Quarterly Essay 81: Getting to Zero - Australia’s Energy Transition
Table of contents.
This QE gently and clearly explains the current scientific consensus on global warming and that it is an urgent crisis which Australia needs to tackle. It then lays out specific ways using today's tech (solar, wind, storage and gas) by which the transition can occur.
- Global warming is happening, and the science is incontrovertible.
- Lots of charts from CSIRO's State of the Climate - video summary
- methane clathrate (concentrated methane gas trapped in a crystal structure of water) could be released as permafrost warms
- methane is 28 times more potent than CO2 and the energy equivalent is more than the known reserves of oil, coal and shale combined.
- A slow response: So far, in most countries, energy from fossil fuels has failed by approx 5-6% e.g Germany from 84 to 78, USA from 86 to 80, Aus 96 to 91.
- Approx 82% of Australia's emissions come from burning fossil fuels for electricity, stationary energy and transport. These can be replaced with electric sources, the remaining 18% is more difficult.
Tech we can't use:
- Nuclear is zero carbon but costly and politically unviable. SMR reactors still far away, and fusion a dream.
- Hydroelectric dams are great but politically difficult, Australia hasn't had any large ones in over 50 years
- biomass isn't practical at scale, currently close to 1% of total energy production, but scaling it puts pressure on agriculture and native forests
- waste to electricity - can contribute only a small portion
- geothermal energy - short supply in most of the world
- wave power and tidal energy - decades of effort has led to 0.005% of global electricity production in 2018.
- Exotics like solar panels in space beaming energy are still science fiction
Solar and Wind
This leaves us with solar and wind, which are very different from traditional generators in that fossil fuel generators are synchronous, while solar and wind are non-synchronous. Electric grids were designed for synchronous generators.
- Solar panels output a constant current which inverters turn into AC.
- Wind turbines output AC but the frequency varies with the wind, so they need mechanical controllers or inverters and sometime synchronous condensers
- solar has no rotational inertia, wind has very little useful inertia. So you need batteries or capacitor to get to the required inertia and frequency output.
- 99% of new capacity in Australia has been solar and wind, globally about 50%.
- In 2019 Australia had the highest per cap solar in the world at 644 watts/person.
- RBA estimates that solar with 6 hr pumped hydro storage would cost $100 MW/hr vs a new black coal cost of $150 MW/hr.
- Coal can generate at 90% capacity, solar ranges from 10-25%, wind 30-50%.
- AEMO estimates a 13GW decline in coal capacity requires 34GW in solar and win.
- Solar panels available commercially in 2021 operate at 22%, theoretical limit is about 33%.
- Wind turbines extract 35-45% of the wind energy passing through the swept rotor area, rising to 50% in strong winds. The theoretical max is 59%.
- Have to consider the efficiency of how the energy is used - there is a lot of improvements possible.
- Rooftop solar could theoretically supply 20-50% of daytime demand, but this requires sophisticated management of all the domestic solar rooftops and batteries.
- Australia is the world's largest exporter of lithium, with 1/3 the reserves of Chile. (51K tons in 2018)
- for grid scale batteries, it's the power - megawatts and the megawatt hours which tell you how long it can operate for at full power.
- round trip efficiency is 85-95%.
- pump water up a gravity potential, release water to convert back to electricity.
- round trip efficiency is 70-80%.
- 94% of grid storage globally is pumped hydro
- ANU estimates that Aus has 22K potential sites for pumped hydro
- Hydrogen is the first element on the periodic table and makes up 94% of all atoms in the universe. On earth it is bound to other elements, mostly water.
- Electrolysis: separate water into hydrogen and oxygen by passing an electric current through water with a bit of salt.
- McKinsey projects clean hydrogen going from USD6 to USD2.6 in 2030.
- round trip efficiency is only 35% so only viable when electricity is essentially free, e.g rooftop solar during the day
- can store underground in natural salt caverns for long term storage
- exists, good for firming, use will lower over time as renewables and storage ramp up
- nat gas allows the use of increasing wind and solar now and closing down coal plants faster than waiting for future storage to be built. Alan argues that some gas is necessary, don't let the perfect be the enemy of the good
- 31% lower total carbon emissions than coal
- can ue a blend of clean hydrogen and natural gas
- manufacturing, energy, building, mining, agriculture, forestry, fishing sectors are the next biggest emitters after electcity.
- all thse sectors have clear ways to decarbonize, e.g using clean electricity for heat vs burning fossil fuels, replacing
- Aus: 18% of all emissions, in the US its 28%
- Battery Electric Vehicles will win
- hydrogen isn't as energy efficient as batteries - for the same initial electricity an electric car would drive 2.5x further than a hydrogen powered car. But hydrogen is easy to store in bulk so is suitable for heavy transport.
- Australia is well positioned to export green energy, in the form of hydrogen or ammonia, or as embodied in products like steel, aluminum and fertilizers produced using renewable energy,
Renewables are here and change can happen very quickly. Australia risks being left behind if it isn't ambitious.
Alan ends on the hopeful note that Australia is well positioned to both transition itself to renewables and export clean energy.