As part of my research reviewing all 100 % renewable electricity studies, I am revisiting the work of ClimateWorks for the Deep Decarbonisation Pathways Project. You can find the report here.


The report includes three scenarios:

  • 100 % renewable grid (of interest to my meta-review, and the major scenario presented by ClimateWorks)
  • Nuclear
  • CCS

In the latter two scenarios, “permission” is effectively given in the model for those energy sources to compete. As a result, each of these energy sources comes to make a significant contribution to the least-cost finding (23 % and 14 % respectively).

The limitation on nuclear to only 14 % seemed surprising to me. It is based (primarily) on the following assumptions:

  • Only a few large nuclear plants can be accommodated in the eastern states before connection limitations are met
  • Western Australia remains separate from the NEM (despite the scenario suggesting it will become the largest electricity user)

On the first point they say “ESM (CSIRO’s Energy Sector Model) only allows nuclear power in the larger states of New South Wales, Queensland and Victoria, since nuclear power stations generally have to be a minimum size, which would preclude their deployment in the smaller states”.

The authors acknowledge that consideration of smaller reactors is important and worthy of further work. They also tested the WA connection in the nuclear scenario and found the nuclear share increased to 27 %. That alone is an interesting signal.

They state further that “with the use of small-scale nuclear plant or a more interconnected grid [we will return to that] there is no technical reason why nuclear power could not supply a major share of electricity consumption”.


In light of these sensible remarks, I am concerned that the assumptions about transmission network limitations and may not have been understood and applied equally. I am not certain of my findings here. All of the following is to be read as open investigation, not conclusion.

The authors state:

“Within the scope of this project, it is not possible to fully resolve the changes to the network that would be required to support the reliable market balancing of the generation mix in each scenario. The relatively high demand growth will necessitate significant transmission network growth and the need to extend the grid to remote renewable resources, given their high contribution to the generation mix”.

Ok… they know it’s essential, it was out of scope. Fine. I have no problem with that. What did they do?

“As a guide, in the absence of detailed transmission network modelling, the transmission cost results from the existing ‘Renewables thrive’ scenario of the Future Grid Forum project have been applied, which is a 100 percent renewable grid scenario, as outlined in Graham et al. (2013)… Under ‘Renewables thrive’, taking into account the required changes to the transmission network, the cost was projected to increase to 4.3c/kWh by 2050”.

So, no modelling, but an effort at costing based on someone else’s modelling. That, again, is fine with me as long as it’s disclosed.

Now, let’s look at the mix for 100 % renewable grid.


It is evident that this mix will require the “significant transmission network growth and the need to extend the grid to remote renewable resources” that the authors discussed. So, I strongly suspect the transmission was assumed to be unconstrained, simply costed in on a per kWh rate on the basis of “we will build what we need”.

Here are the network augmentations proposed by Future Grid Forum. 

Future Grid 1

Future Grid 2

That’s a lot of investment that could be put towards improvements tailored for nuclear generation.

So…why was transmission assumed to be constrained in the nuclear scenarios such that only a few reactors in the eastern states were assumed to be possible? Renewable units are smaller than nuclear units, but that renewable scenario is (much) more dispersed than a nuclear-based system would be. Stronger transmission networks (and other investments) is an answer to both problems. The authors acknowledge that very fact (“with the use of small-scale nuclear plant or a more interconnected grid there is no technical reason why nuclear power could not supply a major share of electricity consumption”).

Every progressive transmission enhancement that would be necessary for the 100 % renewable grid scenario would, just as effectively, contribute to new threshold that enables the connection of more large nuclear units. Has this modelling settled for assuming nuclear connections based on the network of today, but enabled levels of renewable penetration based on the network of “whatever we need tomorrow?”. If so then an assumption that should be uniform across all scenarios is, instead, differentiated between scenarios.

DDPP-au 2

The transmission enhancement requirements for nuclear (which can be close to load and existing transmission) are likely far more discreet than for the needs of the renewables system shown above. I posit dollars invested in transmission upgrade for nuclear would deliver connection capability much more efficiently than dollars spent in transmission upgrade for geographically dispersed renewable overbuild. If spending on networks was applied rationally and even-handedly, nuclear should do well.

The result is that the contribution from nuclear in the scenario where it was permitted would be, at 14 %, a false low. This suggests that the wholesale price of the nuclear scenario (Figure 2.18) is a false high, as more nuclear, earlier, would displace more of the higher-priced renewable electricity that enters the mix later: enhanced geothermal and wave (capital costs, Figure 2.7) and solar thermal (which, while dispatchable, is still variable). It’s likely not delivering an optimised system from the available options.

I find this report is overall clear, well written and offers some important potential directions, as well as giving one of the more even-handed treatments of nuclear generation in Australian literature (my criticisms not withstanding). However I cannot get clarity on this issue. I welcome comments from all including the report authors if they can shed some light on how this assumption was managed.



  1. Hi Ben, quite comprehensive! Do you have a printable version of this literature review (makes it easier for me to read)? Cheers!

  2. How will aircraft be powered?
    What about our defenses?
    Shipping is of major concern especially cruise boats? Will we get the Chinese and Americans to take over those business?
    Best wishes
    John Swainston
    02-9974 4420 or mobile 0439 445 707

  3. Some Tooth Fairies in the all renewables list, frexample enhanced geothermal which has been tried and failed and CCS said to have only one commercial generator (Boundary Dam I think) among dozens of pilot plants.

    Recall Westinghouse-Toshiba told the RC they visited some SA sites like the submarine yards and concluded they could build twin AP1000s (ie 2.2 GW) for $17.5 bn presumably Australian dollars. Since SA can use as little as 0.5 GW in mild weather that’s 1.7 GW that might need interstate buyers. I presume SESA-MEL is the Heywood Interconnector that will max out at 0.75 GW bidirectional capacity. I see no SA-WA link listed as proposed by Beyond Zero Emissions. If the new thinking is single site multiple reactors have the best economics that doesn’t bode well for power generation in SA.

    Apart from single line transmission capacity other factors must be redundancy and loss of load sharing. I see from today’s The Conversation some want the 1.6 GW Hazelwood brown coal plant in Victoria plant shut down and black coal power brought from NSW and Qld. That seems to mean NE Australian electricity keeps the lights on in SA, Vic and Tas up to 2,000 km away. Five minutes ago the same people were talking about ‘distributed generation’.

  4. Hi Ben, briefly summarized the summary to the US contribution to the Deep Decarbonization Pathways Project here. Our approaches may differ; the goals are the same. The US modeled four representative, non-exhaustive, non-optimal scenarios involving varying proportions of nuclear and renewables. Key commonalities:

    1. By 2050 U.S. per capita energy consumption is expected to drop 43%.
    2. Allowing for population growth, net US energy consumption is expected to drop 20%.
    3. To achieve 80% overall emissions reduction, net US electricity generation is expected to double.
    4. Gulp.

    So yes, there will likely be modest transmission build-out, either way.

  5. Great post Ben – all great comments which you know I agree with. Unfortunately it is just the tip of the iceberg when it comes to all the inconsistencies in the assumptions in climateworks analysis. I think they have good intentions but are just too reckless in their treatment of opportunity cost, risk, market forces and energy systems. For instance what cost of capital and discount rates are applied to their supernova sized forestry offset projects to achieve 100s Mtpa of GHG reductions? Where the same assumptions applied to nuclear? Why not?

    The simple answer is that behind the glossy Climateworks charts and publications is a theoretical wasteland where anything goes to make the outcome look easy and nuclear free.

    Jotzo on the otherhand has recently displayed his gun for hire approach to climate policies. His latest paper is a poor attempt to protect Australia’s coal export market share. While I’m sure MCA will be delighted by his paper academics will be less impressed by his failure to include the transport and storage GHGs in Australia’s coal exports when making comparisons to domestic sources in key markets. It is a pity to see such poor work come from him and his German co-authors.

    1. Hi Martin,

      Do you know who the authors’ of the eFuture tool are? I had a bit of a hunt around on the website, but the reports I have sighted do not attribute the tool itself.

      You may also find that all links at on legal notices are broken, so perhaps there is an issue on conditions of use.

      Briefly looking at the tool, it is clear the diagrams Ben critiques are from the ClimateWorks literature (which he references at the head of his article), and they acknowledge “The Australian project is led by ClimateWorks Australia and the Australian National University (ANU) and supported with modelling conducted by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO)”.

      So your assertion is then, the efuture modelling tool used has been made public, and the CSIRO website suggests it generates diagrams ‘similar’ to those in the Australian Government’s Energy White Paper (2012).

      I think Ben has adequately attributed his review of the ClimateWorks literature.

    2. I agree, they look identical.

      But I can’t make that tool produce anything other than a massive majority supply from nuclear when the nuclear option is “permitted”, no matter what I do with the other variables.

      If it is that tool then I have to presume they had access to the back end to change the terms under which nuclear could compete, perhaps in the manner suggested in my post.

      Seems a bit fishy… it looks like it runs on the CSIRO energy sector model (ESM) that ClimateWorks references.

  6. With 2050 generation options I’d erase enhanced geothermal, wave power, CCS and solar thermal as all being tried and failed as too flakey and expensive. By then the climate will be too weird to rely on biomass burning. I suspect that in most places natural gas will also be depleted or too expensive, hence some other Technology X must supply most electricity, heat and transport propulsion.

    AEMO are a strange lot apart from their inability to use the word ‘nuclear’ in any of their reports. It’s OK to mention radioactive decay w.r.t. geothermal but not the N-word. Note AEMO will now be managing the WA grid along eastern state principles presumably such as no capacity payments in future. However there is nearly 1500 km of desert between the NEM at Pt Augusta and the SWIS grid at Norseman.

    I’m getting the impression that many people accept that SA should be the forerunner for an expanded nuclear fuel cycle including electricity. Reasons include loss of nuclear virginity with Maralinga, big uranium deposits and the need for new industry. Therefore SA should have perhaps a gigawatt of transmission capacity to the east maybe the same to the west. If the Future Grid folks overlook this to concentrate on obscure unproven technologies they may be missing the point.

  7. Here’s how SA could justify getting twin AP1000s …. synchronise it with the planned/hoped for closure of Hazelwood power station. The closure of the 1.6 GW Hazelwood with 1400 grams of CO2 per kwhe is now part of Greens official policy
    except they think it can be replaced by wind, solar and efficiency. Moreover the plant’s owners Engie (formerly GDF Suez) seem to want to close it sooner rather than later.

    That would mean replacing the Heywood Interconnector (SESA-MEL in Ben’s chart?) with a bidirectional HVDC cable of say 1.5 GW capacity. Using the same pylons and with converter substations at either end would cost additional billions to the $17.5 bn for the twin reactors. However there was talk of spending more than $20 bn for diesel submarines which I suggest is a low priority. Otherwise any NPP for SA would have to be small or medium sized.

  8. No doubt everybody watched ABC Foreign Correspondent last night about renewable energy with its repeated nervous jibes about nuclear. However the show before that, Back Roads featured the town of Ceduna. The residents spoke of how the Maralinga A-bombs tests 60 years ago still dominate their thinking and how they always adapt. An example being the cleaner who now runs the radio telescope. They didn’t mention the mildly radioactive zircon sand that passes through the town.

    If the WA and eastern NEM grids were connected then Ceduna would be in a plum position to take advantage. That region is facing dire water shortages but the cool ocean currents flowing past could be used for both thermal plant cooling and desalination. Yet the Future Grid people don’t seem to have given it any thought.

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