Massachusetts Considering Desalination Plants 356
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."
Waste of Money (Score:5, Funny)
Re:Waste of Money (Score:5, Funny)
Re:Someone please explain? (Score:5, Informative)
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.
Re:Waste of Money (Score:2)
I don't have an accurate estimate of how much water a typical showerhead uses per min. It takes me roughly 60 seconds to fill up a 5gal bucket when I wash my car. The nice vending machines i've seen in California and am now starting to see in Washington sell water at between 25 cents and 35cents per gallon.
Assuming the rate of consumption of 5gal per min, a 15 min shower (75 gallons of water) would cost you $18.75 - $26.25 based on this cost.
Bathtubs
Re:Waste of Money (Score:3, Informative)
I once in my life took a shower under a 5 gallon/minute showhead, and it was wonderful! They don't make them like they used to. It is illegal in the US for a shower to use that much water. IIRC the most you are allowed in 3 gallons/minute, and likely less.
Weight of Water, Desalination (Score:3, Informative)
15 min shower = 600 gallons
60 gallon tub = 480 pounds
So, how many bottles of Disante water would it take to fill a bathtub? :)
Desalination sounds like a good idea to me. It's not like the Atlantic is going away any time soon and while expensive to start up and maintain, you'll provide proof against fresh water shortages and drought.
This doesn't mean that it will be cool to water your lawn when they kick in the desal units to make up for a la
huh (Score:5, Insightful)
Re:huh (Score:5, Insightful)
However, if you are smart you can use your desalination plant only at times when the demand on the power grid is below average, and i'll burn electricity which would have otherwise been wasted.
Re:huh (Score:2, Funny)
Re:huh (Score:2, Interesting)
Re:huh (Score:4, Insightful)
Re:huh (Score:5, Informative)
The amount of salt in sea-water is measured in terms of salinity (the number of grams of salt in a kilogram of sea-water). Normal sea-water has a salinity of 35%, or around 35 grams. Thus, one metric ton (1000kg) of sea-water would give you 35,000 grams or 35 Kilograms of salt (35 x 1 Kilogram bags of salt).
Of this, the distribution is as follows:
Chloride: 55.04%
Sodium: 30.61%
Sulphate: 7.64%
Magnesium: 3.69%
Calcium: 1.16%
Potassium: 1.10%
Now, the average adult human need 2 litres of fresh water to drink just to survive each day (2 litres = 2 kilograms at 4.0 C). Although some of this can come from food such as meat, vegetables and fruit.
If a desalination plant is used, that's 70 grams of salt being produced per person/day.
At most an individual is only going to require 1 gram of each mineral (Eg. sodium).
So around 65 grams/day of salt is going to have to be placed somewhere.
Multiply this by 1,000 people for a small town (65kg salt produced per day) and
1 million for a large city (65 tonnes salt produced per day).
And that's not including the requirements for washing machines, dish-washers, garden sprinklers, and toilets.
Re:huh (Score:5, Insightful)
Re:huh (Score:3, Interesting)
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.
Re:huh (Score:3, Informative)
Re:huh (Score:3, Interesting)
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
Re:huh (Score:3, Informative)
According to this page [hohusa.com], the low end of the scale is about 11kWhr per 1,000 gallons (3,785L) for reverse osmosis. The Tampa plant produces up to 111,000,000 gallons per day. So that comes to 1,221,000 kWhr per day. We can skip the electrical conversion and use solar heat to evaporate and disti
Re:huh (Score:5, Interesting)
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.
Re:huh (Score:4, Interesting)
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.
Re:huh (Score:2)
Re:huh (Score:5, Informative)
From a tax perspective, these plants will need to be built by somebody, probably with bond issues, and will require taxes to pay off. I'd be more pissed about that than the environmental impact.
Re:huh (Score:5, Funny)
Re:huh (Score:5, Informative)
Filtering of large solids (fish, leaves,twigs)
Removal of unpleasant odors and tastes using carbon filters
Chemical dosing with lime, ferrous sulfate and polymer to remove suspended particles.
Application of chlorine to kill off bacteria.
Application of fluoride to prevent tooth decay.
Filtering through anthracite coal and and sand to remove the last remaining suspended particles.
Desalination plants have the additional task of removing the salt from the water. There are two ways of achieving this. The first method is to boil the water until every last drop has been converted into steam and then recondensed again. Alternatively, membrane filtering can be used, which requires that the water is pumped at high pressure through a water but not salt permeable membrane. Both of these methods require large amounts of energy (Power stations are a good location for this).
More importantly, the areas that require desalination plants, are the same areas which are pouring/or have poured unprocessed sewage and toxic waste into ground water supplies. It would be more energy efficient and environmentally friendly to implement waste water purification, than to run a desalination plant in the first place.
Power? Not a problem (Score:5, Funny)
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.
Better yet, build an OTEC plant. (Score:3, Interesting)
Energy intensity of desalination (Score:5, Informative)
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.
Re:huh (Score:5, Informative)
Actually we would remove only about 10% of the water from the saltwater we pumped through the system. Any higher extraction than that increased scaling problems creating a maintenance nightmare. One poster asked what the communities planned to do with all the "extra" salt. It is pumped back into the ocean with the rest of the brine.
Also, to reduce energy costs and heat loss, all the production is done at partial vacuums to reduce the boiling point. If memory serves, the we reduced the boiling point to 165F, but it was 14 years ago, so my memory is a little fuzzy.
Re:huh (Score:2)
Re:Oppressive to the poor (Score:3, Interesting)
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 th
Re:huh (Score:5, Insightful)
Solution in the form of rationing = greens telling us how to live, meaning more power to them
Call me cynical, but all too often I see the greens (or the Green Khmer as my friend calls them) protesting against good solutions... it seems that they always favour rationing.
Re:huh (Score:3, Informative)
It was exactly the politics that I was questioning. As for conservation being always good; that is not the case. Conservation often carries with it an economic penalty. Consider: if we want to reduce the amount of soot ejected into the atmosphere by 30%, should we a) reduce energy consumption by 30% (assuming we're using coal-powered plants), or b) install scrubbers on the smokestacks, achieving a 30% reduction that way. In Europe at le
Simpson's Relationship? (Score:4, Funny)
I hear [snpp.com] that Ogdenville and North Haverbrook have also installed desalinazation plants and look....it put them on the map!
Re:Simpson's Relationship? (Score:3, Funny)
Conservation only works when... (Score:5, Insightful)
--
Retail Retreat
Re:Conservation only works when... (Score:3, Informative)
Some examples I recall, but since they are from my memory, take them with a grain of salt. I can have messed it up.
Berlin, Germany: The people there were so economical with their use of water, the sewers had not enough water to function properly.
In a quarter of Toyko a person built a tank to collect rain-water, to water his garden and WC. He ran into several problems with the administration, which (somewhere in summer
Re:Conservation only works when... (Score:2)
Note the disparity in industrial and agricultural water consumption between NA and even other developed parts of the world like Europe.
Re:Conservation only works when... (Score:2)
There is a two-pronged approach to dealing situation.
1. Raise water rates drastically over a certain basic usage level. (In effect, taxing excessive lawn watering, car washing , etc.)
2. Heavily promote conservation techniques such as rainwater harvesting and low-water washers. Offer tax credits, free workshops, whatever.
I think you'd find that conservation would get a bit more attention then.
Lets emulate Family Guy in real life (Score:5, Funny)
Re:Lets emulate Family Guy in real life (Score:2)
Try talking to the arabs (Score:5, Interesting)
Re:Try talking to the arabs (Score:4, Informative)
Raise efficiency. (Score:3, Interesting)
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.
Re:Raise efficiency. (Score:5, Informative)
You seem to be completely unfamiliar with all the techniques of water desalination. Saltwater Desalination: Chapter 1 [ca.gov] 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
Re:Raise efficiency. (Score:3, Informative)
An extract from Saltwater Desalination Chapter 1 [ca.gov]
For example, in addition to the 3,500 to 7,000 kWh/AF of energy required for electricity, the thermal energy needs for a MSF distillation plant is estimated at 270 million Btu/AF (about 26,000 kWh/AF);
c.f. th
Still asleep (Score:4, Funny)
When did Massachusetts get so evilly ambitious?
Re:Still asleep (Score:2)
At least not right away. :)
The best way to desolate the planets would be to construct a large reflective ring just sunward of the innermost planet, like a mini-ringworld. The kicker would be, of course, that we'd lose all sunlight on earth 8 minutes later.
And that'd pretty much be it.
There would be more but... (Score:5, Informative)
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.
Anyone done this? (Score:2)
Re:There would be more but... (Score:5, Interesting)
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.
Re:There would be more but... (Score:2)
It's still expensive though. However, it uses far fewer chemicals than regular treatment plants: after desalination, not much else needs to be done.
Re:There would be more but... (Score:2)
Re:There would be more but... (Score:2)
I'm sure it does at 1ATM. However, it becomes easier and easier to boil water when the pressure is lowered. Lower the pressure enough, and the water boils all by itself! However, by the nature of the self-sustaining nature of the distillation plant, the partial vacuum never gets really really low. This is because the vaccum is maintained not by a pump, but by the difference in volume between a litre of water and a litre of vapor. The wate
Re:There would be more but... (Score:4, Informative)
Actually the opposite is more likely. If you're generating/using steam, evaps make the most sense as you've already got a heat source that can be used "directly" to flash more water into steam. Reverse osmosis makes sense if you have a non-heat producing source of power - e.g., you're bringing in electricity off the grid to run pumps that push water through the membranes.
I spent six years as a Gas Turbine technician in the Navy. The majority of them, and all the older steam-powered ships, use evaporators to generate fresh water. I'm not sure about the nukes, but since they produce a crapload of steam to drive the turbines to make electricity, I'm betting they use evaps too.
The main source of heat for the evaps on the turbine ships are the "waste heat boilers" powered by the exhaust of the electric generators (3 Allison 501-K17s on the Ticonderoga cruisers for example). The ultra-pure boiler feedwater used to make more steam for the heat exchangers is produced through evaporation. In other parts of the system, bromine is added to the distilled water, making it into potable water for drinking, etc.
I think there are some ships (the new Arleigh Burke destroyers, and maybe the nuke carriers) that use reverse osmosis - far fewer maintenance headaches than you have tinkering with boiler water chemistry, heat exchangers, etc. Just replace the membranes as needed, and have a good "dirty side" flushing system - if the feed pump is a high enough capacity, a good chunk of the "clean side" water can be used to flush the crud...
Also, ships at have relatively clean water they are starting with - a desal plant close to shore would have a lot nastier stuff to have to filter out, which would require more frequent membrane changes, more $$...
I would hope that nobody is going to build a standalone desal plant. Having desal as a byproduct of electricity generation, especially a multi-fuel (diesel, LNG, methane, even powdered coal is possible now) cogeneration (thus the "co" in cogeneration - use the 'waste heat' to do something besides heat the atmosphere) plant, makes the most sense...
Increasing treatment plants makes the most sense to me, though. You're already starting with "fresh" water... Although at least here in San Diego, the people who don't understand the technology keep getting initiatives to build more treatment plants shot down by using a negative "toilet to tap" campaign...
Re:There would be more but... (Score:3, Interesting)
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
Conservation? Bah... (Score:4, Insightful)
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.
nuclear powered desalination? (Score:3, Interesting)
Most desalination is done with reverse osmosis anyway. It's much more energy efficient than distillation.
Re:nuclear powered desalination? (Score:2, Interesting)
Re:nuclear powered desalination? (Score:3, Interesting)
water wasted for watering lawn (Score:3, Interesting)
Re:water wasted for watering lawn (Score:3, Informative)
Re:water wasted for watering lawn (Score:2, Informative)
Without a doubt, we here in Phoenix may already be living on borrowed time. Water here is pulled from 3 sources. Groundwater, as you mentioned, reservoirs on the Salt and Verde Rivers, and from the Colorado River via the Central Arizona Project.
For goundwater, the aquifer is dropping. As a result, we are banking water from the Colorado River from the States allotment by pumping it back into the aquifer. Actually holding water for other S
Great Idea! (Score:3, Interesting)
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 long view... (Score:3, Insightful)
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.
How about largest functioning plant? (Score:3, Interesting)
Depends on where the watere is. (Score:3, Informative)
And my town is one of them (Score:4, Informative)
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 [swanseamass.org] 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.
Re:And my town is one of them (Score:2)
Re:And my town is one of them (Score:2)
Re:And my town is one of them (Score:2)
Hostile To Business (Score:2, Flamebait)
From the CATO Institute: [cato.org]
Cheapest method? (Score:5, Interesting)
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 [uwa.edu.au].
Only 10% of the city's water supply by 2008? (Score:3, Insightful)
SimCity 2000 (Score:2)
Re:SimCity 2000 (Score:2)
Many techniques! (Score:3, Informative)
waste of $$$ in santa barbara (Score:3, Interesting)
Silly enviro-people, water is for consumers! (Score:5, Insightful)
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
Altering source salinity (Score:3, Insightful)
I haven't done any research on this, but it seems a bit tough to believe. Even if desal. were supplying all of Boston's water, the volume of pure water taken out should be miniscule comp
And this will be powered by...? (Score:2)
Nothing pisses me off more than when I heard of that offshore wind farm near Nantucket and how the locals (headed by the Kennedy folks in their compound) are NIMBYing it.
Oh well... I guess we can always generate more power with coal or nukes, eh?
Re:And this will be powered by...? (Score:2)
Silly conservationists... (Score:2)
As long as population continues to increase, conservation and other increases in efficiency are only short-term solutions. Sooner or later you MUST increase the supply, or you run out.
Look at California's electricity problems for a good example of where this leaves you.
Feasibility? (Score:2)
Most nuclear plants work by boiling purified water, using the steam to turn a turbine.
What if, instead of running it as a closed loop, with the enormous cooling towers, we combined the two together, so that you have water desalinization and nuclear power in one?
This could be, in essence, "free" water!
The main consideration is dealing with the large amount of mineral deposits...
this is ridiculous (Score:3, Informative)
Not real environmentalists (Score:2, Insightful)
Re:Not real environmentalists (Score:3, Interesting)
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.
Cadillac Desert (Score:2, Insightful)
Just like nature? (Score:2)
Nature purifies water by a combination of wind and solar power, is there no way this can be mimicked on a large scale?
Sim City!? (Score:4, Funny)
Right up there with "Metroville Builds Airport".
Thank you Ted Kennedy (Score:5, Funny)
2-tier water system. (Score:3, Interesting)
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.
require reading on water (Score:3, Interesting)
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.
Do you even know what desalinization is? (Score:4, Insightful)
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.
Re:Do you even know what desalinization is? (Score:2)
While des
Re:Enviromental issue anyone? (Score:5, Funny)
Just another example of putting WAY too much emphasis on the "common" and none on the "sense."
Re:Enviromental issue anyone? (Score:2)
I think we have a new winner for most idiotic post on Slashdot....
Re:well, duh... (Score:2)
I wonder what they would say if we had 1 gallon of watter per person per day? Say that we need to conserve more water? I meen, that is about the minimum amount of fluid needed to sustain a human.
Re:anyone know how many urinals are in Boston? (Score:2)
Re:eh, there's so much freshwater in north america (Score:2)
Gray Water and Salt Water Toilets? (Score:4, Insightful)
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 [glowingplate.com]. Reusing the washing machine's water saves me $200/year and gives satisfying soapsuds when I'm doing Number One.
Re:eh, there's so much freshwater in north america (Score:4, Interesting)