For biomass power systems, SAM reports the heat rate and thermal efficiency values from the system's annual energy value calculated by the performance model, and the biomass feed rate and overall feedstock heating values from the Feedstock page.

Gross Heat Rate, MMBtu/MWh

Gross Heat Rate (MMBtu/MWh) = Dry Biomass Feed Rate (lb/year) × Average Overall Feedstock HHV (MMBtu/lb) ÷ Net Annual Energy (MWh/year)

Net Heat Rate, MMBtu/MWh

Net Heat Rate (MMBtu/MWh) = Dry Biomass Feed Rate (lb/year) × Average Overall Feedstock LLV (MMBtu/lb) ÷ Net Annual Energy (MWh/year)

The dry biomass feed rate is the annual feed rate from the Feedstock page (and also shown as Annual Biomass Usage in the Metrics table) converted from ton/year to lb/year (2000 lb = 1 ton), the average overall feedstock heating values are from the Feedstock page, converted from Btu/lb to MMBtu/lb (1,000,000 Btu = 1 MMBtu), Net Annual Energy is from the Metrics table.

Thermal Efficiency HHV, %

Thermal Efficiency HHV (%) = 341.23 (MMBtu/MWh) ÷ Gross Heat Rate (MMBtu/MWh)

Thermal Efficiency LHV, %

Thermal Efficiency LHV (%) = 341.23 (MMBtu/MWh) ÷ Net Heat Rate (MMBtu/MWh)

Where 341.23 MMBtu/MWh is the conversion factor between MMBtu and MWh units, and the heat rates are the values described above.