Why analysts think that renewables simply can't be used for baseload energy

Wind energy's net capacity factor can hit just 25%.

There appears to be a misconception among the general public that renewable energy would be able to supply base load power.

If this were true, there would be no argument about the route Asean would take when determining its energy future. The reason renewables cannot be considered baseload is simple and has almost entirely to do with Net Capacity Factor (NCF) of the generating plant. The NCF of a power plant is the ratio of its actual output over a period of time, to its potential output if it were possible for it to operate at full nameplate capacity continuously over the same period of time.

According to the latest figures from the US-based Electric Power Research Institute (EPRI), wind can only achieve a net capacity factor of roughly 25% and photovoltaic solar is even less at only 20% whereas newer generation nuclear power plants can now achieve a net capacity factor in excess of 92%.

This is simply due to the fact that the output from renewable energy is linked directly with weather conditions. Put simply, the sun does not shine 24 hours a day and the wind does not blow 365 days a year at a particular surface area to generate continuous power. This makes the technology rather unpredictable and is referred to as intermittent power.

Another problem is the fact that storage of renewable energy is hugely expensive and unreliable, and is therefore not yet at a point where it is economically viable. In other words, renewable energy contributes to the grid when it is available, it cannot be stored economically and can therefore not provide base load power.

Another important point to remember is the concept of the dispatchability of power. Dispatchable generation refers to sources of electricity that can be dispatched at the request of power grid operators to meet demand. Because wind and solar are dependent on the weather conditions, the power from these sources is not strictly dispatchable as it is available only when weather conditions are permitting and in the case of solar, only during the day.

As a result, any utility that has an abundance of such sources of energy would need to install standby capacity, in the form of dispatchable power such as gas or diesel generators. Therefore when considering the costs of renewable energy sources, these back-up generators need to be factored into the price.

For instance, Nuclear Industry Association of South Africa made a research that Koeberg Nuclear Power Station is a baseload power station with two 900MW units and a total capacity of 1800MW, with a net capacity factor in excess of 83% over the past 3 years. A wind farm of the same capacity would require 900 2MW units, with a surface area of approximately 112 km², whereas the surface area for Koeberg is 30km² (this includes a 3000 hectare natural reserve that surrounds the reactor) and the capacity factor of the wind farm being merely 25%.

It is now clear to see that among alternative sources for providing baseload power nuclear energy in no way competes with renewable energy sources but rather compliments them. If nuclear is to be compared to anything, it should be compared with other sources of baseload power, such as coal and gas and not renewable energy.