Assuming the projected technical improvements are achieved by an active R&D program and deployment of 8.7 Gwe, tower costs approaching 3.5¢/kWh are feasible.
The high temperature capabilities of tower technology has future application potential with gas turbines and combined cycles as well as for the thermo-chemical production of hydrogen and syngas. These advanced applications were not evaluated by Sargent & Lundy
Key Tower Technology Conclusions
Solar plant and power plant scale-up provide the largest cost reduction opportunity for power tower technologies.
Scale-up of the tower solar plant requires a total redesign and re-optimization of the field, tower, and receiver. This greatly reduces capital and O&M costs, but has only a small effect on efficiency. R&D support in the design, development, and testing of larger receivers, larger heliostats, and larger heliostat fields will reduce scale-up risk.
Scale-up of the steam turbine increases efficiency, and reduces capital and O&M costs. Probability of success here is very high, as existing proven technology is available.
Key technical advances include: increasing receiver solar flux levels, development of new heliostat designs with significantly lower costs, and the use of new highly efficient steam turbines.
Increased receiver flux levels have been demonstrated at the prototype scale and require improved heliostat field flux monitoring/management systems and design optimization for use at large plants.
Revolutionary heliostat designs with significantly lower cost have been proposed that use flexible, durable thin mirrors in a lower-weight ‘stretched-membrane’ design appropriate for manufacturing. Other novel designs like inflatable/rolling heliostats are also possible. Cost reductions up to 20% as compared to current designs are possible with these approaches.
Large high efficiency supercritical steam turbines are now being demonstrated that operate at temperatures compatible with current tower technology or at temperatures that require increasing the operating temperature of the tower technology to 600–650°C.
The major volume manufacturing benefit evaluated for tower technology was related to heliostats.
Heliostat cost reduction will occur when they are produced in volume. Sargent & Lundy’s evaluation of the current heliostat design and cost indicated that cost should decrease 3% with each doubling of cumulative capacity. This would reduce the cost of a field of 148 m2 heliostats from $146/m2 to $91/m2.