In regards to this question: How to determine the efficacy and potential energy of hydro power energy storage?.
I'm searching for a cheap liquid that I can use for a small scale pumped hydro storage. Obviously water came to mind but that has a freezing point of 0C. The average winter temperatures here are min -6C and max +7C. With some extreme days of -24C (a century ago) and more recently (a decade ago) about -18C.
I'm thinking to simply use a water mixture to lower the freezing point.
I'm intending to eighter make saline water at NaCl, wt% 23.3, lowering the freezing point to −21C, which should be more than sufficient. https://en.wikipedia.org/wiki/Saline_water.
Or making a water ethanol mixture to lower the freezing point. But in order to get roughly the same freezing point (-21C) with a 23.3% water ethanol mixture I need to used about 40% ethanol which is much more expensive than salt. https://www.engineeringtoolbox.com/ethanol-water-d_989.html.
- Are there any other cheap liquid solutions or mixtures I could consider for volumes of 200 to 1000L?
- Would (the viscosity of) saline water or an ethanol-water mixture affect the systems performance or degradation? As water alone has a viscosity of 1.002Cp and the 23.2% saline mixture a viscosity above 1.557 Cp.
- Would the ambient temperature (further) affect the behavior's of the liquid?
Probably related: Pump power and fluid viscosity