<![CDATA[Grist - Comment Feed for The unrecognized link between water and energy]]> Grist Comment Feed en Comment #1 by Sean Casten http://www.grist.org/article/2009-04-10-the-unrecognized-link-between/ Fri, 17 Apr 2009 13:33:23 -0700 http://www.grist.org/article/2009-04-10-the-unrecognized-link-between/1 A point that needs to be kept in mind but is too often overlooked is that the water use in power plants is a direct function of their (in)efficiency.  Heat that is put into a steam power plant (roughly 70% of the US fleet) as fuel, but not recovered as electricity gets sent to a cooling tower as soggy steam where it is condensed with prodigous water use.  This is where the overwhemling majority of the water gets used / wasted in a modern power plant as those cooling towers evaporate water into the sky.  (Think about the plume atop a nuclear cooling tower.)

Without in anyway disparaging the value of electricity conservation, it bears keeping in mind that the larger opportunity for water conservation is in the power plant itself.  If you build those power plants as combined heat and power plants instead, replacing that cooling tower with a heating loop going onto industrials, district thermal loops and any other purpose you eliminate the need for substantially all of that cooling tower water - and save a fair amount of fossil fuel as well.

At the other end of the wire, there are many opportunities within industrial facilites to replace process coolers at their end (which also are big water hogs) with heat recovery, either to provide space heating or else - at the somewhat more technologically-adventurous fringe - stick organic rankine cycles that can make power with working fluids that boil at low temperatures.  This brings more efficient generation on line (displacing some of the load on those upstream generators, just like end-use conservation does) and also gets rid of water use at the industrial itself.  The opportunity for that approach is pretty massive - we've been looking at projects using ORCs in chemical plants, atop their distillation & stripping columns.  (Fun fact: for every ~5 MW of electricity consumed by a modern ethanol plant, you could pull 1 MW out via this approach.)

This isn't meant to be exhaustive, nor overly specific as to the solution - just to make sure we don't make the mistake of assuming that the miserably-low generation efficiency of our electric sector is immutable - but do appreciate the water conservation benefits of bringing that sector into the 20th century. 

]]> A point that needs to be kept in mind but is too often overlooked is that the water use in power plants is a direct function of their (in)efficiency.  Heat that is put into a steam power plant (roughly 70% of the US fleet) as fuel, but not recovered as electricity gets sent to a cooling tower as soggy steam where it is condensed with prodigous water use.  This is where the overwhemling majority of the water gets used / wasted in a modern power plant as those cooling towers evaporate water into the sky.  (Think about the plume atop a nuclear cooling tower.)

Without in anyway disparaging the value of electricity conservation, it bears keeping in mind that the larger opportunity for water conservation is in the power plant itself.  If you build those power plants as combined heat and power plants instead, replacing that cooling tower with a heating loop going onto industrials, district thermal loops and any other purpose you eliminate the need for substantially all of that cooling tower water - and save a fair amount of fossil fuel as well.

At the other end of the wire, there are many opportunities within industrial facilites to replace process coolers at their end (which also are big water hogs) with heat recovery, either to provide space heating or else - at the somewhat more technologically-adventurous fringe - stick organic rankine cycles that can make power with working fluids that boil at low temperatures.  This brings more efficient generation on line (displacing some of the load on those upstream generators, just like end-use conservation does) and also gets rid of water use at the industrial itself.  The opportunity for that approach is pretty massive - we've been looking at projects using ORCs in chemical plants, atop their distillation & stripping columns.  (Fun fact: for every ~5 MW of electricity consumed by a modern ethanol plant, you could pull 1 MW out via this approach.)

This isn't meant to be exhaustive, nor overly specific as to the solution - just to make sure we don't make the mistake of assuming that the miserably-low generation efficiency of our electric sector is immutable - but do appreciate the water conservation benefits of bringing that sector into the 20th century. 

]]> Comment #2 by Subaru http://www.grist.org/article/2009-04-10-the-unrecognized-link-between/ Sat, 18 Apr 2009 08:57:47 -0700 http://www.grist.org/article/2009-04-10-the-unrecognized-link-between/2 Someone will need to think to make power out of water, after all there is more water on earth than anything else. But then again, this will be utopia, free energy, no capital... since everyone have access to water. Industry want monopoly and cash. Water as energy is not good for them.

]]> Someone will need to think to make power out of water, after all there is more water on earth than anything else. But then again, this will be utopia, free energy, no capital... since everyone have access to water. Industry want monopoly and cash. Water as energy is not good for them.

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