Dispelling the nuclear ‘baseload’ myth: nothing renewables can’t do better!

This wind farm in Mecklenburg-Vorpommern allows the entire state to run on 100% renewable energy. Photo: Clemens v. Vogelsang via Flickr (CC BY).


The main claim used to justify nuclear is that it’s the only low carbon power source that can supply ‘reliable, base load electricity. But not only can renewables supply baseload power, they can do something far more valuable: supply power flexibly according to demand. That makes nuclear power really redundant.

“In the words of former Green Senator Christine Milne, ‘We are now in the midst of a fight between the past and the future.’ The refutation of the baseload fairy tale and other myths falsely denigrating renewable energy are a key part of that struggle.”

This wind farm in Mecklenburg-Vorpommern allows the entire state to run on 100% renewable energy. Photo: Clemens v. Vogelsang via Flickr (CC BY).
This wind farm in Mecklenburg-Vorpommern allows the entire state to run on 100% renewable energy. Photo: Clemens v. Vogelsang via Flickr (CC BY).

We have all heard the claim. We need nuclear power because, along with big hydropower, it’s the only low carbon generation technology that can supply ‘reliable baseload power’ on a large scale.

For example, the UK Energy Secretary Amber Rudd, attempted to justify the decision to build the proposed Hinkley Point C nuclear power station on the grounds that we have to secure baseload electricity.”

Similarly, former Australian Industry Minister Ian Macfarlane recently claimed at a uranium industry conference: Baseload, zero emission, the only way it can be produced is by hydro and nuclear.”

Underlying this claim are three key assumptions. First, that baseload power is actually a good and necessary thing. In fact, what it really means is too much power when you don’t want it, and not enough when you do. What we need is flexible power (and flexible demand too) so that supply and demand can be matched instant by instant.

The second assumption is that nuclear power is a reliable baseload supplier. In fact it’s no such thing. All nuclear power stations are subject to tripping out for safety reasons or technical faults. That means that a 3.2GW nuclear power station has to be matched by 3.2GW of expensive ‘spinning reserve’ that can be called in at a moments notice.

The third is that the only way to supply baseload power is from baseload power stations, such as nuclear, coal and gas, designed to run flat-out all the time whether their power is actually needed or not. That’s wrong too.

Practical experience and computer simulations show it can be done

But first, take a look at Figure 1, which shows the daily variation of electricity demand in summer in a conventional large-scale electricity grid without much solar energy. Baseload demand is the pale blue region across the bottom of the graph.

Figure 1
Figure 1: Daily electricity demand and supply in a conventional large-scale system with little renewable energy.

‘Baseload power stations’ are inflexible in operation, in the sense that they are unsuitable for following the variations in demand and supply on timescales of minutes and hours, so they have to be supplemented with flexible peak-load and slightly flexible intermediate-load power stations.

Peak-load power stations are hydro-electric systems with dams and open-cycle gas turbines (OCGTs), essentially jet engines set up for power generation rather than aircraft propulsion. They can respond to variations in demand and supply on timescales of minutes.

The assumption that baseload power stations are necessary to provide a reliable supply of grid electricity has been disproven by both practical experience in electricity grids with high contributions from renewable energy, and by hourly computer simulations.

In 2014 the state of South Australia had 39% of annual electricity consumption from renewable energy (33% wind + 6% solar) and, as a result, the state’s base-load coal-fired power stations are being shut down as redundant. For several periods the whole state system has operated reliably on a combination of renewables and gas with only small imports from the neighbouring state of Victoria.

The north German states of Mecklenburg-Vorpommern and Schleswig-Holstein are already operating on 100% net renewable energy, mostly wind. The ‘net’ indicates trading with each other and their neighbours. They do not rely on baseload power stations.

A host of studies agree: baseload power stations are not needed

“That’s cheating”, nuclear proponents may reply. “They are relying on power imported by transmission lines from baseload power stations elsewhere.” Well, actually the imports from baseload power stations are small.

For countries that are completely isolated (e.g. Australia) or almost isolated (e.g. the USA) from their neighbours, hourly computer simulations of the operation of the electricity supply-demand system, based on commercially available renewable energy sources scaled up to 80-100% annual contributions, confirm the practical experience.

In the USA a major computer simulation by a large team of scientists and engineers found that 80-90% renewable electricity is technically feasible and reliable (They didn’t examine 100%.) The 2012 report, Renewable Electricity Futures Study. Vol.1. Technical report TP-6A20-A52409-1 was published by the US National Renewable Energy Laboratory (NREL). The simulation balances supply and demand each hour.

The report finds that “renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the United States.”

Similar results have been obtained from hourly simulation modeling of the Australian National Electricity Market with 100% renewable energy (published by Ben Elliston, Iain MacGill and I in 2013 and 2014) based on commercially available technologies and real data on electricity demand, wind and solar energy. There are no baseload power stations in the Australian model and only a relatively small amount of storage. Recent simulations, which have yet to be published, span eight years of hourly data.

These, together with studies from Europe, find that baseload power stations are unnecessary to meet standard reliability criteria for the whole supply-demand system, such as loss-of-load probability or annual energy shortfall.

Furthermore, they find that reliability can be maintained even when variable renewable energy sources, wind and solar PV, provide major contributions to annual electricity generation, up to 70% in Australia. How is this possible?

Fluctuations balanced by flexible power stations

First, the fluctuations in variable wind and solar PV are balanced by flexible renewable energy sources that are dispatchable, i.e. can supply power on demand. These are hydro with dams, Open Cycle Gas Turbines (OCGTs) and concentrated solar thermal power (CST) with thermal storage, as illustrated in Figure 2. It ‘s not essential for every power station in the system to be dispatchable.

Figure 2
Figure 2: Electricity demand and supply in a large-scale system with a large contribution of variable renewable energy.

Incidentally the gas turbines can themselves be fuelled by ‘green gas’, for example from composting municipal and agricultural wastes, or produced from surpluses of renewable electricity. More on this below …

Second, drawing on diverse renewable energy sources, with different statistical properties, provides reliability. This means relying on multiple technologies and spreading out wind and solar PV farms geographically to reduce fluctuations in their total output. This further reduces the already small contribution from gas turbines to just a few percent of annual electricity generation.

Third, new transmission lines may be needed to achieve wide geographic distribution of renewable energy sources, and to multiply the diversity of renewable energy sources feeding into the grid. For example, an important proposed link is between the high wind regions in north Germany and the low wind, limited solar regions in south Germany. Texas, with its huge wind resource, needs greater connectivity with its neighbouring US states.

Fourth, introducing ‘smart demand management’ to shave the peaks in electricity demand and to manage periods of low electricity supply, can further increase reliability. This can be assisted with smart meters and switches controlled by both electricity suppliers and consumers, and programmed by consumers to switch off certain circuits (e.g. air conditioning, water heating, aluminium smelting) for short periods when demand on the grid is high and/or supply is low.

As summarized by the NREL study: RE (Renewable Energy) Futures finds that increased electricity system flexibility, needed to enable electricity supply-demand balance with high levels of renewable generation, can come from a portfolio of supply- and demand-side options, including flexible conventional generation, grid storage, new transmission, more responsive loads, and changes in power system operations.”

recent study by Mark Jacobson and colleagues went well beyond the above studies. It showed that all energy use in the USA, including transport and heat, could be supplied by renewable electricity. The computer simulation used synthetic data on electricity demand, wind and sunshine taken every 30 seconds over a period of six years.

Storage or ‘windgas’ could also manage fluctuations

The above ‘flexible’ approach may not be economically optimal for the UK and other countries with excellent wind resource but limited solar resource. Another solution to managing fluctuations in wind and solar is more storage, e.g. as batteries or pumped hydro or compressed air.

A further alternative is the ‘windgas’ scenario recently advocated by Energy Brainpool as a greener and lower cost alternative to the UK’s Hinkley C nuclear project. The idea is to use excess wind energy to produce hydrogen gas by electrolysing water and then convert the hydrogen to methane that fuels combined cycle gas turbine (CCGT) power stations.

In fact, not all the hydrogen needs to be converted into methane, and it’s more efficient to keep some of it as hydrogen, a useful fuel in its own right. Another option is to use the hydrogen to make ammonia (NH3) which can both be used as a fuel, and as a feedstock for the fertiliser industry, displacing coal or natural gas.

In Brainpool’s scenario, the system is used to replicate the power output of the 3.2GW Hinkley C nuclear power station, and shows it can be done at a lower cost. But in fact, it gets much better than that:

  • as each wind turbine, CCGT, gas storage unit and ‘power to gas’ facility is completed, its contribution begins immediately, with no need for the whole system to be built out;
  • the system would in practice be used to provide, not baseload power, but flexible power to meet actual demand, and so would be much more valuable;
  • as solar power gets cheaper, it will integrate with the system and further increase resilience and reduce cost;
  • the whole system creates grid stability and cannot drop out all at once like a nuclear plant, producing negative ‘integration costs’.

But in all the flexible, renewables-based approaches set out above, conventional baseload power stations are unnecessary. In the words of former Australian Greens’ Senator Christine Milne: “We are now in the midst of a fight between the past and the future”.

The refutation of the baseload fairy tale and other myths falsely denigrating renewable energy are a key part of that struggle.

This article was first published in Ecologist. Reproduced with permission.


14 responses to “Dispelling the nuclear ‘baseload’ myth: nothing renewables can’t do better!”

  1. Dean Laslett Avatar
    Dean Laslett

    A more direct link for the NREL renewable electricity futures study is:

  2. onesecond Avatar

    For the money the UK government wants to spend on nuclear, they could get something so much better in every way. Even PV with battery storage in England would be cheaper, with no nuclear waste, risk of blowing up and better capabilites such as flexibility and resilience due to the modular build. Really mindblowing that anyone would push for Hinkley C.

    1. Coley Avatar

      Jobs for the boys, as always.

  3. Jim A Avatar
    Jim A

    Too bad nature doesn’t support the same “flexibility” consumers need. The wind doesn’t blow, or it’s cloudy and output goes to zero and you have no backup. Australia has a lot of sun and has low population density. Even the slanted studies still require 20% baseload (which BTW is qual to the US nuclear power percentage). BTW, if you look at the entire solar life cycle, you will see that technology causes some serious environmental damage due to the manufacturing and waste polution.

    1. Calamity_Jean Avatar

      Regarding your first point, it appears that when you read the article, you missed this paragraph:

      “Second, drawing on diverse renewable energy sources, with different statistical properties, provides reliability. This means relying on multiple technologies and spreading out wind and solar PV farms geographically to reduce fluctuations in their total output. This further reduces the already small contribution from gas turbines to just a few percent of annual electricity generation.”

      (Emphasis added.) The gas turbines mentioned are the backup you say the system doesn’t have.

      Regarding your second point, can you provide links to discussions of this manufacturing and waste pollution?

    2. Barri Mundee Avatar
      Barri Mundee

      Jim why not give some evidence to back up your claim that solar PC causes “serious” environmental damage. And also, in the interests of impartiality, as you so obviously are, give us similar evidence regarding the environmental damage caused by fossil fuels

      That would boost your credibility as being more than just a propagandist for the fossil fuel industry.

  4. Mike Ives Avatar
    Mike Ives

    Professor Diesendorf. I am sure you would agree that it would be a most beneficial project for Australian’s, and the world in general if we could transpose one of your theoretical renewable modelling results into a ‘real world’ project. The real world Mecklenburg-Vorpommern (MV) press release referred to in the article seems very sketchy with little data. Unfortunately I was unable to access your South Australian 39% reference for some reason.

    Tasmania and its inhabitants, I feel would be grateful candidates for the opportunity to experience 100% renewable electricity 24/7/52. With the renewable ratios suggested in your 2014 article ‘Renewable energy ready to supply all of Australia’s electricity’ we would offset our extreme reliance on a dwindling hydro resource, even if some fossil OCGT was needed and with or without base load units. This would be very pertinent especially right now as the prospects of power cuts here may be just over the horizon. If realised it would also provide comfort to those in Australia who dispel the prospects of nuclear fission energy with a passion and it may even rule the nuclear option for Australia out once and for all.

    Our population density is considerably less than that of MV and we should be able to match MV’s claim easily with our wind and solar resources and test how reliable it is at first hand.

    Can we somehow impress on one or both of the major political parties to make 100% renewable Tasmania a pledge in this election year do you think? It would set a precedence for the rest of Australia while providing Tasmania with the much sought after alternative energy generation know-how and of course the jobs that go with it.

  5. Ken Fabian Avatar
    Ken Fabian

    It isn’t a case of nuclear actually being a real alternative in Australia – stopping renewables will only see the transition to low emissions stalled and fossil fuel dependence entrenched for decades more. No-one who matters really wants it, not the big power companies, not the public and least of all the LNP/Conservative Right that find it politically useful to criticise ‘green politics’ for not embracing it whilst having no real commitment to it themselves.

    I think anti-climate action politics continues to be the biggest impediment to the deep commitment to low emissions that is a prerequisite for nuclear (and for renewables at the scales needed) and continues to divert the most influential voices of commerce and industry away from fixing the climate problem (and nuclear and renewables) – by the simple expedient of offering the lowest cost option of not fixing it all!

  6. horsedancingwithcrow Avatar

    Cool article, I read a couple today about this important step inside understanding it s a cultural bridge we have to walk together (as i’d say) and not a technological talk only and mainly.

    Senator milne quote is a pretty good one.
    I just want to say that the strongest point is when you mention FLEXIBILITY.
    Nature produces everything with low pressure low temperature. All of its miracles are made like that in long time spans. It s us with the 1750 (uk) to 1900 revolutions that we have to make evrything bidimensional fast growth, accumulation and capitalism.

    All of this is unsustanable (life non sustainable).

    The point is that nuclear makes us individuals which all can even singularly make a huge change with the tools we have at our disposal today, dependent.
    If we go towards renewable energies also our houses and us ourselves we can generate !

    We will be starting becoming connected (if those webs will be built -that s a nations or international community job to be done not by individuals) the solution is found for some time.

    We must think different. Nuclear is control and leverage of lobbies over nations over ppl.
    Renewable and innovtion is challenging the status quo so prepare for a dangerous violent fight unless all the ppl ynderstand this it will be a big fight because lobbies and rich greedy ppl will try to sabotage this transformation (natural) at all cost.

    Nature transforms and so we do because we are nature. Don t forget this. Climate changes but it does not so in such a violent way. We are responsible for this and we will extinguish if we do not give power to professional and experts who act for everyone interest and know what they do.

    In Europe indeed we have nuclear power sources because some countries sell it to countries that are low producing or slow or where politics are stagnant. We must allow politicians to be wise and the best city managers not corrupted bunch of guys covering their words and work with ideology.

    It s a cultural debate.

  7. Michael Jones Avatar
    Michael Jones

    This is just wrong. There is no way that a country like the UK could ever be able to reliably generate electricity all year round without baseload. Renewables rely on intermittent sources and it is entirely possible to have a still, cloudy day generating next to nothing from wind and solar. Currently storage technologies are not nearly developed enough to act as a solution. If they were then fine, but they’re not and they won’t be for a long time. “Windgas” would not be greener than nuclear as ultimately it still leads to running a gas turbine which is far more damaging to the environment than a nuclear power plant. As the article states, it is no more than an “idea”, the cost of developing the infrastructure required to allow for the necessary generation would be huge.

  8. HarryDutch Avatar

    Wind & Solar on the grid will always need the support of dispatchable power plants to balance electrical system (load following, frequency control), to optimize generation dispatch (merit order), to provide requested power spinning reserves, to contribute to clear grid congestions/constraints.When it comes to flexible support from nuclear power generators. For example, the Ontario Bruce CANDU nuclear units have the capability to lower electrical output while maintaining full reactor power. This is done by bypassing steam turbines and dumping steam to the condenser to lower the electrical output of the steam turbine generators. Each of the eight Bruce units has a rated capacity of about 760 MW and each unit can provide 300 MW of flexible nuclear operation. Bruce Power’s 2,400 MW of flexible nuclear output is used by the Ontario market operator to balance the Ontario system when there is low demand and high wind generation. In France, more than 75% of electricity is generated by nuclear power plants. The high level of nuclear power in France requires that some French nuclear power plants operate flexibly to respond to hourly, daily, and weekly variations in electricity demand. To provide this flexible operation, French nuclear power plants can operate in baseload mode, primary/secondary frequency control mode, or load following mode.

    1. Frank Avatar

      Some nukes can operate in load following mode, but that makes them much more expensive. Basically they cost the same to operate, but you sell fewer KWHs. They don’t last longer. You don’t save on fuel or labor. And you sure aren’t getting peak rates for what you produce then either.

  9. Luke Beauchamp Avatar
    Luke Beauchamp

    This article is misleading.
    “The second assumption is that nuclear power is a reliable baseload supplier. In fact it’s no such thing. All nuclear power stations are subject to tripping out for safety reasons or technical faults. That means that a 3.2GW nuclear power station has to be matched by 3.2GW of expensive ‘spinning reserve’ that can be called in at a moments notice.”

    Tripping a failsafe in a nuclear plant is a once in 20 years event that happens to prevent nuclear meltdown.

    Your article makes it sound like tripping a failsafe in a nuclear plant is a daily event. In truth the wind dying down is an actual daily event.

  10. Friso Sikkema Avatar
    Friso Sikkema

    The reality is exactly the other way around. Renewables are far from being capable of delivering baseload generation, because they are intermitent and non-dispatachble. Even with a massively expanded electricity storage network spanning the European continent (at fantastic cost, also for the extra renewable generation required to actually charge the storage), the backups will still be needed, as storage only lasts a few hours.
    In other words, the author just ventilates his opinion, which not at all represents real life data. The author freely cherry picks renewable achievements: “in such and such country, all of the electric energy was provided with renewables”. What is not said is the following; that (1) this is mainly hydro with a few wind turbines and (2) this only lasted a set of days at most, after which fossil generation is switched back on. The simple, elementary school level fact remains; if you have no wind and no solar, you have a problem.
    Please first study the requirements of any industrialized electricity grid, the vast baseload generation (UK: 36 GW full time on average, but with large peaks) required, when there is no wind or solar, and the complete impossibility of storing Gigawatts of energy in storage systems other than pumped hydro, before ventilating your opinions. Please also do not forget that only a few countries have the luxury of large wind and/or solar resources.

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