Water required for electrical generation

In ten years, I have washed mine once! That was to remove accumulated pine pitch. Other than that, the rain does a pretty good job.

Icarus

 

The thing motivating my comment was all the water needed to routinely clean the mirrors at the Kramer's Junction solar plants. I was a bit surprised at how much was used, but once I understood the vast surface area involved it became clear it was no minor amount. Rain is extremely rare in the Mojave and certainly not dependable for cleaning. But your original point is correct and I don't want to come across as objecting to it.

The new Ivanpah solar thermal plant being built uses air cooling instead of water cooling entirely based on minimizing water consumption as a requirement for permitting. That uses a lot less water than water cooled plants but still uses vastly more water than pure PV panels. It remains to be seen if this type of plant succeeds overall. One of the key possibilities is a solar thermal can store energy in molten salts or other storage, but this is not part of the present Ivanpah plant.

 

I am not arguing that PV is not without it's costs, in t his case some minimal water use. But what does a MW steam plant use annually compared to a MW of PV? I'm guessing it is no contest.

Icarus

 

The biggest users of water are hydro plants. According to NREL hydro uses an average of 18 gallons evap/kwh, thermal 0.47 gallons evap/kwh wind and solar are rounding errors. Where solar starts consuming water is when it is backed up by pumped hydro or fossil fuel normally ocgt. Since solar use is also a rounding error (0.11% eia for the first 6 months of 2012) a great deal of solar can be built without it requiring much water. That though is part of the problem of asking solar to replace other sources.

Texas has water problems for power, but these are well known, and have been worked on in the past. Unfortunately in 2011 the drought and all the air conditioning from all heat blew past the 15% safety margin and power needed to be imported, in that year from mexico. The deficit was small though. California needs about 5x more water/kwh and droughts would likely also effect the states they import power. That is where I would expect climate change black outs, as the government does not seem to be able to properly regulate electrical generation for them. There are already plans for renewables, but they need some lower water consuming ccgt plants built quickly and lower dependence on imported power. These seems against current regulation though. If there is a hydro shortage like 2000, I would expect blackouts.

 

It is "no contest" as AG shows in the numbers above. Two interrelated economic issues are raising their heads here. The first issue is water can no longer be considered "free" in any power plant proposal or plans. Plants of any technology must incorporate how they minimize changing the "water distribution" landscape to even be licensed. The other economic issue is exactly what you brought up. If water costs skyrocket, then solar and wind have a big economic boost. I keep seeing the inflection point getting closer and closer.

 

Interesting number about evap at hydro sites. I wonder if this is an average over various climates. For example lake Mead will certainly evap more than James Bay Hydro on some annual basis. Grand Coulee might be somewhere in between.

Run of the river and certain low head hydro might have no added evap.

Icarus

 

i think i read that and it very much sounded like chapter 2 of a 3 chapter story. so we can only guess as to what chapters 1 and 3 say.

around "water logged" WA, car washes are required to use a water capture and filter system to lower their water footprint. this really bumps up the cost (to the point where one of those automated systems is only about a buck more now...) so it really comes down to do you want to wash your own car or not because its no longer cheaper.

during the Winter, washing car at home is ok. during Summer we frequently have car wash bans but I see people violate it all the time. but if the water situation gets worse around here, i suspect taht will change