Abstract

Coal-fired power plants are designed to run most efficiently and cost effectively when running at steady
baseload. Renewable energy systems, such as wind and solar, are much more sporadic in their energy
output, varying with weather conditions. The energy from renewable sources is currently prioritised for
input into the grid in many countries, meaning that thermal plants such as those powered by coal or nuclear
sources must now provide more flexible output to keep the available energy in the network at the required
level. This ramping and cycling of coal plants puts a strain on the boiler and increases the risk of operation
and maintenance problems. This report evaluates the different cost penalties of increasing the flexibility of
coal-fired plants to cope with the intermittency of renewable power source, indicating that cycling
operation can be expensive and, in some situations, costs can increase by orders of magnitude.