An engineer's view on nuclear power

veteran engineers tend to agree that electricity systems run on 80 or 100 per cent renewable energy would be very expensive, insecure and heavily weather-dependent. a net-zero goal requires all options, including nuclear energy. by Geoff Bongers and Stephen Wilson.

First published in the Sydney Morning Herald

Australia’s current energy policies and plans are a recipe for triple failure: rising costs, falling reliability and growing environmental footprints. Wind and solar power plus battery and pumped-hydro storage have roles in a zero-emissions power system, but they cannot do it alone. A net-zero goal requires all options, including carbon capture and storage and nuclear energy. Many of our fellow engineers agree. If only they weren’t too afraid to say so.

The Australian government policy is for 82 per cent renewable electricity generation by 2030, or about 70 per cent if we exclude the historical hydro energy assets. The Australian Energy Market Operator (AEMO) has published a report on a 100 per cent renewable electricity system.

Could Australia run its electricity systems on 80 or 100 per cent renewable energy? No, and it would be foolish to try. Proponents of this unproven alternative system should bear the burden of proof. Since a negative cannot be proven, we offer a non-technical explanation and summarise the weight of evidence for our view.

Such a system would be very expensive, insecure and heavily weather-dependent. It would have vast land footprints and dangerously low energy diversity. And it would be profoundly inequitable. We find that we are far from alone in these judgments.

Veteran engineers generally tend to share our view. Worryingly, many others are afraid to say so, perhaps for fear of being unfashionable, missing out on a grant, offending a client, being trolled on LinkedIn, overlooked for promotion, or dismissed from a job.

But aren’t wind and solar the cheapest form of energy? Isn’t nuclear high cost? Not when we consider value: with zero emissions, nuclear capacity in a system underpins always-available power at a predictable, affordable price where it counts: at the wall socket. This finding transcends the various real-world uncertainties for all technologies and projects.

Contrasting relevant examples are instructive. Germany’s failing Energiewende, or “energy turnaround”, is a cautionary case. Ontario’s well-managed nuclear-for-coal “fuel switch” has been a positive experience.

Every net zero emissions plan needs some carbon capture and sequestration; like it or not, CCS provides the “net” in net zero. If Australia’s current nuclear energy bans and net zero pledges both remain, much larger and more extensive CCS will be demanded. Denying the technology to abate emissions from coal or gas is a contradictory policy.

Professional engineering judgment is inescapable to plan large-scale power systems because they are too complex to be represented with full fidelity by any one computer model. Model results are never “the answer” but must always be the beginning of the discussion. Robust models align with experience and observation, engineering science and principles.

Electrification is the greatest engineering achievement of the 20th century and an indispensable part of our civilisational support structure. A century of experience shows which kind of power systems work reliably at affordable, internationally competitive prices. Such systems are built on a foundation of high-availability plants that can generate on demand, require substantial up-front investment, have low operating costs, and long service lives that can be extended via refurbishment.

Technology meeting that description includes large dam hydropower, coal-fired power and nuclear reactors, one or more of which form the cornerstone of most major power systems. Eastern Australia is no exception, with a thermal-hydropower system underpinned by coal. A large role for gas-fired power is found where pipeline infrastructure is strong, or alternatives limited.

Hydropower and nuclear have low or no operating emissions. Standard coal plants have the highest emissions, while gas-fired power is in between. By investing additional capital in CCS and accepting higher operating costs, carbon dioxide emissions from coal and gas plants can largely be removed. These and other generation technologies are potentially complementary, not merely competitive.

But isn’t Australia well advanced in a transition to decentralised rooftop power? Not really. Solar panels on rooftops contribute nothing for most hours, including the evening peak. The official Integrated System Plan published by AEMO is about a new kind of more remote centralised generation based on doubling or more the high-voltage transmission system.

Wind and solar power can and do play an important supplemental role in many systems, including in Australia. Partially displacing coal-fired generation in markets, such as our National Electricity Market, does not mean they can adequately replace always-available power. We have each worked on various, separate NEM studies. Wind and solar power appear in all the least-cost system results we have seen, but not as the majority share. This finding applies across a wide range of assumptions about technology and fuel costs and emission constraints.

Claims that adding “energy storage” will “unlock” unlimited “free” energy from the wind and the sun are sadly misleading. Excessive hopes for a hydrogen utopia are dangerous. There are no magic bullets. We need all options and a well-balanced mix.

Power systems must balance generation and load – supply and demand to economists – continuously in real time with millisecond precision, not simply on average over a year, day or hour. Failing this technical requirement can lead to full system collapse within a minute.

The lowest total system cost is what matters when planning our future electricity system, not the levelised cost of energy (LCOE) for individual technologies. Systems thinking is required. The US National Renewable Energy Laboratory recognised this back in 1995. Despite its many shortcomings, even the GenCost report from CSIRO recognises that LCOE “is not a substitute for detailed project cashflow analysis or electricity system modelling”.

What should be expected if Australia rigidly pursues renewables-only policies and plans? Total system costs and electricity bills will continue to rise erratically. Alternatively, reliability will fall as load shedding and blackouts increase. Large areas of wild and rural land will be compromised. There is much at stake in this debate.

It is time to remove bans and create real options.

Geoff Bongers and Stephen Wilson are adjunct professors at the University of Queensland, in the School of Chemical Engineering and the School of Mechanical and Mining Engineering, respectively. Bongers is co-author of the report “Keeping the Lights on in a Decarbonised NEM”. Wilson led the study on “What would be required for nuclear energy plants to be operating in Australia from the 2030s”.