Questions about geothermal model

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Questions about geothermal model

I have a few questions about SAM geothermal model.

1. When we resource type, we have choice between hydrothermal resource and EGS resource. According to the help the different between them is that hydrothermal model assume both water and permeability are sufficient while EGS are not. If that is the case don't I need to add water on it. But, I don't see anywhere information about water resource used including on the cost section. Do you know where I can see the the amount of water I need?

2. Regarding binary plan efficiency define in the "Plan and Equipment" how is this different with Renkin cycle efficiency calculated in the power bloc section? The explanation on the help said it is system efficiency minus the pumping power and parasitic load. If it is the case should this number an output rather than input because the system efficiency can be calculated using the given mass flow rate and steam temperature.

Thank you

Paul Gilman

Dear Martinus,

Unfortunately, I do not have very satisfying answers for either of your good questions.

1. SAM's geothermal model does not report the quantity of water required for the EGS resource option. You could estimate the water cost as a variable O&M cost ($/MWh) on the System Costs page, but that would require estimating the water use per MWh of electricity produced outside of SAM.

2. The "Plant Efficiency" input on the Plant and Equipment input page is a measure of how close to a theoretical maximum working-fluid-heat-to-electricity efficiency you want to design the plant. A value of 1 would mean that you want the plant to be as efficient as possible. The "Rated Cycle Conversion Efficiency" input on the Power Block input page is not a percentage of a theoretical maximum efficiency, it is the power block's heat-to-electricity conversion efficiency under design conditions, and depends on the power block inlet and outlet temperatures.

There is obviously room for improvement on both of these questions, but for now we do not have funding for improvements to the geothermal model.

Best regards,

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