Comparing Like for Like

Since you’re reading this blog, you’ve almost certainly encountered this claim:

We don’t need nuclear because we can use renewables.

For renewable sources like geothermal and hydroelectric this may apply, since they can provide guaranteed generation around the clock. But the former has been abandoned in Australia and both can meet only a small portion of our future requirement for climate-friendly electricity.

But in truth the claim invariably refers to solar and wind, not all renewables. For a scalable technology like solar power to hypothetically meet such a demand profile, storage is implicitly included, or at least invoked upon inquiry. David Green of Lyon Solar described it well:

If we really want to address the penetration of large-scale renewables – and not just be able to satisfy the market you can connect large-scale batteries onto the grid – you need to be able to demonstrate that power generated from renewables can be dispatched with power from the batteries like base-load power, so it’s not creating problems.

However, the size of Lyon’s projects instead indicate a peak demand role in the power market. The megawatt hour (MWh) capacity of their batteries are too limited to supply constant overnight power (not to mention the unlikely economics of supplying at low overnight prices). So the question still remains, what would that look like, and how would it compare to the modern nuclear energy technology some believe it supercedes?

Simplified capital costs over time

In this thought experiment, we’ll use

By multiplying the number of 50 MW class solar plants to ensure that excess generation above this number equals overnight requirements, an idealised “solar+storage plant” can be modelled. Slightly more than 3 Broken Hill-sized plants would be needed but we’ll assume three for simplicity. Similarly, operational costs are excluded for both technologies.

Thus, we can compare assumed overnight capital costs for a NuScale plant, 60 year design life, and twelve solar+storage plants which would hypothetically match its nameplate capacity. As mentioned in the Finkel Review, the lifespan of lithium ion technology is 10 years so the cost of regular replacement has been factored in, in addition to renewal of the solar panels after 30 years (assumed to be half today’s cost).

When the capabilities of the two technologies are hypothetically levelised in this simplified way, it appears that the specific argument on cost is reversed.

Estimated required land area

The area of Broken Hill solar plant is 140 hectares. Thirty-six such plants will need about 5,000 hectares, only slightly smaller than the area of Sydney Harbour. However they don’t all need to be co-sited.

NuScale’s plant, which is now under formal design and licencing review by the US Nuclear Regulatory Agency, will cover a little over 36 hectares, including its maximum required emergency planning boundary. It can essentially be situated anywhere that would be suitable for an industrial facility, as water is not necessary for operational cooling. Notably, other options may well be available for the 2030 timeframe.

Material requirements levelised by generated energy

The US Department of Energy 2015 Quaternary Technology Review estimated various levelised material requirements for major electricity sources. Additionally, silver and uranium requirements can be authoritatively sourced. Charting these estimates illustrates the difference in amounts of materials needed by solar and nuclear, for the same amount of electricity produced.

This doesn’t include the materials like lithium, graphite and cobalt needed for the batteries, which aren’t a power source. It is assumed that materials needed for iPWR (intergrated pressurised water reactor) type SMRs are sufficiently similar to conventional PWRs.

This thought experiment attempts to match solar energy capability to that of nuclear. It hardly needs to be said that the reverse is a much less valuable exercise. Cyling a collection of SMRs daily between 0% and 100% output (with considerably less in poor weather) makes little sense in many ways, not least of which is the consequence of diminshed emissions abatement in a system still overwhelmingly supplied by coal and gas combustion. The whole benefit of including nuclear energy sources is they represent a drop-in replacement for dispatchable fossil fuel fired generators.

There are also commercial scale examples of battery storage paired with wind farms, such as the facility in Rokkasho, Japan. The particular battery chemistry used – sodium sulphur – was recently evaluated in California with sobering results.

We won’t compare the potential emissions savings since authoritative research puts solar and nuclear both at desirably low factors. However, the extra material intensity of batteries may contribute dramatically to lifecycle emissions, depending largely on their country of manufacture.

Solar plants and battery modules can be installed rapidly. In contrast, a certain first time regulatory cost and lead-time for that nuclear plant is unavoidable. Yet it isn’t necessary to overstate this hurdle. In its submission to the South Autralian Nuclear Fuel Cycle Royal Commission, Engineers Australia observed that ANSTO’s OPAL research reactor is of similar size but greater complexity than an SMR unit, and concluded:

The OPAL development at Lucas Heights provides an excellent management example for an SMR nuclear power station in South Australia. Extensive international guidance is available from the IAEA to assist in establishing a nuclear power program…

Australia already has a competent and very well managed regulatory regime with staff with wide international experience. Many of the ARPANSA staff have extensive experience in operating nuclear power plants both civil and military. There is no fundamental reason why the ARPANS Act 1998 cannot be amended to include the regulation of nuclear power in Australia.

The results illustrated here should not be taken as any reason not to build solar, especially paired with storage so as to shift generation to meet high demand, like Lyon Solar’s projects. The importance of this was underscored in the Finkel Review.

However, excluding nuclear energy, with its specific supply profile that can’t realitically be emulated by a variable source like solar, is probably unjustifiable on grounds of cost, land use, material intensity or regulatory challenges. This isn’t intended to downplay the regulatory and public education headwinds the technology faces, but rather to emphasise how important it is – considering the results here-in – to face them now and seriously begin the process. As the Engineers Australia submission noted:

The utilisation of a mix of all low emissions electricity generation technologies will be essential to achieve long-term greenhouse gas emissions targets.

What can be more serious than achieving targets that are aggressive as possible with everything available?