Mixing energy-based control

These examples show clearly that any grid that includes NPPs and/or renewable energy sources must also include fast-response power plants such as gas- and coal-fired and/or large hydro power plants. This is due not only to diurnal and seasonal peaking of demand but also the diurnal and seasonal variability of supply. Thus, for any given market, the generating mix and the demand cycles must be matched 24 h a day, 7 days a week, 365 days per year, independent of what sources are used, and this requires flexible control and an appropriate mix of base-load and peaking plants. 

Material and energy balances are based on the conservation law, Eq. (7-69). In the operation of liquid phase reactions at steady state, the input and output flow rates are constant so the holdup is fixed. The usual control of the discharge is on the liquid level in the tank. When the mixing is adequate, concentration and temperature are uniform, and the effluent has these same properties. The steady state material balance on a reacdant A is... 

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