The implicatations of dispatchable versus intermittent electricity generation

System Costs

To make any sense of the matter, we need to compare total system costs and not individual costs of different generators. The ultimate metric is the cost of electricity to consumers, which includes more costs than just the stand-alone cost of a generator. This means taking into account all the costs of delivering electricity to the consumer.

Electricity utilities with a high proportion of dispatchable generators are typically configured as high-density, continuous, centralized facilities, requiring transmission only to supply on demand and taking up minimal area for their output. On the other hand electricity utilities with a significant proportion of 'renewable' generators are characterized by low-density intermittent and decentralized facilities, requiring expensive ancillary facilities, including land and transmission. This comparison alone is enough to show that 'renewables are not a cheap form of energy'. Coal is, and nuclear next, as high-density continuous, centralized facilities. If 'renewables' were so good, subsidies would not be needed to encourage their construction. It is also noteworthy that France, with some 62% of its power from nuclear does not have the highest consumer electricity price in the EU.

Output from dispatchable generators is essentially constant in regard to voltage and frequency. In the case of intermittents, when they happen to be operating at the pleasure of the weather, their output is forever varying. In the case of solar, we have a varying DC output which has to be converted to AC 50Hz for consumption, often with considerable losses in transmission if the panels are located far from consumption. In the case of wind turbines we have ever-changing wind strength varying the speed of rotation of the turbines with consequent change in voltage and frequency output. Again considerable adjustment has to be made to the variable output from these generators for consumption in equipment designed for 50 Hz and 240 V for domestic supply. The cost of the equipment needed to convert the varying electricity output to fit the consumer is hidden from the general public and it is substantial.

Conclusions

Society wants reliable, affordable and now carbon-free electricity on demand, 24/7 and with minimal environmental degradation.

Although solar and wind are cheap to operate, per se, their total costs are not cheap and they are not fit for purpose alone. World experience to date confirms this. Electricity utilities employing 'renewables' must have a component of dispatchable generation in the mix. Gas is a compromise dispatchable. It still emits carbon dioxide, but less so than coal-fired power for the same amount of electricity. The only carbon-free dispatchable electricity generating source generally available at the present state of technology is nuclear fission.