A base load generator provides power at a more-or-less constant output level to the electricity system outside of temporary shut down for maintenance. In Australia, brown or black coal generation plants provide base load power. Base load generation can be contrasted to flexible generation, typically hydro or gas-fired generation in Australia (although some coal plant capacity can perform this function) which varies in response to the level of demand. Base load generation can also be contrasted against intermittent generation, which is available only when the underlying renewable resource is available (e.g. when the wind is blowing). See also Intermittent Generation.