Preliminary cost assessments. Estimates are typically performed in stages of increasing accuracy, aligning with progressive analyses of cogeneration feasibility. "Rules of thumb" and broad assessments of capital costs per kilo-watt of generating capacity may provide early indicators of capital investment costs and pay-back periods.

Order-of-magnitude estimates. "Order-of-magnitude" capital cost estimates allow early evaluation of cogeneration schemes without the expense of detailed cost estimating procedures. Apex Cogen prepares these estimates from its databank of major equipment costs, applying historic factors for accessories, plant tie-ins, electrical inter-connects, civil works, and development expenses. Broad adjustments can be made for unusual site conditions, economic factors, or international locations. Operating and maintenance ("O&M") costs are based on typical costs per kilo-watt-hour for the major equipment selected.

If Apex Cogen provides Project Management services for the installation, review and management of contractor's costs are normally included in the services provided.

Budget estimates. "Budget" capital cost estimates provide more accuracy by including budget quotations for major equipment from vendors. The vendor quotations may be based on preliminary cycle designs by Apex Cogen. Allowances for specific known site conditions such as controls interfaces with existing plant, high voltage electrical transmission tie-ins, substations, and relaying, fuel compression, water treatment upgrading, site building modifications, etc., may be accounted for at this stage. A basic operating and maintenance scheme may be assumed at this juncture so that preliminary staffing can be forecast along with projections for major and minor overhaul and maintenance costs for major equipment.

Once the basic cogeneration scheme has been established, and major equipment selected, budget estimates can be "firmed up" on the basis of additional engineering design to provide cost forecasts sufficient for project financing and controlling the design and construction process. O&M costs can also be firmed with more definitive data for major equipment overhaul costs and maintenance intervals.

Detailed estimates and operating budgets. "Detailed" capital cost estimates are typically prepared after financial closing. They are initiated with the detailed design process upon finalizing plant layout, heat balances, placing major equipment orders, and fixing the plot plan. Detailed capital cost estimates involve "quantification" of allowances previously made in the budgetary process, and may be performed by Apex Cogen or an EPC contractor, depending on the project execution mode. If Apex Cogen provides Project Management services for the installation, review and management of contractor's costs are normally included in the services provided.

Operating budgets can be finalized from preliminary O&M agreements and terms of reference for interfacing with existing plant operations.