POWER COSTS FOR WIND AND WATER TURBINES

Wind Turbine Costs

Because there is no potential for wind turbines in the southeastern states, the only reason for comparing well-placed wind-turbine systems to well-placed Gulf Stream Turbines is to see how their profits would compare.  The figures reveal that the Gulf Stream Turbines would produce substantially better returns than investments in wind turbines.   

 Although the prices for wind systems can vary with tower heights, rotor diameters and local specifications, the average price for large, modern wind farms is about $1,000 per kilowatt of the rated power installed.  As of February 1998, a typical 600 kW wind system would cost between $400,000 and $650,000.  Installation costs include foundations (normally made of armed concrete), road construction to move the turbines and the sections of the tower to the building site, a transformer (necessary to convert the low voltage current from the turbines to 10,000 to 30,000 volt for the electrical grid), telephone connections for remote control and surveillance of the turbine, and costs for the cable that will transmit the power to the local power line.  Obviously, all these costs depend on the terrain and the distances involved.  Remote wind sites result in additional transmission lines, which can cost as much as $300,000 to $1 million per mile.  The economics of transmission for these systems is usually poor because, although the line must be sized for the peak output, wind power’s low capacity factor ensures serious underutilization.

Gulf Stream Turbine Costs

           Depending on the design and the materials used in their construction, the individual Gulf Stream generating units could have costs that could range from $200 to $400 per kW of generating capacity.  That figure does not include the costs of the waterproof transmission cables, miles of anchor lines, monitoring equipment, transformers and the facilities ashore.  These costs would depend on the number of units grouped in the “water farms” and the distances involved.  When all the costs are added up, the total cost for a system would probably range between $800 and $1,600 per kilowatt of generating capacity.  Although these costs per kilowatt of generating capacity are comparable to those for the wind farms, because the “water farms” would have much higher capacity factors and could be used to carry the base load, they would be the better choice – not only because they would produce more power, but because that power would be consistent and predictable. 

Comparing Well-Placed Wind Turbines to Well-Paced Water Turbines

 The cost per kilowatt hour for the following graph were calculated based on the cost per kilowatt of generating capacity being adjusted for the capacity factors.  The capacity factors (CF), the costs per kilowatt of rated capacity and the operational efficiencies are indicated in the schedule on the right. All the costs per kilowatt of generating capacity are amortized over a 20-year period at an interest rate of 7.5%.  These cost comparisons are based on those capacity factors that can be expected for turbines placed in the Gulf Stream’s central axis where the current is both swift and steady.


 

 

            The following tables show the costs per kilowatt-hour for Gulf Stream water turbines with capacity factors of 70%, 80% and 90% with capital costs per kilowatt of rated capacity of $1,000.  The tables are based on financing over 12 and 20 years and a capital return at the percentages listed.

 

                   Cost per kWh for Gulf Stream Turbines Based on Cost of $1,000

                                               per kW of Rated Capacity         

                                                                  Spread over 12 years        

                              capacity

                                 factor             0.0%           7.5%          9.0%          10.0%         12.0%         

                                  90%             .0106           .0201         .0220          .0233          .0258

                                  80%             .0119           .0226         .0247          .0262          .0290

                                  70%             .0136           .0258         .0283          .0299          .0332

                               

                                                                    Spread over 20 years        

                              capacity

                                 factor             0.0%           7.5%          9.0%          10.0%         12.0%

                                  90%             .0063           .0159         .0176          .0190          .0216

                                  80%             .0071           .0178         .0200          .0214          .0243

                                  70%             .0082           .0204         .0228          .0245          .0277

 

           The following tables shows the costs per kilowatt-hour for wind turbines with capacity factors of 23%, 25%, 27% and 30% with capital costs per kilowatt of rated capacity of $1,000.  These tables are also based on spreading the costs over 12 and 20 years and a capital return of the percentages listed. 

 

                          Cost per kWh for Wind Turbines Based on Cost of $1,000

                                                  per kW of Rated Capacity      

                                                           

                                                               Spread over 12 years        

                                 capacity

                                   factor             0.0%           7.5%          9.0%          10.0%         12.0%

                                    30%             .0317           .0602         .0660         .0698           .0774

                                    27%             .0352           .0669         .0734         .0775           .0860

                                    25%             .0380           .0723         .0791         .0837           .0928                  

                                    23%             .0414           .0786         .0860         .0910           .1009  

 

                                                                        Spread over 20 years        

                                 capacity

                                   factor             0.0%           7.5%          9.0%          10.0%         12.0%

                                    30%             .0190           .0476         .0533         .0571           .0647

                                    27%             .0211           .0528         .0592         .0634           .0719

                                    25%             .0228           .0570         .0639         .0685           .0776

                                    23%             .0248           .0620         .0695         .0745           .0844

 

Gulf Stream Turbines Would Require Lower Standby Operating Reserves

            To cover surges in the demand for electricity, base load generators today are backed by both “spinning” and “non-spinning” operating reserves, provided mostly by gas-fired peaker plants.  Typically, one-half of system’s operating reserves are spinning, so that a sudden loss of generation will not result in a loss of load, with the balance of the operating reserve available to go on line within ten minutes.  Wind generated power is unpredictable.  Any probable load or generation variations that cannot be forecast must be considered when determining the amount of operating reserve to carry.  At present wind plant penetration levels in California, the variability of wind plant output has not required any change in operating reserves requirements.  The exact point at which the integration of intermittent generation begins to degrade system economics is unclear, but the technical literature suggests that it is at penetration levels in excess of 5 percent.  Intermittency is becoming an increasing concern to utility operators in California, particularly during low demand periods, since wind plant penetration is beginning to reach this level.  Because the Gulf Stream turbines will produce a much steadier and more predictable supply of power, their use should nearly eliminate the need for any operating reserve to cover those power fluctuations caused by sudden changes in the velocity of the flowing water.  

 

 

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