Cooking the Comparisons

South Australia’s recent Nuclear Fuel Cycle Royal Commission examined many aspects of the complete fuel cycle, from mining to used fuel management and much in between. Considerable research was contracted to consulting firms. The task of comparing the economic viability of electricity generation in a mix of nuclear, gas and renewables was undertaken by DGA Consulting Carisway.

Sanmen AP1000 units in ChinaTwo nuclear options were included: a single AP1000 with a stated capacity of 1125 megawatts, and a six unit SMR plant rated at 285 MW (comprised of NuScale power modules of 47.5 MW each).

Various analyses were carried out to pit these nuclear options against gas and wind and solar, and the report’s details reveal the fundamental conceit utilised to shape the results: to ensure high value of wind and solar to the simulated scenarios, storage was assumed in unspecified but plentiful quantities which would smooth the output of these sources to whatever extent was required. Specifically, this was distributed batteries for rooftop solar (page 33), and grid storage paired exclusively with wind (page 34), justified only by the assertion that storage technology is advancing and will soon be economically feasible, alongside a reference to a newspaper article superficially covering laboratory work on graphene-based supercapacitors. The fact that one of the report’s authors is the chairman of a company connected to this graphene research – and an “international expert” in electricity grids based on high proportions of renewable energy and storage – is a minor detail compared to the absence of any accounting for the cost of this storage capacity.

Battery storage connected to rooftop solar has enjoyed spectacular coverage in Australia. As of the end of 2016, the closest thing to a guesstimate of current capacity is from page 34 of Solar & Storage Magazine – 31,000 installations, markedly lower than celebrated predictions of 100,000 from Morgan Stanley. But how much is this? If each installation is typified by the Tesla Powerwall, with a rated output of 2 kW and capacity of 6.4 kWh, then present distributed battery capacity in Australia might be about 62 MW and 200 MWh. It would take almost 5,000 times as much as this to fulfil the storage requirements in WattClarity’s 62 hour thought experiment.

In addition, the DGA report invokes an unspecified amount of vehicle-to-grid electric vehicle battery discharge to meet demand. This is now largely moot considering how complex and economically unviable it is understood to be.

oki07Recent thorough experience in california with proven battery storage technology at a larger scale – 2 MW, 14 MWh from sodium sulfur batteries – failed to demonstrate financial viability and anything close to the performance of the scheduled energy sources it is habitually touted to replace. Whatever the authors imagine to be coupled with wind in their models is even less proven. There are alternatives to battery storage of course, and seawater pumped hydro is often suggested, however the preeminent example – the distinctively octagonal Yanbaru plant on Okinawa – was this year decommissioned as uneconomical.

These criticisms are not intended to detract from the capabilities of battery storage technologies and their future roles. Storage should simply be respected instead of over-promised.

And why not allow nuclear output to charge these batteries in any of the modelling? The parallel analysis from Parsons Brinckerhoff also made reference to storage, and on page 19 observed:

…it should be realised that storage cost vs. benefit may well be more favourable for storage in a nuclear generation based systems than a renewable based system…

Without investigating the specific characteristics of South Australia, it is probable that the demand variability is more predictable than the supply variability. Since a nuclear-based system requires storage only to address demand variability, it is likely that the storage requirements to supplement a nuclear-based system and minimise the utilisation of fossil fuel-based assets is less than in a system that is highly renewable dependent.

The fundamental problems with the DGA report’s assumptions render it of limited usefulness, yet its ultimate shortcoming lies not in what it tried to achieve, but rather in what it intentionally didn’t. The modelled net present value of building and operating nuclear power stations was established as negative – unprofitable – when various market discount rates were assumed and applied to their costs. This isn’t surprising – reactors are up-front capital heavy, accruing expensive interest on associated loans, which nobody denies. When a lower social discount rate was applied (under direction from the royal commision) these projects abruptly flipped to profitable in all models (page 88). This lower rate is typical of government loan guarantees, public-private partnerships and straight-out public ownerships, which the authors surmise may be relevant if nuclear plants “were believed” to represent benefits for climate change action and the like which markets may not properly value.

There is no belief required here: it is simple scientific knowledge that nuclear energy is climate friendly. This fact has even been specifically supported in energy sector legislation in New York and Illinois this year. Unfortunately, the authors did not pursue the ramifications of finance-supported profitable nuclear capacity in their models and were content to let their chosen conclusions stand.

Yet, clearly this result should be the basis for further careful analysis of the economics of large modern reactors and small modular reactors in Australia, assuming that the recognition of societal benefits start promptly with the amendment of unjustified federal and state prohibitions. The current top-level review of Australia’s electricity sector can’t be excused from acknowledging the potential of using our uranium, not just exporting it, and where ultra-low emissions energy sources are to receive government support, this can be extended to nuclear with precisely the same justification. Indeed, on-going collaborative research by US National Lab experts in energy supply integration is revealing the benefits of supporting renewable and nuclear energy on the same grid.


With the urgency that serious climate action and electricity sector reform deserves, evidence-led inclusive analysis should begin as soon as possible to enable Australia to imagine, transition to and enjoy a clean, modern energy supply.


Note 1: This critique is also not intended to detract from the commendable work of the Nuclear Fuel Cycle Royal Commission, which can be examined here.
Note 2: Quotes and table reproductions from the DGA Consulting Carrisway report itself have been avoided due to the disclaimer at the foot of page 2.

One thought on “Cooking the Comparisons

  1. All the stationary batteries in Australia are not as useful, durable and cheap as a 50 MW gas turbine. As a capital budgeting problem we have to accept that wind and solar is quicker and cheaper to build than nuclear so some future NP will have to load follow. NuScale say they can do this in three different ways. We’ll still need say 50% baseload.

    Europe is apparently reviewing ‘must take’ priority for wind and solar. SA could get a 700 MW AFCR if it could run it at high capacity. High gas prices, coal closures and changes to subsidies could mean things change quickly. We could order an AFCR asap while waiting for SMRs etc to come on the market.

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