One reason the IEA gives for its assessment is that "global energy is increasingly based around electricity", and carbon-free sources contribute around 36% of the electricity supply — about the same as it did 20 years ago.
While renewables have grown, the proportion of output that comes from nuclear plants has declined, with nuclear output remaining more or less unchanged since 2005, at around 2,500TWh a year.
The IEA argues that nuclear plants contribute to electricity security by keeping power grids stable, and they can undertake a certain degree of load-following to compensate for variations in output from wind and solar plant.
The big problem is the high cost of nuclear power.
The IEA tracks the capital cost of plant from 2005, when it was around $2,000/kW, to the present day, when the latest estimates suggest it is in the $7000-8000/kW range.
(As this is an IEA report, the analysis focuses on experience in the US and western Europe.)
One of the problems that has bedevilled nuclear programmes has been the lack of opportunities for series production of power stations, which would be likely to cut costs.
The IEA considers there may be better prospects for the small modular reactors, where research is under way in various places.
The IEA suggests that a way forward to maintain the output from nuclear plants is to undertake refurbishments that will enable them to operate for extended periods and quotes refurbishment costs in the $500-1,100/kW range.
Advantages to this approach include modest costs for construction consents and the fact that a considerable amount of the power station infrastructure can continue to be used.
The IEA suggests that the costs of energy from such facilities, with an 8% weighted average cost of capital, is likely to range from around $40/MWh — with a $500/kW cost of refurbishment and a 20-year life extension — to $55/MWh — with the overhaul at $1,100/kW for a ten-year life extension.
These costs compare favourably with every other generation source, as shown in the chart below, although some recent wind-energy contracts have come in at lower levels.
The IEA then goes on to argue that "when the full value of nuclear power as a dispatchable low-carbon source of electricity is taken into account", the comparison is even more favourable.
The agency makes this comparison by factoring in an allowance for the variability cost of solar and wind, which appears to be around $20/MWh.
Wind lifespan reaches 30
In September, this column reported on the implications of longer lifetimes for wind-energy prices. This issue has recently been studied by the Lawrence Berkeley Laboratory in the US.
Based on a survey of wind-industry experts, this found that current lifetime assumptions vary from 25 to 40 years, with 30 years being the most common.
For new wind projects built in 2018, the generation cost is estimated to be $40/MWh with a 20-year lifetime assumption. An extra five years brings the cost down to $36/MWh, and a 30-year lifespan cuts it further to $33/MWh.
The report notes, however, that this may overstate the benefits, as operation and maintenance costs are likely to increase with longer lifetimes.
At a glance — This month’s report conclusions
Nuclear Power in a Clean Energy System, International Energy Agency, May 2019
Shows how nuclear costs have increased but that lower revenues are needed if lifetimes are extended
Benchmarking Anticipated Wind Project Lifetimes: Results from a Survey of US Wind Industry Professionals, Lawrence Berkeley National Laboratory, September 2019
The study found that the most common assumption of wind-project lifetimes is now 30 years and quantified the reduction in cost of energy this implies