## P

Where:

q = Quantity of heat stored in Btu (kJ) (note that lower case q is used for quantity of heat, as opposed to upper case Q, which is used for rate of heat flow)

V = Volume of the storage material in ft3 (m3) p = Density of the storage material in lbm/ft3 (kg/m3) c = Specific heat of the storage material in Btu/lbm per °F (kJ/kg per °C) T2 = Final temperature in °F (°C) T = Initial temperature in °F (°C)

For a simple closed loop water-to-water heat exchange application, a simplified expression for the Btu/lbm • °F value of thermal energy storage potential is:

Q = Vf(gpm) (60 min/h) (8.34 Ibm/gal) (1.0 Btu/lbm °F)

Where:

Q = Heat available in Btu/h

Vf = Volumetric flow rate in gpm

T2 = Final temperature in °F

Ti = Initial temperature in °F

1.0 Btu/lbm • °F = Specific heat of water 8.34 lbm/gal = Density of water

## Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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