bottled water seems to be pretty expensive anyway, and building one of these big plants is probably well worth the trouble in the long run.
If not now, when?
I dunno. Ask California. California, Nevada, Arizona, and New Mexico really aren't fit for human consumption, nevertheless, the gov't dammed up most of the rivers out west to make it hospitible.
I read somewhere that 80% of the water use in California was for agricultural irrigation - so it seems to me that if environmentalists wish to preach about conservation, they've got bigger priorities than the average consumer.
Quoted from article: They argue that many water shortages could simply be solved by better conservation of existing supplies.
I agree. Couple of things - in coastal areas, do you really need to shower in fresh water? With most new construction around here using plastic hoses instead of copper piping, the biggest residential cost would be an incremental one to install a second (stainless steel) hot water heater. Besides, salt water showers and baths are really nice - or maybe salt water is just a novelty to me because I live inland. Installing the head-end pumping stations, water mains, etc would be a horrendous task, but many cities are already faced with the task of digging up their streets and replacing century-old water mains.
I see the primary uses of this water being the shower/tub and refilling the toilet.
Of course, if you're handy and want to save a few bucks, *anyone* can install a gray-water system like mine. Reusing the washing machine's water saves me $200/year and gives satisfying soapsuds when I'm doing Number One.
Fire and Meat. Yummy.