Auxiliary heater capacity

Dear Paul

I want to simulate a solar plant with a fossil-fired auxiliary heater, in order to supply thermal energy in certain periods of the year.

Nevertheless, I don't know how to define the heater capacity. I mean, during the real operation of a plant, sometimes the auxiliary heater can not supply the thermal energy demanded (for example, if there is demanded 100 MWt and the heater capacity is 20 MWt).

Which parameters define this heater capacity?

Best regards

Igor

Dear Igor,

SAM's CSP models calculate the energy required by a gas-fired backup boiler, and allow you to specify the timing of the backup boiler's "fossil fill fraction" and operation schedule so that you can choose to operate the backup boiler during certain times of day and year. Although you cannot explicitly specify the boiler's capacity, on the Thermal Storage page, you can specify the fossil fill fraction as a fraction of the power cycle capacity for each of up to nine periods. So, for a system with a 100 MWe nameplate power cycle capacity, if you specify a fossil fill fraction of 0.05 for a given period, the backup boiler will supply the equivalent of up to 20 MWe of heat to the HTF in that period.

Best regards,
Paul.

Dear Paul

Just one doubt about your example: If I have a system with a 100 MWe nameplate power cycle capacity and a fossil fill fraction of 0.05, the backup bolier would supply the equivalent of up to 100 * 0.05 = 5 MWe, isn`t it?

Best regards

Igor

Hi Igor,

Yes, you are correct -- sorry about my mistake.

Best regards,
Paul.