Saturated Water

To 2 significant figures:

• Definition of Saturated Water
• Water boiling temperature depends on pressure.
• If you increase pressure, water will boil above 212F.
• Calculator - give it pressure - and it tells you what temperature water boils at and its energy content at that temperature - [1]
• 18 bar water is at 209C and 880kJ/kg, at 1 bar it is 100C and 420kJ/kg. At 18 bar, density is 860 kg/m3
• The difference beween the two is 460 kJ/kg that can be released as steam energy. This appears to be the stored energy that can be extracted by a steam engine
• Thus, a 10,000 gallon (38 cubic meter) tank at 18 bar contains 38*860 kg or 33,000 kg
• Energy releasable from this is 33,000*420kJ = 14 GJ.
• 1 GJ = 280 kWhr
• Thus 3920 kWhr. This paper shows 20-30 kWhr/m3 (about 1000 kWhr for 38 cubic meters) storage capacity which considers the pressure drop or about 1/4 of the theoretical value.
• Extracted at 15% efficiency via a steam engine, that is 590 kWhr. But 1/4 the value for effective extraction due to pressure loss through discharge - and have 150 kWhr. Decent, and probably sufficient.
• Acceptable.
• This means that a 1000 gallon propane tank gets you about 15 kWhr of storage when extracted with a steam engine. At $2500 tank cost - this is $170/kwHr. 2x cheaper than Lithium Ion batteries, and about same as lead acid batteries. But longer life for propane tank.
• For anyone that understands this, this is revolution and end of battery storage on a path to ecological means of storage via solar-heated saturated water.