The short answer is, yes, we can have 100% renewable electricity supply by 2050, or by 2030, but it will cost. Depending on the assumptions the cost will be between $219 and $332 billion, a very large figure. Yet this would yield a wholesale price while more than double the current price or about the same as Treasury’s carbon price modelling projected under government policy for 2030.
It seems that the Greens asked for a report on the feasibility of 100% renewables as part of the deal struck in the Multi-Party Committee on Climate Change which was formed to produce the Clean Energy Future package. The report prepared by the Australian Energy Market Operator (AEMO) was commissioned by the Department of Climate Change and Energy Efficiency and is available here. Articles about the report include Laura Tingle at the AFR (now paywalled), Tristan Edis at Climate Spectator and Giles Parkinson at RenewEnergy.
From the outset we should note that the report covers only the National Electricity Market (NEM), that is, not WA and the NT. Also the report is a draft generated for stakeholder reaction.
The modelling undertaken presents results for four selected cases, two scenarios at two years, 2030 and 2050.
The first scenario is based on rapid technology transformation and moderate economic growth while the second scenario is based on moderate technology transformation and high economic growth.
The resulting energy mix in terms of energy generated is as follows:
Figure 1: Total energy generated
CST means concentrated solar.
It was assumed that there would be no nuclear and no gas or coal with carbon sequestration. Because of this total generation capacity would need to be 100 to 130% above maximum demand to provide reliability. This compares with 15 to 20% in conventional systems. For what happens in the ‘most challenging week’ see p44 ff in the main report. Scenario 2 relies more on wind as an established technology. Scenario 1 makes larger use of geothermal, which becomes a significant part of base-load supply.
Five storage systems were considered: batteries, biomass (as solid matter and as biogas), compressed air, hydro (including pumped hydro), and molten salt associated with CST. Batteries and compressed air were not found to be economic for large-scale storage. They settled on nine hours of molten salt storage for CST.
Rooftop solar was considered too expensive to provide purchased power for the grid. It was assumed, however, that rooftop solar and what they call ‘demand side participation’ (DSP – users altering the time and quantity of usage for economic reasons) would alter the usage patterns in two ways. Firstly the peak usage would change from summer to winter. Secondly the daily peak would move from early evening to midday. Some electrification of vehicles was assumed.
Figure 2: Winter supply and demand, Scenario 1, 2030:
From this you can clearly see how CST with molten salt storage is used to provide power at night, but the final peak load is provided by biogas which is expected to be quite expensive. Concerns were also expressed over where it might all come from. One would think that there may be an opening here for gas with carbon sequestration. Also I’m not sure what assumptions underlie the burning of wood.
Consideration was given to a geographical spread of facilities and the placement of solar utilities inland where the sun shines more. Actual weather records were used to calculate the variation in supply. So this is what the came up with.
Figure 3: Subset of selected technology locations
Each circle represents a centre of activity which would be spread over a wider area. New trnsmission facilities would be needed as shown below.
Figure 4: Transmission facilities
The cost of transmission lines was included, but the purchase of land required (between 2400 and 5000 square kilometres) was not. Nor did they include the cost of dealing with stranded assets.
An immediate criticism of the report made by the Greens and others was that the cost of ‘business as usual’, that is the continues use of fossil fuels if they were cheaper, was not considered. Parkinson makes this comment:
it should be kept in mind, most of Australia’s existing coal and gas fired generation needs to be replaced by 2045 – and as Bloomberg New Energy Finance have pointed out – the cheapest new build generation capacity is already wind, and will soon be joined by solar.
He also criticises the report for not considering energy efficiency gains, which most studies put at about a third of all energy.
No doubt there will be other criticisms, but in truth, whatever the cost, there is no choice if we want a safe climate that doesn’t put at risk civilisation as we know it.
Update: See also John Quiggin’s Decarbonising Australia.