Steam power generation requires boilers, turbines, condensers and generators, which are often integrated into a steam generation “island” at coal, nuclear and CCGT power plants. Steam generation capex costs are estimated at $1,300/kW in this data-file, based on sampling component costs across 35 past projects.
Steam power generation involves an array of boilers, turbines, condensers, generators, cooling towers, piping, instrumentation and controls, which all tend to be integrated together in a coal-fired power plant, a nuclear power plant, or downstream of a gas turbine at a CCGT power plant.
Specifically, in the Rankine cycle, cold water is heated in a boiler to produce high-pressure steam. The high-pressure steam then drives a turbine – or an array of turbines – as it expands. Downstream of the turbines, a vacuum is created by condensing the steam back into water, which also helps to pull steam across the turbine. Finally, turbines drive generators, which turn the rotational energy into electricity.
Hence this data-file estimates steam generation capex costs, by taking a sample of reported costs at past projects, then estimating the percentage of those costs that can be ascribed to the boilers, turbines, condensers and generators.
Economies of scale are visible across all of these components. Each 10x scale-up is generally associated with 20-40% lower unit costs. This is why the industry has generally shifted towards constructing facilities with large power plant capacities. It may also raise questions over the aspiration to deflate nuclear costs via small modular reactors.
When estimating the total capex costs of power plants, additional components must also be added. For coal plants, there is the handling of the coal, and the treating of exhaust gases via desulfurization, SCR of NOXs and electrostatic precipitation of particulates. In a nuclear plant, of course, there is the entire nuclear island.
The data-file nevertheless helps to quantify the costs of other steam plant components, which can be used to stress-test steam generation capex costs, elsewhere in the power industry.