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How fast to 100% renewable electricity?

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Science tells us that, to avoid devastating climate change, we must rapidly cut greenhouse gas emissions to zero. How fast is possible?

This article focuses on the transition of the electricity industry to 100% renewable electricity together with energy efficiency, for the following reasons:

  1. energy generation is the major contributor to emissions;
  2. energy efficiency together with renewable energy form the cheapest, safest and cleanest combination of energy technologies; and
  3. a renewable energy future is likely to be based mostly on renewable electricity, because electricity is the least difficult form of energy to transition.

So far two extreme viewpoints have characterised the debate. On one hand, the ground-breaking Zero Carbon Stationary Energy Plan set a decadal transition as its aspirational target.

However, the argument that this is possible appears to be based on two general points – Australia’s huge renewable energy and raw material resources, which no-one would deny, and the belief that Australia’s manufacturing industry has the capacity.

While the report was strong and detailed on technological hardware, there was no analysis of the time needed to train the workforce, which is already overstretched by the growth of renewable energy.

It would take at least a decade to train just the first cohort of engineers and give them essential experience. Amateurs cannot design a manufacturing process or connect a wind or solar form to the grid.

Furthermore, the report didn’t address the challenge of rebuilding our declining manufacturing industry, or the long time it takes to build transmission lines, or the impact on energy prices of a rapid transition. So a decadal transition is unproven and unlikely.

At the other extreme, Vaclav Smil, an expert on historical energy transitions, argues in his book that ‘the process of restructuring the modern high-energy industrial and postindustrial civilization on the basis of nonfossil, that is, overwhelmingly renewable, energy flows will be much more challenging that [sic] was replacing wood by coal and then coal by hydrocarbons.’

To question Smil’s conclusions it’s sufficient to refute the assumptions underlying his key arguments.

A more extensive critique, in Section 6 of our recent peer-reviewed paper ‘The feasibility of 100% renewable electricity’, is available free upon request from

One of Smil’s key arguments is that beliefs in the possibility of a rapid transition are inadequate because they are based on transitioning electricity alone.

Smil appears to be unaware that most scenarios for 100% renewable energy involve transitioning almost all transport and non-electrical heat to renewable electricity.

The main exceptions are long-distance rural road and air transport, which will need renewable fuels.

Smil seems to be under the incorrect impression that we must focus on changing the fossil fuel primary energy inputs – coal, oil and gas – to renewable energy, presumably because the traditional energy flow diagram (see figure) starts with primary energy on the left, then flows through transformation processes (e.g. combustion in a power station) in the middle of the diagram – to provide on the right-hand-side, after substantial energy losses, the end-use energy and hence the energy services we demand: a warm home in winter, hot showers and cold beer.

This puts the cart before the horse.

However, if we start by considering what energy services we really need, we can integrate energy efficiency and conservation with renewable electricity, thus reducing the demand for end-use energy, which will be used mostly as electricity.

Then, when we reduce electricity use by a certain amount, we substitute for approximately three times that amount of energy in primary fossil fuels used for electricity generation.

This is because of the low efficiency of conversion of fossil fuels into electricity, as illustrated. A strategy that moves from right to left is much easier than the opposite.

Smil also asserts that the successful transition of a few countries is irrelevant to a global transition. Presumably he thinks that the rapid ongoing transition of Denmark, with 44% of its electricity in 2017 coming from variable RElec (wind), and Germany with 26%, are special cases.

However, we can also consider the north German states of Schleswig-Holstein and Mecklenburg-Vorpommern (100% net, mostly wind), South Australia (45%, wind + solar PV), Scotland (44% of consumption and over 60% of generation, mostly wind) and several states of the USA (each with 25-30%).

These successful examples are relevant as the pathfinders for other regions, demonstrating how reliability, security, affordability and environmental sustainability can be achieved with high and increasing contributions from variable renewable electricity.

They also continue to drive down the costs of renewable technologies for the rest of the world, which then experiences an easier transition than the pathfinders. Germany’s success in driving the market for solar PV, and so bringing down its costs, brought China into manufacturing PV, resulting in further reductions in costs.

Thus the successful examples are relevant both as symbols and in practice.

To achieve 100% renewable electricity, wind and solar power must be scaled up. Smil assumes incorrectly that this can only be done by increasing the size of wind turbines and their efficiency of conversion to impossible levels.

This overlooks the fact that wind and solar technologies (and batteries) are mass-produced in factories and so the principal increase in capacity and reduction in cost comes from rapidly producing more wind turbines and solar modules to meet the demand of an expanding market, and from improving supply chains.

Bigger, more efficient wind turbines and solar modules play a role in the scale-up, but it’s a minor one.

Because Smil’s assumptions are questionable to say the least, his argument that the transition to renewable electricity will take longer than historical energy transitions, is poorly based.

On the other hand, the facts that wind turbines, solar PV, CST, batteries and energy efficiency technologies can be mass produced rapidly and are less expensive per unit of electricity generated or saved than new fossil fueled and nuclear power stations, gives confidence that a rapid transition is technically and economically possible.

A future article will propose a transition scenario that’s much faster than Smil’s, but doesn’t assume the unrealistic decade.

Dr Mark Diesendorf is Education Program Leader (part-time)  at the Cooperative Research Centre for Low Carbon Living at UNSW.

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