Why is nuclear power baseload?
July 1st, 2007 by William Nuttall, University of CambridgeIf there is nuclear power in the generation mix, whether in liberalised electricity markets or in vertically integrated monopoly electricity systems, one tends to always find it playing a baseload role. The only examples where nuclear power output is adjusted to follow changes in demand are in those countries, such as France, where nuclear power is the technology used for the vast majority of electricity production and there is insufficient other scope for flexibility.
In its 2006 Energy Review, the UK government noted: “[Nuclear power] has the disadvantage that it cannot easily follow the peaks and troughs in energy demand”. This statement implies; that nuclear power is used as a baseload source of electricity production simply for technical engineering reasons. In recent months my former student Laurent Pouret and I have been considering to what extent technical factors force nuclear power to be used as a baseload technology. We note that for the UK the first and second generation (graphite-moderated and gas cooled) reactor types were either never designed or never licensed for load following operations. As such those technologies do indeed have engineering and regulatory obstacles blocking any role beyond baseload operation.
One purpose of the 2006 UK Energy Review, and the subsequent 2007 Energy and Planning White Papers, has be to renew UK debate concerning the possibility of new nuclear power plants. For new designs it is for the most part not the case that they “cannot easily follow the peaks and troughs and energy demand”. In that context there is the possibility of UK policy being developed based upon flawed information. Britain’s modern nuclear power plant Sizewell B in Suffolk was built in the 1990s. It, and any new build nuclear power plants, will be capable of flexible operations and perhaps even load following. I accept that in the future nuclear generation will continue to be operated as baseload power, but I question the assumption that this is for simply technical reasons.
In our recent working paper , we consider factors affecting choices for next generation nuclear power-plants and we conclude that they will indeed continue to operated as baseload generators. The reason for this will not be technical, rather it will be economic. The extremely low marginal costs of operation of a nuclear power plant conventionally favour maximal operations at all times. Our paper discusses the technical aspects mentioned above in greater depth than is possible here, and it also explains the relationship between nuclear power plant operations and the economics of electricity systems.
We would welcome comments from all readers of www.energypolicyblog.com on the role of nuclear power in both liberalised electricity markets and its place in the merit orders of vertically integrated monopoly systems. It seems likely that in the decades to come nuclear power will be deployed in ever more flexible modes and our work aims at broadening understanding of the issues involved and seeks to challenge some common misconceptions.
July 2nd, 2007 at 10:12 am
In the UK the inability of nuclear generators to power down led to the introduction of night storage heaters with low tarriffs for off-peak consumption, currently known as Economy 7 and pumped storage schemes. In any case, to offset the high capital cost, maximum use and longevity of operation are essential, so a decrease in load factor by variable operation would worsen the poor economics of nuclear power. It would also reduce the revenue gained from the carbon credits needed from levies on fossil fuelled generators that nuclear power needs to make its case (as set out in the UK Energy White Paper).
Wind power would benefit from pumped storage, whereby water is raised when the wind blows to provide power when it does not, in the same way as it compensates for the inability of nuclear power to turn down at night.
The worsening uranium supply situation will in any case cause the nuclear “renaissance” to stall, so all things considered the flexibility of output from its decreasing contribution is a minor issue.
June 19th, 2008 at 10:03 am
On June 8th 2008 Anne Lauvergeon, chief executive of Areva, declared to the Financial Times that the UK was « the most exciting place in Europe » for nuclear. The British government’s recent decision to develop nuclear energy has without doubt something to do with it. Therefore, the question of the possibility of a new nuclear program in Great Britain is (at least partly) solved.
Yet the question of the necessity of nuclear plants to provide base-load power remains unanswered. It is generally admitted that base-load power can only be provided by nuclear or coal-fired power stations. They are characterized by high capital costs, low operating costs and the technical impossibility for them to handle chaotic fluctuations of energy demand. Even though technological advance has made next-generation nuclear power plants more flexible to the energy demand, it would be an economic aberration not to use them to full capacity all the time.
Besides, one cannot leave aside the possibility that renewable energy could also provide base-load power. In an article called The Base-Load Fallacy, Mark Diesendorf gives several examples of renewable electricity sources that can generate base-load power: bioenergy, based on the combustion of crop residues (not very different from coal), hot rock geothermal power, solar thermal electricity combined with electricity storage systems (in water or through a thermochemical process)… Even wind power can be base-load if a large number of wind turbines are separated by several hundred kilometers and subject to different winds.
April 23rd, 2009 at 5:42 am
Electrical power generation is an interesting subject to me. The technical aspects appeal to me and I even worked for a time as a power plant operator for the military. I don’t normally follow the topic closely, but I recently reaquanted myself with the subject for a report for a college paper.
I’ve read “The Base-Load Fallacy” a few times. It gives general answers that would be difficult to evaluate quantitatively from the article, alone, so it is difficult for a reader to determine whether the author’s claims are reasonable or mere wishful thinking. I am skeptical that bioenergy will ever provide more than a small percentage of electric power generation, for several reasons, including the amount of extra energy required to produce, harvest and process the biomass compared to the amount of energy it provides. Coal has much greater energy content per unit mass than biomass does. Hot rock geothermal power looks great, where one can get to it economically. In many locations, the installation would not be economically feasible, even if technically possible. Solar thermal electricity could provide cold regions with heat, but most of the people in my country are moving to warmer regions, where cooling is a bigger concern. Water storage systems for electrical power aren’t practical in my region of residence, due to the general lack of water and relatively flat elevation. Thermochemical storage is experimental and not yet practical. Wind power in my region of residence (an area of millions of square kilometers) is generally available only during off-peak times. Although it might be possible technically to produce a stable base load from wind power by increasing the geographic distribution, this also increases the area of electric demand, and demand usually increases at a greater rate than supply over the region the expansion would require to achieve base load stability. Wind power has the capacity in my region to provide 5 times the energy we require, but it would be mostly at 5 a.m.
March 5th, 2010 at 12:31 pm
True, nuclear power stations do not modulate well. However, if domestic heating systems had more energy storage capacity this perhaps be a solution. A house’s requirements fluctuate greatly, and this is a great limitation of nuclear and some renewables too.