First off, you're going to want to be getting away from coal by and by, for both availability reasons (turns out Peak Coal may well hit us sooner than expected) and for greenhouse gas (CO2) emissions. An alternative would be to have biomass plants available for weak-supply periods, and some solar plants (the solar thermal plant in Spain for example) use this method.
Second, solid-fuel plants don't ramp quickly. If you're keeping them in standby, you're burning a lot of fuel just to keep your boilers hot. Most peaking plants today are either hydroelectric (which can literally spin up in seconds) or natural gas (not quite as quick, but still capable of demand-matching in a few minutes). Natural gas is also subject to depletion and CO2 concerns.
For base-load power, nuclear and geothermal would be good options. Geothermal also doesn't ramp particularly quickly in most cases, though it's very reliable. Enhanced geothermal (ground holes dug into which water is injected) has proven to be much more expensive and accident prone, and less productive, than hoped.
Second, solid-fuel plants don't ramp quickly. If you're keeping them in standby, you're burning a lot of fuel just to keep your boilers hot. Most peaking plants today are either hydroelectric (which can literally spin up in seconds) or natural gas (not quite as quick, but still capable of demand-matching in a few minutes). Natural gas is also subject to depletion and CO2 concerns.
For base-load power, nuclear and geothermal would be good options. Geothermal also doesn't ramp particularly quickly in most cases, though it's very reliable. Enhanced geothermal (ground holes dug into which water is injected) has proven to be much more expensive and accident prone, and less productive, than hoped.