24/7 Non-Intermittent Stream

In his April editorial Solving the Energy Trilemma, the president of the Australian Academy of Technology and Engineering states that small modular reactors may change the equation on nuclear energy economics and, “if that turned out to be the case, Australia would lag behind the rest of the world”, because Australia prohibits it outright.

He goes on to say,

Suppliers of variable renewable electricity generated from the sun and wind need to ensure 24-hour supply through the use of energy storage. While there has been a lot of noise in the media about whether renewables can achieve continuous supply, the answer is very clearly that they can. It will require storage but the massive investments going into batteries and other grid storage solutions… give us confidence that we shall be able to meet this need.

Courtesy of futurENERGY

So, it’s definitely time for a good old-fashioned comparison of climate-friendly energy sources. This has been made possible by anticipated sizes, costs and operating parameters reported in online media and the literature. More fundamentally, the energy sources are solar photovoltaic with seawater pumped hydro, and nuclear energy, both effectively dispatchable and therefore hypothetically directly comparable.

In August 2014 the combined Valhalla Cielos de Tarapacá and Espejo de Tarapacá project in Chile was announced. It will supply the Chilean grid by day with solar and by night from hydro, using seawater stored on a clifftop reservoir, pumped there with excess solar electricity.

PV capacity………………………………………………..600 MW
Annual generation………………………………………1,800 GWh
Average daily generation……………………………..4.93 GWh
Average capacity factor……………………………….34%
Land area…………………………………………………..1,570 hectares
Expected cost…………………………………………….$900 million USD

PHS power capacity……………………………………300 MW
Max. input energy………………………………………2.28 GWh
Max. output energy…………………………………….1.75 GWh
Round-trip efficiency………………………………….76%
Duration at 300 MW output………………………..5.8 hours
Ave. output supplying for approx. 16 hours……….109 MW
Land area…………………………………………………..374 hectares
Expected cost…………………………………………….$400 million USD

Combined average annual capacity factor
after max. daily charging and discharging*……….31%
Combined cost……………………………………………$1.3 billion USD
Combined land area…………………………………….1,945 hectares
Expected commissioning date………………………June 2020

*This capacity factor is estimated from the average daily PV output, taking into account the maximum energy first stored, then released from the reservoir, subject to the reported round-trip efficiency.

Crucially, this is billed as 24/7 supply in arguably the world’s most favourable location for this combination of technologies. It will be built at about 20.7 degrees south latitude. The Broken Hill solar farm is at 32 degrees south, and using a random full-day’s 5 minute output data as a proxy, a hypothetical “average day operation” of Valhala’s project can be reasonably pictured. This is also important as solar plus pumped hydro is being pursued for Australian electricity supply.

Pumped hydro is the most mature form of grid-scale storage, although it can be argued there is limited experience with seawater pumping. The unique, universally cited Yanbaru facility in Okinawa (substantially smaller than Valhalla’s project) was decomissioned after 17 years. However, storage capacity is not generation capacity. Where the former is added to support the latter, it effectively increases the cost of generation without adding any further capacity. What is fundamentally changed is the dispatchable value of the generation. This has already been stated as being directed toward “24/7 supply”, often thought of a baseload.

In November 2017 Canadian nuclear energy start-up company Terrestrial Energy concluded the first phase of the pre-licensing vendor design review after several succesful rounds of capital raising, with the potential for building a prototype at the Chalk River Labs site. In March 2018 the company signed an MOU with Idaho National Labs regarding building another reactor unit at that site. This is a molten salt reactor design, the IMSR®, which features liquid fuel and intrinsically passive operation based around gravity and convection.

The company’s key commercial claim is:

IMSR power plants are a low cost clean energy alternative to fossil fuel combustion and they can be deployed in the 2020s.

A recent article in Annals of Nuclear Energy, along with other presentations, provided some specifications.

IMSR capacity………………………………………………..291 MW
Annual generation………………………………………….2,343 GWh
Typical daily generation………………………………….6.98 GWh
Average capacity factor……………………………………92%
Land area………………………………………………………6.8 hectares
Expected cost…………………………………………………$1.08 billion USD

Expected commissioning date……………………………after 2026

The major precursor to this reactor design development effort was Oak Ridge’s MSRE in the 1960s. Terrestrial Energy is only one of dozens of companies planning such a design.

Courtesy of Terrestrial Energy

The emergency shutdown capabilities are incorporated directly into the design of the IMSR vessel and building. By operating as a liquid at high temperature, shutdown intrinsically leads to cooling of fuel instead of overheating. By operating at close to atmospheric pressure, no driving force exists to expel any material from the power plant building. The homogenous nature of the fuel salt allows a six-fold higher efficiency utilisation of uranium than conventional reactors.

The estimated cost listed above is the literature overnight cost (ca. $0.83 billion) plus 30% financing on a five year project as described by the World Nuclear Association.

All else being equal, the Valhalla project will take just about 6 years to come online, while the 291 MW IMSR is more than 8 years from commercial readiness. In total, the former will require 286 times the land area of the latter, and as the IMSR is intended for factory production in the manner of commercial aircraft, with 4-year construction cycles, it has the potential for superior deployability.

To illustrate the land footprint aspect, the conventional Barakah nuclear power project in the UAE is sited on a coast moderately similar to the ocean-bounded Atacama desert. (The most dramatic difference is the absence of a 600 metre cliff – such geography isn’t necessarily common.) By 2020 it will feature four operational South Korean APR-1400 reactors.

Plant capacity……………………………………………………5,360 MW
Annual generation……………………………………………..42,260 GWh
Average capacity factor………………………………………90%
Land area………………………………………………………….8 hectares approx.
Final cost………………………………………………………….$6.1 billion USD per reactor

To “match” the output of one Barakah unit, Valhalla would hypothetically need to build 6.6 PV+PHS projects, requiring nearly 13 thousand hectares (over 1,600 times Barakah’s footprint) at a cost of $8.5 billion USD.

FURTHER COMPARISONS

Plant lifespan (years):
Photovoltaic Solar………………………………………25–30
Seawater Pumped Hydro………………………………17
Molten Salt Nuclear……………………………………..60

We are yet to see what will happen at the end of “the industry standard life span” for solar, or how long hydro involving seawater should economically operate for. Terrestrial Energy has indicated a plant lifespan which involves regular 7 year replacement of reactor core units (doubling as secure used fuel storage). The original Molten Salt Reactor Experiment operated for more than 4 years at Oak Ridge National Labs until funding arrangements abruptly changed. Consequently, these figures are only included for interest’s sake.

There are several other parameters which would be valuable to compare, namely the discreet material weight-requirements per TWh, the energy returned on invested, the comprehensive life-cycle GHG emissions, and the levelised volumes of other life-cycle by-products. Values for all of these depend substantially on operating assumptions and the rigour of the associated research. Robust values for both renewable energy/storage systems and advanced nuclear are not readily or publicly available, but will become increasingly important if national policies regarding clean and climate-friendly energy are to be comprehensively, scientifically informed.

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How To Tell

Replacing fossil fuel combustion with nuclear energy to supply our electricity should hopefully appear a lot more achievable to everyone after today, with the publication of an open access peer-reviewed paper by Qvist and Brook in PLOS One. These are my favourite parts:

Why consider a large-scale nuclear scenario? The operation of a nuclear reactor does not emit greenhouse gases or other forms of particulate air pollution, and it is one of few base-load alternatives to fossil energy sources currently available that has been proven by historical experience to be able to be significantly expanded and scaled up. Large-hydro projects are geographically constrained and typical have widespread impacts on river basins. The land use, and biodiversity aspects of a large-scale expansion of biomass for energy make its use as a sustainable global energy source questionable.

…Between 1960 and 1990 Sweden more than doubled its inflation-adjusted gross domestic product (GDP) per capita while reducing its per capita CO₂ emissions through a rapid expansion of nuclear power production. The reduction in CO₂ emissions was not an objective but rather a fortunate by-product, since the effect on the climate by greenhouse-gas emissions was not a factor in political discourse until much more recently. Nuclear power was introduced to reduce dependence on imported oil and to protect four major Swedish rivers from hydropower installations. As illustrated [below], in the pre-nuclear era (1960–1972), the rise in Swedish CO₂ emissions matched and even exceeded the relative increase in economic output. Once commercial nuclear power capacity was brought online, however, starting with the Oskarshamn-1 plant in 1972, emissions started to decline rapidly. By 1986, half of the electrical output of the country came from nuclear power plants, and total CO₂ emissions per capita (from all sources) had been slashed by 75% from the peak level of 1970.

Importantly, the paper does not seek to neglect the contributions from other technologies. But it does redress the habitual exclusion of any nuclear potential in the bulk of “energy plan by this-or-that year” scenarios – which undeniably tend to optimistically favour dilute renewable sources like wind and sun.

Oskarshamn NPP. 3 reactors. 10% of Sweden’s power. Beautiful spot.

But with all these studies, models and scenarios, how to tell which are realistic? How, without a nerdy interest in terawatt hours and capacity factors, can a normal blog reader decide which ones are really just written to reinforce a preconception? How about these for pointers:

• Proposed technology rollout rates are given in kilowatt hour per person per year, or an easily convertible metric, as in the Qvist and Brook paper. This allows quick comparison between technologies, historical rates, countries and so on.
• Technology tribalism. Failing to consider nuclear’s role, while succeeding in heroic optimism for other technologies, speaks directly to the authors’ bias (and even more clearly when an author’s bias is taken to ridiculous extremes elsewhere).
• The authors have no problem with consulting industry professionals and scientists who work in the relevant field.
• The authors keep coming back to carbon emissions reduction. Alternatives to coal, oil and gas are supposed to reduce emissions. Sometimes one has to dig deep into a “100% Renewables” study to find out where it connects to “0% Fossil Fuels”.

On that last point, wouldn’t it be something to see environmental non-governmental organisations – routinely so vocal regarding climate action – promoting this latest historically-grounded analysis as part of a technology-inclusive, rapid fossil fuels phaseout?

The results indicate that a replacement of current fossil-fuel electricity by nuclear fission at a pace which might limit the more severe effects of climate change is technologically and industrially possible—whether this will in fact happen depends primarily on political will, strategic economic planning, and public acceptance.

 

But, Fukushima

The Great East Japan Earthquake (as it is known locally) and the resulting tsunami in March 2011 officially killed 15,883 people, with 2,652 still missing. 6,149 people were injured. Save the Children reported an estimated 100,000 Japanese children were displaced from the security of their homes as their world appeared to crumble. A large populated area, well north of Tokyo on the east coast of Honshuu, already devastated by earthquake and monster waves was evacuated of roughly 300,000 residents after containment failed at a forty year old nuclear power plant.

Pictured: Not Fukushima

But, Fukushima.

As a result, approximately 1,600 people have died before being able to return home. Importantly, these deaths were not related to radiation exposure. In fact, the World Health Organisation has stated that no statistical increase in mortality is to be expected due to leaked radiation. It is possible that the extensive evacuation saved many residents from higher or longer-term radiation exposure, which may have ultimately resulted in a worse outcome. But it is also quite possible, indeed entirely probable that even so, nothing like 1,600 people would or could have died.

But, Fukushima…

Estimates of actual leaked radioactive material vary fairly widely, and are reported in tera- and petabecquerels, which give a technical indication of how much radiation people could potentially be exposed to. These numbers correspond to actual masses which have been spread finely over land and sea, so when one considers that the reported leak of 15 PBq of relatively dangerous caesium-137 for example (with a radioactivity of 3.215 TBq/g) is due to no more than about 4.7 kg of the isotope, which mostly is expected to have settled within the 20 km restricted zone around the plant, a different perspective of the risk of excessive contamination to individuals, and the scale of the clean-up process, is apparent.

But, Fukushima..?

Let’s keep a sense of perspective. I mean, there’s this guy, somehow. And the fact that the Pacific already contains relatively large amounts of Cs-137. (and K-40, and U-238, and Th-232…) So, no, not Fukushima, if the implied question was should nuclear power be expanded to meet electricity demand and mitigate pollution and anthropogenic carbon dioxide.

After spending 2 years enacting energy austerity and scrambling to expand natural gas electricity generation, Japan is being patted on the back for erecting a wind turbine off the Fukushima coast. In itself, wind energy is great – in suitable locations. But hardly to replace base load electricity supply. And while this is being applauded as an environmental victory, in perspective it is not: Japan is already admitting it will be 3% over its 1990 GHG emission levels, instead of 25% under, by 2020. All as most recent predictions about anthropogenic climate change indicate a bleak future for our oceans.

Sadly ironic, when all anyone’s worried about is releasing a heap of dilute contaminated water into the sea.