A new Danish study comparing nuclear and renewable energy systems (RES) concludes that, although nuclear systems require less flexibility capacity than renewable-only systems, a renewable energy system is cheaper than a nuclear based system, even with full backup: it says ‘lower flexibility costs do not offset the high investment costs in nuclear energy’.
It’s based on a zero-carbon 2045 smart energy scenario for Denmark, although it says its conclusions are valid elsewhere given suitable adjustments for local conditions. ‘The high investment costs in nuclear power alongside cost for fuel and operation and maintenance more than tip the scale in favour of the Only Renewables scenario. The costs of investing in and operating the nuclear power plants are simply too high compared to Only Renewables scenario, even though more investment must be put into flexibility measures in the latter’.
In the Danish case, it says that ‘the scenario with high nuclear implementation is 1.2 billion EUR more expensive annually compared to a scenario only based on renewables, with all systems completely balancing supply and demand across all energy sectors in every hour.’ It goes on ‘to achieve a more cost-efficient system based predominantly on nuclear power- the investment costs would have to drop to 1.55 MEU/MW. This is significantly below any current or future cost projection for nuclear power. Such a high cost-margin indicates that a combination of low-cost RES and sector coupling presents a cost-effective energy transition making it very hard for nuclear power to deliver a competitive alternative’.
It's an interesting exercise in systems modelling. In the ‘smart energy’ concept used in the study ‘most of the required flexibility can be established through demand and supply flexibility and low-cost storage outside the electricity system, such as thermal storage, hydrogen storage and gas/fuel storages’, with sector coupling allowing for ‘increased energy efficiency using, for instance, excess heat from industrial processes to provide space heating for dwellings through district heating systems.’
In its 100% renewables scenario, ‘flexibility kicks in to utilize or store excess [power] as heat or hydrogen in hours with abundant wind and solar production. The storages then assist the system by delivering the heat and hydrogen needed in hours with less wind and solar production. In the remaining gaps, in hours with low wind and solar resources, combined heat and power stations and peak load power plants running on biogas covers the load in combination with electricity exchange’.
In its nuclear based scenario, the nuclear plants are run continually with hydrogen produced flexibly and ‘used for hard-to-abate sectors such as transport and industry’. While this means a lower flexibility requirement than for the renewables based system, as indicated above, they found that this lower flexibility requirement does not offset the costs of nuclear power. You can get to net zero without it.
Interestingly, in the UK context, Lord Turner, Chair of the UK Energy Transitions Commission, has also said that costly new nuclear plants may not be needed for net zero, since there are cheaper, low-carbon alternatives that could back up intermittent renewables. Hydrogen fuel or gas power plants fitted with CCS could fill the gap when wind or solar was not enough to keep the lights on. ‘I don’t think it is the case that you need new nuclear to balance the system. The systems of the future don’t absolutely need a base load.’ The power system ‘can work on a combination of intermittent variable renewables, wind & solar plus some hydro. I think the challenge for new nuclear is that it is just expensive. Bluntly, new nuclear can play very little role in a 2030 target.’ Well maybe that’s why there seems to have been some second thoughts about the new EPR reactor proposed for Sizewell in the UK, with the final investment decision for the Sizewell C nuclear plant evidently facing delays. Initially, EDF, the project’s developer, aimed to secure funding by the end of this year, but the timeline may now extend into 2025.
The prospect for nuclear do seem a bit uncertain, with the case for it these day relying in part on the claim that it can back up renewables and help avoid climate change. But that also seems to be uncertain, as is argued in a new comprehensive review of nuclear issues by academics from Germany and Finland, arguing that it has no role to play in responding to climate change. It says that it is ‘not a sustainable and affordable source of energy for the low-carbon energy transformation’ given its ‘cost-intensive nature, coupled with safety considerations’. And crucially it says that it is ‘characterized by very long construction times, and even longer developments of new technical generations, too far away and uncertain to contribute to climate change mitigation anytime soon’. In addition ‘from an energy system perspective, nuclear power is not compatible with a system based on renewables, but rather hinders its expansion. Last but not least, nuclear power is particularly unfavorable in a future with higher temperatures and weather extremes and more military threats’.
That sounds pretty damning, even leaving aside radioactive waste handing, and also weapons proliferation and terrorism-related issues, with, as Prof. Ramana discusses in his recent powerful overview book ‘Nuclear is not the solution’, in addition to its other problems, reliance on civil nuclear power making ‘catastrophic nuclear war more likely’. Even if, hopefully, we can avoid that, there are still concerns about nuclear blackmail. And all this just to generate expensive energy. Yes, going for renewables does mean we have invest in flexible balancing technology and energy storage, but that is cheaper overall and it also getting even cheaper, with many new options emerging. As Ramana says, to balance the variability of renewables, ‘we must invest in a mix of renewable energy technologies across various regions, and in battery and other storage technologies to store excess energy. In addition, we need to shape electricity demand to more closely match supply.’ In common with the German and Finnish researchers, he too sees that as the way ahead.
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