Appendices - GSA

Biomass initial cost ($)=boiler size * cost per MBH + electric cogen size * kW of
cogen * city cost adjustment factor from RS Means cost estimating manuals
Biomass cogeneration size (kW)=variable determined by optimization
Biomass gas savings (therms/year)=minimum of site gas use and thermal energy
provided by boiler minus that converted to electricity divided by heat recovery
steam generator effectiveness
Biomass electric delivery (kWh/year)=minimum of electric energy generation as
calculated by cogen capacity times capacity factor or as limited by boiler
capacity, boiler efficiency, and boiler capacity factor
Biomass capacity factor=electric delivery divided by cogen capacity and 8760 h/y
Biomass annual utility cost savings ($/year)=minimum of cogen capacity or
demand (kW) credited at retail rate plus any generation in excess of that credited
at avoided cost plus federal production incentive times electric generation plus
gas savings times gas rate
Tons of fuel used=boiler heat delivered for both process heat and cogen divided
by boiler efficiency and divided by heating value of fuel
Radius to collect fuel (miles)=radius calculated from area quotient of fuel required
(tons) and density (tons/square mile)
per ton fuel cost ($/ton)=fixed cost ($/ton) plus trucking cost ($/ton/mile)
Fuel cost ($) =fuel used minus fuel available onsite times fuel cost ($/ton)
State tax credit (%)=variable to be input by user
Federal tax credit (%)=variable to be input by user
Rebate ($)=variable to be input by user
Biomass cost w/incentives ($)=boiler cost above minus any rebates or tax credits
Biomass O&M cost ($/year)=$ per MBH of boiler capacity per year
Biomass payback period (years)=cost with incentives subtracted divided by cost
savings minus O&M costs and minus fuel costs.
NREL’s consultant, Econergy International, has assembled indicative metrics for
energy efficiency, equipment capital costs, and plant operation and maintenance
costs. [ref. 13]. While some of these numbers have come from specific projects
that Econergy has been involved with, others are representative estimates
provided to Econergy by technology providers active in the space. Other costs
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