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100% Renewables? Mostly nonsense!

by Dave Elliott

So says a new study by a group of mostly pro-nuclear academics, who look critically at some of the many ‘100% renewables’ global or regional energy scenarios that have emerged in recent years. 24 were deemed to have forecast regional, national or global energy requirements in sufficient detail to be considered potentially credible but, on inspection, none were considered to have provided convincing evidence that basic feasibility criteria, in relation to energy supply reliability, grids and balancing, could be met.

The paper, by Heard, Brook, Wigley and Bradshaw, says that 8 of the scenarios looked at provided no form of system simulation, while 12 relied on what were considered to be unrealistic forecasts of energy demand. It adds: ‘Only four of the studies articulated the necessary transmission requirements for the system to operate, and only two scenarios, from the same authors, partially addressed how ancillary services might be maintained in modified electricity-supply systems. No studies addressed the distribution-level infrastructure that would be required to accommodate increased embedded generation’.

In addition to feasibility issues, the study concludes that ‘heavy reliance on exploitation of hydroelectricity and biomass raises concerns regarding environmental sustainability and social justice’. They also complain about the ‘explicit exclusion of nuclear power and fossil fuels with carbon capture and storage’  in many of the scenarios, and saythe early exclusion of other forms of technology from plans to decarbonize the global electricity supply is unsupportable, and arguably reckless’.                         

Overall a 100% renewable electricity supply would, at the very least, demand a reinvention of the entire electricity supply-and-demand system to enable renewable supplies to approach the reliability of current systems. This would move humanity away from known, understood and operationally successful systems into uncertain futures with many dependencies for success and unanswered challenges in basic feasibility’.

Pretty damning then. However, it seems both very broad-brush stroked and also selective: some scenarios the paper looked at explicitly avoid or limit biomass (e.g. Jacobson et al), some it doesn’t look at (e.g. ICL/UKERC’s various system integration studies) go into great detail on grid balancing and development. To be fair , two fully developed grid balancing studies are cited, but mainly it seems to suggest the rest do not live up to them:

It’s certainly hard to win on the feasibility criteria the paper set out. Some may do well on some measures but fail on others. It says ‘The work of Jacobson et al. is an example of this because it depends strongly on extraordinary assumptions relating to electrification, energy storage and flexibility in demand. Although this work scored 3 for a fine-grained timescale simulation, the results of such a simulation are likely to be meaningless because the underlying assumptions are unrealistic.’

No doubt the dissed authors will come back with their own reactions on specifics, but the overall thrust seems to be based on the belief that there is too much optimism about the role of renewables and storage, coupled with resentment that there is no backing for nuclear!

The rapid expansion of renewables globally clearly worries nuclear enthusiasts, as do projections for even more growth. They often fall back on the problems of dealing with their variability. However, that has not exactly been ignored by the renewables enthusiasts, who point to a wide range of ways of dealing with the problem. Some are already in use and, for short term balancing, batteries are gaining ground rapidly. It may be true that long-term storage, to deal with the occasional long-term lulls in renewables, is only just taking off seriously. Storage of surplus output from wind and PV, converted to hydrogen, and then maybe methane, looks like a winner, but it will take time to deploy widely. However, so would the new nuclear options – and, given varying demand, they too will at times have surpluses to deal with, so to some extent it’s really just a matter of which supply option you like and their relative costs. The supply variations would of course be different with renewables, the short term variations being the most obvious, but smart grid demand management could help deal with these, and reduce demand peaks. The longer term lulls are also seen as unique to renewables, although nuclear plants can also go off-line suddenly and for some while. Given proper flexible balancing and storage, and top-ups from supergrid imports and exports, it’s not clear whether a system based on renewables would be any less robust than one based on nuclear.

That’s exactly the sort of thing now being discussed in papers. In which case it’s not very helpful for Heard et al to just dispatch any alternatives as hopeless. It’s the same for demand reduction. Smart grid DSM may avoid waste and reduce overall demand. Shifting to green heat supply may also help. It’s true that this is all new, but so too are molten salt thorium fuelled reactors and the like. Take your pick…and do the sums.

That after all is what Energy Matters did, to its credit, in its recent comparisons of near 100% renewables and nuclear 2050 scenarios, with full attention to grid balancing. See my earlier post, as well as and Energy Matters found that both the high nuclear and high renewables options were viable, assuming some quite radical technical changes and developments in both cases. Either way that seems unavoidable. Maybe Heard et al just don’t relish change? Or just want nuclear – which they evidently see as the main answer to climate change. Maybe they should now run nuclear and CCS through their criteria?

Although, with the mainstream debate (e.g. between the IEA and IRENA) now being whether renewables can supply 70% or 82% globally by 2050 (see my last post), maybe that is not very relevant. Much more relevant is how to speed things up. A report from Carbon Action Tracker says that bold, fast track, approaches by early adopters reap benefits, with lead countries stimulating wider take-up as the technologies mature and markets spread: ‘A major determinant of whether a new technology achieves a competitive market position is the presence of bold action by a few countries with long-term targets that send a market signal, supporting policy packages, and efforts in innovation, research, and development that continually improve and reduce the cost of the technology. With these three elements in place, the technology can spread to other regions and support global decarbonization’. 

Certainly as prices for renewables continue to fall dramatically, wider diffusion seems likely, with some looking to competitive auction processes to speed it up: see my next post. That does seem to be working in Germany with offshore wind: 1.5GW of new contracts were recently agreed for start-ups in 2025, with very low average auction prices, some at, in effect, zero subsidy.

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One comment to 100% Renewables? Mostly nonsense!

  1. Tim

    Technically, there are no renewable resources. Even the sun will burn out in a few billion years. But because it will take billions of years, it is called renewables. There is enough uranium in seawater to last a billion years.

    If the number of years that a source of energy will last has more than six zeros on the end, it might as well be labeled renewabe.

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