Why can’t legislators connect nuclear power and water shortages? 11

Comments View as Flat

1. 

   KenG Posted 9:01 am
   31 Oct 2007

   Don't Get It?The thing you apparently don't get, although comments keep explaining it, is that all steam cycle generation plants (nuclear, fossil or solar) currently utilize water for cooling. However, they don't "use" it as much as they warm it up a few degrees. Ultimately the heat is rejected to the atmosphere. At the expense of a few percent efficiency, the heat can be directly rejected to the atmosphere.
   New nuclear plants, if located on the ocean, can actually solve some of the water shortage issues by incorporating desalinization into the design.
   Time to give this one a rest. There is just no issue here.

   Permalink

2. 

   JMG Posted 10:10 am
   31 Oct 2007

   A few percent efficiency is a BFDSorry, KenG, but a hit of a few percent is a BFD on the economics side; surmountable with proper carbon pricing (big coal burners "use" just as much water as big nukes for cooling) but not a trivial issue in any sense.
   
   Save the world: Reduce greenhouse gas emissions 5% annually.

   Permalink

3. 

   Karen Street Posted 1:26 pm
   31 Oct 2007

   a few percentLet's see, 3 - 5% of 5 - 6 cent/kWh, works out to, nope, I'm going to have to go with KenG on this one.
   A Musing Environment
   
   Karen Street

   Permalink

4. 

   KenG Posted 10:48 pm
   31 Oct 2007

   Cost ImpactNot only is the efficiency hit only a few percent on the wholesale (busbar) cost of electricity, it only occurs during a limited part of the year when the temperature. So it's really a 3 to 5% hit on 3 to 4 cents per kw that applies probably about 10% of the year.

   Permalink

5. 

   Sean Casten Posted 11:59 pm
   31 Oct 2007

   It's the efficiency, stupidKenG is right about the cause, but I disagree with the conclusion.  This isn't a nuclear issue, it's an efficiency issue.  It applies to all steam-cycle power plants that don't recover their waste heat.  (As an example of the problem, ask a 10 year old kid to draw a powerplant.   Betcha they draw the cooling tower.  Betcha they don't draw anything else.)  Wisdom from the mouths of babes, since the vast majority of the footprint and energy flows in a power-only steam cycle is the heat rejection system.  In otherwise, they exist primarily to piss away their energy.  The operative issue is not the 3 - 5% efficiency hit on hot days, but rather the 60%+ energy that gets thrown away in the cooling tower.  So long as the plant isn't next to a big body of water, that 60% = massive water use.  Not because it's nuclear per se, but simply because it's an inefficient steam cycle.  You could, alternatively cogenerate from a nuclear plant and cut way down on water use without changing the fuel (or coal, or biomass, or any other thermal fuel for that matter.)

   Permalink

6. 

   amazingdrx Posted 12:33 am
   01 Nov 2007

   Cognitive dissonance?Or junkets?
   The nuclear power lobbying industry is second only to AIPAC in flying politicians around the planet, for free.  Follow the money, it's always the dollars.
   Nukes shut down in France from heat during that heat emergency where air conditioning outage was deadly.  There wasn't enough water to cool the plants and people died.
   As GHG disaster raises temps and lowers water levels, nukes shut down and air conditioners stop.  110 degrees in the southwest anyone?  Rely on nuclear power and the death toll might rival hurricane and firestorm events.
   
   http://amazngdrx.blogharbor.com/blog

   Permalink

7. 

   amazingdrx Posted 12:38 am
   01 Nov 2007

   Candy lobbyThe candy lobby delayed daylight savings time a week.  So kids could consume more trick or treat candy.
   Hmmm..  maybe a combination?  Nuclear active glow in the dark candy?  Three mile island already did that to Hershey candy, according to Helen Caldicott.  As she says, Hershey's has not sued over her claim.
   The glowing candy would keep the kids safer while trick or treating!
   
   http://amazngdrx.blogharbor.com/blog

   Permalink

8. 

   Baby Boomer Posted 1:03 am
   01 Nov 2007

   Another problem in GeorgiaBecause of our drought and our rising temperatures, what water we have in our lakes and rivers has become warmer.  Some smart dudes commenting above explained this, but evidently it is a consideration that is being examined in regard to nuclear plants and the efficiency of operating them in Georgia.
   We do have a nuclear power plant on the Savannah River near the coast.  I don't think they're desalinizing water there, and the neighbors aren't so happy about the water being returned to the river. Plus, there's a small problem with trucking the nuclear waste across Georgia to some other state.
   I lived in New Jersey when 3-Mile Island occurred, and I had 3 small children.  I am not a big fan of using nuclear power to address our needs.  And is there a problem with "peak uranium" - just asking?
   By the way, poor Senator Johnny isn't as bad as Senator Saxby Chambliss, who is the guy that ran an ad sliming a triple amputee Vietnam War veteran.  He linked Senator Max Cleland in an add with Osama Bin Ladin.  That has to be as low as humans go, right?  

   Permalink

9. 

   KenG Posted 3:51 am
   01 Nov 2007

   EfficiencySean is right about the amount of energy rejected from steam power plants of all sorts. And there are some uses for that low temperature. However, you need to keep in mind that this energy is at a very low temperature - typically only a little over 100 deg F. As long as the power generation is using a thermodynamic cycle, the energy rejection is inevitable. That's the second law of thermodynamics.
   The only way to get around this is to use a non-heat form of generation - wind or photovoltaic. However, these options have their own set of limitations which are, at least in the forseeable future, economically much more restrictive than thermodynamic limitations.
   And a couple of other quick responses. For Baby Boomer, uranium is available for 500 or 50,000 years, depending on how you feel about breeder reactors. Transportation has been dealt with ad infinitum. The internet has plenty of videos of transport containers being tested with 80 mph locomotive collisions.
   Amazing - When the famous French heat emergency occurred, the nuclear plants didn't shut down and cause electic outages. The deaths resulted from lack of air conditioning, not electricity (plus lack of a responsive public health system). The main French a anti-nuclear organization (SdN) just issued their plan to phase out nuclear in France. It includes elimination of residential air conditioning, so I guess heat wave related deaths in France aren't as important as eliminating nuclear (at least to them).

   Permalink

10. 

    Sean Casten Posted 3:57 am
    01 Nov 2007

    Ken - exhaust pressures are not immutableKen:
    Note though that there is nothing that says that nuke or coal plants have to exhaust at vacuum pressures (= very low temperatures).  Raise the pressure from the turbine exhaust and you cut back on power output, obviously, but not find yourself with useful heat on the backside - and heat where you can recover the full heat of vaporization rather than just a few degrees of temperature.
    (For the non-technical: a pound of steam gives up about 1000 Btu when it condenses into water, but only 1 Btu when it cools by 1 degree.  Steam coming out of "condensing" turbines isn't really condensed - it's just soggy, but still mostly steam.  Ergo, you've still got several orders of magnitude more energy in that steam than you got out in the turbine.  By raising the exhaust temperature even by a few hundred degrees, you sacrifice much less in terms of lost power than you gain in the fact that you can now send that steam out to a thermal use where it can give up the full 1000 Btus and achieve vastly higher overall efficiencies.)

    Permalink

11. 

    KenG Posted 8:17 am
    01 Nov 2007

    Missing the PointSean -
    
    What you are saying is technically correct until you get to the part about not "giving up" the heat of vaporazation by exhausting at a higher temperature. No matter what temperature/pressure you exhaust from the turbine, you will recover the entire energy when you condense. You just do it at a different temperature. At 1.5 psia (13.2 psi vacuum) the enthalpy of evaporation is 1028 btu/lbm, at 14.7 it is 970 btu/lbm, at 100 psi it is 889 and so on.
    The problem is what you lose in cycle efficiency and what you can do with low temperature heat. I did a quick comparison (using ideal Carnot cycles, I was too lazy to run out a full Rankine spreadsheet). Using typical nuclear parameters (550 deg F supply saturated steam, condensing at 1.5 psia) the theoretical maximum efficiency is 43%. Raise the condensing pressure to atmospheric and that drops to 33.5%. Raise it up to 50 psi (281 deg F) and it drops to 26.5%.
    For that significant drop in efficiency what do you get? A bunch of hot water. While that may be attractive for a limited amount of district heating, you can do most heating services with the 115 deg steam and a small amount of add on reheat.
    Like most students, I thought I had discovered something wonderful in my first thermo class when I realized how much energy was available in condensing steam. 40 years later, I realize how little need the world has for low pressure steam.
    
    

    Permalink