Originally Posted by roadkill

Modern generation plants are more efficient than older ones (I recall seeing reports that each time China commissions a new coal-fired plant, it decommissions a smaller, old, far less efficient one.)

Modern coal-firing and also gas-burning power plants are more efficient than older ones primarily because they are operated at a higher temperature.

This is also, why nuclear power plants are so inefficient (efficiency roughly 33% as compared to 50% that you get with power plants burning fossil fuels). Nuclear power plants are operated at a much lower temperature to extend the life time of the burning chamber. In a power plant that burns fossil fuel you can simply exchange the burning chamber after 10-20 years. In a nuclear power plant you cannot because of radiation. Hence nuclear power plants are operated at much lower temperatures to extend the life time of the burning chamber (and thereby the entire nuclear power plant) to about 40-50 years.

There are three types of losses in power generation: generation losses, transmission losses, and storage losses. All three have physical reasons and are unavoidable.

Generation losses are the losses that I referred to in my previous message. They are the losses incurred in converting primary energy to secondary energy, e.g. fossil fuels to electricity.

Transmission losses are the losses that we incur in transporting the energy from the power plant to the end user. In the case of electricity, these are Ohmic losses along the power line. They are reduced by transporting the electricity at a higher voltage. The transported power is P=U*I (power = voltage times current). Yet the loss is PL = R*I^2 (lost power is proportional to the square of the current). Thus in order to reduce the Ohmic losses, we increase the voltage, and thereby transport the same power with much less current.

Storage losses are losses that we incur in storing the energy for later use. For example here in Switzerland, we pump water uphill into a reservoir in the mountains during times when we have surplus electricity, to let it flow down again into the turbines during times when we don't have enough. Running the pumps consumes roughly 30% of the electricity that we regain later.