Nuclear energy and renewable energy (RE) are the principal competitors for low-carbon electricity in many countries.

As RE technologies have grown in volume and investment, and become much cheaper, nuclear proponents and deniers of climate science have become deniers of RE.

The strategies and tactics of RE deniers are very similar to those of climate science deniers.

To create uncertainty about the ability of RE to power an industrial society, they bombard decision-makers and the media with negative myths about RE and positive myths about nuclear energy, attempting to turn these myths into conventional wisdom.

In responding to the climate crisis, few countries have the economic resources to expand investment substantially in both nuclear and RE. This is demonstrated in 2016 by the UK government, which is offering huge long-term subsidies to nuclear while severely cutting existing short-term subsidies to RE.

This article, a sequel to one busting the myth that we need base-load power stations such as nuclear or coal, examines critically some of the other myths about nuclear energy and RE. It offers a resource for those who wish to question these myths. The myths discussed here have been drawn from comments by nuclear proponents and RE opponents in the media, articles, blogs and on-line comments.

Myth 1: Base-load power stations are necessary to supply base-load demand.

Variant: Base-load power stations must be operated continuously to back-up variable renewable energy systems.

Variant: Renewable energy is too variable to reliably make the principal contribution to large-scale electricity supply.

This myth is refuted in my previous article, 'Dispelling the nuclear 'baseload' myth: nothing renewables can't do better!' To quote three introductory paragraphs:

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 an electricity system that includes a 3.2GW nuclear power station needs at least 3.2GW of expensive 'spinning reserve' that can be called in at a moment's 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.



Myth 2: There is a renaissance in nuclear energy

Global nuclear electricity production in terawatt-hours per year (TWh/y) peaked in 2006. The percentage contribution of nuclear energy to global electricity peaked at 17.5% in 1993 and declined to under 11% in 2014. Nowadays annual global investment in nuclear is exceeded by investment in each of wind and solar.

Over the past decade the number of global start-ups of new nuclear power reactors has been approximately balanced by the number of closures of existing reactors. While several European countries are phasing out nuclear energy, most growth in nuclear reactor construction is occurring in China, Russia, India and South Korea.

See also Dr Jim Green's detailed article busting this myth wide open: 'Nuclear renaissance? Failing industry is running flat out to stand still'.

Myth 3: Renewable energy is not ready to replace fossil fuels, and nuclear energy could fill the (alleged) gap in low-carbon energy supply

Most existing nuclear power reactors are classified as Generation 2 and are widely regarded as obsolete. The current generations of new nuclear power stations are classified as Generation 3 and 3+. Only four Generation 3 reactors have operated, so far only in Japan, and their performance has been poor. No Generation 3+ reactor is operating, although two are under construction in Europe, four in the USA and several in China.

All are behind schedule and over-budget - the incomplete European reactors are already triple their budgeted prices. Not one Generation 4 power reactor - e.g. fast breeder, integral fast reactor (IFR), small modular reactor - is commercially available. So it can be argued that modern nuclear energy is not ready.

On the other hand, wind and solar are both growing rapidly and are still becoming cheaper. Large wind and solar farms can be planned and built in 2-3 years (compared with 10-15 years for nuclear) and are ready now to replace fossil and nuclear electricity.

Myth 4: Nuclear weapons proliferation is independent of civil nuclear energy

Variant: Nuclear weapons explosives cannot be made from the type of plutonium produced in conventional nuclear power reactors, or from the thorium fuel cycle, or from the IFR.

Six countries (France, India, North Korea, Pakistan, South Africa and the UK) have covertly used civil nuclear energy to assist them to develop nuclear weapons. In addition, at least seven countries (Argentina, Australia, Brazil, Iran, Libya, South Korea and Taiwan) have used civil nuclear energy to commence covertly developing nuclear weapons, but then terminated their programs (references in Diesendorf 2014).

Thus nuclear energy is facilitating proliferation and therefore is increasing the probability of nuclear war. Even if the probability of nuclear war is small (and this is debatable), the potential impacts are huge. Therefore it is inappropriate to ignore the proliferation risk, which is probability multiplied by potential impact.

Thorium reactors are under development in India. Thorium is not fissile, so it first has to be bombarded with neutrons to convert it into uranium-233, which is. Like any fissile element, U-233 can be used either to generate heat and hence electricity, or as a nuclear explosive. Nuclear weapons with U-233 as part of the explosive have been tested by the USA (Teapot MET test), Soviet Union and India.

Some nuclear proponents incorrectly claim the hypothetical IFR would be proliferation-proof. The IFR has only ever operated as a single prototype in the USA. The project was cancelled by Congress in 1994 for reasons including funding, doubts about whether it was needed, and concerns about its potential for proliferation.

The IFR offers at least two proliferation pathways. Once it has separated most of the highly radioactive fission products from the less radioactive transuranics by means of an experimental process known as pyroprocessing, it would be easier to extract the plutonium-239 from the transuranics by means of conventional chemical reprocessing and use it to produce nuclear weapons.

An alternative proliferation pathway would be to modify an IFR to enable it to be used as a breeder reactor to produce weapons grade plutonium from uranium-238. (Wymer et al. 1992).

Myth 5: The death toll from the Chernobyl disaster was 28-64 people

These absurdly low estimates are obtained by considering only short-term deaths from acute radiation syndrome and ignoring the major contribution to fatalities, namely cancers that appear over several decades.

For Chernobyl, the lowest serious estimate of future cancer deaths was "up to 4,000" by the Chernobyl Forum (2006), a group of United Nations agencies led by the International Atomic Energy Agency (IAEA).

The IAEA has the conflicting goals of promoting nuclear energy and applying safeguards against inter alia accidents and proliferation. Estimates from authors with no obvious conflict of interest range from 16,000 from the International Agency for Research on Cancer to 93,000 from a team of international medical researchers from Ukraine, Russia and elsewhere.

See also Dr Jim Green's excellent article: 'Radiation harm deniers? Pro-nuclear environmentalists and the Chernobyl death toll'.

Myth 6: The problem of permanently storing high-level nuclear wastes has been solved

All high-level waste is currently in temporary storage in pools or dry casks. Not one permanent repository is operating in the world.

Development of the proposed US repository at Yucca Mountain in the USA was terminated after expenditure of $13.5 billion. Underground repositories are under construction in Sweden and Finland. Even if the technical and economic challenges could be solved, the social problem of managing or isolating the repositories for 100,000 years remains.

Myth 7: The IFR could 'burn up' the world's nuclear wastes

The Integrated Fast Reacor or IFR only exists as a design. If it were ever developed, it would become another proliferation pathway (see Myth 4). At best it could convert most transuranics to fission products, so underground long-term repositories would still be needed.

For a fuller exposition of the problems of IFRs and other 'new' reactor designs, see Amory Lovins's classic 2009 essay, recently republished on The Ecologist: ''New' nuclear reactors? Same old story'.

Myth 8: Nuclear energy emits no or negligible greenhouse gas emissions

Neither nuclear energy nor most renewable technologies emit CO 2 during operation. However, meaningful comparisons must compare whole life-cycles from mining the raw materials to managing the wastes.

Nuclear physicist and nuclear supporter Manfred Lenzen (2008) found average life-cycle emissions for nuclear energy, based on mining high-grade uranium ore, of 60 grams of CO 2 per kilowatt-hour (g/kWh), for wind of 10-20 g/kWh and for natural gas 500-600 g/kWh.

Now comes the part that most nuclear proponents try to ignore or misrepresent. The world has only a few decades of high-grade uranium ore reserves left. As the ore-grade inevitably declines, the fossil fuel used to mine (with diesel fuel) and mill uranium increases and so do the resulting greenhouse gas (GHG) emissions.

Lenzen calculates that, when low-grade uranium ore is used, the life-cycle GHG emissions will increase to 131 g/kWh. Others have obtained higher levels. This is unacceptable in terms of climate science. Only if mining low-grade ore were done with renewable fuel, or if fast breeder reactors replaced burner reactors, could nuclear GHG emissions be kept to an acceptable level, but neither of these conditions is likely to be met for decades at least.

For more on this topic, see also Professor Keith Barnham's excellent article: 'False solution: Nuclear power is not 'low carbon''.

Myth 9: Nuclear energy is a suitable partner for renewable energy in the grid

Making a virtue out of necessity, nuclear proponents claim that we can have both (new) nuclear and renewables in the same grid. However, nuclear energy is a poor partner for a large contribution of variable renewable energy in an electricity supply system for four reasons:

1. Nuclear power reactors are inflexible in operation (see Myth 10), compared with open cycle gas turbines (which can be biofuelled), hydro with dams and concentrated solar thermal (CST) with thermal storage. Wind and solar PV can supply bulk energy, balanced by flexible, dispatchable renewables, as discussed previously.

2. When a nuclear power station breaks down, it is usually off-line for weeks or months. For comparison, lulls in wind last typically for hours or days, so wind does not need expensive back-up from base-load power stations - flexible dispatchable RE suffices.

3. Wind and solar farms are cheaper to operate than nuclear (and fossil fuels). Therefore wind and solar can bid lower prices into electricity markets and displace nuclear from base-load operation, which it needs to pay off its huge capital costs.

4. Renewables and nuclear compete for support policies from government including scarce finance and subsidies. For example, the UK government commitment to Hinkley C, with enormous subsidies, has resulted in removal of subsidies to on-shore wind and solar PV.

Myth 10: Nuclear power reactors can generally be operated flexibly to follow changes in demand / load

The limitations, both technical and economic, are demonstrated by France, with 77% of its electricity generated from nuclear.

Since the current generation of nuclear power stations is not designed for load-following, France can only operate some of its reactors in load-following mode some of the time - at the beginning of their operating cycle, with fresh fuel and high reserve reactivity - but cannot continue to load-follow in the late part of their cycle. This is acknowledged by the World Nuclear Organisation.

Load-following has two economic penalties for base-load power stations:

Substantially increased maintenance costs due to loss of efficiency and the expansion and contraction cycles associated with rising and falling reactor temperatures;

Reduced earnings during off-peak periods. Yet, to pay off of their high capital cost, the reactors must be operated as much as possible at rated power.

France reduces the second economic penalty by selling its excess nuclear energy to neighbouring countries via transmission line, while parts of Australia soak up their excess base-load coal energy with cheap off-peak water heating.

Myth 11: Renewable energies are more expensive than nuclear

Variant: Nuclear energy receives smaller subsidies than RE.

Both myths are false. Levelised costs of energy (LCOE) depend on the number of units installed at a site, location, capital cost, interest rate and capacity factor (actual average power output divided by rated power). LCOE estimates for nuclear are $108/MWh based on pre-2014 data and $97-132/MWh based on pre-2015 data (Lazard 2015).

The IPCC estimate does not include subsidies, while the Lazard estimate includes US federal government subsidies excluding loan guarantees and decommissioning. None of these US estimates takes account of the huge escalation in costs of the two European Pressured Water Reactors (EPR) under construction (mentioned in Myth 3).

The EPR proposed for the UK, Hinkley C, is being offered a guaranteed inflation-linked price for electricity over 35 years, commencing at £92.5/MWh ($144/MWh) in 2012 currency. That's now pushing up towards £100 in today's money, almost three times the current wholesale price of electricity in the UK. The subsidy package also includes a UK Treasury loan guarantee of originally £10 billion ($15.3 billion). Its capped liability for accidents and inadequate insurance is likely to fall upon the British taxpayer.

In 2015 multinational financial consultants Lazard estimated unsubsidised costs for on-shore wind across the USA of $32-77/MWh. An independent empirical study by US Department of Energy (Fig. 46) found levelised power purchase agreement prices in 2014 for wind in the US interior (region with the highest wind speeds) of $22/MWh, and in the west (region with lowest wind speeds) about $60/MW.

The US government subsidises wind with a Production Tax Credit of $23/MWh over 10 years, so this must be added to the DoE figures to obtain the actual costs. In Brazil in 2014, contracts were awarded at a reverse auction for an average unsubsidised clearing price of 129.3 real/MWh (US $41/MWh).

Lazard estimated unsubsidised costs of $50-70/MWh for large-scale solar PV in a high insolation region of the USA. In New Mexico, USA, a Power Purchase Agreement for $57.9/MWh has been signed for electricity from the Macho Springs 50 MW solar PV power station; federal and state subsidies bring the actual cost to around $80-90/MWh depending on location.

In Chile, Brazil and Uruguay, unsubsidised prices at reverse auctions are in the same range (Diesendorf 2016). Rooftop solar 'behind the meter' is competitive with retail grid electricity prices in many regions of the world with medium to high insolation, even where there are no feed-in tariffs.

For CST with thermal storage, Lazard estimates $119-181/MWh.

Comparing subsidies between nuclear and RE is difficult, because they vary substantially in quantity and type from country to country, where nuclear subsidies may include some or all of the following (Diesendorf 2014):

government funding for research and development, uranium enrichment, decommissioning and waste management;

loan guarantees;

stranded assets paid for by taxpayers and electricity ratepayers;

limited liabilities for accidents covered by victims and taxpayers;

generous contracts for difference.

Subsidies to nuclear have either remained constant or increased over the past 50 years, while subsidies to RE, especially feed-in tariffs, have decreased substantially (to zero in some places) over the past decade.

Myth 12: Renewable energy is very diffuse and hence requires huge land areas

Hydro-electric dams and dedicated bioenergy crops can occupy extensive areas, but renewable energy scenarios for few regions have large additional contributions from these sources.

Ground based solar farms located may occupy significant land, however this is often marginal land, and need not preclude other uses such as grazing. Rooftop solar, which is widespread in Germany and Australia, and bioenergy derived from crop residues, occupy no additional land.

On-shore wind farms are generally located on agricultural land, with which they are highly compatible. The land occupied is typically 1-2% of the land spanned which deniers often ignore and misleadingly quote the land area spanned.

For an economic optimal mix of 100% renewable electricity technologies calculated for the Australian National Energy Market, total land area in km2/TWh/y is about half that of equivalent nuclear with a hypothetical buffer zone of radius 20 km, as belatedly established for Fukushima Daiichi (Diesendorf 2016).

Myth 13: Energy payback periods (in energy units, not money) of renewable energy technologies are comparable with their lifetimes

Nowadays typical energy payback periods in years are: solar PV modules 0.5-1.8; large wind turbines 0.25-0.75; CST (parabolic trough) 2; nuclear (high-grade-uranium ore) 6.5; nuclear (low-grade-uranium ore) 14 (references in Diesendorf 2014, Table 5.2).

The range of values reflects the fact that energy payback periods, and the related concept of energy return on energy invested, depend on the type of technology and its site. Critics of RE often quote much higher energy payback periods for RE technologies by assuming incorrectly that each has to be backed-up continuously by a fossil fuelled power station.

Myth 14: Danish electricity prices are among the highest in Europe, because of the large contribution from wind energy

Danish retail electricity prices are among the highest in Europe, because electricity is taxed very heavily. This tax goes into consolidated revenue - it does not subsidise wind energy. Comparing tax-free electricity prices places Denmark around the European average.

Wind energy in Denmark is subsidised by feed-in tariffs funded by a very small increase in retail electricity prices, which is offset by the decrease in wholesale electricity prices resulting from the large wind energy contribution.

Myth 15: Computer simulation models of the operation of electricity grids with 80-100% renewable electricity are meaningless over-simplifications of real systems

Although a model is indeed a simplified version of reality, it can be a powerful low-cost tool for exploring different scenarios. Most modellers start with simple models, in order to understand some of the basic relationships between variables. Then, step-by-step, as understanding grows, they make the models more realistic.

For example, initially the UNSW Australia group simulated the operation of the Australian National Electricity Market with 100% RE in hourly time-steps spanning a single year. Wind farms were simply scaled up at existing sites. The next model included economic data and calculated the economic optimal mix of RE technologies and then compared costs with low-carbon fossil fuelled scenarios.

Recently the simulations were extended to six years of hourly data, the RE supply region was decomposed into 43 sub-regions and a limit was imposed on non-synchronous supply. Meanwhile, researchers at Stanford University have shown that all energy use in the USA, including transport and heat, could be supplied by renewable electricity.

Their computer simulations use synthetic data on electricity demand, wind and sunshine taken every 30 seconds over a period of six years. Using synthetic data allows modellers to include big hypothetical fluctuations in the weather. Such sensitivity analysis strengthens the power and credibility of the models.

Strangely, some of the loudest critics of simulation modelling of electricity systems, a specialised field, have no qualifications in physical science, computer science, engineering or applied mathematics. In Australia they include two biologists, a social work academic and an occupational therapist.

Renewables could be scaled up long before nuclear



Computer simulation models and growing practical experience suggest that electricity supply in many regions, and possibly the whole world, could transition to 100% renewable energy (RE).

Most of the RE technologies are commercially available, affordable and environmentally sound. There is no fundamental technical or economic reason for delaying the transition.

The pro-nuclear and anti-RE myths disseminated by nuclear proponents and supporters of other vested interests do not stand up to examination. Given the political will, RE could be scaled up long before Generation 3 and 4 nuclear power stations could make a significant contribution to electricity supply.

Mark Diesendorf is Associate Professor in Interdisciplinary Environmental Studies in the School of Biological, Earth and Environmental Sciences at the University of New South Wales.

References

Diesendorf M (2014) Sustainable Energy Solutions for Climate Change. London: Routledge and Sydney: NewSouth Publishing.

Diesendorf M (2016) 'Subjective judgments in the nuclear energy debate'. Conservation Biology doi:10.1111/cobi.12692. (See the Supporting Information as well as the short article.)

Wymer RG et al. (1992) An Assessment of the Proliferation Potential and International Implications of the Integral Fast Reactor. Martin Marietta K/IPT-511 (May); prepared for the Departments of State and Energy.