How do we adapt the electrical output of a fossil powerplant according to the demand on the grid ?
In: Engineering
The power plant have a lot of rotating mass in its turbines and generators which are synchronized to the frequency of the grid through the electromagnets in the generator. When you use more power you will change the magnetic fields in the generator slowing it down. But because there is so much rotating mass this takes time. Meanwhile grid operators will see that the frequency of the power grid is going down and is able to change valves to allow more steam into the turbines to increase their speed. This can be done anywhere in the power grid as long as the transfer cables is able to keep up. When this is done the steam pressure will drop and the steam temperature drops so the power plant operators will need to add more fuel to generate more heat to keep the temperature in the steam up.
One of the issues with replacing fossil fuel power plants is that they have a lot of energy stored up in rotating mass and in the temperature of the water and steam which can be released very fast or stored up very fast as needed. Sometimes even without human or computer control. That is the basis for a very stable power grid where you only need regular shipments of fuel as everything can be throttled as you want. With solar and wind power there is no way to store up the energy and release it to the grid as needed. The only other current options are hydro, nuclear and geothermal but they can not be built everywhere as there are geographical and regulatory issues. So we need to either build more transmission lines so the power can be sent elsewhere when not needed and sent back when it is needed or we need to build storage facilities like batteries and pumped hydro.
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