APR 18

When using water as a cooling fluid, water would not be destroyed, but heated and perhaps polluted. I don't think using water is a problem. Polluting it, that's the real problem.

The use of massive amounts of water to cool our powerplants is a danger as outlined; it though also has the following problems both "upstream" and moreso "downstream": citing of the plant's location for sufficient water supply, discharge of heated water into the local environment and it's significant discruption of aquaculture in the area or as steam and modifying local weather patterns. Also, what happens if the upstream supply of water for say a nuclear plant drops due to drought, there might not be enough water to keep the plant operational within prescribed safety limits (this issue has already been experienced in some regional French reactors in the past couple of years), possibly leading to a melt-down if the issue becomes too severe.
I would though disagree with Haichen's post, it is a problem in that the water, even if not "destroyed" is returned to the environment in a way that was not as it went out of the environment and could lead to my issues noted above. That said, pollution is a real problem as well and only of our making (barring naturally occurring pollutants (ie. natural radioactive deposits over/through which water travels)).

Please see
http://mydocs.epri.com/docs/ANT/1015362_Water.pdf

It's worth 8 months of winter to live next door to the biggest body of fresh water (surface area) on the planet. And thankfully, there aren't many of us here.

Hello Hank.I am typing this from my bedroom in a small settlement in N.S.W. Australia,by the name of Tyringham.It is after 11pm at night obviously,and I am burning a fluoro as assisting light...and I hate it.I got to your site via KeeleyNet.com, who does an excellent job I reckon.Anyway this is to state,as you might already know similar argument stuff has occured in Australia,and well frankly,cannot stand the corporations and tardy politics etc. but,I still think people are being held back from forcing some new analysis,of the grid and carbon dioxide producing plant,by a sort of dont frighten the rich and let the poor pay in some way in any change to grid related matters.Although government will protest about those conclusion by its care by paying partially the use of electricity from the grid,etc.Me thinks that maybe Americans are slow,until pointed out,at what other Americans could do.A U.S.A. company has improved the Hilsch or Vortex Tube technology,which is capable of blowing in cool compressed air into water cooled sites.Check out EX-AIR to see if you think like me this could maybe reduce water use.although powering compressors does require some form of energy to do so.These Vortex Tube stuff are and can have further applications,on farm and around home,where either the hot or cold ends,may assist in seasonal as well as other matters of direct or indirect use of temperature variable technologies and temperature modifying requirements.I think there isnt enough thought going into using technology in new ways,as can be seen by a YouTube devoted to cooking a turkey by incandescent globe.Thats about all.If you havent come across EX-Air before and Vortex Tubes..you might have your own unique use.Which could pay for itself..and your own requirements.

I have a couple of issues with this post. The first issue is the method for calculating the amount of “fresh water” required for the 60 watt bulb powered by a nuclear plant. The second issue is the method of comparison between Rankin cycle needs v “water-efficient” needs like hydroelectric. Traditional steam power plants have a tremendous need to reject heat. A majority of the heat that is released from the fuel is rejected to a heat sink. That heat sink is generally a large body of water or the atmosphere. In the case of a nuclear plant with a cooling tower that heat sink is the atmosphere. It is a pseudo closed loop with a make up requirement equivalent to the volume of water lost through evaporation in the tower. During the peak of summer when the plant is it’s least efficient this make up requirement might be 6% of the volume flow through the condenser. On a 900 MW nuclear plant this volume might be 40,000 gallons per minute or 625 gallons for the .26 MWh consumed during the year by the 60 watt bulb.
In a once through condenser using a river as a heat sink the dynamics of the flow are identical to that of a hydro facility. The only difference is you are using the thermal properties of the water as a heat sink instead of the water as a working fluid. In the case of an 800 MW nuclear plant using a river your water needs during the height of summer might be as much as 1,000,000 gallons per minute (600,000 gallons per minute during the winter). This water is pumped from the river through a condenser and then pumped back to the river. The net difference in volume in the river is only the amount of water that evaporates due to the increase in BTUs in the river. In a hydro facility, a dam is built to produce a reservoir behind the dam. This results in a head delta between the high side and the low side of the dam. The amount of water that leaves the dam is equivalent to the amount of water entering the reservoir minus the evaporative loss due to the surface area increase in the reservoir. When reservoirs are 500 miles long as is the case with the three gorges dam, or in arid climates as is the case behind Hoover this evaporative effect can be quite significant. To look at the water needs for a traditional power plant and use all water that flows through the condenser and compare it with only the evaporative effects in a reservoir behind a dam is quite misleading.

I will agree that currently when most people talk about the negative externalities of power generation they are generally fixated on CO2. There are so many more negative externalities to power generation than simply the CO2 that is produced. Take for instance the heat. If I make some basic assumption about the US power stack I come to some pretty astounding numbers. Installed MW – 600,000, capacity factor 50%, Heat rate 10 MMBTU/MWh – gets me to about 3,000,000,000,000 BTU’s burned per hour by US power plants. This translates to enough heat to melt ~20 billion pounds of ice per hour. A good number of the thermal power plants in the eastern interconnect use the Mississippi River or a tributary as their primary heat sink. If I assume this number to be 100,000 MW I get roughly 139 million BTUs rejected to the Mississippi river per second (assuming 50% of the BTUs burned are rejected to the river). If we assume that none of these BTUs are lost to the atmosphere (a terrible assumption but I don’t have the time to model it) it translates to an increase in the temperature of the Mississippi river of 3.5 degrees as it enters the gulf (assuming 600,000 cubic feet per second).

If I look for another negative externality I have to look no further than trace elements in Coal. Trace elements aren’t really of consequence till you start consuming massive amounts. In coal you have elements like Uranium (1.3 parts per million), Thorium (3.2 parts per million) and mercury (.11 mg per kg). If I assume a heat content of 10,500 BTU/lb and a plant efficiency of 10,500 BTU/kwh with a coal stack percentage of 65%, one 100 watt light bulb over 1000 hours translates to .00027 lbs of radioactive waste (sum uranium and thorium) along with 0.000009 lbs of mercury. Granted these are very small numbers but it is for 1 light bulb rated at 100 watts for 1000 hours of use.

the massive cooling towers reduce water use by ~95%. it's the older nukes that are very thirsty.
http://en.wikipedia.org/wiki/Cooling_tower#Industrial

Haichen: Nuclear power doesn't contaminate water supplies through normal operation. There are several fluid loops involved in operating a nuclear reactor, and between each one is a heat transfer system designed to prevent radioactive contamination. Aside from being warmer, the water's no more polluted when it leaves the plant than when it entered it.

Anthony: Nuclear power plants don't melt-down when rivers dry up, they just shut down. It's a simple water-flow/-pressure/-temperature cutoff system, and is completely automated. The NRC publishes information about the status of nuclear reactors on their website, and includes any abnormalities or reasons for shutdown. Also, nuclear containment domes are rated to survive earthquakes (Up to 5.0, IIRC), carpet bombing, tornados, hurricanes, and sub-/super-sonic plane strikes by large passenger planes and/or figher jets without breaking. The reactors themselves are also earthquake-rated. I don't know why people seem to think that nuclear reactors explode at the drop of a hat, but I blame crappy Sci-Fi films.

The way the study is being portrayed is quite dubious; people are talking as if the water is completely consumed and then gone forever.
Worse still is that it senselessly factors in the water cost of manufacture, which seems reasonable until you realize that the places making such things are generally going to be located in places where water is not in short supply. Solutions need to be matched to the local environment, and there isn't one band-aid solution for all our ills. Building a solar panel fab plant in the desert is about as silly as trying to grow pine trees on a life raft in the middle of the Atlantic.

Local shortages and global shortages are wildly divergent animals: Globally we have more than enough fresh water to go around, but locally we care piss-all for the 20% of the world's fresh water in the Siberian lake Baikal.