Net Zero: What Would Be Needed

For goodness’ sake, consider what a 2050 Net Zero target would mean.

6 min readSep 25, 2020

In the absence of holistic energy/climate policy, Australia’s federal government has launched a technology investment roadmap. Despite “aiming to steer the nation’s transition to reducing carbon emissions”, one thing it doesn’t do is commit to net zero emissions by 2050 (such as promised by the opposition).

I was immediately reminded of a visualisation employed by Professor Roger Pielke Jr to put what would be needed into some sort of context.

We’re going to do something similar for Australia. First, we need to clearly state our assumptions:

Emissions and energy data is from Australia’s emissions projections 2019 and Australian Energy Update 2019
Steady, linear trend for the sake of simplicity
PV and wind do most of the heavy lifting, or at least that seems to be what we’re encouraged to expect, and therefore will be used to illustrate scales. Distributed PV is not considered
Lifespans are ignored
Energy conversions are granted the most optimistic values
Energy amounts are at the annual timescale. Energy storage works perfectly and is ignored. Transmission is ignored (thanks Kevin S Krause)
1 billion kilowatt hours (kWh) = 3.6 petajoules (PJ, a trillion megajoules)
Overall energy consumption doesn’t change (except buildings)
No international offsets
Equity issues on impacted communities and segments of the economy are neglected

This chart is the official current emissions projection. We’re going to take the numbers at 2020 and project out to 2050. Where the coloured components are related to energy or fuel usage, we can power them with solar and wind, either directly (electricity, transport, industrial processes) or via green hydrogen (direct combustion). Others (waste, agriculture and fugitives) must be offset by Land Use Change.

Electricity

Australia’s emissions projections 2019 put national electricity generation at just over 242 billion kWh in 2020. 73% of this is still fossil fuels. We’ll replace it all with the equivalent solar or wind, specifically multiples of defined plants. For solar we’ll use one of Queensland’s newest installations, the 100 MW(ac) Clare Solar Farm, which produces 0.26 billion kWh per year. For wind, Queensland’s largest wind farm at Coopers Gap makes 1.51 billion kWh each year from 453 megawatts. That 73% equates to 176.6 billion kWh now served by 679 additional solar farms or 117 additional wind farms.

Transport

The primary energy consumed by road transport was 1,239.4 PJ for FY2018 according to Australian Energy Update 2019. For our purpose we’ll assume the same for 2020. Then, assuming the efficiency of conventional engines as 30%, and the efficiency of battery electric vehicles as much higher at 77%, we can reduce this consumption to 428 PJ, without traveling less, by trading in all vehicles over the next three decades. Since 428 PJ ≈ 134 billion kWh, we need another 516 solar farms or 89 wind farms.

(We’ve actually neglected air travel energy consumption, which is only a quarter of the size of road transport. In the past this has been justified in decarbonisation plans through enhancing national rail capacity, which itself consumes dramatically less energy.)

Industrial processes

Industrial processes are dominated by mineral, metal and chemical industries. There’s no annual PJ consumption figure for the mineral industry component in Australian Energy Update 2019, so we’ll infer it from the million tonnes CO₂-equivalent value, MtCO₂-e (Australia’s emissions projections 2019 Figure 17) which is roughly similar to that of the chemical industry. The total is 863.1 PJ, about 240 billion kWh after achieving complete electrification, which is admittedly rough since this is covering a multitude of industrial processes. But it would need to be supplied by another 922 solar farms or another 159 wind farms.

The remaining category under industrial processes is “Product uses as substitutes for ozone depleting substances” — we’re going to have to offset this like for agriculture etc.

Direct combustion

We’ll swap out today’s fossil fuels with green hydrogen in this component.

Again, the MtCO₂-e value for “energy” in Australia’s emissions projections 2019 Figure 9 must be used to infer a proportional PJ value, giving us a total of 2,883 PJ for energy + mining + manufacturing + agriculture. “Military” is miniscule and safely excluded. Low energy buildings are assumed to abolish the need for corresponding gas combustion by 2050.

55 kWh of electricity is required for electrolytic production of 1 kg of hydrogen, which holds 0.000000143 PJ, thus 20.16 billion kg of hydrogen are required, produced by about 1,108.8 billion kWh.

We’ll have to add a final 4,265 solar farms or 734 wind farms to supply this electrical energy each year.

Final tally

Under this simplified estimate of what would be needed in 2050, we need to add a total of about 1,660 billion kWh per year extra, generated from solar or wind, to Australia’s supply. The implied construction rate is equivalent to almost 213 Clare Solar Farms, or over 36 Coopers Gap Wind Farms, every year for three decades.

We might be feeling rather daunted at this point. This is about 7 times the scale of the 2020 estimated electricity generation in Australia’s emissions projections 2019, which itself is only a quarter renewable (including hydro). The scale, the build rate, how long we need to sustain it, the implications for associated enabling technology to make it work, and so on, are compounding challenges that make what would be needed to get to zero by 2050 frankly dismaying. It certainly doesn’t look absolutely achievable in a canter.

Maybe putting it in terms of all just one energy source or another seems at best simplistic, and at worst vexatious. But again, we already see pretty much this being proposed at far more influential blogs.

With the context we’ve now worked through, with the scale there in plain numbers, we can surely appreciate the potential value of swiftly welcoming additional ultra-low emission technologies into this effort within the next thirty years, and the sooner the better. With an appropriately broad mix, perhaps the magnitudes of individual energy sources can decrease to something that looks achievable.

Finally, the data provided in our chosen references don’t perfectly match up, so some approximation was unavoidable. This and other simplifications could have impacted the accuracy of what would be needed to hit this 2050 net zero ambition. Similarly, changes in growth forecasts for things like population and GDP will directly affect the real numbers. And in the case of hydrogen, the calculations assume it’s all used here — exports would naturally demand higher total energy production. We can gladly discuss refinements in the comments section below, and revise where appropriate. Comparison to other independent estimates of what would be needed is also encouraged.

Oscar Archer holds a PhD in chemistry and has been analysing energy issues for over 15 years, focusing on nuclear technology for six, with a background in manufacturing and QA. He helps out at Adelaide-based Bright New World as Senior Advisor (we want your support!)and writes for The Fourth Generation. Find him @OskaArcher on Twitter.